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HotRod308

Increase accuracy, eliminate the gas rings

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Any hard evidence this improves accuracy or is it anecdotal/theory? Curious just how it would do this, I always figured that tiny bit of play from rings would allow a more uniform seating of the lugs.

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How much slop is in the bolt lugs once they are engaged in the barrel extension? I would think the bolt face and lug clearance would be the biggest factor. Am I looking at the wrong thing here? Why would the lock up be any different than a bolt action rifle?

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The bolt was welded by an ex certified aircraft welder and experienced machinist. He had no worries in doing this nor machine it back to a slip fit. The bolt has a fwd bearing and the rear bearing is the taper in which the firing pin is inserted into. The slip fit allows both bearing surfaces to work just as before with gas rings and also the lugs contact the lugs on the barrel extensions same way it would with gas rings.

The increased accuracy comes from that when the gas pressure is passed into the chamber that the bolt carrier starts to move more constantly the same each time as there is zero drag from gas rings or from carbon build up upon them.

I did a test were I fired 66 rounds and then chronograph two 10 shot strings with a bolt with gas rings and did the same test with a bolt without gas rings. The results were that difference between each showed that the ammo tested without gas rings was more consistent. The difference between the two highs/lows were closer and so forth.

 

 

AR Bolt Test.xlsx

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I've seen this mod before, but never heard of it increasing accuracy. Don't really see how it has any effect on accuracy in the slightest. Sure as heck don't want to fish one out of a carrier after it bottoms out without a cam pin. 

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 The rings wearing down instead of the bolt, prevents wear on the bolt, and because the parts are mass produced  to allow more clearance between the bolt and the inside of the carrier, by making a seal with the rings, without having to precision size the bolt to the carrier? since you eliminated the gas rings and welded  up the piston and custom sized the bolt piston clearance, that may actually improve accuracy  until the welded bolt wears down.  The gas rings can be replaced when they wear down without having to replace the bolt. Maybe I think too much like an engineer, which I can't help, because I is one.  

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18 minutes ago, mrmackc said:

 The rings wearing down instead of the bolt, prevents wear on the bolt, and because the parts are mass produced  to allow more clearance between the bolt and the inside of the carrier, by making a seal with the rings, without having to precision size the bolt to the carrier? since you eliminated the gas rings and welded  up the piston and custom sized the bolt piston clearance, that may actually improve accuracy  until the welded bolt wears down.  The gas rings can be replaced when they wear down without having to replace the bolt. Maybe I think too much like an engineer, which I can't help, because I is one.  

I think you hit the nail on the head. There are reasons things are done a certain way, and sacrificial rings save the rest of the system.Friction is both necessary and the enemy and the gas rings allow and compensate for this.

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7 minutes ago, Sisco said:

I think you hit the nail on the head. There are reasons things are done a certain way, and sacrificial rings save the rest of the system.Friction is both necessary and the enemy and the gas rings allow and compensate for this

Sisco, I think you esplainded that better than I did!

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7 hours ago, mrmackc said:

Sisco, I think you esplainded that better than I did!

mrmackc coming from you that is flattering sir, I am no engineer, but I am the son of an ordnance engineer who worked on everything from the 30mm Gau 8 to the Bradley Fighting Vehicle to the F-4 Phantom. Some of it must have rubbed off.

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I can't help but think of the continuous cleaning that would be required for this modification. I am so used to treating my rifles as "equipment" or a "tool" I barely have enough care to go beyond a simple wipe down. 

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2 hours ago, Robocop1051 said:

I can't help but think of the continuous cleaning that would be required for this modification. I am so used to treating my rifles as "equipment" or a "tool" I barely have enough care to go beyond a simple wipe down. 

Very true, the rings act like wiper blades cleaning the carbon out. I wonder if that test would give the same results 500 or a 1000 rounds later. Even with an increase in cleaning I have to think there will be some wear that would change the results.

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I have a 223 bolt modified and cycles fine and 4 LR uppers 308, 260, Creedmoor and between all of the have some 3 to 4 thousand rounds fired without any problems. The machined area doesn't touch the wall of the carrier and I haven't notice any wear at all. 

I do use a thicker oil but cleaning it is no more dirty than with gas rings. I fired as much as 264 rounds and only cleaned the chamber and added some oil around 150 rounds. The rifle cycled just fine and accuracy was the same on day one of the nationals. 

I know it's an up hill battle to convince anyone of this idea is worth while. I have shot some very good scores with it. 

I did loan one BCG to a guy in Nebraska and first time out with it won the long range portion of the tactical match and placed second on the short range after loosing the shoot off.  He was impressed with the accuracy it had during the match throughout the day. 

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As I've written in other "similar" posts regarding modifications to well established designs, Mr. Stoner knew what he was doing. I'll stick with the 3 gas rings.

Whatever you do, just be safe. If it yields better results, more power to you!

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I have always compared gas rings to piston rings in an engine. You can run a nitro engine for one pass with a minimal low drag ring and it won't hurt the engine but do it a second time and .... Boom !

Just don't feel comfortable without a 3 ring setup in my guns...

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My Aunt shot her toe off and won $1000 in the lottery the following week. If I felt that the outcome were directly attributable to the action taken, I might try it myself, but I need my toe and $1000 isn't that much money.

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1 hour ago, Matt.Cross said:

My Aunt shot her toe off and won $1000 in the lottery the following week. If I felt that the outcome were directly attributable to the action taken, I might try it myself, but I need my toe and $1000 isn't that much money.

You can get a good look at a T bone steak by sticking your head up abutchers ass but I'd rather take the bulls word for it

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Maybe I'm just that much of a crappy shot, but I feel that most people here build guns at a higher quality that creates accuracy already better than I can even shoot. If it turns out that it really does help with accuracy, I am all for it, but would need some good testing I think.

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