So.. I ordered a 80% lower fixed mag from DSI and I built a AR-10 .308, love it. I decided to order a 80% Fixed Mag Lower Receiver from again from DSI (Dark Storm Industry) for an AR-15 and when it got to my FFL I noticed it said .556. I bought it and kept it because it said “MULTI”. Turns out it’s a Multi Mil-spec receiver. Cool right?. My complete upper is set for a 7.62x39 and I understand it will fit on the .556 lower with some rounds being limited. As of right now I can fit only 5 successfully. Why the heck are there not fixed mags for a 7.69x39?? Can I shoot this the way it is and not blow my hand up? Recommendations?
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AR-15
- Thread starter Mr AR
- Start date
Golddiggie
NES Member
300 Blackout has the same ballistic characteristics as 7.62x39 and WILL work 100% with any AR15 lower (that's not made specifically for AK ammo).
Pretty sure the info about how 7.62x39 needs a specially lower (magwell) configuration is easily found on the interwebz. Also, "multi" typically means ammo that will fit into a magazine of the same geometry as a standard AR15 magazine. AK ammo doesn't fall into that category. That's why the AK mags are shaped as they are. If you compare the rounds side by side you'll see the difference (it's not minor).
Here's 300blk next to 7.62x39:
300blk cases have the same bottom section (below the shoulder) as 5.56/.223 does.
Pretty sure the info about how 7.62x39 needs a specially lower (magwell) configuration is easily found on the interwebz. Also, "multi" typically means ammo that will fit into a magazine of the same geometry as a standard AR15 magazine. AK ammo doesn't fall into that category. That's why the AK mags are shaped as they are. If you compare the rounds side by side you'll see the difference (it's not minor).
Here's 300blk next to 7.62x39:
300blk cases have the same bottom section (below the shoulder) as 5.56/.223 does.
5-7 rounds of 7.62x39 is all you are going to fit in a 5.56 mag. Buy a 10 round 7.62x39 AR mag, remove the 5.56 mag that is fixed to the lower (all you need is a drill), add the 7.62 mag and buy yourself Means Arms fixed mag kit to make it fixed again.
Better yet, forget the stupid fixed mag. Fixed mag lowers are as gay as Healey.
Better yet, forget the stupid fixed mag. Fixed mag lowers are as gay as Healey.
They sell 7.62x39 mags for AR lowers; Duramag/C Products/ASC to name a few.
Golddiggie
NES Member
IIRC, the bend in those are different than typical AR mags though. Plus the feed lips are different (also IIRC). I don't have anything in 7.62x39. I do have a 6.5 Grendel upper that mates without issue to a typical AR15 lower. Mags are different due to the round geometry (lower count, different bend).
BTW, being limited to 10 round mag's (max capacity) is more ghey than Healey.
I see. It’s funny because I was looking at the .300 black out and the 7.62x39. I didn’t take account as to the shape of the 7.62x39 and how you stack up several side by side it starts to curve. My error Ofcourse but I’m down for the learning.
Golddiggie
NES Member
As long as you learn from your missteps, it's not that bad... Worse case you could offload the 7.62x39 upper, build a 300 blackout upper (easy as hell) and not need to dick around with the lower.
Trust me the fixed mag was definitely not my preferred method just due to the stupid state I had to get it. I thought we had to get a fixed mag cuz of the “assault weapon” ban. For legal reasons wouldnt that be a bad thing? I live in Massachusetts
Yea, C Products and ASC make 10 round 7.62x39 mags, which take the round geometry into consideration, that the OP can utilize if he wants to remove the fixed 556 mag.
ASC 7.62x39 10 Round AR Magazine
DURAMAG / C Products SS 7.62x39 10 Round AR Magazine
The 20 and 30 rounders have that weird ass bend you are talking about:
Most people on here were fixing 10 rounders to their lowers to get around the whole AR pistol restriction. Some do it to as a CYA from Healey's notice (which is not a ban). Others don't give a shit IE me.
Got it thank you for the tag/input. I’ll look into this some more as I am seeing a lot of ppl on other forums list this type of information. From what I hear C products and Duramag are pretty good.Yea, C Products and ASC make 10 round 7.62x39 mags, which take the round geometry into consideration, that the OP can utilize if he wants to remove the fixed 556 mag.
ASC 7.62x39 10 Round AR Magazine
DURAMAG / C Products SS 7.62x39 10 Round AR Magazine
The 20 and 30 rounders have that weird ass bend you are talking about:
I put together my own fixed mag lower a year and a half ago (then sold it) as a FU to Healey. Super easy to do yourself.
