Varmiter71
Well-Known Member
- Joined
- Oct 14, 2015
- Messages
- 129
I have been wondering how one times drilling the gas port so it winds up in a groove.
Barrel timing
- Thread starter Varmiter71
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I can't explain it but there are several posts on LRH. Do a search.
Just be like Faxon and don't worry about it'll be fine <-- sarcasm laced with irritation
From other articles it states from testing "it doesn't matter and plays no part in function, accuracy and fouling". This is on whether it's in the groove, land or in both (like @Mike6158 posted). You have to think about it like a shouldered barrel being headspaced. In this case you have to have the extension indexed to the land or groove then chambered based on "X" length (how shouldered barrels are timed/threaded).
lyle2231
Well-Known Member
I've heard different accounts of how jackets were stripped/burred from the gas hole as shown. Never experienced it myself.
Nice pic for an amateur
How did you get it? It almost looks like the BBL is cut off just in front of the hole?
lyle2231
Well-Known Member
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.
I have shot many barrels til there future life was a tomato stake .
In all my experiences the throat seems to be the line in the sand for accuracy degradation.
Ive had gas ports 1/2 on 1/2 off a groove and the eroding from hot gases has been very ugly but bbl still shot great.
I bore scope barrels throu out they're life .
Gas ports in a groove 100% or out 100% makes you feel good and does hold up better to erosion , when the barrel is shot out , i have not been able to notice the life of these barrels being longer.
These barrels ive tracked are all hi end barrels ,cut rifling ,hand lapped .
In all my experiences the throat seems to be the line in the sand for accuracy degradation.
Ive had gas ports 1/2 on 1/2 off a groove and the eroding from hot gases has been very ugly but bbl still shot great.
I bore scope barrels throu out they're life .
Gas ports in a groove 100% or out 100% makes you feel good and does hold up better to erosion , when the barrel is shot out , i have not been able to notice the life of these barrels being longer.
These barrels ive tracked are all hi end barrels ,cut rifling ,hand lapped .
lyle2231
Well-Known Member
Thinking out loud here... A few choices might be to call customer service @ Colt, Armalite, Rock River,
or Robert Whitley in VA. .
Seems like it could help as being less stress on the jacket, but then again the bullet has already taken shape. As far as burrs goes, that can happen in other places excluding gas ports. Deburring where necessary is always best.
Wallie
Well-Known Member
I think possibly it could matter, like in the picture in post #3, which side of a rifling is affected. Like gears in a mechanism, there is a "load" side and a "coast" side. If the bullet is getting shoved out the barrel by 60,000 psi in a right hand twist, after the bullet jacket is initially scribed into the leade, the right side/face of the riflings would resist forward motion and force the bullet to twist/spin, but the left side/face of the rifling is more or less irrelevant I would think. Since barrels never have to operate in reverse!
Possibly? But at port the pressure is less than half of chamber pressure on a carbine system. Bearing length could make a difference. Removing sharp edges should cure it.
quigley257
Well-Known Member
My experience with gas operated rifles has been that the port location doesn't matter as long as the hole is free from burs. As previously stated, the bullet is already fully engraved by the time it reaches the port and it touches both land and groove albeit with varying degrees of pressure.
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Nice pic for an amateur
I used a borescope. It's a handy little thing... except for when it tells you that the cleaning job you just did is bs and you need to spend a lot more time on it. There's a mirror on the end of the light source / lens. I tried shoving a 70-200mm DSLR lens into the barrel and that doesn't work.
16" Faxon 8.6BLK barrel. Pay for shipping and it's yours.
This pic is after one round of cleaning. About 45m worth. I got the carbon off of the shiny bits. 3 hours later I got the pretty photo of the hole drilled through the land and groove. No mirror in this photo of my top secret barrel accurizing method.
And another photo of the hole. No mirror. This was taken after hours of cleaning followed by the hyper secret, experimental accurizing method that I'm about to share. I cleaned it... then I shot it... Accuracy SUCKED because the pencil thin barrel and supersonic 300 grain .338 bullets don't agree so the barrel slings them all over the target at 100 yards. Not that I'm bothered by that or anything...
