Tuning .223 AR15 Reloads for Accuracy

[RegionRat]

Very little has been stated about an adjustable gas block? Can slowing down the unlock aid in accuracy very much? I know there is a limit there, while still allowing the semi-auto function to work properly.

The gas port drilled in the bbl is the foundation of the gas cycle. In a WOA bbl, that port is drilled to a standard for the length of the system.

It will give a reliable margin on function and an ejection pattern that shouldn't require you to adjust with typical loads. John is an expert gunsmith and also an accomplished marksman. His designs are margined and well proven.

If I were having trouble with one of his bbls, I would start by sending him a well organized description of the problem in an email and seeking his advise.

You can always experiment with adjustable gas blocks or even piston systems to see their effect on accuracy, but that said, in your context something else is wrong. Adjustable gas blocks can be handy when the context is non-standard loads, suppression, extreme environments, full auto, etc. If you are having trouble now, why complicate the system even more?

My experience with setting up a batch of ARs where accuracy and boresight retention was the focus, I didn't find the gas block was the place to tune the group.

The last time I looked at piston systems for example, they were not as easy to wring out accuracy as a regular DI system. That was a while back and things may have changed by now, so YMMV.

 

[dnellans]

Great thread guys - you've inspired me to try and fix up my AR a bit.

My bolt guns are capable of .2 and .3 groups of 5 at 100 consistently but my off the shelf 18 inch armalite AR 3-gun model shoots solid 1.1's - doh! Its good enough for banging 4moa steel out to 600 consistently but 2moa steel is another story. I just show shot some groups yesterday so the baseline is in place.

I looked into getting an unchambered AR blank but kreiger and other are 9 months plus out and I would prefer to do the barrelwork myself.

So I'm going to try and tweak this one a bit and see if it tightens up. I've got an accuwedge on order and am turning a mandrel to be able to true the reciever front face (currently its headspaced at min +.005 so I've got a few thou to work with) and then I'm going to bed the barrel extension with loctite 620.

Will report back in about a week hopefully.

 

[RegionRat]

Nowadays, I just order the bbls on an interval even if I am not ready for them. This last year my usage is way down, but their lead times have gone up, so it may work out.

 

[jelenko]

start by sending him a well organized description of the problem in an email and seeking his advise.

++

As mentioned, John is conservative in his designs/approach.

 

[dnellans]

Nowadays, I just order the bbls on an interval even if I am not ready for them. This last year my usage is way down, but their lead times have gone up, so it may work out.

I have XX bolt barrels in stock, didn't think I would ever find myself wanting to improve a blasting AR

 

[jelenko]

Great thread guys - you've inspired me to try and fix up my AR a bit.

My bolt guns are capable of .2 and .3 groups of 5 at 100 consistently but my off the shelf 18 inch armalite AR 3-gun model shoots solid 1.1's - doh! Its good enough for banging 4moa steel out to 600 consistently but 2moa steel is another story. I just show shot some groups yesterday so the baseline is in place.

I looked into getting an unchambered AR blank but kreiger and other are 9 months plus out and I would prefer to do the barrelwork myself.

So I'm going to try and tweak this one a bit and see if it tightens up. I've got an accuwedge on order and am turning a mandrel to be able to true the reciever front face (currently its headspaced at min +.005 so I've got a few thou to work with) and then I'm going to bed the barrel extension with loctite 620.

Will report back in about a week hopefully.

I think an AR headspaces off the barrel extension => the length of the upper doesn't matter.

 

[dnellans]

I think an AR headspaces off the barrel extension => the length of the upper doesn't matter

You’re right - I was thinking about the shoulder moving rewards as the face is machined off but the lugs are also moving back. It moves the whole assembly rearwards but won’t affect headspace meaningfully as long as the bolt head moves back when locking too (which it should for a minor change like this).

 

[BondJamesBond]

I know this thread cooled off over a month ago...I spent a lot of time over on the 6.8 forum...there were several guys very dedicated to that cartridge and spent a lot of time and effort to get all the velocity and accuracy out of it.
The one thing that allowed them to load a little longer (for seating depth and case capacity) was to "window" the mags. Some would dremil the feed ramp.
I windowed several of mine and could load five longer than mag length...1/8" makes a big difference but has to be a metal mag.
I think Cavity Back bullets sells windowed mags as well as really good machined copper bullets, the guy that started this shop was one of those dedicated guys as well as mad dog weapons owner