Home Forums Hunting & Shooting Ask The Gunwriters Question about barrel shortening?

You will end up with a very hard kicking 308.

..............A 300 Wby down to 18"????? Oh boy!!! Holy Moe---ly!!!

Ok! Go read this that was recently posted on another thread here on this forum concerning short barrels.

"Hunting Rifles" section
Thread titled..."Short Barrels?" originally by Silver78
Pg 3 of that thread.

Find the article by Charlie Sisk that someone just posted there testing the chrony results from various cartridges when cutting the same barrels down by 1" at a time. Note how much velocity the 300 Win Mag actually loses with the same barrel. A reasonably good comparison to the 300 Wby!

Cutting down the "same" barrel, it lost 95 fps going from a 27" barrel down to a 22" barrel. 95 fps divided by 5 = 19 fps per inch. I would be willing to bet that the 300 Wby would fall much more in line with that figure, than would 50 fps per inch someone else posted. That figure also falls about right on par with chrony testing my own 300 WSM shorty carbine vs two other 24" tubed 300 WSMs using the same identical loadings, which was from 16.4 to 19.5 fps per inch.

Also see the loses from the other cartridges that were also tested. Not as much velocity lost as many might think!

You should lose about 20 fps per inch, or about 120 fps off the 3300 you are getting now. But only with some chrony readings after the cutdown, will you know for sure.

Day Packer!!!

On second thought,,,,,,,,,,,DON`T!!!!

The 300 Wby cartridge is not really designed for a shorty tube. Too much powder in that casing.

If you want a handy 30 cal mag, go find the same 16.5" barreled 300 WSM Ruger Frontier rifle that I own on G/Broker assuming any are still available. The 300 WSM is much better suited to a shorter barrel and won`t be nearly as loud as a shortened 300 WBY.

Using some RL17, I can move a 175-180 grainer in the mid to latter 2900s.

Do you really need more than that?

The .300 Win isn't so big a case as the .300 Wea, and Sisk's data started with a long barrel at reasonable pressures. The differences in expansion ratio and peak pressure will cause a far greater fall off in efficiency for the .300 Wea proposed. For reference, the Powley predicts Sisk's .300 Win ending up at about 2940 fps vs the 2960 measured. I'd assume at least 30 fps/in for the Wea; the Powley is predicting 35 fps/in.

The velocity loss will be 25-30 fps per inch of barrel removed. So you may EFFECTIVELY end up with an18" barreled carbine with .300 WSM OR 30/06 muzzle velocities. How much increase in muzzle blast are you willing to tolerate to get there?

Please let us all know how your project goes. And good luck.

I do not mean that a shorter barrel 270 is faster. I just seems to loose less velocity per inch than a magnum round. Yes I hand load my rounds. If I drop the amount of powder down, yes can get rid of some of the blast and noise but you lose more velocity. I looking for a nice easy handling rifle to shoot. I know some people kill elk with a 243 but I consider the 7mm-08 and the 270 on the low end for elk. Other people may have better ideas.

I think an important point that you can learn from Sisk's experiment, is that the idea that the fast "magnum" loses 50 fps per inch of barrel cut off, and the slower rounds lose much less (like 20 fps) isnt really true. 20-25 fps is a pretty estimate for all of them. This is contrary to the most common opinions you read on the internet about the fast magnums.

For example, a 300 magnum doesnt "need" a 26 barrel for velocity anymore than a .308 win does. Cutting down a 300 mag to 20 inches doesnt make it a .308. The 300 will be faster (by almost the same amount) than a 308 if they are both 20 inches or 26 inches. Also, another incorrect, but common thought, is that the 300 winne will need a faster powder when it cut to 20". The same powder that gives highest velocity at 26" will probably give the highest velocity at 20".

But the muzzle blast is real. My 20" 30-06 is fairly obnoxious at the range, so ive been told.

...................Very good post!.....I`d really like to know when and how, this falsehood of a "50 fps" loss in velocity for every "inch" of shorter barrel length came to be.

In the old days using powders that aren`t as high-tek as today`s powders??? From older cartridges??? From the bigger bores???

This fallacy seems to have embedded itself right into the thought process of some, and just sticks there like super glue.

All I know is that I picked up 100 fps in my regular 270Win when I went from 22" to 24". Verified on my chrono with both factory loads and handloads.
Ken Waters and Jack O'Connor found the same thing. Read about it in Pet Loads.

A 300 Win Mag in a Browning A-Bolt SS LH in 26" format gave me 3200 fps with 180s and 3000 fps from 200s. I've owned six different 300 Winchesters. That Browning would easily beat my 300 WBY with a 24" shooting the 180s and 200s.

My current 300 WM has a 24" and will not come anywhere near 3200 fps with 180s.

