When your rifle doesn't get the velocity the books say it should...

[Major Dave (retired)]

do you go beyond the max published load until you get the expected velocity?

Specifically, I am loading a 7 X 57 Mauser (in a strong, modern bolt action), with 140 grain Barnes TSX bullets, using IMR 4350 (a new powder for me).

Starting load (43.0 gr) produced a chronographed MV about 150 fps slower than the book says it should.

Same for 45 gr load, same for 46.0 gr load. Got only a little over 2,600 fps from the 46 grains.

I didn't have any heavier loads, so now I will go back to my loading bench and work up some. BUT, the loading manuals say that 47.0 grains is MAX load, and I know I will barely achieve 2,750 fps (at the most) with that. Not nearly what the case capacity should allow.

I have been getting 2,950 fps (chronographed) MV from a 139 gr Hornady Interlock behind 44.5 gr of IMR 4320. Could I just use IMR 4320 behind the Barnes TSX, and go happily along my way? Of course I would reduce the IMR 4320 load and work up to the 44.5 gr load, if I tried that powder with this bullet.

My rifle has an extremely long throat, and I seated the TRX bullets with minimum neck tension. With the Hornady Interlocks, I always use my Lee Factory Crimp die - but didn't do that with the Barnes TRX. Could that be the problem, at least partially?

[Brian Pfleuger]

What is the length of your barrel in relation to the test barrel(s)?

[jaguarxk120]

Many published velocities are from a 26 inch barrel or longer. Usually from a test fixture (universal reciever), thats one reason you can't get what they get. It's a good chance you have a 22 inch barrel, that alone will account for the drop of 150fps. Another reason is barrel bore dimentions your bore is not the same size as the test barrel, nor is the bore surface the same. All adds up to differences in velocities from rifle to rifle.

[Old Grump]

Even if you had a match barrel 26" long it won't be the same as their test barrel. Part of it is marketing hype. Advertising types who write copy don't look at the high and low velocities and they don't care about mean or average velocities. 7 of the 172 bullets fired left the barrel and passed the screens at 2750 and you are getting 2688. Closer to what they were getting than what the ad man wrote up. Only rifle maker who advertises actual un-exaggerated velocities that I know of is Weatherby.

Can you hit your target with your load, does your deer, squirrel, antelope, mountain goat get dead when you shoot it. Good enough. Pushing the envelope rarely is good for accuracy and the extra 125fps you might get won't make a hill of beans worth of difference in the field.

[flashhole]

Measure the ID of your barrel. Barrel length is important but only if you get optimum bullet obturation to build up pressure.

[SL1]

Major Dave,

First, please tell us whether the load data you are using was for the same bullet you are using, or for a different bullet of the same weight? For bullets as different as the TSX and the Interlock, you should not expect to have even the same max load, much less the same velocity.

IF you are using pressure-tested data for the same bullet that you have, there are still several factors that can make the velocity different. One is that, even if you were using their same test barrel on your rifle, the different lot of the same powder can give significantly higher or lower velocity by having a somewhat different burn-rate. That means that the pressure you are getting may also be different, and that the actual load that gives you the same velocity would be at a different pressure.

Another factor is that your chamber may be a different size, so your actual pressure may be different even with the same powder lot, and that would give you different pressure and velocity. Or, your jump to the rifling may be substantially different, and that would change your peak pressure and velocity.

People who consider the second and third factors above and neglect the first factor sometimes advocate using whatever charge it takes to reach the published velocity. That isn't necessarily going to get you to the same pressure, because of that first factor, so I don't consider it to be a good strategy. But, in a strong gun, you can probably safely shoot loads that are over SAAMI max by a little, and just wear-out the barrel faster.

In the situation with the 7mm Mauser, the SAAMI standard is significantly below the SAAMI standards for more modern cartridges that are chambered in the same gun. For instance, 51,000 psi compared to 65,000 psi for the .270 Winchester. Since those two cases have the same head diameter, it is safe to assume that a gun that can safely shoot .270 Winchesters can also safely shoot 7mm Mausers loaded to .270 Winchester pressures. Some loading manuals provide data at several different pressure levels for the different gun strengths that are available, while others say that is a bad practice because one of those hotter rounds may accidentally get into a gun that CANNOT shoot them safely.

