Riddle Me This

[Madrox]

WHAT A TUNER DOES.... It is possible to "Tune" a rifle barrel so that where it is pointing at bullet exit time will compensate for small variations of muzzle velocity. In the "tuned" condition the slower bullets are launched at a slightly higher angle than the faster bullets. The difference in launch angle can allow the slower bullets to hit the target at the same elevation as the faster bullets. That is the simple explanation and now the details.

That's a quote from Varmint Al's Website for anybody who does not know.

I really don't want to start anothter tuner thread but there's an issue here.

Shooting rimfire, I don't care if I can tune the bullet to hit the same elevation as the faster/slower bullets. That's meaningless to me. What I want to do is tune the barrel so that I get maximum accuracy from the lot in use. I can use the scope to change elevation.

I can see where that may be of benefit in varmint shooting and I don't argue with the physics of it. My issue is with the benefit of it. Does simply timing the barrel to increase the arch of the ballistic curve have any value whatsoever in increasing accuracy. (And by accuracy I mean smaller groups, which has been pointed out is really precision).

 

[RLHBUSL]

Shooting rimfire, I don't care if I can tune the bullet to hit the same elevation as the faster/slower bullets. That's meaningless to me.

I understand that in a match you shoot a single lot of ammo that has a stated speed, but is there ZERO variation in the velocity from shot to shot?

Ryan

 

[MKnarr]

Here are the average speeds, spread and Standard deviation of velocities from ten lots of Eley Match I have tested in an Anschutz 28 inch barrel. CED MII chronograph set 10 feet from the muzzle. I don't know what other folks get but this is my variation.

The 103 is 1038 fps.

 

[cpeters]

Would it not make sense that the change of Point of Impact would be less if your rifle was tuned that way if you had small variences in your velocity from round to round. Thereby giving you better groups.

Charlie

 

[Madrox]

I understand that in a match you shoot a single lot of ammo that has a stated speed, but is there ZERO variation in the velocity from shot to shot?

Ryan

Well, maybe not a single lot of ammo, but no I don't think there's ZERO variation from shot to shot.

 

[Madrox]

Would it not make sense that the change of Point of Impact would be less if your rifle was tuned that way if you had small variences in your velocity from round to round. Thereby giving you better groups.

Charlie

It wouldn't make sense to me. From what I understand, the tuner causes it to leave the barrel from a different point. As one engineer said velocity is not one variable, it's the only variable. I assume he meant the only one that counted. So the vibrations are different with each shot. The ammo is accurate anyway, it doesn't shoot with a shotgun pattern. So, from what I see in VA's graphics are a way of putting the shot on target with different speed not necessarily increasing it's accuracy (again grouping ability. Shooters call grouping accuracy when that is actually the ability to put the shot on target. Groups are really precision) So, I see no reason that VA's method would increase precision although it may be helpful in varmint shooting. Again, I have no argument with the graphics. They appear to be what I would expect.

 

[Bill B]

"Would it not make sense that the change of Point of Impact would be less if your rifle was tuned that way if you had small variences in your velocity from round to round. Thereby giving you better groups."

I think that when we tune our rifles to shoot the best groups/patterns that is precisely what we are doing. There is going to be velocity variation from shot to shot as well as from lot to lot and I think the printed velocities on the Eley box don't mean much. I've had this proved to me several time. I've shot an ammo lot listed in the low 1050s into a group and then had a friend hand me a few rounds from a lot listed at 1080 which I shot into the same group.

This is what I'm looking for, and I don't care much about the why, though I think Al's theory makes the most sense in explaining this phenomenon.

 

[gambler]

what is the largest group that will not break thru the 100 line on an ARA target ?

if tuners make groups smaller , then tuners would make the rifle more forgiving
of human error !

 

[Fred J]

.500

If your gun will shoot a 3/8" ctc group, perfectly cented on the Dot. they would all be inside the 100 ring. I thinks some times the weather will make the paper grow and then you can get by with a slightly but not much larger group.

 

[Bill B]

The 100 ring in the ARA target is .500" in diameter. Since ARA is worse edge scoring that would be .500" max outside to outside edge. But since groups are measured center to center, you would need to subtract .224" to get the max center to center group that will stay inside the ARA 100 ring. That would be to be .276".

 

[David K]

tune?

