Failure to Eject due to excessive gas port, UPDATE: Problem solved w/custom gas plug

[montana]

Nice job, I love it. Great pictures and info.

[VASCAR2]

[DeanD]

What I like is the only alteration was threading an existing hole. I can always drill the hole a bit larger if necessary. Must say those set screws are hard. Annealing it first would help or getting a cheap softer set screw. I finished drilling the hole after grinding the screw down, getting it hot and letting cool slowly several times probably annealed it a bit.

[DeanD]

I like the carburetor jet analogy. Part of my motivation here was to teach my grandson how to fix things with what you have or can make. He is a total AR fan and 6.5 fan.

[FRB6.5]

Stainless set screws would likely be a bit softer to deal with if had to make more.

[DeanD]

Did a couple of modifications: polished the chamber using 1500 wet-dry lubed with WD-40 wrapped around a lapping tool and then finished off with a .410 shotgun swab coated in Semichrome polish with the cleaning rod chucked up in a drill motor. The fired cases look really nice now, no scuffs, nothing. Polished a slight radius on the sharp edge on the ejector and put a radius/bevel on the inside. This allows the case to pivot to the right when ejecting, same as you do to a fixed ejector on a 1911pistol or FAL rifle, etc. A lot of AR guys swear by this and it did improve the ejection plus the ejector was digging into the case head with a nasty smear streak and it no longer does that, just rubs through the lacquer coating on the Wolf ammo now. The cycling feels so good now. I was getting stovepipe jams about every 5 rounds and forward ejection, today I fired 80 rounds and it ran like a sewing machine! Every detail thing helped it function better but reducing the gas port from .094" to .063" made most of the difference.



Empty cases ejected about 8-9' perfectly at 3:00 and piled up in a beautiful pile about 3' across. Wolf 100 gr. 6.5 Grendel ammo. Nice!

[DeanD]

I added a Sprinco extra power buffer spring and an H buffer. Both made the gun cycle smoother and better. Up to 140 rounds now and not a single malfunction.

[peak98]

I added a Sprinco extra power buffer spring and an H buffer. Both made the gun cycle smoother and better. Up to 140 rounds now and not a single malfunction.

[LRRPF52]

Excellent thread really. That was a great fix for the oversized gas port.

I knew you had plenty of gas since you were getting Last Round Bolt Hold Open every time, but stovepipes and 1 o'clock ejection.

You can also tune the corners of your extractor lip and it will baby brass more, without any chance to impinge the case rims during ejection articulation from the bolt face recess.

I do that on my builds if they don't have a precision ground edge on the extractors.

Keep an eye on the chromed bolt, as that is usually a recipe for hydrogen embrittlement and stress risers at the lug roots and cam pin hole.

If fed a diet of Wolf, it should last longer though since projectiles are smaller diameter and charge weights aren't very high.

[DeanD]

I am up to 165 rounds now without a single malfunction of any type since reducing the gas port. No more stovepipe jams, no faulty ejection, nothing. Just runs like a sewing machine! Even though it worked well with the .063" gas port I added an H buffer and a Sprinco extra power buffer spring and both made it cycle even smoother and more consistent.

[rasp65]

Check out the last part of this video comparing ejection patterns between 6.5 Grendel and 223. My own high speed videos are similar to these. http://www.brassfetcher.com/Rifles/6...20Grendel.html

[Mustangfreek]

Good work Deand

[DeanD]

tried to post a video, didn't work

[VASCAR2]