*Buy the 10 round 7.62x39 mag specifically for AR15 lowers
*Drill out the bolt that fixes the mag through the bolt release hole
*Insert 7.62x39 AR specific mag
*Order and install a Means Arms MA lock to make it fixed again. MA Lock | Mean Arms
Believe me I saw a fixed mag but for 10 rounds which I almost bought however I was unsure at the time and didn’t know what to think. I live in Massachusetts so not sure if that would be considered an “Illegal” mod by this stupid state law. If I went that route it’s MUCH cheaper than buying another upper and ammo.
Golddiggie
NES Member
The only thing different on a 300blk upper compared with a 5.56/223 upper is the barrel and muzzle device (due to threading on the barrel). Everything else is the same. That was one of the design parameters given. I've built up two 300 blackout uppers so far. Also being able to swap parts (that are easy to do so) between the two calibers is really nice. Since the cartridge base is identical, the BCG can be easily moved between them.
As for the 7.62x39 ammo... I'm sure you could sell that along with the upper if you wanted to and not take too much of a hit.
Jesus Christ. Should have just bought a standard non-fixed mag lower and avoid any headaches. Let me guess, did a dealer on the south shore say fixed mag lowers or pre-ban (1994) lowers are the only legal option??
I see. The .300 black out was my 2nd choice of ammo but for some reason the 7.62x39 jumped at me. I should have researched a little more. Wouldn’t the .300 blk out need the the 7.62x39 BCG and charging handle?
I would actually keep the 7.62x39 and I think I’ll keep the upper. One of those swap if need be or if some how some way the law gets revoked and we can insert mags. That would be terrific
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No actually. The state law I was not so sure about and decided to buy a fixed lower. Due to my ignorance I did not know the AR-15 fixed mag I bought was a .556. Not I didn’t ask. Yes I could have researched more but the AR-15 platform is unique which I like.
Standard AR lowers are plentiful and legal in MA
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I loved my 9" 300 BO upper. Sold it because wanted to finance something else and at the time, subs were like $1.50/2 a round. Now that I can find 200 grain subs for under $1 now, I am having the urge to maybe put together another 300 BO upper.
Buck F
NES Member
pastera
NES Member
300 AAC (black out) is the correct SAAMI designation.
The cartridge has the 223 Rem as a parent cartridge so you can just cut a 223 case at the shoulder and form it into a 300AAC case.
Max COAL for 300AAC is the same as 223.
And you can insert mags, they just need to be 10rnd max or pre-94.
Unless you have other evil features like a threaded barrel, flash hider or adjustable stock there is little legal reason to have a fixed mag lower.
Are you serious?Standard AR lowers are plentiful and legal in MA
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AR15 and AR10 lowers at unheard of prices in Mass! Aero M4A1 Stripped Black 150 Aero M16A4 Stripped Black 150 Aero M4E1 Complete Black 325 Aero M4E1 Complete FDE 350 Aero M4E1 Stripped Black 150 Aero M4E1 Stripped FDE 175 Aero M5 Complete Black 400 Aero M5 Complete FDE...
you mean to tell me if I had bought one of those instead and slapped a 10 round msg I would have been good to go? If that’s the case shit. Well I’m learning and this AR-15 is 2nd built AR.
Buck F
NES Member
Live & learn... we have all made mistakesAre you serious?
If that’s the case shit. Well I’m learning and this AR-15 is 2nd built AR.
That’s the part of the law that I was very confused about. The law states “
Semi-automatic rifles manufactured after 9/13/1994 with detachable magazines and two or more of the following features:
- Folding or telescoping stock
- Pistol grip
- Bayonet mount
- Flash hider or threaded barrel designed to accommodate one
- Grenade launcher
- Magazine that attaches outside the pistol grip
- Threaded barrel to attach barrel extender, flash suppressor, handgrip, or suppressor
- Barrel shroud safety feature that prevents burns to the operator
- Unloaded weight of 50 oz (1.4 kg) or more
- A semi-automatic version of a fully automatic firearm “
pastera
NES Member
No - He's giving you shit because that's what we do around here.
There's what's legal and what people believe is legal.
The "copies and duplicates" memo/press release did not change what is actually legal.
His "brain is breaking' because you stated a 80% fixed mag.
So you know that "ghost guns" are actually legal but don't understand that fixed mags aren't required unless you want a different evil feature.
He's having trouble understanding the disconnect and is being very polite by NES standards about how he states it.
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