Explain lowers marked "multi cal" please.

[fritz1919]

It sounds self explanatory, but am I missing something??

I got out three different caliber mags. 5.56x45, 5.45x39 and 7.62x39. Granted all three are different brands, but only one of those three is going to go into my AR.

Is it all about the brand used? Would a Magpul mag in 7.62 or 5.45 fit my AR.

One of these days I just may have enough spare time to build a rifle. I want to make sure I don't drop coin on the first part to find out it can't be used for what I intended.

Thanks in advance.
fritz

[daschnoz]

I have a feeling that the alphabet boys don't like people swapping uppers and having a 5.45x39 upper on a lower that is marked 5.56NATO.

[Nate7667]

Multi caliber means nothing when you're building a normal 16"+ upper. You can make it into what ever caliber you want in the AR world. (22LR/9mm/45ACP/556/5.45/7.62x39/300Blk)
Build away with your "multi" lower.

The only time you need to be specific is when you are filing a Form 1 to create and Short Barreled Rifle. Then you must pick a caliber and file the paperwork as such. You can always swap the upper later with any different caliber you want at any time without issues, the ATF just wants to keep the registry clean and easy. But i dont think you are heading that direction.

As for the Magpul 7.62 and 5.45 mags, or any other AKM style mags, unless you have a Palmetto KS47 lower or an MGI lower that can take AK47/AK74 specific magazines, you will NEVER get either of those mags to fit into your AR lower.
You need to find AR platform mags that made for those calibers, AK style mags will not work.
ASC and C-Products were making both calibers last i checked. My C-products 5.45x39 mags worked fine when i got into that caliber 6-7 years ago.

[Noah_Zark]

^^^ THIS.

Beat me to it.

Noah

[Orlov556]

What everyone else said. Just to add, as a general rule, if the round wont fit in a standard AR mag, the lower isnt going to work with your bulid. Of course there are exceptions such as the 9mm block available if you are building a 9mm carbine, but a round like 7.62x39 round is never going to fit into a standard AR lower.

The multi mainly pertains to exotic calibers such as the .300 BO, .50 Beowolf (i think the springs and follower are changed with that one tho) and some of the 6.5 stuff that I don't know enough about to speak intelligently about.

.308 on the other hand requires a receiver larger than a standard AR receiver. Look at the size difference between a .308 PMAG and a standard and you will see why they would never work.

[Nate7667]

What everyone else said. Just to add, as a general rule, if the round wont fit in a standard AR mag, the lower isnt going to work with your bulid. Of course there are exceptions such as the 9mm block available if you are building a 9mm carbine, but a round like 7.62x39 round is never going to fit into a standard AR lower.

The multi mainly pertains to exotic calibers such as the .300 BO, .50 Beowolf (i think the springs and follower are changed with that one tho) and some of the 6.5 stuff that I don't know enough about to speak intelligently about.

.308 on the other hand requires a receiver larger than a standard AR receiver. Look at the size difference between a .308 PMAG and a standard and you will see why they would never work.

Any mil-spec AR15 lower can take the 7.62x39 cartridge. The 7.62x39 round is shorter than the 5.56x45 round.
So yes, it will fit inside a standard AR/556 mag and a standard lower receiver.
It wont feed very well do to the mag shape and follower being designed for the 556 case/shoulder though.

[Orlov556]

Any mil-spec AR15 lower can take the 7.62x39 cartridge. The 7.62x39 round is shorter than the 5.56x45 round.
So yes, it will fit inside a standard AR/556 mag and a standard lower receiver.
It wont feed very well do to the mag shape and follower being designed for the 556 case/shoulder though.

I guess I should have said "function." Unless you know of some way of getting a 7.62x39 to function in a standard AR mag, I think my point was pretty clear. But I guess we are nitpicking.

[ftownkev]

As for the Magpul 7.62 and 5.45 mags, or any other AKM style mags, unless you have a Palmetto KS47 lower or an MGI lower that can take AK47/AK74 specific magazines, you will NEVER get either of those mags to fit into your AR lower.
You need to find AR platform mags that made for those calibers, AK style mags will not work.
ASC and C-Products were making both calibers last i checked. My C-products 5.45x39 mags worked fine when i got into that caliber 6-7 years ago.

Don't listen to Nate if you have a saw, file and a hammer you can make that AK mag fit in your AR. LOL

[Nate7667]

Don't listen to Nate if you have a saw, file and a hammer you can make that AK mag fit in your AR. LOL

Amateur...Do it the right way, use a Dremel

[USMC3531]

I guess I should have said "function." Unless you know of some way of getting a 7.62x39 to function in a standard AR mag, I think my point was pretty clear. But I guess we are nitpicking.

http://gunmagwarehouse.com/asc-7-62x...-magazine.html