So, I would say that you need to not only be using pressure-tested data for the Barnes bullet that you are using, you also need to know what pressure that max load was producing in the test gun and what pressures you particular gun is designed for. IF the data was at 50,000 psi and your gun is also chambered for cartridges that go to 65,000 psi, THEN you can go to somewhat higher charges. BUT, it is not safe to ASSUME either of those things, because they are not always true. AND, if you can safely go to higher charges in your gun, then there is still the question of how high. You do not have a pressure-tested max to avoid exceeding. That is where a program like QuickLOAD can help. If you can get it to match your results in your rifle with respect to velocity vs charge weight, and the pressures look reasonable, then it gives you SOME confidence that you can use it to extrapolate the data a little without getting too far off in pressure. But, remember factor #1 above.

You also asked about using IMR-4320. It might be a better powder because it is faster than IMR-4350, and QuickLOAD is saying the your max load of 47.0 grains of 4350 is already filling the case (assuming default QuickLOAD values for the Mauser). A smaller charge of 4320 would give higher pressure without filling the case. BUT, DO NOT USE THE DATA FOR THE INTERLOCK BULLET WITH THE TSX BULLET! QuickLOAD indicates that there is an 8% pressure increase when changing from the Hornady cup-and-core bullet to the solid-copper Barnes bullet with that load 4320 max load. Try to get some data for IMR-4320 with the Barnes bullet before deciding what to load with that powder.

SL1

[QBall45]

When your loads don't reach the published velocity in the manual... Don't worry about it. Its just a number.
I load for accuracy. I don't really care how fast the bullet is going.

[GeauxTide]

In my 40 years of handloading, only one load came within 20fps of the manual. Don't worry about it. Use the load that your rifle and you shoot best.

[Major Dave (retired)]

First, thanks for the input, and keep it coming.(all of you)

Barrel length - mine is 23 inches, and I think the test barrel is 24 inches.

Load data I am using - comes from Barnes Reloading Manual Number 4, specifically for the TSX bullet.

I already knew that all 7 X 57 load manuals are based on 46,000 CUP/51,000 PSI due to the prevalence of M93, M95, M96 military actions being weak, so I plan to "slightly" exceed manual maximums, because I know my rifle action is strong enough to take another 5,000 PSI, the same as a .270 Win, or even the .270 WSM. However, as you pointed out, SL1, "how much" to exceed the manual data is the real question. Your QuickLOAD info gives me something to think about along those lines - thanks.

QBall45 - I care about how fast the bullet is going, because the flatter the trajectory, the less holdover is needed when hunting. Any shot less than 200 yards - 2,750 fps MV is OK, but if a 300 yard or 400 yard living target presents itself, I would probably not take the shot with only 2,750 MV. I want to be able to take those shots, with a MV in the neighborhood of 2,950 fps, like I get with the Hornady Interlocks and IMR 4320 powder.

Then, you probably wonder why don't I just stick with the Interlocks?

Glad you asked that question. I want to hunt elk - the Interlocks don't hold together on big boned, big bodied game like the Barnes TSX does. For punching paper, with precision, only precision matters. Speed is irrelavent, as you mentioned. For different size game animals, terminal performance of the bullet when it impacts the animal is a high priority, as well as a flat trajectory that enables a good hit, more so than sub-MOA accuracy.

[SL1]

Major Dave,

If you want some help using QuickLOAD, I'll need some more info.

First, what is your COL for the TSX load? Also, is it the TSX or the TTSX (is there a plastic tip)? And, is there pressure data specified with the charge/velocity data for that bullet, or does the manual just say something like "all loads are below the industry standard maximum pressure of 46,000CUP"? Finally, it would really help if you could give me the water capacity of a few cases that have been fired in YOUR gun, along with the lengths of each case that you measure capacity in.

