"Secret" barrel length

cohunt said:

Anyone actually tried 21.75" barrels ???

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I've had a few shorter, and get more than acceptable accuracy. No 0.025", I think I had one that came out that when I had it cut short behind front sight, still shot like crap.

Maybe its discipline specific, as the variables in this group might prevent a qualified answer.

cohunt said:

BUT what if it was 21.75" ..... could it have been better ?

I'm guessing if there really was a "magic" length we would see it consistently in matches---- but why was Virgil so adamant about the fact that that was the most important thing he learned there?

They tried different powders, bullets, primers, seating depths etc ( if I rember)-- yet he claimed that 21.75 was the most important part of the accuracy equation

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They did not have tuners back then the knowledge just was not out there in the community. Heck look at the present day many people do not believe or understand the science of it. You can tune certain harmonics thru barrel length. Despite what is frequently stated tuners and changing seating depth do not do the exact same thing. Those harmonics tuned are also to those ppc case sizes of cartridges. You then have the rules and other attributes of the gun.

Of course there is also the benefit of barrel stiffness. But so much more. Do not forget the low max weight limit of LV BR. So they have to work inside that 10.5lb limit. Next rifle balance in the rests during recoil is critical. Barrel weight contour and length has a critical effect on this as well. If you look at 6mm PPC LV guns most are running 22" +/- 0.5". Makes sense when you combine rules with balance and barrel stiffness. 1.250" diameter @ face not more than 5" length and then must taper to muzzle. Hence the HV taper which is 0.0146?/in. . That would likely still not make weight in LV. You also have min barrel length of 18". That means when factoring in everything you really are working with only 4" of barrel length in LV.

For SR LV I would take the stiffest barrel contour with enough length to get a few inchs more than 100% powder burn in all conditions taking into account those factors mentioned above. Basically 21.5-22" barrel so for many reasons a 21.75 would work well. But even HV @13.5lb many are running 22" - 24".

BTW, Virgil did lots more than just load dev and barrel length.

FURMAN said:

I can't tell if you're actually trying to learn something here or what? It's because he was only focused on short range bench rest.

Edited to add and centerfire only

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That's what I kept wondering following it.

I do still find it amazing the group sizes shot even back in the 80s when you compare it to the level of precision we are capable of today in everything from machining to loading. Those were cool times when you still saw tons of wildcats people experimenting. Most everyone was a machinists.

I remember hearing a story from or about speedy gonzalas shooting and turning a load in a warehouse. The load shot great, he took the load to a match and it fell apart in out door conditions. What works in a controlled environment with a small sample size?

You get a load on the ragged edge where the slightest change causes it to implode.

Harmonics are everything, have seen barrels of 30" difficult to tune, barrels of 32" easy to tune. A happy medium appears to be 28"-29" and for me, 29.5" has been a sweet spot in 6.5mm cartridges. Is this a real thing, I am not sure, but even at 29" tune was easy. I have only 1 34" barrel, it is my wildcat 375-416 Rigby Improved 40° and this was desired for maximum velocity, it is finicky, yet H50BMG settles it down nicely, the pressure curve is very smooth, so maybe this length has more harmonics. When I change to 37XC I will also use 34" barrels, 32" in 33XC.
I am still experimenting, 7mm looks promising at 28"-30" with 29" thrown in, maybe a 29.5" barrel will also tune nicely.

Cheers.

MagnumManiac said:

Harmonics are everything, have seen barrels of 30" difficult to tune, barrels of 32" easy to tune. A happy medium appears to be 28"-29" and for me, 29.5" has been a sweet spot in 6.5mm cartridges. Is this a real thing, I am not sure, but even at 29" tune was easy. I have only 1 34" barrel, it is my wildcat 375-416 Rigby Improved 40° and this was desired for maximum velocity, it is finicky, yet H50BMG settles it down nicely, the pressure curve is very smooth, so maybe this length has more harmonics. When I change to 37XC I will also use 34" barrels, 32" in 33XC.
I am still experimenting, 7mm looks promising at 28"-30" with 29" thrown in, maybe a 29.5" barrel will also tune nicely.

Cheers.

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It's funny you said that. I have seen the same thing. I've also seen an improvement taking an inch off of a 26" barrel, making it 25" and also in more than one contour. It's all about harmonics.

cohunt said:

Virgil was shooting 22 ppc

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I appreciate the caliber correction, although the logic remains the same.

cohunt said:

So you are saying that .025" 5 shot group at 100 yards goes to shiznet at 800+ yards? Didn't litz prove that a small group size at 100 equates to a small group size at distance ? Or al least no one ever disproved him any way

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Depends...1/4moa at 100 is no guarantee of 1/4moa at LR.

in 100 yd benchrest they shoot very short/light bullets that would be horrible at long range in any kind of wind and what were the size of the groups with longer barrels that would provide better speed to fight the wind, they could have been horrible groups like .050. In long range velocity with heavy for caliber high bc bullets is every thing because the wind moves your bullet way more than any effect cutting barrels off to gain perhaps a very small accuracy gain . that group of .025 would transpose to a 1/4 inch group at 1000 if group size was linear which it is not. cutting off barrels is the opposite of what you want if you are trying to get the best results for long range

I own a Rem. 783 in 243 factory 26 in. varmint contour. It was very front end heavy so had it cut to 20 in. If anything it shot a little better and was so much easier to handle when hunting. Small drop in velocity (less than 100 fps). Maybe slightly stiffer may have been the difference ?

cohunt said:

Has anyone here on lrh ever owned a rifle with a 21.75" barrel?

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I have one, but we didn't pick it because of the accuracy test. In our cut down tests we found that most velocity loss is slow fairly linear curve until a certain pont and then has a sharp decline. So our model estimated that the ultra mag goes from high 40 fps to upper 70 low 80 fps per inch around 21.5 inches so we built a rifle at 21 and 5/8 but it finished dowel measured closer to 21 3/4.

Not a great accuracy test rifle, it has a leupold ultralight with a mountian light taper in a carbon stock that's been fluted and slabbed to the max. With a load burning 100 grains of retumbo... it's tough to bench.

Whacks critters and packs nice, but not a great advertisement for group accuracy.

cohunt said:

So has anyone had an exceptionally accurate rifle and then chopped the barrel down to 21 3/4" to see what happened to the accuracy?

The Houston warehouse secrets say you "must" use 21 3/4" barrel for optimal accuracy.......is this really the "secret length"?

I've seen some pretty darn accurate rifles that weren't 21.75"--- could they print better groups?

I bought a26" 300wsm to cut down and thread for suppressed hunting--- I was originally gonna go for 22" but why not 1/4" less just to try----- but it's pretty accurate at 26" and I hate to ruin a good thing ( never should have shot it before I chopped it cause now I'm doubting if I should go for it)

Thoughts on the "secret barrel length" from those who have tried it .....?

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Where did you read about the Houston warehouse secrets? I have read a very basic account somewhere. If there's a detailed account, I would love to find it.

Thanks, Muddy.