Barrel timing

[bamban]

Here's a melonited barrel that had 10471 rounds before I coerced buddy that we need to pull it out before he went to Perry. The last 600 yard match he shot was 198-8X. The 8 came in on shot 20.

 

[bamban]

I have been wondering how one times drilling the gas port so it winds up in a groove.

Dave Tooley showed me his process, and tooling he made. Readers Digest version. Cut the tenon. Come up with a way to view or determine the groove relative to the shoulder. Adjust shoulder using the BE guide pin for reference, cut the port. With 6 groove 224 barrels, good luck..

 

[lyle2231]

Here's a melonited barrel that 10471 rounds before I coerced buddy that we need to pull it put before he went to Perry. The last 600 yard match he shot was 198-8X. The 8 came in on shot 20.

View attachment 550329

Cut rifled? Also take notice of gas port location compared to previous picture.

 

[bamban]

As far as burrs, I have an internal chamfering tool that I use sometimes. Drill small and then ream to desired port hole, slow feed at 1500 rpm with both drill and reamer made with carbide, I usually get burr free holes.

 

[bamban]

Cut rifled? Also take notice of gas port location compared to previous picture.

Shilen button, I chambered the barrel for my buddy and so is his current one that is now running over 8K on completion rounds. On the average, we are confident melonited barrels last longer than non melonited.

FYI, I don't make the extra effort to time the gas ports as of late. Too lazy. Not in the business, my choice

 

[DirectDrive]

I have been wondering how one times drilling the gas port so it winds up in a groove.

It would have to start with the barrel extension. The BE location determines TDC.
The BE would have to be timed to put a groove at TDC at the gas port location.
I imagine that the barrel maker would have to have some Big Medicine to hit that just right.

 

[Taj]

When the AMU started using the AR platform testing indicated improvement in accuracy putting the gas hole in the groove to avoid sharp edges in the barrel.

Talk to John Kreiger in that regard. He will absolutely agree with you. All of his pre-turned AR barrels are set up with the gas port in the groove. I was fortunate to have dinner with the man last year while he was visiting North Idaho and that very issue was discussed over a great bottle of wine. As well as gunsmithing, cut rifling, fast cars and skydiving. He is a very smart man and a real gentleman. He also jumps out of perfectly good airplanes( Really, no such thing). When he found out I have over 3K jumps the conversation turned to that. He's a stud. He still jumps at 70 something years old.

 

[Coyote Shadow Tracker]

Talk to John Kreiger in that regard. He will absolutely agree with you. All of his pre-turned AR barrels are set up with the gas port in the groove. I was fortunate to have dinner with the man last year while he was visiting North Idaho and that very issue was discussed over a great bottle of wine. As well as gunsmithing, cut rifling, fast cars and skydiving. He is a very smart man and a real gentleman. He also jumps out of perfectly good airplanes( Really, no such thing). When he found out I have over 3K jumps the conversation turned to that. He's a stud. He still jumps at 70 something years old.

Bule Skies - Black Death!!!

 

[lyle2231]

Here's a melonited barrel that had 10471 rounds before I coerced buddy that we need to pull it put before he went to Perry. The last 600 yard match he shot was 198-8X. The 8 came in on shot 20.

View attachment 550329

That 8 probably came from the chip at the rim . How's it been shooting pre-rebarrel? Just curious….

 

[quigley257]

For the barrel nerds... Sorry, no pics of the ports inside, but here is a shot of a 24" 1/10 twist 270 Winchester, five port piezo test barrel that we made a while back. Piezo barrels require the ports to be centered in the grooves. The guy who does the porting uses a formula of twist rate and distance to ensure the ports are centered. These barrels are used in a universal receiver setup by ammo manufacturers for measuring pressures.

 

[bamban]

That 8 probably came from the chip at the rim . How's it been shooting pre-rebarrel? Just curious….

Before this barrel was installed? Don't have data as it was a build from scratch. I chambered the barrel for a junior, outside our program. The smell of gasoline and perfume was too overwhelming that he abandoned the quest to shoot service rifle. The dad sold the barrel to a friend, who in turn completed the upper build.

 

[lyle2231]

Before this barrel was installed? Don't have data as it was a build from scratch. I chambered the barrel for a junior, outside our program. The smell of gasoline and perfume was too overwhelming that he abandoned the quest to shoot service rifle. The dad sold the barrel to a friend, who in turn completed the upper build.

Yes sir them good Ol' days! Hemi Plymouths on Saturday night! ;-)