If you want to push the TSX bullet to 2950 fps, you are definitely going to be in the .270 Winchester pressure range with IMR-4320. There are some other powders that QuickLOAD says can save you about 5,000 psi. But, frankly, it is really going to depend on what lot you got of any of those powders. Some of the powders that are supposed to be identical, like H-4350 and AR-2209, show velocity differences like 132 fps and 6,000 psi in that calc., using the same charge weights. (That is what I meant in my first post about how different the results can be with different lots of the same named powder.)

SL1

[SL1]

Since hold-over is one of your concerns for long-range shots, another solution is to get a good laser range finder. Then, for long ranges, you can adjust sights or hold-over a certain number of hash-marks on your scope's reticle. That would save you from trying to push the bullet so fast to minimize drop. Of course, the bullet also needs the energy to do the job when it gets there, so you do need to push it some for long-range shots.

SL1

[Major Dave (retired)]

You asked:
1. What is the COL
2.980 to 2.989, average 2.985 inches.

2. Does the manual show pressure data for each load?
No. This statement is made:
"This load data was fired up to the SAAMI maximum average pressure (MAP) to 51,000 psi".

3. TSX, or TTSX (plastic tip?)
TSX Boatail - no plastic tip (part number 28444)

4. Water capacity and length of several cases fired in my gun.
I will have trouble with that, because both of my scales are balance beam, and have small bowl shaped receptacles for powder, i.e., it will be difficult to stand a water filled case upright in the powder receptacle. Maybe I can just fill a case with water, then dump the water out of the case into the powder receptacle.

All I can tell you right now is that the cases are Rem-Peters, while the load manual calls for Winchester.

Other manual data, FYI
trim length, 2.225 - I complied with that spec in my case prep.

Primer, Federal GM210M - does that mean "magnum", or "Match" Fed primers? Or Magnum and Match?
I used Win WLR, i.e., standard Win Large Rifle, and CCI #200 Large Rifle. The CCI's gave me from 4 to 9 fps greater velocities than the WLR's.

barrel length, 24", Krieger
My rifle - 23", DuBiel Arms Co. (Sherman, TX, from 1978 to 1992, IIRC)

Another FYI:

I went to www.reloadersnest.com and pulled up "Load 10303 in caliber 7 X 57 Mauser, which states -

using a 140 gr Nosler Partition, 49.5 gr of IMR 4350, in a 24 inch custom Lilja barrel, a velocity of 2,901 fps was achieved and a 0.75 inch 3 shot group was made!!!!!! Comments? All I can think of is that the Partition is a much shorter bullet, due to the lead components, resulting in the shank not taking up as much room, thereby allowing more powder capacity. But, 49.5 gr is a LOT of IMR 4350, IMO.

[SL1]

Dave,

If you want to push things hard, I think you really need to check the water capacity of at least one case of the type you intend to load hot.

Dumping water out of the case into the pan is not very accurate, because some of the water will stay in the case.

Can you remove the pan and hang a case from THE SAME PLACE on the end of the balance beam with a paperclip and a piece of scotch tape? If you put it near the edge of the table where the case can hang over the edge, will that work? If so, then the idea is to get the case filled without bubbles so that the water surface is flat across the case mouth. I add enough water to bulge out of the case and wet the surface of the wall all the way to the mouth edge, then suck out enough with an eye dropper to make the surface flat. Looking at the reflection of a bright object with a straight edge or line (like a window or a flourescent tube) can let you see when the surface is flat. Of course, weigh the case empty first, then full and calculate the difference.

FYI the Federal 210M primer is a match grade NON-magnum primer.

SL1

[langenc]

You can throw in 5 grain or more powder and see what happens. One thing for sure it will kick about 20% more and the group size will go to pot.

I DONT RECOMMEND 5 grain extra on any load.

[amamnn]

Proper chrono testing in the lab is also done with controlled lighting and a blast/flash screen to prevent errors. Home chrono use should just be for reference or to spot problems with loads.

