TargetTalk

Ive gotten into an arguement with a guy who thinks that 18" is the optimum length for 22 LR velocity, Im sure its longer than that. Can someone tell me what is the optimum lenth?

I've always heard it's closer to 16" but not longer than 18" with standard velocity ammo.

GA Guest wrote:I've always heard it's closer to 16" but not longer than 18" with standard velocity ammo.

Then why do olympic shooters use long barrels? And Federal ballistics charts rate all the 22 LR ballistics with a 24" barrel.

Then why do olympic shooters use long barrels?

Because the gain in accuracy of an extended sight radius outweighs the loss caused by a longer barrel (which is in itself a topic to be debated), but then again, most of them are using bloop tubes and getting the best of both worlds anyway.

For issf 50m disciplines, optimum barrel length for accuracy is about 49 metres. In general optimum for velocity is about 16 inches.

Anonymous wrote:

GA Guest wrote:I've always heard it's closer to 16" but not longer than 18" with standard velocity ammo.

Then why do olympic shooters use long barrels? And Federal ballistics charts rate all the 22 LR ballistics with a 24" barrel.

Because that's the industry standard test barrel length.

The question so far has been "what is the best length of barrel for optimum velocity?"

But the real question is

"What is the optimum velocity for accuracy"?

Speed isn't everything.

ksilver wrote:The question so far has been "what is the best length of barrel for optimum velocity?"

But the real question is

"What is the optimum velocity for accuracy"?

Speed isn't everything.

I don't think there is a single answer to that question. At the very least you'll have to add "at what distance?" A very real problem is avoiding trans-sonic flight before the target.

Supersonic muzzle velocity is fine as long as it's still supersonic at the target. Doing that and staying within the SAAMI pressure limit seems impractical.

Larry Durham builds some fantastically precise and efficient airguns producing about 20fpe for .177 10.5grain pellets. Basically, the barrel length affects efficiency more than accuracy with longer barrels being more efficient (more shots per charge of air). At some point, there are diminishing returns and accuracy and pellet speed have to degrade if the length becomes "excessive."

He posts actively on the "BullDurham" forum on Delphi. Here is a URL to one of his recent posts: http://forums.delphiforums.com/dir-app/ ... m&msg=2851

Bill Calfee, a very well known rimfire benchrest gunsmith, has written quite a bit about this in precision shooting lately. It is true that max velocity is achieved at about 18" or so but his theory is that 28" or so is better as it allow pressures to decrease in the barrel somewhat so the bullet is purturbed less when it exits. In practice though he says that he determines actual barrel length based on bore dimensions. He says best accuracy is achieved by putting the crown at the tightest part of the bore. He says that sometimes this spot results in a somewhat shorter barrel. Anschutz barrels are always (at least all that I have ever had) very tight at the muzzle. Of course we have balance and sight radius considerations to contend with that is i assume less of an issue in benchrest.

Another issue to consider is the lock time - shorter barrels would be less sensitive to recoil variations, no?

I don't think there is a single answer to that question. At the very least you'll have to add "at what distance?"

As this is the Olympic Rifle section of the forum can we limit this discussion to ISSF 50 m rifle. On the basis that the speed of sound is somewhere in the region of 1100 ft/s, depending on air temperature, to keep the bullet sub-sonic where should we draw the line on muzzle velocity to prevent instability? and "how low do you go"?

Well, 1060 seems to be the number the manufacturers "shoot" for:-)

Limiting the "discussion to ISSF 50m" will only decrease the advantage that visiting this website provides you in your discipline...as the benchrest guys have the technical details worked out...the prone guys have the technique details worked out.

My opinion of course.

Mike Tiehen

Anonymous wrote:Limiting the "discussion to ISSF 50m" will only decrease the advantage that visiting this website provides you in your discipline...as the benchrest guys have the technical details worked out...the prone guys have the technique details worked out.

My opinion of course.

Mike Tiehen

Could it be argued that the the benchrest guys have the technical details worked out...for benchrest?

While 'similar', there might be enough differences to make the comparison not quite total.
While seeking a rifle/ammunition 'accuracy' combination, most ISSF shooters tend to accept a 'practical' accuracy (i.e. better than the shooter's ability/technique) rather than the benchrest shooters' seeking of an 'absolute' accuracy.

Regards to all,
Spencer c

Being both a prone competitor and occasional benchrester, I find that "absolute" confidence in my equipment" allows me to perform to the best of my ability.

Every prone shooter that I know that has done some kind of work to their gun, will bench it to gather results of their work. I feel trigger work is best tested in position though.

I never bought into the thought that "My rifle (1912) shoots better than I can."

Mike Tiehen

How much does it matter?

Ordering a 16" barrel as opposed to an 18" barrel won't garantee you any more accuracy. You have to test each individual barrel to figure that out.

So, figure out what kind and length of barrel you want for the rifle to balance the way you want it to and then start testing barrels that match your criteria. That's where it can get expensive unless you can fly to Ulm and test barrels until you get one you like.

My personal preference is to err on the side of being too short (and that's what i'm going to do when i buy my next barrel) because you're not going to get a barrel from any major manufacturer and a good gunsmith that is too short to be at least somewhat reasonably accurate...and you can always make a rifle more barrel heavy. moving the balance point back on a free rifle, now that's a bit more difficult.