IMR4320 Powder

Hunter Customs · January 18, 2008, 08:15 PM

I've worked up some nice accurate loads in one of my 223 bolt guns using a compressed charge of IMR4320 topped off with Sierra's 55 gr HPBT bullet.
I see no signs of pressure in these loads however I've heard that IMR4320 has a bad reputation for being very unstable.
Has anyone experienced any problems with IMR4320? If so please list the caliber you were loading it in.
Regards
Bob Hunter
www.huntercustoms.com

WIL TERRY · January 18, 2008, 09:55 PM

In addition all of the IMR powders would be thought the same as they're all made of the same stuff in varying degrees.
IMR4320 is one of the old time smokeless propellents that has done it's job very well for 7 or 8 decades in a myriad of cartridges.
And furthermore : how could it be unstable, whatever that means ???

Scorch · January 19, 2008, 01:29 AM

I have never known anyone who loaded IMR 4320 in a 223, but there is no reason it should not perform well. Burn rate for IMR4320 lies between WW748 and WW760, and I have shot loads for the 223 using both of those powders, so I imagine you will be quite happy with the results. I used IMR4320 for years with my 7X57 and 8X57 rifles, and it delivered superb accuracy.

Hunter Customs · January 19, 2008, 10:05 AM

Thanks for the info gents.
The story I received was it does have a reputation for creating pressure spikes in some cartridges, that's what I meant by unstable.
One of the cartridges that it seems to have a bad reputation with as having excess pressure is the 243.
I am interested if anyone out there had any experienced with high pressure or pressure spikes while using IMR4320.
I have used it in the past in two other cartridges, 22-250 and 300 Savage without any problems.
I usally try to choose powders that will give me a compressed charge, in most cases they will produce the best accuracy. I know this does not always hold true but it certainly has worked well for me most of the time.
The compressed charge is one of the reasons for loading IMR4320 in the 223.
The Sierra manual I have list my load as moving the 55gr HPBT bullet at 3200 fps when tested in two 20 inch barrel Colt AR's.
As a matter of fact my Sierra manual list my load as their recommended hunting load.
I'm shooting these loads from a 20 inch bull barrel gun. As of now my chrono is not wanting to register any loads shot accross the screens, once it decides to work I will find out just what these loads are doing.
I do know that in the past I've used a good quanity of IMR powders and never had any problems with any of them.
Thanks again for the replys.
Regards
Bob Hunter
www.huntercustoms.com

Al Norris · January 19, 2008, 03:34 PM

About 2 years ago, I was given a can of IMR 4320 from an old friend who no longer loads. Not knowing what I could use it for, but also knowing I could possibly trade for something I do use, I accepted it.

This last summer I started using it with 55gr & 60gr bullets. Here's what data I have:

Rifle: KelTec SU-16B (18.4" barrel)(The SU-16 was a gift from my son)
Brass: Federal, trimmed to 1.755
Primer: WSR
OAL: 2.210

55gr FMJ-BT Hornady #2267
55gr FMJ-BT Speer #1044 (M193)
25.6gr IMR 4320

55gr Hornady V-Max #22271
25.5gr IMR 4320

60gr Hornady SP #2270
60gr Sierra HP #1375
25.4gr IMR 4320

No Chrony (sigh), but all rounds shot 1" consistent groups at 100yds from prone position (using the integral bipod), slow fire.

I don't own an AR, so I can't say what these loads will do with that platform. I mostly use Varget or H335, but decided to see what this IMR would do.

crowbeaner · January 19, 2008, 06:49 PM

IMR 4320 is one of the all time great powders. It was the traditional favorite for the 22 Varminter (22-250) until H380 came along. I've loaded .222,.222Mag.,.243,.257,.25/06,.308, and 30/06 with it over the years and it has performed superbly in all. It is very stable and predictable, and properly stored your grandkids will be able to use the leftovers. I'm going to load some .243 and .257 this spring with some. It is a favored tailored load powder for many calibers and even works well with cast bullets in some. CB.

