Accuarcy and adjustable gas screw???

[Orlando]

Anyone here been able to increase accuracy with tuning a adjustable gas screw?
I have heard some claims that people have, myself the jury is still out

[Orlando]

No one???????

[cuppednlocked]

Sorry, can't help you with that. Don't have an adjustable plug.

[jak]

I don't have an adjustable plug either.
I can understand using an adjustable gas plug if you were shooting commercial ammo.

Now I am thinking out loud.
I can't see how an adjustable gas plug would help shooting HXP since HXP would have more variables built into it versus hand loads or match ammo. Now I can see an adjustable gas plug working for hand loads. It's seems to me that you would be customizing the rifle to shoot the hand loads, rather than customizing the ammo to shoot in a garand with a regular gas plug. Does that make sense ???

[timshufflin]

I'll get back to you on this one.

[Oh Mr. Wilson]

Orlando,

I can't really say yet. I just don't shoot much anymore these days, I doubt I have more then 200 rounds through any one of the Garands or the Mini-G. When I was shooting Bullseye Pistol Matches I shot three nights and around 300 rounds a week. I was tip toeing my way from Expert to Master class when life took a turn and all the shooting came to a sudden halt. Now I'm lucky if I can keep ten rounds on the paper with a pistol, my Bullseye days are just a memory of plaques and metals won that hang on the wall in my office here at home.

I bought Schuster plugs for each of my Garands but I didn't install them until this summer. I put new Orion-7 springs and Schuster plugs in my rifles mainly to reduce as much battering from the bolt smacking the heal of the receivers as I can on these sixty year old rifles. If I can play with them and reduce the group size, well that will be a bonus.

The first time I ever back one all the way out to fire single shot was the day I shot the targets for Tim's Match. I don't know if the planets aligned and I just had a really good day or if I can consistently get groups like that but I will be back to the range soon and see what I can do.

Backing the plug out to wide open and loading one round at a time makes the chambering more consistent then semi-auto and I would think that would make a difference. How much I think would depend on the rifle, ammo, shooting conditions of the day and lastly the finger on the trigger. According to the instructions that came with the Schuster plugs, it says to try different adjustment settings (while still keeping the rifle shooting semi-auto reliably) and noting the group size at each point. By memory it read something like, "many shooters have reported finding a sweet spot that reduces group size." And this makes sense, when reloading, you can often find a "Pet Load" combination of powder type, powder weight, bullet and seating depth that gives good groups, "for YOUR gun". That can be a lengthy and tedious process but very satisfying and rewarding when you do find a load that gives you clover leaf groups, and it helps to justify the money spent of all that reloading equipment LoL.

When you fire a round in a rifle, the barrel flex's and whips like a wet noodle while the bullets is traveling down the bore. You can't stop it but if you can reduce this harmonic and time the bullet to leave the barrel near the same time during this flexing, then you'll see your group size shrink. That's why match grade rifles have big diameter barrels, they flex less then a thin barrel. By playing with the adjustments on the gas plug, your changing that harmonics.

I bet if a guy had a "perfectly built Garand", (good barrel, tight chambered, tight fitting stock, list goes on), played with loads of different bullets and powders, had the patents to go through all the testing, he would hit be able to consistently shoot some really amazing long range groups. I just don't have the time, patents and funds to go down that road, I will however strive to get the best groups I can with the resources I have and with my physical abilities.

Usually you'll find a load of powder that works best is near the middle between the low and high sides listed in reloading manuals with jacketed bullets for both rifle and pistol. When reloading with hard cast bullets it's usually a little more toward the lower end, that what I found reloading cast bullets for pistols, I've yet to reload cast bullets for rifle. I don't like the idea of scrubbing lead from rifle barrels, how ever with the .30 Carbine I am going to try some hard cast bullets. The barrel is short and I won't be pushing near factory velocities, just looking for a light, short range plinking load. I'm thinking of trying the copper plated hard cast bullets like Berry's sells, cheaper, still copper coated to keep from leading or ending up with a lot of lead behind the gas piston.

Guy

[Orlando]

Thank you Mr Wilson

[musketjon]

I really can't see how it would affect the accuracy in any rifle. All it does is slow down the bolt speed basically.
Jon

[Orlando]

I really can't see how it would affect the accuracy in any rifle. All it does is slow down the bolt speed basically.
Jon

From Mr. Wilsons post:

"When you fire a round in a rifle, the barrel flex's and whips like a wet noodle while the bullets is traveling down the bore. You can't stop it but if you can reduce this harmonic and time the bullet to leave the barrel near the same time during this flexing, then you'll see your group size shrink. That's why match grade rifles have big diameter barrels, they flex less then a thin barrel. By playing with the adjustments on the gas plug, your changing that harmonics."

