Gunsmithing AR308 Barrel Smith

[Thumper580]

Beside the name brand barrel makers, Shilen, Hart, Lilja, etc. can anyone recommend a smith to make a AR308 barrel who can cut a specific freebore depth/length. I want to provide them a dummy round with a specific bullet at a specific length so I end up with 10-12 thousandths bullet jump. Thanks.

 

[JB02]

GAP and American Precision Arms can do this. I'm pretty sure Mark Gordon at SAC and RW Snyder can do this work too.

 

[FCS]

Beside the name brand barrel makers, Shilen, Hart, Lilja, etc. can anyone recommend a smith to make a AR308 barrel who can cut a specific freebore depth/length. I want to provide them a dummy round with a specific bullet at a specific length so I end up with 10-12 thousandths bullet jump. Thanks.

You've got 3 threads going on this and seem to be most interested in changing barrel, not solving the issue you have with current barrel. If you really want to get new bbl, that is one option but I think you are missing obvious on how to fix your current rifle.
You are running a factory DPMS 24" bbl, most of those I've been around need to have adjustable gas block as port is too big. Add in a heavier buffer and stiffer buffer spring and you'll be on your way to correcting issue.
If you are running same load at 0.010" jump and 0.100" jump you shouldn't expect same accuracy as initial combustion chamber is different. You need to adjust powder charge.
You said rifle will shot 0.5 MOA or so with 0.010" jump but 1-1.5" groups when jumping 0.100". Issue isn't your barrel if that is the case, it is how you are loading the ammo.

Your $ and rifle...good luck.

 

[Thumper580]

I've done OCW tests from below minimum to just above maximum on IMR4064, IMR4895, XBR8208 and TAC. They all do the same, large groups from the magazine and 1/2" from .010" off the lands. I take exception to adjusting the powder charge. Already did that. Each of the above powders respond the same way..... It's the jump that is cause. I have an adjustable gas block already.

 

[JJones75]

So you are wanting a chamber cut with a shorter throat so you can load your rounds to fit the magazine but only have .010" bullet jump??
If the above is the case then a new chamber is definitely in order if you plan to feed from the mag.

 

[Mike_in_FL]

Brux will make you an AR barrel and when I asked they were reasonably priced for a cut rifled barrel. I can't say they'll do a special chamber unless you buy the reamer, although they might have it. If you're sticking with .308 they probably have some that will work as you're not reinventing the wheel. Be aware of one thing regarding .308 in an AR. Most of the people making these barrels set the headspace for 7.62x51, longer than SAAMI .308. This is probably CYA in the age of the attorney, but if you buy something custom I would discuss that with them.

 

[Thumper580]

So you are wanting a chamber cut with a shorter throat so you can load your rounds to fit the magazine but only have .010" bullet jump??
If the above is the case then a new chamber is definitely in order if you plan to feed from the mag.

That's sort of were I think this will end up at. Haven't heard any recommendations so far that I haven't tried or already done. The only variable at this point is a .080" bullet jump. I was hoping to hear a suggestion that I had totally missed, but haven't seen it yet.

 

[Lucky Jack]

I'm not getting what's so complicated about this.

 

[Thumper580]

I'm not getting what's so complicated about this.

What part don't you understand?

 

[cblanchard]

That's sort of were I think this will end up at. Haven't heard any recommendations so far that I haven't tried or already done. The only variable at this point is a .080" bullet jump. I was hoping to hear a suggestion that I had totally missed, but haven't seen it yet.

What bullets have you tried?


Sent from my iPhone using Tapatalk

 

[Lucky Jack]

What part don't you understand?

If you want to shorten up the neck or throat couldn't you chamber with a .243 reamer then come back and customize the neck with a .30 cal necking reamer? If you need the throat a certain distance couldn't a uni-throater be used to give you the jump you're looking for? If someone says they can't do this they may just not have the tooling. Once again: I'm not getting what's so complicated about this.

 

[Thumper580]

If you want to shorten up the neck or throat couldn't you chamber with a .243 reamer then come back and customize the neck with a .30 cal necking reamer? If you need the throat a certain distance couldn't a uni-throater be used to give you the jump you're looking for? If someone says they can't do this they may just not have the tooling. Once again: I'm not getting what's so complicated about this.

I was trying to resolve it with an existing barrel, but that is more involved and costly than beginning with a blank. I ordered a 308 reamer with no lead or throat. The throat can then be cut with a throat reamer to give me the "jump" I want, much less than the .170" it is jumping now. I was very surprised at the excessive freebore when the round was loaded to 2.80" to fit the mag in the current barrel. If all goes well I'll end with rounds that fit the mag and shoot 1/2" groups.