[Major Dave (retired)]

Okay, here's the water capacity info you needed - 3 cases fired in my rifle

#1. 56.8 gr of water, 2.225 inch case length

#2. 57.3 gr of water, 2.226 inch case length

#3. 57.5 gr of water, 2.226 inch case lenth

See what you can do with that.

And thanks for your help - I'm way in over my head, at this point!

[Colorado Redneck]

The nosler load and velocity data for my son's 25-06 has been interesting. The 100 gr. ballistic tip data from the book was slightly less than the chrony indicated from that gun. For the 110 gr. accubond the chrony results were 90 fps under the book. For 115 gr partition, the chrony showed 120 fps less than the book. Barrel length was 24" for the test barrel and the gun we used.

In my 270, the Barnes 110 gr TTSX velocities were almost identical to the book.

The 22 hornet loads we have worked up are about 100 fps faster than the book says they should be.

Moral of the story is, the book, the test rifle, the cases, your gun, your scale, your chrony etc can all skew results. Makes it fun, huh.

[FrankenMauser]

When your rifle doesn't get the velocity the books say it should... do you go beyond the max published load until you get the expected velocity?

Never.

I find the most accurate load within the range I tested, and stick with that. Lightning-fast bullets don't do any good if they aren't accurate.

[croc4]

that is just crap!

honestly, the key is accuracy, a fast inaccurate bullet is the same as a slow inaccurate bullet, they both MISS!, if you find an accurate load and it happens to be a little slower than listed specs, who cares, certainly not your target, dead is dead.

There are far too many variables that exist to give your powder load the same velocity as stated in the manual, more than you could imagine (temp, alt, bullet hardness, age of powder, lot #, etc, etc). The manual is there as a guide, nothing more it should never be taken as an absolute, except in the case of max loads, they should be slowly worked to with care and attention to detail on any of the over pressure signs.

Spend your energy on finding an accurate load, you'll be much happier.

Croc4

[SL1]

Dave,

OK, I'll start working with those water capacities and see what I come-up with. They are about 2 grains less than the default value in QuickLOAD wihch is not typical for QuickLOAD defaults (they are usually minimums).

One of the things that has been bothering me about the information that you have provided so far is that your Hornady 139 grain bullet with IMR-4320 seems to be getting about 150 fps MORE velocity from your rifle than QuickLOAD indicates, while your Barnes 140 grain TSX with IMR-4350 is getting about 150 fps LESS than QuickLOAD indicates. (But, both calcs were with the default case volume.) That is making me wonder if you don't have a lot # of 4320 that is extra hot and a lot # of 4350 that is extra mild. The 2950 fps chrono readings on the Hornady bullet seem a lot faster than I would expect for the 7 mm Mauser with a 140 grain bullet. My old Hornady manual #4 only showes only 2700 fps with 44.6 grains of IMR-4320 from a 22" barrel. That is 250 fps slower than what you indicated in your first post. That chrono velocity wasn't at typo or bad memory, was it?

Anyway, at this point, I would urge you NOT to just substitute the Barnes bullet for the Hornady with that load, because it seems to be giving such unexpectedly high velocities that I am concerned that the pressures are also higher than expected. Substituting the solid copper bullet would raise pressure even more.

It is going to take some thinking on my part before I am going to be ready to offer some advice. One of the problems is that there isn't just one variable in QuickLOAD that represents a powder's characteristics, there are SEVEN. In comparing the values of those parameters for pairs of powders that are SUPPOSEDLY identical, it seems that several of those seven parameters differ, but give a combined result that is roughly the same with respect to performance. I can try to match your IMR-4320 performance by modifying just the burn rate, and see what that does to pressure, but there is no way for me to tell if that really represents what your particular can of powder is actually doing.

Also, I am familiar with some pressure-tested data (different cartridge and powders) where two supposedly identical powders had much different max loads with much different performance. One powder seemed "slower" in that it gave less velocity with the same charge weight, but it maxed-out at the SAAMI pressure limit with a velocity that was substantially below the max velocity achieved (with a lighter charge) by the apparently "faster" powder of that pair.

