M1A Light Primer Strike/Jammed Bolt

[richv74]

Hope someone can help me with this...Was shooting some reloads in my M1A Loaded, when I got a misfire. I attempted to pull the bolt back and found the bolt was jammed and would not pull back. After several attempts it finally released and I was able to eject the unspent round. There was a slight dent in the primer.

What would cause the light strike accompanied with a jammed bolt. This happened several times during this shooting session. The last jam, I had to field strip the rifle to get the bolt to release.

COL of Bullet, Bad Primer, ? .... I'm stumped.

[HiBC]

Loading for an M1-A involves (among other things) loading to specific head clearance.

Head clearance is the amount of clearance the ammo has within the rifle's headspace.

Some head clearance is necessary to allow the bolt to lock into full battery without resistance, There are tools and techniques to set your sizing die for proper head clearance.
There is even more advice on the internet on how to do it . Some of it is correct,and there is more than one good way. There is also plenty of bad advice.

When you set up your seating die,do you screw it down to full contact with the shellholder? If you do,realize the seater die has a built in crimp function.
That would severely over crimp the cartridge. But there is no place for the crimp to go. So the shoulder collapses a bit,and when it does,the case diameter at the shoulder expands.....enough to get stuck in a tapered chamber.

I had a book by Precision Shooting Magazine about "loading for Competition."

Good book. Out of print. Last one I saw for sale was over $300. I don't know if its that good!

Someone here may recommend a good book reloading for competition.


There are other books but I'm not sure of a title.

[richv74]

Thank You...I will readjust my seater die...I also just ordered a micro click seating die adjuster for a more precise bullet seat...I'll give a search for one of the books you mentioned.

[georgehwbush]

what HiBC said; plus even though it's quicker i do not like a seating die with roll crimp too many damaged shells. it requires an extra step but i use generic seater and a crimping die that does "factory crimp" it squeezes the end of the neck rather than pushing on it. (that does assume that you service and lube your dies often)

[richv74]

Please excuse my ignorance - Does the COL of the cartridge, which in this case for a .308 Service Rifle listing is 2.810", correspond to the proper headspace? Or, does the headspace for each rifle differ and should be measured separately?

[44 AMP]

Please excuse my ignorance - Does the COL of the cartridge, which in this case for a .308 Service Rifle listing is 2.810", correspond to the proper headspace?

No, it does not correspond to the headspace.

The max Cartridge Overall Length is length of the loaded round, measured from the case base to the bullet TIP.

It is an industry standard length that should fit in the magazine, feed through the action and chamber fully without the standard profile bullet touching the rifling.

Headspace is the space in the rifle for the cartridge to fit. It was, originally the space for the case head to fit into, and was measured from the bolt face to the point in the rifle that physically stopped the cartridge from moving forward. Since all the early cartridges were rimmed, and the rim was on the case head, the term was "head space", meaning the space the rim fit into.

Today, the term refers to the majority of the chamber, or even all of it depending on case design. Generally speaking bottle necked rimless cases are stopped by contacting the shoulder area of the chamber. The point on the case shoulder where this contact occurs is referred to as the "Datum line" or point. There are exceptions. Belted rimless cases headspace on the belt, the same way rimmed cases headspace on the rim. Again, there are exceptions.

Rimless straight cases are intended to headspace on the case mouth. There are exceptions.

A cartridge with a bullet seated too long (over max COL) can have the bullet jam into the rifling, possibly creating a situation where the bolt will not properly lock shut, even when the case is properly sized, and in tolerance for the rifle's headspace.

The two terms are not related, or connected with each other, other than they that describe things that happen inside the rifle's barrel and action.

Clear as mud now??

[georgehwbush]

richv74; might i suggest that you look up a technical drawing for your cartridge and chamber, it is a good reference point to have handy when things don't go as planed. i keep a copy of the saami drawings on my pc for quick reference.

[bamaranger]

I suspect loading for the M1A is similar to loading for an M1 Garand. The M1 taught me a lot about reloading, one issue was headspace.