When a rimfire rifle is really tuned you can forget about the tuner. All there is to do is search for good lot #. If you cant achieve a good tune, then change tuners or barrels.

 

[mks]

Good data

Here are the average speeds, spread and Standard deviation of velocities from ten lots of Eley Match I have tested in an Anschutz 28 inch barrel. CED MII chronograph set 10 feet from the muzzle. I don't know what other folks get but this is my variation.

The 103 is 1038 fps.

Thanks for posting. How many shots for each lot?

Thanks,
Keith

 

[Vibe]

Shooting rimfire, I don't care if I can tune the bullet to hit the same elevation as the faster/slower bullets. That's meaningless to me. What I want to do is tune the barrel so that I get maximum accuracy from the lot in use. I can use the scope to change elevation.

Using the scope to change elevation in order to "shrink groups" is only useful IF you are psychic enough to know what the velocity of the NEXT shot will be. Most of us are not so blessed - so having a rifle that will compensate for those unforseen differences is quite beneficial.

 

[Madrox]

Unless centerfire is drastically different from rimfire, I've not seen such a magical rifle. What I want the "tuner" to do, and I don't care how it does it, is to tune the barrel in such a manner that I get the maximum precision from the ammo I use. Whenever I've been able to do that, slow bullets hit low and fast hit high. However, they will converge around 38-42 yards. The magic in the scope is I can adjust for elevation changes at 50 yards. That's what those little dials are for. Twist them sometime and watch the reticle. It moves in relation to the target. Magic!

 

[Vibe]

Unless centerfire is drastically different from rimfire, I've not seen such a magical rifle.

All sarcasm aside, I think the first example of this effect was noted about the 303 Enfield at 600 yards - some were noted to shoot smaller groups at 600 than they would at 300 or 100. This "should" have been impossible, but happened quite regularly. It's not "magic", just applied physics. Which is what this whole discussion, going back several years, has been about.

Any sufficiently advanced technology is indistinguishable from magic.
Arthur C. Clarke, "Profiles of The Future", 1961 (Clarke's third law)

The only way to discover the limits of the possible is to go beyond them into the impossible.
Arthur C. Clarke, "Technology and the Future" (Clarke's second law)

When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
Arthur C. Clarke, Clarke's first law

 

[Madrox]

All sarcasm aside, I think the first example of this effect was noted about the 303 Enfield at 600 yards - some were noted to shoot smaller groups at 600 than they would at 300 or 100. This "should" have been impossible, but happened quite regularly. It's not "magic", just applied physics. Which is what this whole discussion, going back several years, has been about.

Same load?

 

[MKnarr]

Thanks for posting. How many shots for each lot?

Thanks,
Keith

Anywhere from 25 to 30 rounds from one box. I'm certain that any lot will have more than zero variation and I though that was the point of the tuner unless madox is talking about adjusting the scope for each round.

 

[Madrox]

That would be no different that adjusting the tuner for each round. Where the round initially hits on the ultimate target is of no consequence to me as long as the precision is excellent. I think tuners tune the barrel for maximum precision. I don't even give a crap about the velocity variation if the grouping is excellent, which it probably won't be with major variations in the same lot. This is no different than benchrest shooters have done for years. They don't worry about where the group prints as long as it prints within the range of the target that is legal and can be measured. IF they wanted that tiny little group to hit the center of the target instead of off to the side, what on earth would they do? They would, in my opinion, use those things in the center of the scope, that adjust the reticle relative to the target in order to effectively move the group to the center of the target. Any argument there? So, I'm unconcerned if I can get various velocity rimfire rounds to hit the same place at 50 yards, if, in fact, I can determine the maximum precision at 38 to 42 yards. If I use a slower, precise bullet, I'll adjust the scope to hit the target where I want. Vice Versa with a faster round. Not real hard to understand really. You don't even have to go back to the physics books or watch The Big Bang Theory. By the way, how many of you techies have Flash comics and Spiderman T-shrits?

 

[Vibe]

Same load?

One would think so. The shooter had NO control over the load what so ever. IIRC it was a 155gr bullet, but could have been the 165gr. Those competitions used issued ammo - not shooter handloads. Whatever you got, is what you shot. In a way it was even worse than todays rimfire situation.

 

[Vibe]

That would be no different that adjusting the tuner for each round.

Again that would work IF (and only if) one were psychic enough to know how much the next round to be fired was going to vary from the "normal" velocity.