.50 caliber pistol and rifle bore measurement >>> a Cali legal .50 BMG alternative!

[EBR Works]

I have seen numerous discussions that for DD classification .50 caliber pistol bores are measured groove to groove and rifle bores are measured land to land. Can someone point me to actual regulation that specifically states that this is how it's done? No opinions please, just show me the regulation/ATF guidlines. I have done searches to no avail. Thanks.

[vanderjack]

I have talked to the tech branch today on this, 1/2 hour ago.
Anyone saying rifles and pistol bore diameters are measured differently is nuts, PERIOD!

[bwiese]

That probably came about due to me.
I was relaying what I heard from Calgunner Mike Searson (who now lives in NV).

Mike was involved in some 50cal pistol development matters and I recall him saying there were some problems in initial development of some IMI/Magnum Research 50 stuff - and he's a knowledgeable guy.

Something may have gotten lost in translation from him to me, or from some piece of info to him....

However, anytime you get info from ATF Tech Branch (or DOJ) "get it in writing".

[EBR Works]

There we go. Thanks John and Bill!

So....pending written ATF agreement, a .50 BMG pistol would be legal in California since it is not a DD in Cali or at the Federal level. Plus it would not be a ".50 BMG rifle", so it would not violate the Cali BMG rifle ban.

Yes, I'm aware of the armor piercing ammo issue, but this has not happened with the few .308 AR pistols that are in existence. Obviously, if some manufacturer were to make a boat load of BMG pistols, it might cause a stir. Obviously, there is no big market for something like this.

I'm not saying that I'm going to do it, just final clarification that it is legal to do one....today.

This would need a forward grip to be manageable, hence an AOW transferred to a trust or corporation. It would also need a bullet button....Hmmmm



I love this:



It needs a bigger, more effective brake.



Let the firestorm of comments begin...now.


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[Bhobbs]

I think the issue was a .50 bore gauge would slide down the .50 AE Desert Eagle bore because it used polygonal rifling. They switched to using .50 dia bullets instead of .510 and changed the rifling which fixed the problem. At least that is what I have read.

[NightOwl]

Wrong forum?

[EBR Works]

Wrong forum?

We are discussing Federal and State regulation. Seems like it is the correct venue. I'll defer to the mods, of course...

[CHS]

I'm not saying that I'm going to do it, just final clarification that it is legal to do one....today.

This would need a forward grip to be manageable, hence an AOW transferred to a trust or corporation. It would also need a bullet button....Hmmmm

That wouldn't be a pistol. It would be a Title 1 "other" and not be subject to AOW requirements because there is NO WAY it could possibly be less than 26" in length.

Basically, it would be the legal equivalent of the Ma Duece. Legally, they can have a sub-16" barrel because they are not rifles, though California defines anything less than 16" as a pistol, even though it's not. So you would want to keep a 16" barrel.

So yeah, legal today Federally and in CA.

[JagerTroop]

So, how is the bore measured? Largest possible measurement of the bore?

Also, .500" (actual measurement) is no-go, but .499999999999999" is OK, yes?

That wouldn't be a pistol. It would be a Title 1 "other" and not be subject to AOW requirements because there is NO WAY it could possibly be less than 26" in length.

Basically, it would be the legal equivalent of the Ma Duece. Legally, they can have a sub-16" barrel because they are not rifles, though California defines anything less than 16" as a pistol, even though it's not. So you would want to keep a 16" barrel.

So yeah, legal today Federally and in CA.

So.... No fixed mag.

[EBR Works]

So.... No fixed mag.

It would not be a rifle or a pistol, so it would appear that you would not need a BB.


So, you could have a forward grip with a 16" barrel and not be an AOW. Alternatively, this would be cool to mount on a tripod with spade grips. Detachable mag fed, semi-auto .50BMG that is easier to lug around than an M2 with huge fireball and blast. Hmmm.

[CHS]

It would not be a rifle or a pistol, so it would appear that you would not need a BB.

Correct, no bullet button needed unless barrel goes below 16" and trips California's stupid "pistol" status.

So, you could have a forward grip with a 16" barrel and not be an AOW. Alternatively, this would be cool to mount on a tripod with spade grips. Detachable mag fed, semi-auto .50BMG that is easier to lug around than an M2 with huge fireball and blast. Hmmm.

You could have a forward grip even if the barrel was less than 16" and not trip AOW status. Unfortunately, at that point CA would consider it a pistol and you would need a bullet button. It still wouldn't be an AOW though because it would be greater than 26" and there's no such thing as an AOW in CA (except when referencing the Federal description). But yeah, the feds would still consider it a Title 1 "other" and not a pistol, even though CA would.

[CHS]

So, how is the bore measured? Largest possible measurement of the bore?

Also, .500" (actual measurement) is no-go, but .499999999999999" is OK, yes?

Not positive. However, since the M82 is already federally legal, and California doesn't regulate .50cals that aren't 50bmg rifles, it doesn't matter. California DD status doesn't kick in until .60cal, so you're fine as long as the feds say it's fine, which they do

[EBR Works]

I wonder if we could entice Barrett or some other manufacturer to do a California legal, detachable mag, semi-auto variant in BMG. It would be pricey though!

[ke6guj]

Yes, I'm aware of the armor piercing ammo issue, but this has not happened with the few .308 AR pistols that are in existence. Obviously, if some manufacturer were to make a boat load of BMG pistols, it might cause a stir. Obviously, there is no big market for something like this.

yes, it already has happened to the .308 pistols. That is why .308AP ammo is not available to the public. .308 pistols were available long before people started making .308 AR pistols.

ATF has listed the following rounds as AP ammo:

All KTW, ARCANE, and THV ammo.
Czech made 9mm Para. with steel core.
German made 9mm Para. with steel core.
MSC .25 ACP with brass bullet.
BLACK STEEL armor and metal piercing ammunition.
7.62mm NATO AP and SLAP.
PMC ULTRAMAG with brass bullet (but not copper).
OMNISHOCK .38 Special with steel core.
7.62x39 ammo with steel core bullets.

ATF has specifically exempted the following rounds:

5.56 SS109 and M855 NATO rounds, with a steel penetrator tip.
.30-06 M2 AP ammo.

http://www.recguns.com/Sources/IIG1.html

If .50BMG ammo was declared to be pistol ammo, then it would ban all steel core .50BMG ammo (basically all surplus ammo) and all the monolithic solids.

I think the issue was a .50 bore gauge would slide down the .50 AE Desert Eagle bore because it used polygonal rifling. They switched to using .50 dia bullets instead of .510 and changed the rifling which fixed the problem. At least that is what I have read.

thats the way I understand it to be, it was the polygonal rifling that got them. Otherwise, how come Linebaugh has been able to sell his .500Linebaugh revolver for years, and that uses .510" bullets without it being a DD?

[ke6guj]

I have talked to the tech branch today on this, 1/2 hour ago.
Anyone saying rifles and pistol bore diameters are measured differently is nuts, PERIOD!

thanks for the info John.

this has been one of my pet-peeves, people continually saying that "pistols and rifles" are measured differently, with no proof to back it up. They always point to the DE.50, but fail to realize that the DE has a polygonal barrel which means that a poly barrel designed to shoot .510" bullets would be larger than .500" (and accept a .500" bore gauge, therefore a DD), but a conventional barrel of .500" would not accept the bore gauge, and not be a DD.