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Posted: 1/28/2012 3:23:47 PM EDT
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http://www.ar15.com/forums/t_6_2/361949_Bushmaster_ACR_in_7_62x39.html
If you read down in this a bit you'll come to the following: "I talked to a Busmaster engineer at SHOT 2012 and he said that the ACR 7.62x39 conversion will not use AK mags because they couldn't get it to work reliably with the rifle. Each rifle would require too much individual fitting and testing to confirm function to make it practical. It has nothing to do with AK mags being unreliable, it has to do with the design differences between the ACR and the AK." Why is this so difficult? I can understand that getting a straight AK-47 magazines to work in an AR-15 is a problem but in the ACR you could take out the entire piece that has the magazine well in it and replace that with one specifically designed for the AK-47 style magazines. After all the ACR was suppose to be adaptive so why cann't you just swap out the magazine well area and use one designed for an AK-47 magazines? If ever a rifle should have been able to use both AR-15 and AK-47 style magazines I would have thought that the ACR would have been it. So why is this so hard? |
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Quoted: http://www.ar15.com/forums/t_6_2/361949_Bushmaster_ACR_in_7_62x39.html If you read down in this a bit you'll come to the following: "I talked to a Busmaster engineer at SHOT 2012 and he said that the ACR 7.62x39 conversion will not use AK mags because they couldn't get it to work reliably with the rifle. Each rifle would require too much individual fitting and testing to confirm function to make it practical. It has nothing to do with AK mags being unreliable, it has to do with the design differences between the ACR and the AK." Why is this so difficult? I can understand that getting a straight AK-47 magazines to work in an AR-15 is a problem but in the ACR you could take out the entire piece that has the magazine well in it and replace that with one specifically designed for the AK-47 style magazines. After all the ACR was suppose to be adaptive so why cann't you just swap out the magazine well area and use one designed for an AK-47 magazines? If ever a rifle should have been able to use both AR-15 and AK-47 style magazines I would have thought that the ACR would have been it. So why is this so hard? My guess would be bolt carrier interference with the AK mags. If you had to change the barrel w/ gas system, lower, bolt w/ carrier and mags... what are you actually keeping? The upper, stock, and lower handguard is all I can think of... (I suppose you could argue that the trigger group could be moved to the second lower) Even if there isn't a bolt carrier issue, I think needing to change so many components would make an AK mag conversion a hard sell. |
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Well ok. But the AR's that I'm aware of that shoot 7.62x39 seem to have magazine issues. One company told me that all you have to change in a 223 magazine is the follower. Do that and everything is ok. Another company said that they buy special magazines. Ones specifically designed to feed the 7.62x39 into AR's without any problems.
But some people say that they two approaches work and some claim that they don't work particularly well. What is the truth here? Could you expect a Yankee Hill 7.62x39 or a Bushmaster ACR 7.62x39 to work reliably? |
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Quoted: Well ok. But the AR's that I'm aware of that shoot 7.62x39 seem to have magazine issues. One company told me that all you have to change in a 223 magazine is the follower. Do that and everything is ok. Another company said that they buy special magazines. Ones specifically designed to feed the 7.62x39 into AR's without any problems. But some people say that they two approaches work and some claim that they don't work particularly well. What is the truth here? Could you expect a Yankee Hill 7.62x39 or a Bushmaster ACR 7.62x39 to work reliably? I doubt you'd have much success with 5.56 mags w/ swapped follower as the taper of the rounds require different curvatures of the mags. (but I have not tried it) My experience with AR mags designed for 7.62x39 has been good with 30 rounders but bad with 10 round mags. Although it seems the most recent AR 7.62x39 mags are improved over initial attempts, I can't say I really trust them either. Nor do I like the relative lack of options (1 current manufacturer). Also, forgot to mention earlier that the fact that the AK mags would cause the ACR to loose it's bolt hold open capability probably is another reason why they'd shy away from them. |
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I'm going to toss my completely uneducated .02 in.
I suspect the problem comes to the essential design. Take a look at the AK47. The magazines rock in and the bolt and barrel is right there. As already mentioned, the 7.62x39's case has significant taper to it, so when you stack them against each other, they curve rather dramatically. AK mags have a consistent curve built into them. AR 7.62x39 mags, however, must have a straight section at the top to fit into the straight magwells on ARs. So there isn't consistent curvature. This makes for a propensity for rounds get wonky. I also suspect the differences between bolts and magazine feed lips may contribute to the problems. Now, it's obviously not an insurmountable task. As I've said, my XCR has been great with both 5.56 and 7.62x39. But I just got my 7.62x39 kit last year. I didn't have the experience of going through all the problems with the magazines that others did. C-Products had at least 3 generations of magazines trying to work out spring tension and followers and what have you. There are other AR type magazines too. Some Colt mags were 5.56 with different followers. Some were hybrids, where people would chop up an AR mag and an AK mag and weld them together so that there was an AR straight section for the magwell on an AK curved mag. As I stated before, the only manufacturer making AR 7.62x39 mags seems to be ASC. They appear to have built on C-Products work and have a solid product from my experiences. I really don't see how you could do an AK lower on the ACR easily. To me, it's all about the distance from the bottom of the receiver to the bolt. Very little distance on the AK...much more on the AR/ACR. But then, I'm not an engineer and have no expertise whatsoever. |
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I asked this question to CZ concerning their new 805. Here is their answer.
Dear Ken, Thank you for your interest in our products. In my opinion there is a misunderstanding and I would like to clear it up. The assault rifle CZ 805 BREN is chambered in TWO different calibers: 5,56 x 45 NATO and 7,62 x 39. It means that the CZ 805 BREN cal. 5,56 x 45 differs from the CZ 805 BREN cal. 7,62 x 39 in - the barrel - the bolt assembly - the magazine With regard to the magazines I would like to call you attention to the fact that the assault rifle CZ 805 BREN is delivered with the original magazines made by our company. However, in case of the CZ 805 cal. 5,56 x 45 the original magazine well can be replaced by an interchangeable magazine housing that enables the use of magazines cal. 5,56 x 45 intended for the M4/M16 rifles. On the other hand, the AK-47 magazines cannot be used in the CZ 805 BREN (there are various reasons, firstly there is quite a big difference between this kind of magazines and the original CZ magazine for CZ 805 BREN. Besides, the AK 47 magazines are made by so many producers in all the world that the qualities and properties of these magazines differ too much and our company could not guarantee their general and correct functioning in CZ 805 BREN). Looking forward to hearing from you. Yours truly Richard Zapletal Media Liaison Manager CESKA ZBROJOVKA A.S. SVATOPLUKA CECHA 1283 |
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Quoted:
Quoted:
"Com-bloc tolerances". Is that supposed to be a joke? 
Irony: "Typically imply a meaning in opposition to their literal meaning. A situation is often said to be ironic (situational irony) if the actions taken have an effect exactly opposite from what was intended." 
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