So, on the basis of both pressure-tested data and QuickLOAD calculations, I want to caution you that you cannot assume that you can just keep adding powder until you reach the max velocity stated for that powder in the manual and still be assured that you are not over the pressure limit set for the manual's pressure testing.

As I try to figure this out, it would help to know if you used the same cases for the load with your Hornady bullet and if you used the same COL.

EDIT: Using your case capcity and COL, to get 2950 fps with 44.5 grains of IMR-4320, I needed to jack-up the burn-rate to the point that the pressure reached 66,500 psi. When I then substituted the Barnes TSX bullet for the Hornady, I got 75,400 psi and 3,000 fps. I don't think we want to go there! What else can you tell me about your Hornady bullet load? Am I using some information that misrepresents it? For one thing, is this Hornady bullet the flat-base or boat-tail version and does it have the SST plastic tip? (There are 5 possibilities for the bullet in the QuickLOAD database, so the part number would help.)

SL1

[TheNatureBoy]

Don't even worry about matching a reloading manuals test results. If your load works in your rifle all is well.

[confirmed shooter]

48.2 gr of 4350 is max, I have allways found this to be a hot load. messure your group size, and use sierra ballistic soft-ware to get your drop and wind drift. usually your best group will come at a slower speed than max.

[Unclenick]

Major Dave,

Since SL1 is handling the QuickLOAD calcs for you, if you'll bear with me, I'll just make a few points about practice and principle so you may apply them to your gun and hunting objective. First, though, for identification purposes, I'll repeat that the Federal 210 and 210M (match) are standard power large rifle primers, and add that the magnum power versions are the 215 and 215M (match).

In addition to powder lot (which can vary pressure 10%) and primer choice (also can vary pressure 10% in some instances, as in going between a Federal 205 standard primer and a Remington 7 1/2 magnum primer in the .223), pressure has dependency on the volume the powder has to burn in and on how hard it is to start a bullet into the rifling. The Barnes solids are less dense than lead so they are longer, using up more powder space for a given COL. They are also harder for rifling to deform than a thin jacket with a soft core underneath. Both factors tend to raise pressure. I don't know precisely how much the newer banded (rings) design on the solids affects the comparison—QuickLOAD just has one starting pressure compensation recommendation for solids— but I am going to ask Barnes about it? In any event, these differences are why you cannot simply take data for an equal weight bullet of jacketed construction and assume it applies to your bullet. Such equivalence actually requires the bullets both be the same weight, same construction, and same ogive departure-to-base length, and be seated to the same base depth in the case.

What causes confusion is a lot of manuals group all their same-weight bullets together over the same table of charges and velocities, even when they don't have the same shapes or same recommended COL's (e.g., the Hornady manual). This makes people assume loads and bullet weights are the only things of concern in pressure. Case brand and primer number are most frequently ignored, even though they can be as significant as several steps of difference in charge weight in the powder tables. At least the Hornady bullets are all the same construction in each group (i.e., jacketed, lead, or solid). But what you will find if you experiment is the load tables for groups of same-weight Hornady bullets are maxed for the highest pressure-producing bullet in the group. All others in the group will actually perform at lower pressure and velocity. They just hope the differences will be small enough to have enough overlapping velocity extreme spread so the error is unnoticeable to the customer. If you load carefully enough, it isn't.

The one aspect of your gun that will tend to reduce pressure is the long throat. A long throat allows gas more time to escape the case and go around the bullet and out the bore before the bullet seals the bore. QuickLOAD has no way to compensate for this. It simply shows pressure dropping as you seat a bullet out further. In reality, in seating a bullet out longer from a deep starting point, peak pressure drops, then is followed by a rise as the ogive of the bullet gets closer to the lands and constricts the bypass path for gas. A long pointy shape will also cause more gas restriction earlier in seating depth than a round or flat nose bullet that doesn't stick far into the throat. I've got a graph of this somewhere which was done for round nose bullets in .30-06 in a lab in the mid-sixties. The minimum pressure point turned out to be about 10,000 psi below the maximum pressure point as the bullet approaches touching the throat.

