AR upper question

mmacro · Oct 9, 2016

Can someone clarify an AR question?

Under the MD law an AR-15 must have an HBAR.

But I started reading the specific code and list of banned/allowed weapons.

The list specifically stated that the state made the determination that an HK MR556A1 was not an AR-15 because it is a gas piston design and the bolt system is not interchangeable. And there are other companies that make clones of the HK piston system.

Do the piston systems need a HBAR? Or, because they are not considered an AR-15 are they exempt from the HBAR requirement?

Lastly, does the state consider a M4 collapsible stock a "folding stock" for the purposes of it becoming an "assault weapon"?

I'm just tying to figure out what I can put together in a legal configuration... piston driven, muzzle brake, collapsible stock, government barrel.

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lazarus · Oct 9, 2016

Not sure on your first question. On your last, it is an adjustable stock, it is not a folding stock so it is not an evil feature.

mopar92 · Oct 9, 2016

Piston driven is not subject to the HBAR requirement but pistons suck for reliability and accuracy (picture a mini jackhammer attached to your barrel) and they weigh more than a DGIS. Collapsing stock such as on the AR is legal, folding is also legal but eliminates the chance to use a flash hider or a grenade launcher.

mmacro · Oct 9, 2016

lazarus said:
Not sure on your first question. On your last, it is an adjustable stock, it is not a folding stock so it is not an evil feature.

The document published by the state that outlines banned guns clearly states clearly that the HK MR556A1 was not an AR-15 because the bolts are not interchangeable due to it being a piston driven system.

My question is... because they don't classify it as an AR-15 is it required to have the HBAR barrel in MD?

As far as I know HK does not make the rifle with an HBAR.

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mmacro · Oct 9, 2016

mopar92 said:
Piston driven is not subject to the HBAR requirement but pistons suck for reliability and accuracy (picture a mini jackhammer attached to your barrel) and they weigh more than a DGIS. Collapsing stock such as on the AR is legal, folding is also legal but eliminates the chance to use a flash hider or a grenade launcher.

I was under the impression that the HK system is very reliable, and because it does not vent the gasses into the receiver it is much cleaner and thus less susceptible to carbon fouling/stoppages.

I've not had any experience with them... just exploring options.

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mopar92 · Oct 9, 2016

Slightly more reliable if you have a need to shoot directly after emerging from the water but is subject to cam pin drag and carrier tilt. There's also a full auto gun range (I think the name is Battlefield Las Vegas) that has reported very substandard accuracy and reliability with the uppers.

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Hawkeye · Oct 10, 2016

mmacro said:
My question is... because they don't classify it as an AR-15 is it required to have the HBAR barrel in MD?

No, because it is not legally a copy of an AR-15, due to the non-interchangeability of the parts.

davsco · Oct 10, 2016

just fyi but my lwrc m6a3dmr (piston) has been 100% no ifs, ands or buts over a bunch of 2 and 3 gun matches, so there are certainly some piston guns out there that run. likewise a local range had a rental full auto lwrc upper that ran and ran. maybe the other 99.99% of them suck, who knows, but the couple i'm familiar with, run.

k9guy · Oct 10, 2016

So you can put a piston upper without an HBAR on your newly built lower? I was under the impression that only HBAR were allowed on any purchased lower's after 10/1/13?

outrider58 · Oct 10, 2016

k9guy said:
So you can put a piston upper without an HBAR on your newly built lower? I was under the impression that only HBAR were allowed on any purchased lower's after 10/1/13?

I would warn you to stay away from piston conversions. Most are crap.

jonnyl · Oct 10, 2016

k9guy said:
So you can put a piston upper without an HBAR on your newly built lower? I was under the impression that only HBAR were allowed on any purchased lower's after 10/1/13?

I think it would be more accurate to say that you can't build a banned rifle (by the list or their copies) or a copycat weapon on a post 10/1/13 lower. There's a specific exemption for Colt HBAR AR15's (and their copies) so you can build an HBAR AR15. A piston upper operates differently enough from an AR15 that it is not considered a copy, so they are different categories.

I've never used a piston upper, but would put a lot of weight on the opinions of the experts here.

k9guy · Oct 10, 2016

outrider58 said:
I would warn you to stay away from piston conversions. Most are crap.

I was looking at an upper something like this.

http://www.adamsarms.net/16-mid-tactical-evo-upper

Just wanted to make sure it's ok to put it on a post 10/1/13 lower.

outrider58 · Oct 10, 2016

k9guy said:
I was looking at an upper something like this.

http://www.adamsarms.net/16-mid-tactical-evo-upper

Just wanted to make sure it's ok to put it on a post 10/1/13 lower.

Had two of them. They run on the edge of reliability(which is no bueno). I dumped them both.

Hawkeye · Oct 10, 2016

jonnyl said:
I think it would be more accurate to say that you can't build a banned rifle (by the list or their copies) or a copycat weapon on a post 10/1/13 lower. There's a specific exemption for Colt HBAR AR15's (and their copies) so you can build an HBAR AR15. A piston upper operates differently enough from an AR15 that it is not considered a copy, so they are different categories.

This is exactly right. The way that the law is written, the AR-15 and it's "copies" except the HBAR are banned. With the way that MSP defines "copy" which is interchangeable parts, a piston gun is different enough from a DI gun that it's no longer a "copy" of an AR-15, and thus not banned as long as it passes the copycat test.

bkuether · Oct 10, 2016

davsco said:
just fyi but my lwrc m6a3dmr (piston) has been 100% no ifs, ands or buts over a bunch of 2 and 3 gun matches, so there are certainly some piston guns out there that run. likewise a local range had a rental full auto lwrc upper that ran and ran. maybe the other 99.99% of them suck, who knows, but the couple i'm familiar with, run.

A few years ago, when my eyesight was better, I put 30 rounds in the ten spot, at 50 yards, with iron sights.

My Stag Arms Model 8 has never given me an issues. And carrier tilt is understood and most manufacturers have mods in place to compensate.

Now, would I take it into battle? No. As Cladestine said, "Piston guns have no spare parts among other DI guns".

But it is accurate and reliable.

AR upper question

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