I would stick to one mfg of brass....one headstamp. I would purchase an RCBS precision mic, which will allow reference measurements on your fired and later sized cases. I will not go into reading of the precision mic, but it is an important piece of gear if you are loading for M1/M1A.

Fire 10 rds of ammo thru the rifle, take the corresponding headspace measurements from the fired cases and combine to get an average. Any reading that is notably high or low I would not use in my calculations. The number produced by the RCBS gauge is a reference. As an example, the fired cases from the Garand I shoot the most gauge "+.009". on average I then adjust my sizer until it is producing sized cases which are ".003" less than what my fired cases measure.....in this example "+.006". Proper sizing is important. Undersized cases or high primer can result in slamfires.
A bolt rifle with its manual feeding and strong camming/locking action will tolerate wonky head space and primers. The .30 service rifles are not so forgiving.

Use primers intended for large service rifle, RCBS #34 are recommended. These primers have a tougher skin and will help avoid slam fires. TheM1 and the M1A (I think) have free floating firing pins. An undersized case can slam into the chamber, bounce rearward, and contact the firing pin still moving forward and result in a slam fire. Not good.

I would buy a primer pocket uniforming tool from an outfit like Sinclair. That will help insure your primers are seated to the same depth. An undersized case, a high primer, a thin skinned primer are all contributors to a slamfire. Not good.

Finally, load from a magazine and do not drop the bolt on a manually chambered cartridge. The resistance of stripping from the mag will lessen the inertiall forces of the bolt and help prevent slamfires.

[44 AMP]

My M1A is not a match rifle. Its not "loaded", its not SOCOM, or anything but a "rack grade" gun with all GI parts on a Springfield Armory receiver.

So, I take a slightly different approach to its ammo than the gun shooting matches.

For my reloads, I just duplicate GI ball ammo. 150gr FMJs at spec speed (2750fps +/-).

I generally run GI brass, with the primer crimp cut out, last few batches I used W748, bullets seated to the cannelure and crimped.

My .308 dies are Lyman and actually the very first die set I ever got, bought in the early 1970s

Sizer die is FL and set for solid contact with the lyman shell holder with all play out of the press linkage. Seater die is adjusted correctly (does not contact the shell holder) to seat and crimp in one step. Very uniform, IF your brass is. Which is something that I do, brass is checked and trimmed to a uniform length and die adjusted for that brass.

I use CCI 200 primers, because I have them, and they have always worked safely, IN MY GUN.

The M14 (M1A) has a floating firing pin. When the bolt stops moving forward the pin still is, and as the bolt cams shut the pin bounces off the primer, often leaving a little dent in commercial primers with regular thickness primer cups. The slightly harder primers that meet the GI specs may or may not be visibly dented. I do not argue with the people who say the GI spec primer is the one you should use. I don't, but that's my choice, and I won't say you should , your rifle is not my rifle.

I graduated second in my class (and made PFC because of that) of Small Arms Repairman (MOS 45B20) from the US Army Ordnance Center and School at Aberdeen Proving Grounds in 1975 and my class was the last class trained on the M14 rifle.

I couldn't build you a match rifle, won't even try. But I know the basic service rifle, rack grade, inside and out. I've owned or had experience with some variant of all the world's primary service rifles from 1890s on up through the 1980s, the actual rifles or semi auto legal copies of the select fire ones. All the semi autos have gone on to new homes, my M1A is the one I kept. It fits me and I do ok with it. It shoots better than I do, I suspect.

Was shooting some reloads in my M1A Loaded, when I got a misfire.
I attempted to pull the bolt back and found the bolt was jammed and would not pull back. After several attempts it finally released and I was able to eject the unspent round. There was a slight dent in the primer.

Are you aware of the "soldier's drill" for when that happens?? I don't think its taught any more,, but I got taught by some experienced Sgts when I was in.
(and, bear in mind this is for when no one is shooting directly at you )
First off, STOP, and look at the rifle to see if the bolt is fully shut and locked. IF not, smack the hell out of the back of the op rod handle to see if you can force it closed. Kicking it is also an option but that's quite awkward.