January 19, 2008, 01:29 AM	#3
Scorch Senior Member Join Date: February 13, 2006 Location: Washington state Posts: 15,248	I have never known anyone who loaded IMR 4320 in a 223, but there is no reason it should not perform well. Burn rate for IMR4320 lies between WW748 and WW760, and I have shot loads for the 223 using both of those powders, so I imagine you will be quite happy with the results. I used IMR4320 for years with my 7X57 and 8X57 rifles, and it delivered superb accuracy. __________________ Never try to educate someone who resists knowledge at all costs. But what do I know? Summit Arms Services

January 19, 2008, 06:49 PM	#6
crowbeaner Senior Member Join Date: June 4, 2007 Location: Upstate SC Posts: 1,943	IMR 4320 is one of the all time great powders. It was the traditional favorite for the 22 Varminter (22-250) until H380 came along. I've loaded .222,.222Mag.,.243,.257,.25/06,.308, and 30/06 with it over the years and it has performed superbly in all. It is very stable and predictable, and properly stored your grandkids will be able to use the leftovers. I'm going to load some .243 and .257 this spring with some. It is a favored tailored load powder for many calibers and even works well with cast bullets in some. CB. __________________ If you want your children to follow in your footsteps, be careful where you walk. Beware the man that only owns one gun; he probably knows how to use it. I just hope my ship comes in before my dock rots.

January 18, 2008, 08:15 PM	#1
Hunter Customs Senior Member Join Date: March 26, 2005 Location: Osborn, Missouri Posts: 2,697	IMR4320 Powder I've worked up some nice accurate loads in one of my 223 bolt guns using a compressed charge of IMR4320 topped off with Sierra's 55 gr HPBT bullet. I see no signs of pressure in these loads however I've heard that IMR4320 has a bad reputation for being very unstable. Has anyone experienced any problems with IMR4320? If so please list the caliber you were loading it in. Regards Bob Hunter www.huntercustoms.com

January 18, 2008, 09:55 PM	#2
WIL TERRY Senior Member Join Date: July 6, 2000 Location: BLACK HILLS Posts: 1,322	If Imr4320 Were Unstable We'd Have Known It By Now !!!!! In addition all of the IMR powders would be thought the same as they're all made of the same stuff in varying degrees. IMR4320 is one of the old time smokeless propellents that has done it's job very well for 7 or 8 decades in a myriad of cartridges. And furthermore : how could it be unstable, whatever that means ???

January 19, 2008, 10:05 AM	#4
Hunter Customs Senior Member Join Date: March 26, 2005 Location: Osborn, Missouri Posts: 2,697	Thanks for the info gents. The story I received was it does have a reputation for creating pressure spikes in some cartridges, that's what I meant by unstable. One of the cartridges that it seems to have a bad reputation with as having excess pressure is the 243. I am interested if anyone out there had any experienced with high pressure or pressure spikes while using IMR4320. I have used it in the past in two other cartridges, 22-250 and 300 Savage without any problems. I usally try to choose powders that will give me a compressed charge, in most cases they will produce the best accuracy. I know this does not always hold true but it certainly has worked well for me most of the time. The compressed charge is one of the reasons for loading IMR4320 in the 223. The Sierra manual I have list my load as moving the 55gr HPBT bullet at 3200 fps when tested in two 20 inch barrel Colt AR's. As a matter of fact my Sierra manual list my load as their recommended hunting load. I'm shooting these loads from a 20 inch bull barrel gun. As of now my chrono is not wanting to register any loads shot accross the screens, once it decides to work I will find out just what these loads are doing. I do know that in the past I've used a good quanity of IMR powders and never had any problems with any of them. Thanks again for the replys. Regards Bob Hunter www.huntercustoms.com

January 19, 2008, 03:34 PM	#5
Al Norris Moderator Emeritus Join Date: June 29, 2000 Location: Rupert, Idaho Posts: 9,660	About 2 years ago, I was given a can of IMR 4320 from an old friend who no longer loads. Not knowing what I could use it for, but also knowing I could possibly trade for something I do use, I accepted it. This last summer I started using it with 55gr & 60gr bullets. Here's what data I have: Rifle: KelTec SU-16B (18.4" barrel)(The SU-16 was a gift from my son) Brass: Federal, trimmed to 1.755 Primer: WSR OAL: 2.210 55gr FMJ-BT Hornady #2267 55gr FMJ-BT Speer #1044 (M193) 25.6gr IMR 4320 55gr Hornady V-Max #22271 25.5gr IMR 4320 60gr Hornady SP #2270 60gr Sierra HP #1375 25.4gr IMR 4320 No Chrony (sigh), but all rounds shot 1" consistent groups at 100yds from prone position (using the integral bipod), slow fire. I don't own an AR, so I can't say what these loads will do with that platform. I mostly use Varget or H335, but decided to see what this IMR would do.