substituting magnum primers in 7.62x39

Boomer58cal · September 2, 2013, 03:50 PM

I'd like to ask a question just out of curiosity.

I have a friend that has been reloading for many decades. He uses H4895 with LR magnum primers in 7.62x39 for his SKS. His reasoning he says is twofold...

1. Magnum primers have a thicker cup( maybe harder too? ) and help prevent slam fires.

2. 29g of H4895 is Hogdens max load with a 125g bullet. Basically all the powder that will fit in the case. This reaches a pressure of approximately 33,600 cup. Max pressure for 7.62x39 is around 45,000 cup.

He says magnum primers give him a 50 fps increase without reaching unsafe pressures.

Basically I just wanted to know what you guys think.

Is any of his reasoning true?

Or is he just trippin?

Is this even safe?

Boomer

reynolds357 · September 2, 2013, 07:19 PM

The magnum has no harder or thicker cup than the standard lr. They are both designed to work at the same max pressure. In my opinion, all you are going to do is screw up your accuracy.

iraiam · September 2, 2013, 09:16 PM

CCI armory primers have a harder cup (#41 and #34) and are magnum primers.

I load 7.62X39 with the #34 primer and AA2015 or AA1680 powder, but I have used plenty of standard primers without trouble too. As far as accuracy goes, my reloads are more consistent and accurate than any of the steel cased ammo I have shot, but that may have more to do with the brass case than anything else.

When the bolt closes on a live round in an SKS, the free floating firing pin does leave a tiny mark on the primer. I have seen a couple SKS slam fires (never mine), in both instances the root cause was lack of cleanliness/maintenance of the weapon.

steve4102 · September 2, 2013, 09:34 PM

Yes, he is correct on all counts.

Boomer58cal · September 3, 2013, 11:09 AM

Thanks for the replies. This question came up because I asked him what primers he was using after reading the recent CCI # 34 thread. Here... http://thefiringline.com/forums/showthread.php?t=531540

Quote:

The magnum has no harder or thicker cup than the standard lr. They are both designed to work at the same max pressure. In my opinion, all you are going to do is screw up your accuracy.

Why would this screw up your accuacy?
His loads are far more accurate than any factory ammo I've seen.

Quote:

When the bolt closes on a liveround in an SKS, the free floating firing pin does leave a tiny mark on the primer. I have seen a couple SKS slam fires (never mine), in both instances the root cause was lack of cleanliness/maintenance of the weapon.

I've never had an issue with CCI LR but I clean the heck out of my firing pin channel and pin. I also visually inspect the pin and make sure it go's jingle jingle before firing my sks.

Boomer

reynolds357 · September 3, 2013, 08:33 PM

Iraiam, you are using a special purpose, special spec. primer.

Boomer58cal · September 3, 2013, 08:51 PM

Quote:

Iraiam, you are using a special purpose, special spec. primer.

CCI #41 & #34's are milspec. Isn't that special

Boomer

Mobuck · September 3, 2013, 09:01 PM

I use CCI#41 and 34 primers in several loads. In every case, I've found a slight charge reduction is required compared to standard CCI LR and SR primers. In addition, I have noticed a slight to moderate lowering of potential accuracy compared to standard primers.

Boomer58cal · September 3, 2013, 10:55 PM

res45 pm'ed me this link. Great info on primers. http://www.sksboards.com/smf/index.php?topic=56422.0

Rifle Primer Dimension Chart
http://www.jamescalhoon.com/primers_and_pressure.php

As always thanks for the help guys.

Boomer

armoredman · September 3, 2013, 10:59 PM

I quit using the special CCI milspec primer in my 7.62x39mm loads years ago - too hard to find reliably, and more expensive than I needed, plus I haven't loaded for an SKS in about 8 years. I have been using Remington 9.5s now for a few years with excellent results. I also use mostly AA# 1680, but have some great loads with H-4895 and the Berry's plated 125 grain bullet.

Boomer58cal · September 4, 2013, 11:25 AM

I haven't been able to find AA1680. I have found some N120, But I haven't been able to try it yet. I lost about 100 fps with H4895 compared to factory, but it shoots strait.

Boomer

armoredman · September 4, 2013, 12:05 PM

I bought 1680 in bulk a few years ago, when it was plentiful and cheap, (relatively speaking), and it's good stuff. The data has changed in the last two years, so if you shoot Accurate Arms, make sure you are using the latest data. This is why the old standby load of 24 grains of AA1680 for 7.62x39mm is now considered below starting loads.

iraiam · September 5, 2013, 01:57 AM

Quote:

Iraiam, you are using a special purpose, special spec. primer.

Yep

I have also used plenty of CCI 450 and 250 primers (small rifle magnum and large rifle magnum) in their place. Per CCI, the 41 and 34 primers; Use the same data as CCI Magnum primers.