SL1 asked for water capacity of cases fired in your chamber, which is correct, but in helping others with QuickLOAD in the past, I've found it isn't always obvious that this means fired but not resized. In other words, they need to be fireformed to your chamber because the size the case expands to in your chamber is what affects peak pressure in loads over about 30,000 psi. Not the sized case capacity. The easiest way is to leave the case unsized and the spent primer in place to plug the case for water, then make the measurements.

Your low water capacity measurement may be the result of your case brand or of your measuring technique? You didn't say how you did it? If you have Excel or can download and install the free Open Office Suite, you will be able to run my Excel file for water capacity. It has temperature compensation for water expansion built-in. It is listed in my shooting file repository at http://drop.io/unclenick. When you put your cursor over the file name, a download arrow in a box appears at the right to click on. Note that the file's method is to first weighing the case, then the case full of water at a known temperature (which you enter) and then taking the difference. Since you can't weigh a standing case full of water on your scale, you will want to first weigh the dry case laying across the pan. Then fill with water, pour the water into the pan, then balance the case with its damp insides across the pan to get the total +water weight. Note also that the case should be filled to the mouth dead even with no meniscus. The instructions are detailed in the file. Failure to weigh the case with its damp insides can indeed make a couple of grains difference.

Trajectory tables showing total bullet drop make us think we have to get every last foot per second of velocity for flat shooting from our bullets. The problem is, the total drop in the bullets below horizontal are only true for you if you go into the field with your sights lined up parallel to your bore. Nobody does that. You sight in at some zero range, which puts the bullet in an upward trajectory from which it must fall back across the line of sight before it starts subtracting from point of impact. The slower your MV the higher that trajectory is for a given bullet and zero range, so the slower MV bullet has further to drop before crossing the line of sight on its way down from the apogee of the trajectory. This compensates for greater drop.

Let me work an example with your bullet. Suppose you take the late Jeff Cooper's advice and zero your gun at 200 yards. The idea is, even allowing for roughly 2 moa of combined shooter position and rifle accuracy error, this will keep you inside an 8" kill zone circle to about 230 yards, give or take. More for a flatter shooter, less for a high trajectory round like a 45-70.

Let's start the pointed TSX out at two muzzle velocities, 2800 fps from one load and 2600 fps from another. If we fired with sights set parallel to the bore, the fast bullet would have dropped 24" at 300 yards, while the slow one will have dropped 28" at 300 yards. That would be a a lot of hold over with either one and is a 1.25 moa difference.

But now let's zero both at 200 yards. The faster round will reach apogee about 1.9 inches above the sight line at around 117 yards. The slower one will be half an inch higher, or 2.4" high at 115 yards. At 300 yards the fast bullet is -8.3" below the sight line. The slow one is -9.6" below sight line, or 1.3" lower. The holdover for either, if estimated at eight inches will stay well within the kill zone. You could probably hold an extra 4", or 1 1/4 moa over at 300 yards, but would you honestly be able to hold an extra .4 moa high from a field position? The Elk won't notice the difference in POI, I'm sure. The 15% drop in ME is also barely perceptible, I expect. Catch baseballs, human nerves about 10% difference to tell there is a difference at all.

[SL1]

Dave,

I will be going where I have no Internet access for a couple days, so I will not be getting back to you until maybe Wednesday evening.

Also, did you see my questions in my last post? It would help for you to tell me everything you know about your 139 grain Hornady bullet load.

Unclenick,

Please feel free to jump-in with QuickLOAD advice or calculations. I am getting the impression that I would need to know a lot more about internal ballistic calculation methods to properly unravel the mystery that Dave is presenting with these two loads.

I have started looking at the way that the different powders from the same manufacturers differ with respect to burning rate (ba), progressivity (aO), progressivity burn limit (z1) and (b) [whatever that is called] and I see that IMR's different powders don't necessarily decrease (ba) to get slower. These four factors seem to be varied in not-so-obvious ways to give a net performance that is slower on a burn-rate comparison chart, even when (ba) is not slower. So, I am really groping to find a way to make sense of what Dave has seen with his two IMR powders. If I understand what he is saying about his 139 grain bullet load, it just seems awfully fast for that charge weight of IMR-4320, and it scares me to try to tell him how to use it for another bullet that will certainly raise his pressure for a given charge weight. Since he wants to push the presure limit, I am trying to see where it would be best to stop with that particular lot of IMR-4320. If you have any good ideas about how to do that, please speak-up.

