"Secret" barrel length

Very interesting project where virtually most external variables are eliminated by shooting inside a controlled environment within a warehouse. Groups were achieved that were astounding.

Muddyboots said:

Very interesting project where virtually most external variables are eliminated by shooting inside a controlled environment within a warehouse. Groups were achieved that were astounding.

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Yet all known load data is tested in the same way with controlled size barrels and lengths, and load data varies considerably from one manufacturer to another. So those tests and groups may only be exceptional in those conditions.
I have my own experience with this. My home range is only 1 metre above sea level, I have a load there for 600 metre F-class that is phenomenal, it produces sub 1/4 MoA there, and only there. Take it to any of the other ranges I compete at and it falls apart to best 3/4MoA. The worst is the 880 metre elevation range 4 hours drive away, this range holds 300, 600, 800, 900 & 1000 metre comps. I had to make a load there to compete, my loads from my home range would not shoot the same there, even my 22-250AI loads I use for 300 metre at home were different there.
People that say atmospheric conditions don't play a part are kidding themselves…

Cheers.

Muddyboots said:

Secrets of the Houston Warehouse – Lessons In Extreme Rifle Accuracy

Back in 1993, Precision Shooting Magazine printed a landmark article about the findings of a group o...

precisionrifleblog.com

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I came across this before, and saved it. I found it to be very interesting, and informive too.
Thanks! Saved it again.

Sample size of one but my Sako 75V 223 has a 22" barrel (I know it's a common length but it's pretty close to 21.75") and it's literally a one hole machine. I have other very accurate rifles but this one is the best. If you have never shot a 5 shot one hole group and it's on your bucket list lmk.

Notes: 100 yds & 40 gr bullet. Heavy varmint contour.
So kinda similar to the baseline (100 yd benchrest, 22 ppc) but all my shooting is outside. I have taken it to 400 and it is decent but definitely not the .1's & .2's it does at 100. Also the sd/es is terrible too lol.

Interesting, so 21.75 is magic. My unscientific question is the shooter sees the 21.75" length, the bullet sees a somewhat shorter length with the 22ppc, a 308, an even shorter length and one of the ultra mags even more so. Perhaps we need a video about the effect of the color of the walls in ones reloading room? An old professor told me if it won't repeat it on demand it is not science.

pavementends said:

Interesting, so 21.75 is magic. My unscientific question is the shooter sees the 21.75" length, the bullet sees a somewhat shorter length with the 22ppc, a 308, an even shorter length and one of the ultra mags even more so. Perhaps we need a video about the effect of the color of the walls in ones reloading room? An old professor told me if it won't repeat it on demand it is not science.

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I also wondered about the 21.75 as its measured from bolt face to muzzle---- yet the length where bullet hits lands definitely changes due to length of cartridge

So if you subtracted 22ppc length to lands from 21.75 --- then add that to the length to lands for other cartridge-- (let's use 300wsm)--- would that mean the magic length for 300wsm would be about 22.25" due to longer cartridge length?

Did Virgil only test 22ppc? Or did he test other cartridges/calibers too?

cohunt said:

I also wondered about the 21.75 as its measured from bolt face to muzzle---- yet the length where bullet hits lands definitely changes due to length of cartridge

So if you subtracted 22ppc length to lands from 21.75 --- then add that to the length to lands for other cartridge-- (let's use 300wsm)--- would that mean the magic length for 300wsm would be about 22.25" due to longer cartridge length?

Did Virgil only test 22ppc? Or did he test other cartridges/calibers too?

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The harmonic waves travel the full length ofthe cantilever beam or barrel and reflect back. Thus its from bolt face to muzzle.

tim_w said:

The harmonic waves travel the full length ofthe cantilever beam or barrel and reflect back. Thus its from bolt face to muzzle.

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Wouldn't harmonic waves only travel to the supported barrel part and back?

Isn't that why Melvin used full length bedding on his nula rifles? And isn't that why some barrels use a pressure point at the end of the handguard? To change the harmonics?

Yes it will dhange the harmonics. Honestly I am far from an expert and its far more complex than any single harmonic.

I make a living building rifles. A lot of Benchrest stuff, thats where the accuracy comes from and I love it. F-class and LR hunting. Even some rimfire BR stuff. Most of it transfers over. Especially the LR BR to LR hunting. But a 6ppc is a different animal. Do not try to base anything about your LR hunting rifle off of a 6 ppc. Dont expect it to act like a ppc, dont tune it like a ppc, just ignore the ppc. If you want the most accurate rifle you will ever own, build a ppc But it aint your LR hunting rifle.