September 2, 2013, 03:50 PM	#1
Boomer58cal Senior Member Join Date: February 18, 2013 Location: closer than you think Posts: 967	substituting magnum primers in 7.62x39 I'd like to ask a question just out of curiosity. I have a friend that has been reloading for many decades. He uses H4895 with LR magnum primers in 7.62x39 for his SKS. His reasoning he says is twofold... 1. Magnum primers have a thicker cup( maybe harder too? ) and help prevent slam fires. 2. 29g of H4895 is Hogdens max load with a 125g bullet. Basically all the powder that will fit in the case. This reaches a pressure of approximately 33,600 cup. Max pressure for 7.62x39 is around 45,000 cup. He says magnum primers give him a 50 fps increase without reaching unsafe pressures. Basically I just wanted to know what you guys think. Is any of his reasoning true? Or is he just trippin? Is this even safe? Boomer __________________ The number one cause of death in the 20th century. 290,000,000 citizens were first disarmed and then murdered by their own governments. This number does not include those killed in war. We're from the government, we're here to help Last edited by Boomer58cal; September 4, 2013 at 10:31 AM.

September 3, 2013, 10:55 PM	#9
Boomer58cal Senior Member Join Date: February 18, 2013 Location: closer than you think Posts: 967	res45 pm'ed me this link. Great info on primers. http://www.sksboards.com/smf/index.php?topic=56422.0 Rifle Primer Dimension Chart http://www.jamescalhoon.com/primers_and_pressure.php As always thanks for the help guys. Boomer __________________ The number one cause of death in the 20th century. 290,000,000 citizens were first disarmed and then murdered by their own governments. This number does not include those killed in war. We're from the government, we're here to help

September 4, 2013, 11:25 AM	#11
Boomer58cal Senior Member Join Date: February 18, 2013 Location: closer than you think Posts: 967	I haven't been able to find AA1680. I have found some N120, But I haven't been able to try it yet. I lost about 100 fps with H4895 compared to factory, but it shoots strait. Boomer __________________ The number one cause of death in the 20th century. 290,000,000 citizens were first disarmed and then murdered by their own governments. This number does not include those killed in war. We're from the government, we're here to help

September 2, 2013, 07:19 PM	#2
reynolds357 Senior Member Join Date: December 10, 2012 Posts: 6,165	The magnum has no harder or thicker cup than the standard lr. They are both designed to work at the same max pressure. In my opinion, all you are going to do is screw up your accuracy.

September 2, 2013, 09:16 PM	#3
iraiam Senior Member Join Date: September 6, 2012 Location: Lakewood, CO Posts: 1,057	CCI armory primers have a harder cup (#41 and #34) and are magnum primers. I load 7.62X39 with the #34 primer and AA2015 or AA1680 powder, but I have used plenty of standard primers without trouble too. As far as accuracy goes, my reloads are more consistent and accurate than any of the steel cased ammo I have shot, but that may have more to do with the brass case than anything else. When the bolt closes on a live round in an SKS, the free floating firing pin does leave a tiny mark on the primer. I have seen a couple SKS slam fires (never mine), in both instances the root cause was lack of cleanliness/maintenance of the weapon. __________________ NRA Lifetime Member Since 1999 "I ask, sir, what is the militia? It is the whole people except for a few public officials." George Mason Last edited by iraiam; September 2, 2013 at 10:03 PM.

September 2, 2013, 09:34 PM	#4
steve4102 Senior Member Join Date: December 23, 2005 Location: Minnesota Posts: 2,955	Yes, he is correct on all counts.

September 3, 2013, 08:33 PM	#6
reynolds357 Senior Member Join Date: December 10, 2012 Posts: 6,165	Iraiam, you are using a special purpose, special spec. primer.

September 3, 2013, 09:01 PM	#8
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	I use CCI#41 and 34 primers in several loads. In every case, I've found a slight charge reduction is required compared to standard CCI LR and SR primers. In addition, I have noticed a slight to moderate lowering of potential accuracy compared to standard primers.

September 3, 2013, 10:59 PM	#10
armoredman Senior Member Join Date: May 22, 2007 Location: Arizona Posts: 5,299	I quit using the special CCI milspec primer in my 7.62x39mm loads years ago - too hard to find reliably, and more expensive than I needed, plus I haven't loaded for an SKS in about 8 years. I have been using Remington 9.5s now for a few years with excellent results. I also use mostly AA# 1680, but have some great loads with H-4895 and the Berry's plated 125 grain bullet.

September 4, 2013, 12:05 PM	#12
armoredman Senior Member Join Date: May 22, 2007 Location: Arizona Posts: 5,299	I bought 1680 in bulk a few years ago, when it was plentiful and cheap, (relatively speaking), and it's good stuff. The data has changed in the last two years, so if you shoot Accurate Arms, make sure you are using the latest data. This is why the old standby load of 24 grains of AA1680 for 7.62x39mm is now considered below starting loads.