Been wondering for a while why good working mags in 7.62x39 have trouble so often so I rounded up what I have on hand and started measuring with the Brown & Sharpe Slantline one inch micrometer. Here are the results of how thick the metal is that the mags are made from.
Colt 20 rd Cal 5.56 metal follower -- .040" of aluminum
Colt 30 round GI, the same
Adventure Line 20, the same
Adventure Line 30, the same
no-name curved 20--.022" of steel
no-name 40-- .025" of steel
C-Products 6.5 G 10rd--.021"
Seems to me some of these needed to be made of thicker metal, at least in the feed lip area.
Now there is a problem with rounds based on the 7.62x39 Soviet round, by the time you allow the rounds to proper double stack there isn't a lot of space left between them and the magwell,bout .090" and thats not allowing for clearance to insert he mag. Oh and take a look at your mags, see those pressed in ribs? There aren't there to look cool, the keep the rounds positioned for proper feeding and allow dirt and give such a chance to get out of the way so rising rounds don't jam up.
If you followed Colt's practice you would have bout -.010" left. How did I get that number? Well the blueprint calls for the well to be .898" wide though everything I have measured comes in at .900 to .920" and a double stack of 7.62 is .825" so that leaves .075". Two walls of .040" plus clearance to insert and you have a problem.
What to do.....
Enlarge the mag well? Several have been made and not sold that well.
Build a single stack? I see this selling poorly too, the largest market is guys who want hi-cap.
Build thin mags with reinforced mag lips? Can't go as far as the AK pattern but it could be done and easier for 7.62 than 6.5 or 6PPC as only the back of the mag is tight.
Give up and downsize to the base and rim dia of the 6.8 and 30 Rem? Personal opinion, I have a thing against 270s, never understood the need for a size between the 6.5s {wrote in error 30-06} and 7 Mauser. That said if SPC brass got cheap and plentiful necking it up to 7mm should make for a great eastern/woods round, infact I'm suprised Rem didn't as they have a love affair with the number 7.
Anybody else want to measure the metal thickness of their mags, or have an idea on how to run 7.62x39 in a AR15 doublestacked in a economical fashion?
BTW, at least in this thread, stuffing rounds into a underwide mag so that the two stacks of ammo don't touch the round above or below is not doublestacked.
Colt 20 rd Cal 5.56 metal follower -- .040" of aluminum
Colt 30 round GI, the same
Adventure Line 20, the same
Adventure Line 30, the same
no-name curved 20--.022" of steel
no-name 40-- .025" of steel
C-Products 6.5 G 10rd--.021"
Seems to me some of these needed to be made of thicker metal, at least in the feed lip area.
Now there is a problem with rounds based on the 7.62x39 Soviet round, by the time you allow the rounds to proper double stack there isn't a lot of space left between them and the magwell,bout .090" and thats not allowing for clearance to insert he mag. Oh and take a look at your mags, see those pressed in ribs? There aren't there to look cool, the keep the rounds positioned for proper feeding and allow dirt and give such a chance to get out of the way so rising rounds don't jam up.
If you followed Colt's practice you would have bout -.010" left. How did I get that number? Well the blueprint calls for the well to be .898" wide though everything I have measured comes in at .900 to .920" and a double stack of 7.62 is .825" so that leaves .075". Two walls of .040" plus clearance to insert and you have a problem.
What to do.....
Enlarge the mag well? Several have been made and not sold that well.
Build a single stack? I see this selling poorly too, the largest market is guys who want hi-cap.
Build thin mags with reinforced mag lips? Can't go as far as the AK pattern but it could be done and easier for 7.62 than 6.5 or 6PPC as only the back of the mag is tight.
Give up and downsize to the base and rim dia of the 6.8 and 30 Rem? Personal opinion, I have a thing against 270s, never understood the need for a size between the 6.5s {wrote in error 30-06} and 7 Mauser. That said if SPC brass got cheap and plentiful necking it up to 7mm should make for a great eastern/woods round, infact I'm suprised Rem didn't as they have a love affair with the number 7.
Anybody else want to measure the metal thickness of their mags, or have an idea on how to run 7.62x39 in a AR15 doublestacked in a economical fashion?
BTW, at least in this thread, stuffing rounds into a underwide mag so that the two stacks of ammo don't touch the round above or below is not doublestacked.
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