[musketjon]

["When you fire a round in a rifle, the barrel flex's and whips like a wet noodle while the bullets is traveling down the bore. You can't stop it but if you can reduce this harmonic and time the bullet to leave the barrel near the same time during this flexing, then you'll see your group size shrink. That's why match grade rifles have big diameter barrels, they flex less then a thin barrel. By playing with the adjustments on the gas plug, your changing that harmonics."]

That doesn't make any sense either because the gas vent hasn't anything to do with the bullet traveling down the barrel. The gas vent doesn't come into play until the bullet has passed the gas hole. The barrel is still gonna' flex and whip the same. The gas plug doesn't affect the bullet velocity.
Jon

[Dave Waits]

Bill, you can tune an adjustable plug to where nothing happens operation-wise til after the bullet leaves the muzzle. This cuts down on movement of the barrel which of course, increases accuracy slightly. Wrench in the works is that you have to retune every time you change ammo-lots or loads.

[Oh Mr. Wilson]

That doesn't make any sense either because the gas vent hasn't anything to do with the bullet traveling down the barrel. The gas vent doesn't come into play until the bullet has passed the gas hole. The barrel is still gonna' flex and whip the same. The gas plug doesn't affect the bullet velocity.
Jon

Hmm.... you might be right on Jon, I didn't think of it that way. I wish I had a crony so I could put it to the test, anyone?

Guy

[timshufflin]

The gas system does start working with the bullet in the barrel, does it not? It the oprod travels at a slower speed would the force imparted on the shooter not be less? I'm theorizing now and theory really doesn't matter, results do. I'm going to do a little test. I've had others test and tell me that the plug mattered but I'm going to do it myself.

[musketjon]

Bullet traveling at 2800fps. Whether you have the gas port wide open or closed tighter than my wife's legs, the bullet is still gonna' travel down that barrel at 2800 fps. If you close off the gas port so no gas is imparted to the op rod, how fast does the bullet travel? 2800 fps. If you open up the gas port so the gas impinges on the op rod, how fast is the bullet traveling down the barrel? 2800 fps. The barrel is still gonna' whip and flex. Trust me on this one--the adjustable gas plug isn't gonna' do a thing one way or t'other to the accuracy of the rifle. All it does is regulate the amount of pressure on the op rod. By the time the op rod even starts to move, the bullet is a L-O-N-G ways away from the muzzle/gas port. It's really pretty simple physics.
Jon

[timshufflin]

Musketjon, I'm not talking about barrel flex or whip. That barrel flex, bullet speed, means nothing to me. It's oprod speed that means something to me.

I'm not convinced that the bullet is long gone before the oprod moves. I'd love to trust you but the only thing I trust is if the thing works when I try it. Now, have you tried it? I'm going to see if this thing changes my patterns and then I'll be able to say for myself if the thing matters. Of course, I'd not believe that anyone else would believe my results unless they too try it.

[Orlando]

Alright now I got ya all thinking .
Jon, you may be right about bullet speed but by adjusting the volume of gas in the cylinder arent you changing the speed of the op-rod and the harmonics of the barrel? By doing so the bullet is either gone or almost out of the barrel?
I to am going to do more testing but wanted to see what anyone elses personal experiences are
Lets keep the discussion going

[jak]

Ok, here is another idea
There is air in the barrel. When the bullet starts to travel down the barrel at 2800 fps the column of air in the barrel doesn't move forward with bullet at 2800 fps. The air compresses in front of the bullet and actually slows down the bullet. Now as the compressed air is moving forward in front of the bullet, the air (in a garand) has 2 places to go. The front of the barrel and the gas port. So the op rod should start to move as the compressed in front of the bullet passes over the gas port. If more or less air goes out the gas port ( depending on how the adjustable gas plug is tuned), then you will have a different amount of air pressure in front of the bullet for that last inch or so of travel.

Yes, the barrel whips and flexes, sort of like a sine wave. This sine wave is the vibration of the barrel at a certain frequency (the whipping and flexing) caused by the bullet and the compressed air traveling down the barrel. Now adjusting the gas plug ( and the air pressure in front of the bullet) could possibly change and/or counteract the sine wave and therefore reduce the whipping and flexing.

Hell, my high school physics teacher would be proud. He may say I'm full of it, but he would be proud

[musketjon]

jak,
The air pressure generated is not enough to move the op rod. If it were, JCG would've designed something different.
Jon

[Dave Waits]

Gentlemen, one does have to concede that, that steadier the muzzle is, the less it can affect bullet-flight. I don't care if the rest of the barrel looks like Al-dente Speghetti, as long as the muzzle is in the same place the bullet will exit at the same spot. This is why, on average, Boltguns are more accurate than Semi-autos, all things being equal. Now, it only makes sense that, if you can slow down the start of the Op-rods' movement there will be less barrel-movement muzzle-wise. All the things we do to make the barrel as free-floating as possible are to negate these wobbles in the barrel and have the muzzle at the same spot every time. Removing the op-rod motion will also help in this respect, how much though, is up for grabs.