There is a restrike capability in the M14. Its awkward, but possible. Unlatch the trigger guard, and pivot it all the way forward, like using the lever of a lever action rifle. This will recock the hammer without needing to open the action. close and latch the guard, and refire the rifle. IF the bolt is fully shut, it should fire. IF it does not, then try to eject the unfired round.

IF you can't get the action open, then it's time for the other part of the drill. Place the butt on the ground, hand on the barrel just below the flash suppressor, leaning the muzzle away from your body slightly and, maintaining control of the muzzle, stomp down on the op rod handle. This will normally pop the action open, ejecting the unfired round.

Chamber another round and get back in the war!

This "drill" is rough on the gun, it is a field expedient for use in situations where what's best for the rifle is of no concern. I wouldn't think of using it under any but the gravest of circumstances. (meaning actual combat)

If you're feeding a match grade rifle match grade ammo, do what the match shooters tell you to do. If you're not, and regular "rack grade" results are good enough (as they are for me) do what then do what you need to do with the ammo so your rifle runs right, and save the "fiddley stuff" for rifles that can use it.

[mehavey]

Was shooting some reloads in my M1A . . .

What you most likely experienced was the case shoulder being too long (undersized) and jamming into the front of the chamber.
- Bolt did not completely close (very dangerous in a Garand action)

~~~~~~~~~~~~~~~~~~~~~~

1. FULL length resize cases for any/all Garand-based action (which the M1A is)
-- That means sizing-die screwed down/in full contact with the shell-holder -- plus another 1/8 turn so you can feel slight camming at the end of the downstroke while actually sizing cases.

2. The COAL is individual bullet dependent. Go to the bullet manufacturer's website and they will tell you recommended over-all length for 308Win -- with their bullet.
- You do not want the bullet too long/jamming in the throat and (again) interfering with the bolt fully closing in a Garand action.

.

[HiBC]

Reference 44 AMP post # 9

He raises a good point and I agree with him.
An M1A is a battle rifle and it ought to run fine on NATO grade military ammo.

Handloading can introduce variables and any semi-auto is to some degree dependent on its ammo.

Used correctly, standard SAAMI spec dies SHOULD be able to produce SAAMI spec case sizes to fit proper SAAMI rifle chambers. Thats the plan a d everything is SUPPOSED to be tolerance accordingly. Of course, that may be a touch optimistic but its reasonable to hope.

We CAN do a little better than hope.
Length of the loaded round overall. Thats case head to bullet tip. It must fit the magazine. Load to the manual spec. Yes,be sure the bullet does not jam int the rifling lands.

Sizing length, head clearance vs headspace. This can be an interesting discussion. Folks generally agree on the idea but they have a lot of ways of expressing it with language. And there are a number of ways to verify or measure whether your resizing operation is forming the shoulder in the right place.
The Soldier is shooting (ordinarily) virgin factory loads made to military specs to work in that rifle. Thats usually pretty trouble free. The military doesn't reload them. Shooting factory loads ought to be pretty trouble free.
Uncle Nick knows his stuff! He knows the M1A and he knows handloading.
He uses a hardware store aluminum bushing and dial calipers to check his resized length.
Hornady makes a "Lock-N-Load " dial caliper attachment that does what Uncle Nick does.Or at least "Before" and "After" sizing. We want the bolt to freely rotate fully into battery. And we don't want to much head clearance or our brass will stretch excessively. Where it stretches it thins. Eventually,where it thins it fails. Control head clearance and your brass will last longer. The "lore" I recall reading is .004 to .006. No,I don't want to argue the point.
As bamaranger wrote in his post, RCBS makes a different tool to measure the same thing a different way.The "RCBS" Precision Mic" Good tool,does a fine job.
I use a different tool and method.
Forster,Dillon,Lyman and others make a "Cartridge Headsace Bushing" . Its another good tool for this job.