SL1

[SL1]

Major Dave,

I see nobody has added anything while I was away. So, I'll tell you what I can with what you have given me.

First, using IMR-4350 with the Barnes bullet does not look like a good choice if you want to push pressures toward 65,000 psi. QuickLOAD says your case will be full with 43.6 grains and that would give 47,500 psi and 2685 fps. A 10% compressed load would be 47.9 grains for a pressure of 63,500 psi and a velocity of 2953 fps. But, your experience with your lot of IMR-4350 gave you only 2600 fps with 46.0 grains, while QuickLOAD predicts 2835 fps. Adjusting the burning rate factor for IMR-4350 in QuickLOAD to match your velocity with your charge gives only 2660 fps for 47 grains and 2717 fps with 47.9 grains. None of the charges with the adjusted burning rate get to 50,000 psi.

On the other hand, when I try to match your other load with the Hornady Interlock bullet and 44.5 grains of IMR-4320, QuickLOAD gives 2868 fps and 58,712 psi, while your chronograph says 2950 fps. So, your lot of IMR-4320 seems significantly hotter than what QuickLOAD uses. Modifying (only) its burning rate factor to match your measured velocity gives 66,434 psi with that Hornady bullet. But, that was with a burning rate factor that ended up between IMR-3031 and IMR-4198, really fast for a 7mm Mauser case. There are 5 other factors that QuickLOAD allows me to change (and one it does not). By changing those, I could make "IMR-4320" act like Bullseye, so these mods are not necessarily realistic. QuickLOAD does give some guidance for modifying the burning rate factor and the specific heats ratio together to match velocity AND pressure measurements together, but you don't have pressure data to match, so we are basically flying blind here on pressure. I did notice that IMR-4895 in QuickLOAD does match your performance with IMR-4320 in your rifle with the Hornady bullet: 2957 fps and 63,076 psi. At least that is probably a realisic mix of parameter values, so I used that for some guidance, too.

Switching to the Barnes bullet that you want to get to 2950 fps, the modified IMR-4320 powder gave me 2976 fps at 71,677 psi, and the unmodified IMR-4895 gave me 2989 fps at 68,189 psi, both with your 44.5 grain charge weight. Neither seems like a good idea. Most reloading manuals stop a little above 60,000 psi (maybe 63,000 psi) for cartridges like the .270 Winchester with a SAAMI limits of 65,000 psi. And, that is DATA, not calculations that seem to be able to jump around by thousands of psi with various GUESSES at the powder parameters that are producing the observed velocity.

IF you are really interested in getting to 2950 fps while staying under 65,000 psi, QuickLOAD suggests using Reloader 17. According to QuickLOAD at least, Reloader 17 has more energy per unit weight and is a denser powder, allowing you to get more energy into the case, and it burns slow enough to keep pressures lower. QuickLOAD predicts 2952 fps at 62,323 psi with 47.0 grains of Reloader 17 filling 98.5% of your cases (57.3 grains of water capacity). If I had your performance goal, I would buy some of that and try working-up a load. But, frankly, we just saw two examples of powders that do not perform in your rifle very closely to what QuickLOAD predicts, probably due to lot-to-lot variations. SO, going out and buying the powder QuickLOAD says it best for your purpose is not really a guarantee that it will produce the results that you are seeking.

Also, if you really want to push pressure limits, I suggest that you learn how to estimate pressures in YOUR rifle by measuring case pressure ring diameters and case head expansion measurements. It isn't nearly as good as pressure-testing, but it can help you spot problems as they are starting to develop, BEFORE primer pockets start opening-up and bolts start sticking.

Whatever you decide to do, please stay safe. And, please report back any results.

SL1