Some Lage 10/15 7.62x39 goodness
- Thread starter techspy
- Start date
That was my thought but be aware that steel doesn't work so well. I got constant out of battery discharges. Almost ruined my 10-15. I ended up having to stock up on more expensive brass cased 7.62x39.
Gaujo
UZI Talk Supporter
I'd consider selling it. Russian steel case is worth a premium.
No idea. I had spent a ton of time reviewing slow motion video of the issue and posted here and even Richard chimed in. Perhaps it was the extra friction of the steel that caused the firing pin to hit before it went all the way into battery? Or the primers are more sensative on the steel? Whatever it was it never has an issue using brass.
A&S Conversions
UZI Talk Life Member
Have you ever thought of comparing the steel cased to the brass cased ammunition? The Russian steel cased is known to have hard primers rather than soft sensitive primers. The AR system is designed to be locked (the bolt rotates in line with the locking lugs of the lugs of the barrel extension) before the firing pin can protrude from the bolt face enough to activate the primer. It would seem to me that since the brass cased ammunition works properly, I would think that the steel cased ammunition might be out of spec?
The only time I have had an out of battery discharge with the AR system was with a bad mag. The round came out of the mag way too early. The point of the bullet wedged into the top of the upper and the barrel extension. One of the top lug corners struck the primer when the round stopped the bolt group and the round went off.
What brand of barrel did you use? Did the feed ramps of the 7.62X39 barrel get modified for use with that ammo? My first machine gun was a Colt M16. I bought a Colt 7.62X39 carbine for the upper. Since 7.62X39 is larger in diameter and the larger diameter, so the standard M4 feed ramp would need to be widened and lowered. The magazine is fixed for height. So I have found that widening and deepening the feed ramps on an upper with standard feed ramps makes a huge difference. If your 7.62X39 barrel has a standard M4 feed ramp, maybe rounding the top of the feed ramp for the wider round then polishing it would help the steel cased ammo to feed into the barrel?
What comes to my mind is that the follower of the 7.62X39 AR mags are not pushing up the front of the round and/or the feed ramps are not deep enough to catch the tip of the round to guide the round into the chamber. The roughness or stickiness of the steel cased ammo might be just enough resistance to not allow the nose of the round into the feed ramp. Where as, the brass is slippery enough to allow the nose of the brass cased ammo to nose up enough to feed into the chamber.
The two lowest lugs push the rounds out of the magazines. If the round nose dives, I would think that the nose of the round diving down would tend to stop the round. With the round tipped down, I could see where the sharp corner of the lug of the bolt could push the primer hard enough to activate the primer causing an out of battery detonation.
It could also be the shape of the bullet nose between the brass and steel cased ammunition effecting how the ammunition interacts with the feed ramps.
For me modifying the feed ramps on a PSA 7.62X39 upper, is no big deal. Of course modifying the feed ramp profile of a Lage 3,000.00 upper would be a much bigger deal. I have shot a friend’s Lage Max-11/15 upper on my M11/NINE, but I don’t remember if the upper has M4 feed ramps. I would think that it would. But I don’t remember. I am glad you have your Max- /15 running in 7.62X39. It’s too bad that it won’t run your steel cased. What does the feed ramps on your 7.62X39 look like?
I bought a bunch of the 1,260 round cases of the corrosive primer brass cased Yugoslavian 7.62X39 ammo. SG Ammo has the Yugoslav brass cased in 1120 round cases on stripper clips for $588.00 per case shipped. Just remember it is corrosive baridium primed and red lacered sealed. This is the link, if anyone is interested.
sgammo.us8.list-manage.com
Please keep us updated.
Scott
The only time I have had an out of battery discharge with the AR system was with a bad mag. The round came out of the mag way too early. The point of the bullet wedged into the top of the upper and the barrel extension. One of the top lug corners struck the primer when the round stopped the bolt group and the round went off.
What brand of barrel did you use? Did the feed ramps of the 7.62X39 barrel get modified for use with that ammo? My first machine gun was a Colt M16. I bought a Colt 7.62X39 carbine for the upper. Since 7.62X39 is larger in diameter and the larger diameter, so the standard M4 feed ramp would need to be widened and lowered. The magazine is fixed for height. So I have found that widening and deepening the feed ramps on an upper with standard feed ramps makes a huge difference. If your 7.62X39 barrel has a standard M4 feed ramp, maybe rounding the top of the feed ramp for the wider round then polishing it would help the steel cased ammo to feed into the barrel?
What comes to my mind is that the follower of the 7.62X39 AR mags are not pushing up the front of the round and/or the feed ramps are not deep enough to catch the tip of the round to guide the round into the chamber. The roughness or stickiness of the steel cased ammo might be just enough resistance to not allow the nose of the round into the feed ramp. Where as, the brass is slippery enough to allow the nose of the brass cased ammo to nose up enough to feed into the chamber.
