Barrel lengths vs. Velocity gain/loss

[jhibbard24]

My big question is how much velocity is lost by going with a little shorter barrel. I strongly believe the fact that out of two barrels of the same diameter, but having a two inch difference in length will result in the shorter barrel being more accurate (in theory) because of more barrel stiffness and less vibration.. So if 2" less barrel isn't robbing too much velocity then why not?

I've currently got a rem 700 VLS .22-250 26" barrel. Wanna rebarrel with a 24" kreiger fluted and chambered in .22-250 AI and shoot the new 53gr. VMAX. Obviously the Ackley is faster. I'm looking to make this varminter a bit more handy and lighter in weight.

Lets hear some good input from the guys who know what they are talking about.

 

[SBruce]

There are WAY too many variables going into this to give a straight yes/no answer.

Plain and Simple, depends on too many things! The old rule of thumb is 30-50 fps per barrel inch. But that is so general, it's kinda useless under today's component list.

Powder burn rate, land/groove diameters, twist rate, bullet weight, primers (hot or cool), on and on and on.......... fast barrel, slow barrel, ect...........tight chamber, loose chamber, long throat, short throat......on and on and on.

FWIW, I've owned and shot a few 22-250's with both 24's and 26's. When you're talking 53 grn bullets, the suitable accuracy powders are burning fast enough that it really doesn't matter (yes, generally speaking the 26's shot a little faster than the 24's), enough to matter to a varmint.......NO.

Now change the subject to 69, 75, 80 grn bullets..........different story, that's really where you need the long barrel and slow burning powders. On the same page, include 22-243's, 22 CHeetahs, 220 Swift Improved, 22-6mm's and the like.........again, this is where we need long barrels and slow powders.

 

[eddybo]

My buddy has done a great deal of experimenting with this. He would chamber a new barrel and crown it off. Work up the best load he could find them chronograph it. He would then put it back in the lathe part off an inch and recrown and work up a load and chronograph. I do not know how much value his results have on larger cases, but his results showed an average of 17fps per inch in 6PPC for five inches of barrel removed.

 

[Gene]

My buddy has done a great deal of experimenting with this. He would chamber a new barrel and crown it off. Work up the best load he could find them chronograph it. He would then put it back in the lathe part off an inch and recrown and work up a load and chronograph. I do not know how much value his results have on larger cases, but his results showed an average of 17fps per inch in 6PPC for five inches of barrel removed.

Some time ago I saw an experiment where a smith did this, removed one inch of barrel at a time, and reported an average loss of 25 fps per inch. There are variables.

I like short 20" barrels , for BR rifles out to 300 yds., because, generally - they balance better and the vibration nodes are shorter. Beyond that distance, I feel the added velocity is an advantage, and prefer 26" barrels.

 

[backwoods83]

My opinion is the same as stated before, more of a matter of drag, amount and size of lands and grooves, bullet weight, seating depth, powder burn rate, etc. Every caliber is different. Honestly going to the AI version is ****ing in the wind, nothing you shoot with that particular bullet from either version will ever know the difference!

 

[JeffVN]

Mr. Lilja of Lilja barrels performed that very same experiment and documented his results here:

Lilja Precision Rifle Barrels - Articles: Barrel Lenghts and Velocities in the 338/378 Weatherby Magnum

interesting. The results are, in part, based in part on the powder burned, case capacity, and bullet weight.

Jeffvn

 

[Trickymissfit]

My big question is how much velocity is lost by going with a little shorter barrel. I strongly believe the fact that out of two barrels of the same diameter, but having a two inch difference in length will result in the shorter barrel being more accurate (in theory) because of more barrel stiffness and less vibration.. So if 2" less barrel isn't robbing too much velocity then why not?

I've currently got a rem 700 VLS .22-250 26" barrel. Wanna rebarrel with a 24" kreiger fluted and chambered in .22-250 AI and shoot the new 53gr. VMAX. Obviously the Ackley is faster. I'm looking to make this varminter a bit more handy and lighter in weight.

Lets hear some good input from the guys who know what they are talking about.

quite honestly a 26" barrel in a 22-250 is nothing more than a barrel harmonics disaster looking for a place to happen. The .250 savage case is not exactly a big case, and is known to work quite well with a 22" barrel, so a 24" barrel should be plenty of barrel even with the Ackley case.

A given barrel profile will be stiffer the shorter it is verses the the same contour but longer. A typical #7 contour 21" long is 2.75 times stiffer than the samething 26" long (275%). A 24" barrel will probably be 33% stiffer, making everything group a little better. The stiffer the barrel, the more controll it has over harmonics.
When you goto the shorter and stiffer profile, you simply adjust the powder burning range you work out of. With today's huge array of powders, this shouldn't be much of a problem with the .250 case. It might with a .300 mag case.

I shortened a .223 barrel six inches, and lost a huge 75 fps! (not close to a max load by the way). Still use the same three or four basic powders I was using before, and everything's better with it. Plus the balance is so good that I can shoot a heavy barrel offhand without any trouble what so ever.
gary

 

[jhibbard24]

my wanting of the AI cartridge over the standard .22-250 case is just for something new to have and do. but i do love the difference in how ground squirrels blow up with a 4200 fps 40gr vmax compared to a slower 50 gr. so i guess that is part of the reason of wanting the little extra umph of the AI with and 53 gr. bullet to keep to squirrels airborne

 

[Trickymissfit]

Mr. Lilja of Lilja barrels performed that very same experiment and documented his results here:

Lilja Precision Rifle Barrels - Articles: Barrel Lenghts and Velocities in the 338/378 Weatherby Magnum

interesting. The results are, in part, based in part on the powder burned, case capacity, and bullet weight.

Jeffvn

The problem with Dan's tests are that he was using a large overbore case, but was surprised that his results sorta paralled what others found with smaller cases. Somewhere around the house I have one that Precision did using several different rounds, and Ackley published data that somebody else did with the 30-06 and others. I'd like to have seen the same tests ran with a .308 and a .338 Win mag
gary

 

[jhibbard24]

hey Tricky, so i like what you said about the AI performing in the shorter barrels ie. 22". something like that would make that an even more versatile and handy varminter. maybe a barrel length of 23" would be a good mediocre that would still perform good. this .22-250 AI would be getting some action in out to 450-600 yds for ***** and giggles, makes for some good challenges. realistically though, it will see most of its squirrel and yote killing from 50 to 350 yds.

If we don't create challenges for ourselves then what the hell are we doing here.

 

[backwoods83]

The Ai is your preference but it is like a 220 swift due to case capacity it has no advantage until you use the heavy weights, except premature throat erosion. I can pass 4300fps with a standard 22-250 but accuracy begins to fall off with 40grn nbts. Its like comparing a 338 win mag to a 264 win mag, same case but the 264 has more of a bottle neck so to speak so you can run 60+ grns 4064 in the 338, try that in a 264! With that said try running identical charge densitys of RE10X in a AI 22-250 and you will hurt yourself, you might have a chance of keeping up velocity wise with compressed 4064 or 4320 but I doubt it. All I'm saying is that extra power capacity does you no good until you step the bullet weight up and use a slower powder. I think you should do a 22-250 AIwith a 1:8 twist and shoot 80grn bergers or the like. No I'm not bashing just putting it out there.