I've also owned a couple .338WMs. One had a 20" and the other a 26". The difference was 200 fps with 250s.

I had a 375 H&H shortened from 26" to 22" and lost 185 fps from 300s. That works out to 46 - 47 fps per inch!

That's from the FWIW dep't.

Bob

www.bigbores.ca

Velocities are general measured using 26 or 24 inch barrels. I think we can agree that any barrel that is shorter will have less velocity whether it is a magnum or not. Each rifle is a different too. Some rifles are faster and some are slower. The trick is to find the perfect match for the person using the rifle.

Excellent informative post based on actual experience CZ.

Jives with my actual experience with my 270 as well.

My 338-06 lost ~220 fps going from 24" to 19" and that was in the exact same barrel as I shortened it myself for a Mannlicher stocked project I was working on.

Bigsqueeze, our resident short barrel proponent has experienced different results however.

................Yes! My per inch #s when comparing my 300 WSM shorty and my 20" 375 Ruger Alaskan to the longer barrels in the same cartridges, average far less than were your #s.

But what the hey, by your #s, a 44 fps loss per inch, is still better than 50. I`m very suprised at that 44 fps per inch #.

In looking over the last few posts, I see a possible pattern??

At least with the 338/06 anyway, the #s into the 40s seem to suggest a greater fps "per inch" disparity, which is generally not found in other rounds like the 300 WSM and other shorty mags.

Other than inside bore dimension which control slower vs faster bores, does this mean that possibly "cartridge design" may play a role in determining the fps "per inch" loss???

I`ll be doing some thinking on this one!!!

Chub Eastman's tests of the .375 Ruger (in HANDLOADER No. 248)show a HUGE difference between the Hawkeye Alaskan with it's 20" tube and a 24" Pac-Nor barrel, WITH THE SAME LOADS!

Example: a handloaded 270gr Woodleigh using same load in each:
2558 fps in the Hawkeye and 2832 fps in the Pac-Nor. Difference? 68.5 fps per inch!!

270 Hornady SP factory load made 2684 fps in the Hawkeye (20") and 2882 in the Pac-Nor (24"). Difference? 49.5 fps per inch!

That's pretty close to 50!

Other loads indicate the same trend! 225 Speer/2800 fps in the Hawkeye and 3056 fps in the Pac-Nor! With the exact same load in each.

For my money, I'd buy the 23" African! In fact my dealer has a couple in LH which interests me very much. That is one of 'em, NOT both!

Bob

www.bigbores.ca

My 338-06 is the only time I've ever gotten results from the very same barrel at 2 different lengths however. Therefore it is the only one where other possible influences on velocity are not a possible factor.
All of my other observations were based on different barrels in different lengths.

I agree that DIFFERENT barrels may make a DIFFERENCE, but that could be in either direction, not always favoring the longer barrel. There's no denying there's a trend.

I chronographed loads in a SAKO carbine (20")in 300WM for a guy at the range years ago. First off, the recoil was brutal, and it was LOUD! With a typical "hot" load using 180s, it made 2900 and change.

To put that matter of recoil in perspective: I shoot heavy loads in my 11 lb (all up)CZ in .458WM as a regular thing. I mean 350s at 2750 fps and 500s at 2200+ fps. And a lightweight Ruger No.1 in 45-70 Improved using those same two bullets at a couple hundred fps slower. The CZ makes over 60 ft-lbs of recoil energy and the Ruger over 80! I would rather shoot them than that little SAKO 300WM firing 180s at 2900 fps! I know, there are many factors in "felt" recoil (see my blogs on it) but noise is one and a sharp too-high comb is another.

The guy's load would have made at least 3100 fps in a 24". THAT WORKS OUT TO A LOSS OF 50 fps per inch!!!

Bob

www.bigbores.ca

I agree completely Bob but the only time in my experience where all barrel factors other than length were constant was my 338-06 experience.

.............Very interesting! I dup`d an H-4350 270 gr Horn SP loading from Jeff Quinn @ gunblast.com, in which in his 23" tubed 375 Ruger African got 2875 fps. That same 270 gr loading from my 20" Alaskan was 2808 fps. Only 67 fps behind or 22.33 fps per inch!

Figure that one out!!!!!! A faster bore perhaps? Maybe Quinn`s test African has one too?

Just goes to show that nothing is absolute when it comes to barrel ballistics and its relation to velocities.

As an added thought, that 24" Pac Nor barrel probably had a faster bore, while the opposite was so with that 20" Alaskan bore, making the "per inch" velocity spread further apart.

The only precise way to know, is to cut the same barrel down in 1" increments and then chrony identical loadings after each cutdown.

Since we can`t do that, we can only compare results using seperate rifles which are chambered in the same cartridges with different barrel lengths.