The two lowest lugs push the rounds out of the magazines. If the round nose dives, I would think that the nose of the round diving down would tend to stop the round. With the round tipped down, I could see where the sharp corner of the lug of the bolt could push the primer hard enough to activate the primer causing an out of battery detonation.
It could also be the shape of the bullet nose between the brass and steel cased ammunition effecting how the ammunition interacts with the feed ramps.
For me modifying the feed ramps on a PSA 7.62X39 upper, is no big deal. Of course modifying the feed ramp profile of a Lage 3,000.00 upper would be a much bigger deal. I have shot a friend’s Lage Max-11/15 upper on my M11/NINE, but I don’t remember if the upper has M4 feed ramps. I would think that it would. But I don’t remember. I am glad you have your Max- /15 running in 7.62X39. It’s too bad that it won’t run your steel cased. What does the feed ramps on your 7.62X39 look like?
I bought a bunch of the 1,260 round cases of the corrosive primer brass cased Yugoslavian 7.62X39 ammo. SG Ammo has the Yugoslav brass cased in 1120 round cases on stripper clips for $588.00 per case shipped. Just remember it is corrosive baridium primed and red lacered sealed. This is the link, if anyone is interested.
1120 Round Crate 7.62x39 M67 Non-magnetic Copper FMJ Brass Case Corrosive Yugo Surplus Ammo on SKS Stripper Clips | SGAmmo.com
SGAmmo.com, bulk ammo sold by the case at the best lowest prices for sale anywhere online
Please keep us updated.
Scott
Believe me I racked my brain trying to figure out the cause. You can read about it in THIS thread. It was really damaging my upper so once I found out brass would work I stopped messing with the steel. THIS specific post has slo-mo video linked. I would LOVE to be able to shoot steel but not at the expense of having to spend another $3k on a new 10/15 upper.
A&S Conversions
UZI Talk Life Member
In rereading the original thread, it seems to me that bolt bounce was the issue along with the hard primers of the steel cased ammo delaying the ignition of the round. That delay in the ignition of the round would allow the carrier to bounce off of barrel extension, partially unlocking the bolt. If the bolt was partially unlocked, that, I would think, would cause the damage that occurred. If the bolt was completely unlocked, it would come flying back crashing into the back of the M10 registered receiver. But it seems like the bolt was not completely out of battery, but enough out of battery to cause the damage you have had a couple of times.
In the M16 system, typically there is a buffering system to help hold the carrier to the barrel extension such that, if the hammer release timing isn’t exact, the bolt will still be in battery enough for the firing pin to activate the primer. So in the typical M16 bolt bounce situation, the buffering system holds the bolt locked but not close enough for the firing pin to be close enough to the face of the primer for reliable ignition. The M16 system when used with Eastern Block hard primers tends to have better function with a larger diameter point of the firing pin that has a little more protrusion for the hard primers.
With the Lage fixed firing pin system, I would think that if there would be a delay in the activation of the hard primer from the standard AR firing pin, that delay of ignition along with no mechanism to mitigate bolt bounce, could partially unlock the bolt after that delayed ignition.
“Techspy”, I would think that with a firing pin specifically designed for the hard Russian primers that have a larger diameter tip and a little more protrusion would eliminate the out of battery detonations that you have experienced with the steel cased ammunition. Again , I think that you aren’t experiencing the out of battery detonations with the brass cased ammo, because it tends to have softer primers that activate much easier.
Of course I could be wrong but that seems like the problem to me. Certainly the extra power recoil spring could help drive the standard firing pin into the hard primers. But the higher spring pressure would also tend to increase the rate of fire. Some guys like a high rate of fire. I tend to like a slower rate of fire for better controllability. Good luck with the 7.62X39 configuration.
Scott
In the M16 system, typically there is a buffering system to help hold the carrier to the barrel extension such that, if the hammer release timing isn’t exact, the bolt will still be in battery enough for the firing pin to activate the primer. So in the typical M16 bolt bounce situation, the buffering system holds the bolt locked but not close enough for the firing pin to be close enough to the face of the primer for reliable ignition. The M16 system when used with Eastern Block hard primers tends to have better function with a larger diameter point of the firing pin that has a little more protrusion for the hard primers.
With the Lage fixed firing pin system, I would think that if there would be a delay in the activation of the hard primer from the standard AR firing pin, that delay of ignition along with no mechanism to mitigate bolt bounce, could partially unlock the bolt after that delayed ignition.
“Techspy”, I would think that with a firing pin specifically designed for the hard Russian primers that have a larger diameter tip and a little more protrusion would eliminate the out of battery detonations that you have experienced with the steel cased ammunition. Again , I think that you aren’t experiencing the out of battery detonations with the brass cased ammo, because it tends to have softer primers that activate much easier.
Of course I could be wrong but that seems like the problem to me. Certainly the extra power recoil spring could help drive the standard firing pin into the hard primers. But the higher spring pressure would also tend to increase the rate of fire. Some guys like a high rate of fire. I tend to like a slower rate of fire for better controllability. Good luck with the 7.62X39 configuration.
