Getting it ready to run

[Shotcaller6]

This is my first foray into the large frame AR and I'm close to function testing. I'm positive the gas port will need enlarging, the port measures .845 and it is supposed to be .890. My plan is to go to .960.

AP M5 upper & lower with their 308 18" cmv nitrided barrel, rifle length gas system

.750 Gas Journal with AP standard gas block and AP ar15 rifle length gas tube (15-3/16") which is centered in the cam pin cutout

AP barrel spec says gas port should be .890 this barrel measures .845

7" RET and 2-1/2" buffer have been replaced with a Griffin AR10 tube (7-5/8") Spring 13-1/2" 35 coils and SOB buffer @ 4.9 oz. that I borrowed from another rifle

BCG is an AP melonited with the MPI + HP bolt which has the round ejector

If the new .960 port proves to be too large, I have an adjustable gas block I can pilfer if need be. Am I on the right track or not?

[392heminut]

Stand by, our gas port guru @98Z5V should be along shortly to advise. It looks like you have all the info in your post that he will need to tell you exactly what size port will be best.

[98Z5V]

10 hours ago, Shotcaller6 said:

Am I on the right track or not?

How is it shooting?  That's the bottom line right now.

You should be around 0.090" port diameter for that barrel config, and it you jump that thing to 0.096" - you'll have some hard-recoiling gun that is truly overgassed. 

No need to burn an adjustable gas block if you don't need to.  Are you ever gonna shoot this rifle suppressed?

Lemme know on that, it's important stuff. 

[Shotcaller6]

11 hours ago, 98Z5V said:

How is it shooting?  That's the bottom line right now.

You should be around 0.090" port diameter for that barrel config, and it you jump that thing to 0.096" - you'll have some hard-recoiling gun that is truly overgassed. 

No need to burn an adjustable gas block if you don't need to.  Are you ever gonna shoot this rifle suppressed?

Lemme know on that, it's important stuff. 

I have not shot the rifle yet and I have no plans for a suppressor. I have not drilled the barrel yet, planning on doing that this Thursday so no problem on drilling the port at .090. Might get to shoot over the weekend.

[Shotcaller6]

EDIT: A suppressor is not out of the realm of possibilities in the future just not possible at this time.

 

[98Z5V]

1 hour ago, Shotcaller6 said:

EDIT: A suppressor is not out of the realm of possibilities in the future just not possible at this time.

 

Adding a suppressor will only increase port pressure (for most suppressors), so even at 0.090"-ish, putting a can on there is increasing port pressure, but probably at a manageable level.  Let's get the gun to run first, as is, and see what happens.  

With what you already have on there for the recoil system, I think you'll be fine at 0.090". 

[Shotcaller6]

Thank You, I'll post up how it all works out.

Another question if I may, number 10 on the waterboarding list those pictures are with the BCG fully compressing the recoil spring, correct?

[98Z5V]

1 hour ago, Shotcaller6 said:

Thank You, I'll post up how it all works out.

Another question if I may, number 10 on the waterboarding list those pictures are with the BCG fully compressing the recoil spring, correct?

Wasn't my pic, but that was a great thread, with accurate information.  You seeing something different in your results, your tests?  If so, let us know.

[Shotcaller6]

So far everything appears to be looking good, we'll see when I get to the range.

[Shotcaller6]

Got some nice weather today so dropped by the range. No problems whatsoever, bolt locked back on all magazines (D&H) no failures to feed or eject. Final settings on gas block (SLR Sentry 7 Adjustable) about 1/2 way with empty's landing apx. 6' away @ about 2:30. Brass looks great, no dings, scrapes or ejector marks.

I drilled the gas port to .093, changed out the Aero carbine recoil system to the Griffin Maritime AR10 setup and had to install 2 quarters to make it 7 5/8". I also upped the buffer to 5.7oz from 4.9oz. With the VG6 Epsilon muzzle break and a Limbsaver recoil pad on the Magpul STR stock evrything just purrs right along.

I thank you all for all the valuable input, the plan came together smoothly.

Todays testing was done with 308 Win 150grn FMJ, I'll most likely have to adjust some things when I run the better ammo. For now I'm pretty stoked!

[shooterrex]

Glad it's running  well for you.

[98Z5V]

I love a success story!   Excellent work! 

[Rsquared]

Who doesn't love a happy ending right?