Fireform/Neck only with an AR platform

[generalquark]

I know that you are not supposed to neck only ammo that comes out of a semi auto, but is there anyone out there that can explain why in great detail? Does it have anything to do with the round not being perfectly fire formed because of the quick eject out of the rifle? If this is the case, is it possible to remove the gas block on an AR platform and load it one round at a time and fire and then manually eject the round like a bolt gun? This way you could use a collet die and use the brass in semi the next time you shoot? Is there anything unsafe about shooting an AR without a gas block? I have never tried this before. These might be dumb questions, but I have no mentor locally to help with my reloading questions, so I rely on people on this board.

Thanks

 

[SnkBit]

Re: Fireform/Neck only with an AR platform

The fire formed brass won't extract from the chamber. I've had the same problem with loads that were a little too hot, brass swelled just a tad too much and I had to manually extract. It was not easy.

 

[generalquark]

Re: Fireform/Neck only with an AR platform

Why would brass extract fine out of a bolt gun, but not a semi?

 

[chuckhammer]

Re: Fireform/Neck only with an AR platform

There are no safety concerns with firing NS-only brass in a semi-auto. The problem that ***might*** arise is the now-larger-than-factory dimensions of the case body may not feed or extract reliably. That's it.

You can fire an AR without a GB if you cover the port with something substantial. Such as a blind (undrilled) gas block. Otherwise you'll have a miniature compensator-style hole in your bbl blowing hot gas upwards.

 

[TaterInTheSouth]

Re: Fireform/Neck only with an AR platform

To insure reliable feeding of the rifle is why you FL size.
Someone probably makes an Adjustable Gas regulator, It would
Simply be a matter of turning off the gas. I am sure that the New
Short-stroke piston models probably do...

But, Yes, a lot of bench type people single feed. I think you are
Probably looking at the platform wrong..Look into “JP enterprises”
I think they make what you are look’en for.
HTH

 

[427Cobra]

Re: Fireform/Neck only with an AR platform

Neck sizing only is a dumb idea in semi auto weapons, do it and you'll understand why

 

[generalquark]

Re: Fireform/Neck only with an AR platform

Cobra,
Instead of me wasting time and having something bad happen, can you please explain further and possibly share your bad experiences so I do not have to repeat them?

Thanks
Ben

 

[RH4540]

Re: Fireform/Neck only with an AR platform

Ammo that has been neck sized only is generally more accurate, and it is a lot easier than full length resizing.

Several years ago I neck sized, and loaded 3,000 rounds that I THOUGHT had been fired in the AR that I was taking out to South Dakota for prairie dogs, only to find out that apparently, some of them had been fired in a different rifle, and the bolt wouldn't close on some of them! Let me tell you,it is a PITA to chamber-check over 2,000 rounds of .223 ammo in an AR! (With the firing pin removed-of course)

If you have a "JP" adjustable gas block on your AR, you can just shut the gas off and turn it in to a single shot.

 

[generalquark]

Re: Fireform/Neck only with an AR platform

So,
The only thing I have as a reason not too so far is possible feed problems and snkbit mentioned that the brass would not eject from the chamber. Can anyone tell me why the brass would not eject from the chamber? I am kinda confused why you could in a bolt gun but not in a semi. Thanks for all the comments thus far.

 

[Jerkface11]

Re: Fireform/Neck only with an AR platform

On a bolt gun you can apply more force to closing the bolt than an auto can. So you can get away without full length sizing for a bolt gun whereas on an auto, lever, pump, or straight pull bolt action you won't be able to get the bolt closed. Keep in mind that this is not an ALWAYS thing but more of a general rule.

 

[MitchAlsup]

Re: Fireform/Neck only with an AR platform

I ran 2000 rounds of NO sized 223/5.56*45 through my AR last year with zero FT<pick failure mode>. If you do it right, you can run NO sized brass.

What you cannot do is take short cuts. Every case has to have its sholder measured and base measured to see that it will fit in the chamber (and thus come back out). This actualy takes longer than FL sizing the brass.

 

[SnkBit]

Re: Fireform/Neck only with an AR platform

Thats just it, you can apply more force with a bolt gun. If you've got a fired case go ahead and slam the bolt home on it and then pull it out by hand with the charging handle. You'll figure out real quick that you can't apply as much force to that charging handle as you can a bolt.

 

[LRS_Ranger]

Re: Fireform/Neck only with an AR platform

With a bolt gun, you can go ahead and push the round into the chamber with the bolt-cam. There is nothing to push the round in when it's a tight fit when you are using an AR. Also, you have to think about what happens if you get any dirt, sand, crud, whatever on the ammo. If you have a gust of wind that blows some dirt on your box of loaded ammo, that could make enough of a difference that your ammo will no longer chamber. Same goes with carbon in the chamber. You want enough tolerance to make sure that your gun still works.