Scott
m11stuff@hotmail.com
UZI Talk Life Member
- Joined
- Nov 30, 2004
- Messages
- 2,136
Anytime you change the barrel on one of our rifle caliber uppers, you need to check the headspace with a GO/NO GO gage. For 7.62x39 we recommend using one of the Toolcraft brand 7.62x39 bolts and firing pins for reliable functioning. I also have a micrometer case gage that I use to test a new lot of ammo before and after firing to make sure the case does not stretch. Do not use lacquer coated steel case ammo EVER. I have used steel cased 7.62x39 ammo without issue.
Yep. I have go and no go gauges and they indicated it was fine. Don't recall the specific brand at the moment but tried 2 different bolts and pins and even 2 barrels. One was an "enhanced" firing pin. I tried lacquer and non coated with the same behavior.
Last edited:
SG has been doing wacky things. no longer the best price around. I've bought a lot of ammo from them.Have you ever thought of comparing the steel cased to the brass cased ammunition? The Russian steel cased is known to have hard primers rather than soft sensitive primers. The AR system is designed to be locked (the bolt rotates in line with the locking lugs of the lugs of the barrel extension) before the firing pin can protrude from the bolt face enough to activate the primer. It would seem to me that since the brass cased ammunition works properly, I would think that the steel cased ammunition might be out of spec?
The only time I have had an out of battery discharge with the AR system was with a bad mag. The round came out of the mag way too early. The point of the bullet wedged into the top of the upper and the barrel extension. One of the top lug corners struck the primer when the round stopped the bolt group and the round went off.
What brand of barrel did you use? Did the feed ramps of the 7.62X39 barrel get modified for use with that ammo? My first machine gun was a Colt M16. I bought a Colt 7.62X39 carbine for the upper. Since 7.62X39 is larger in diameter and the larger diameter, so the standard M4 feed ramp would need to be widened and lowered. The magazine is fixed for height. So I have found that widening and deepening the feed ramps on an upper with standard feed ramps makes a huge difference. If your 7.62X39 barrel has a standard M4 feed ramp, maybe rounding the top of the feed ramp for the wider round then polishing it would help the steel cased ammo to feed into the barrel?
What comes to my mind is that the follower of the 7.62X39 AR mags are not pushing up the front of the round and/or the feed ramps are not deep enough to catch the tip of the round to guide the round into the chamber. The roughness or stickiness of the steel cased ammo might be just enough resistance to not allow the nose of the round into the feed ramp. Where as, the brass is slippery enough to allow the nose of the brass cased ammo to nose up enough to feed into the chamber.
The two lowest lugs push the rounds out of the magazines. If the round nose dives, I would think that the nose of the round diving down would tend to stop the round. With the round tipped down, I could see where the sharp corner of the lug of the bolt could push the primer hard enough to activate the primer causing an out of battery detonation.
It could also be the shape of the bullet nose between the brass and steel cased ammunition effecting how the ammunition interacts with the feed ramps.
For me modifying the feed ramps on a PSA 7.62X39 upper, is no big deal. Of course modifying the feed ramp profile of a Lage 3,000.00 upper would be a much bigger deal. I have shot a friend’s Lage Max-11/15 upper on my M11/NINE, but I don’t remember if the upper has M4 feed ramps. I would think that it would. But I don’t remember. I am glad you have your Max- /15 running in 7.62X39. It’s too bad that it won’t run your steel cased. What does the feed ramps on your 7.62X39 look like?
I bought a bunch of the 1,260 round cases of the corrosive primer brass cased Yugoslavian 7.62X39 ammo. SG Ammo has the Yugoslav brass cased in 1120 round cases on stripper clips for $588.00 per case shipped. Just remember it is corrosive baridium primed and red lacered sealed. This is the link, if anyone is interested.
1120 Round Crate 7.62x39 M67 Non-magnetic Copper FMJ Brass Case Corrosive Yugo Surplus Ammo on SKS Stripper Clips | SGAmmo.com
SGAmmo.com, bulk ammo sold by the case at the best lowest prices for sale anywhere online
Please keep us updated.
Scott
Telammo is around $450/1000 right now. Box says non corrosive but until proven to be so I'd treat as corrosive.
Why not lacqure? Only problem I've had with lacqure was filling in the FP hole on an AK I was running very hot and hard. I use lacqure most frequently in my AR in x39. Tends to run better in my AKs, my AKSU doesn't like the other stuff.
m11stuff@hotmail.com
UZI Talk Life Member
- Joined
- Nov 30, 2004
- Messages
- 2,136
In my testing with a hot barrel, a round would fire, but not extract, with the bolt locked in battery. This typically happened around the 4th round fired.
Interesting. too bad I don't have a M16 lower to test with in my x39 AR upper and see if I get the same results.
My AKSU has similar issues, poor extraction, but only with poly coated ammo. Lacqure ammo fixed my issue.
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