Its a bushing that is reamed sort of like a chamber but to slightly different tolerances. The shoulder that provides the headspacing stop or datum is carefully controlled.
On what would be he breech end of the bushing, a groove about 1/8 in wide and a few thousandths deep is precision ground. That groove represents the tolerance zone for for the high and low limit of controlling the sizing of the shoulder.
If you size your brass and drop it in the bushing gauge,the case head height should fall within that groove. If it does,you are sized to SAAMI spec.
There are ways to measure "Before"and "After" sizing so you are sizing to a desired head clearance.

Setting your seating die. First,check case length and trim as necessary.

Screw the seating die in the press till its about 1/8th in off the shellholder.

Insert a sample of brass in the shellholder. Run the ram up so the case enters te seater die . Take the press to he top of the stroke. . Now ,with your fingers,screw the die in till you feel it contact the case mouth..
Take a look and note the die has not contacted the shellholder. There is a gap. Thats how much you crunch your ammo if you bump the die to the shellholder.
Decide if you want to crimp with your seater die. I don't. If you back the die out 1/8 turn or 1/4 turn,more or less,you will know you get zero crimp.
I suggest you find a flat washer or feeler gauge you can drop in your die box.
Do that and you can repeat exactly your die height to lock down your die body. Repeatable.
Now set your seating stem for seating depth/cartridge length.Lock it down.
This die setting/crimp thing gets learned the hard way by a lot of AR-15 shooters.

A Lee factory crimp die can be a good thing to experiment with if you want a crimp.

A Lee universal decap die can be good to deprime your brass before you clean it.
IMO,never run range gritty brass into your nice dies.

Don't forget to lube your cases. I've come to like the spray lubes.You can use what you want. Lanolin dissolved in alcohol. Put the brass n a tub. Spray it down. Shake it up. Spray it Shake it. Does it feel like you lubed it?
Now,IMPORTANT STEP! Give it time to dry. The alcohol will defeat the lube and you will stick a case in your die if you don't.



If you find you have crimped primer brass, on Youtube I just discovered the Lee primer pocket swage tool. I'm going to order one.

Get a couple of good loading manuals. Not just for the data. As a high school kid late 1960's,there was no internet. Dad was gone and not a shooter. I had no one to learn reloading from. I found my way.
The reloading manuals will teach you the process. Youtube can help.
Your favorite powder company is one good manual to have. So is your favorite bullet company.
Lee and Lyman have worthy offerings.

[richv74]

Thank you for the in depth information...I have ordered the Hornady Headspace attachments for my digital caliper as well as a Hornady Micro-Click seater. I have been using the Hornady Reloading Manual which has a chapter on .308 Winchester and .308 Service Rifle.

I guess step one - get the headspace measurement for my rifle. Step Two measure my brass for proper headspace. Then re-read all the great information you all shared with me and get back to reloading.

[HiBC]

You will get there!

There is another point where 44AMP has a valid point.
Its the "Keep it simple" approach.

You can use "What should work" And it nearly always works. Its what I did for decades.
The rifle, the ammo, the dies, all should be made to SAAMI standards.
We SHOULD be able to trust that if our factory built rifle isn't worn out, if our quality shell holder and dies are set up per the die instructions,if our press does not spring too much, etc,

We SHOULD be able to bring the sizing die down to firmly contact the shellholder and just size the brass.

We SHOULD get brass sized to SAAMI spec that will work just fine in any SAAMI spec rifle,which includes a rack grade M1A.

We need to appreciate our manufacturers and the great job they do supplying us with quality stuff.

Ordinarily, if we as reloaders learn and do our part, use quality stuff, and follow the process we will get safe, reliable ,good ammo without a lot of extra tools and steps .
A couple of current manuals, a scale, calipers ,dies and a press SHOULD be nearly enough gear to load ammo.
OK, a powder funnel and loading blocks and maybe a powder measure and a trickler and a chamfer tool,maybe a case trimmer ...

But you can keep it simple.