.375 H&H barrel length comparison ... 24" vs 19.5"

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MCMXI

MCMXI

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I recently sent a PM to H&Hhunter to ask about cutting down the barrel of my .375 H&H Mag. I'm having the entire rifle and scope dipped soon so this would be the time to do it. He has a .375 H&H with a 20" barrel and mentioned that if he were doing it again he'd go no less than 22". With this in mind, I asked a friend who has a custom X-Bolt with a 19.5" barrel to stop by so that we could compare velocity using a CED M2 chronograph. We were able to compare a factory Remington load, his handload and my handload. Here are the results. I did all of the shooting so as to have consistent rifle recoil and all shooting was prone which should result in the highest velocity. Obviously a larger test would be better since the barrels probably have other differences in addition to the length. After seeing the results below I've decided not to cut the barrel down. I consider my Talkeetna to be a 500 yard hunting rifle for mule deer, elk and whitetail so I feel that the extra 100+ fps is worth the added length.

375_h&h_vel_comp.jpg
 
Thanks for sharing data. Less velocity loss than I would have thought. I understand you not wanting to lose the velocity.
 
Thanks for the data. When I was looking into getting a .338 vs. .375 in a 20" barrel, I ran across this post with some velocity testing on the certain rifles, as the barrel was cut shorter and shorter. Interesting stuff. No .375 data there, but somewhat relevant. Eased my mind on .338 velocity out of a 20" barrel, which is the direction I ultimately went.
 
Thanks for posting the data. I have a 20" 375H&H encore barrel I was debating on having made and I think for the 130+/-fps compared to the 7+ inches saved in OAL, I don't feel too bad about it now.
 
Interesting. Think the effect is more pronounced in the smaller bore diameters.

I would expect say something like a step down in barrel length in .243W would be much more pronounced than in say .338 Federal chambered rifles

ATB, Scrummy
 
It's difficult to extrapolate much from two different rifles. You can't assume that 100% of the difference between the two is the length. Chamber dimensions, throat, bore dimensions and the finish inside the bore all affect velocity. Although it's safe to say that you will lose something.

That said, I really don't see 4" as being a huge difference in handling or weight, depending on the contour.
 
CraigC said:
It's difficult to extrapolate much from two different rifles. You can't assume that 100% of the difference between the two is the length. Chamber dimensions, throat, bore dimensions and the finish inside the bore all affect velocity. Although it's safe to say that you will lose something.
Click to expand...

I made that point in my first post, but if you look at the results the velocity loss from the three loads is fairly consistent with only 17 fps difference.
 
You can't form hard data, no, but you can put those numbers in a ballistic program and come to the conclusion that all the shorter barrel means, is you lose a good bit of muzzle energy (~300-400 ft. lbs.), but past that, you are at a 50 yard deficit in energy across the board....

Example, the 270gr load (using Nikon SpotOn software).
Length - ME - 50y - 100y ----- 450y - 500y
20" - 3966 - 3571 - 3195 ----- 1356 - 1194
24" - 4370 - 3943 - 3537 ----- 1523 - 1341

Same trend on the other loads as well. So, if that energy is critical, get 50 yards closer.
 
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Did both rifles have the same twist rate? I can't help but wonder if you would be giving up any accuracy with reducing the barrel length?

Ron
 
I made that point in my first post, but if you look at the results the velocity loss from the three loads is fairly consistent with only 17 fps difference.
Click to expand...
But cutting the Kimber's barrel could result in half as much loss as was witnessed between the two rifles. It could also be double. The only way to gain data that could be used across the board is to take one very long barrel and test it at 1" or 2" increments.

Either way, unless it's a very heavy contour (many .375's are) I don't think cutting 4" off it is a good idea if this is your long range rig. It this rifle was to be used as a relatively short range gun for dangerous African game or the great bears of the north, it would make much better sense. That said, I'd love to add two or three inches to my new .338 but my barrel stretcher is in the shop. ;)
 
It is very common to see 25-50 fps with the same loads in different rifles with the same length barrel. While not common I've seen 130 fps difference when using 2 different rifles. I've seen individual 20" barrels shoot faster than some 22" barrels.

Larger bores lose less as a rule than shorter small bore rifles, so a 375 should work better than a 7mm or 300 mag. There is a lot of data out there where folks have started with long barrels and recorded data as they cut them shorter. But I cannot find any on a 375. The closest I can find is for a 338 and 340 mag. They lost 150 fps and 106 fps respectively between 27" and 21". The 338 lost 87 fps between 24" and 20". A 375 should be less than that.

http://www.longrangehunting.com/forums/f19/short-barrel-magnum-velocity-19346/

For poking around in thick stuff after stuff that bites back I want short, in fact if I were buying a 375 it would be a 20" barreled 375 Ruger

http://ruger.com/products/guideGun/models.html

Up close 100, even 200 fps won't matter much. Even at 300-400 yards 100 fps less isn't something that would be terribly difficult to overcome.
 
http://rifleshooter.com/2013/12/300...rrel-length-change-velocity-a-16-300-win-mag/

A test a friend of mine participated in (there's quite a few out there now). A lot of changes since then, hes cut and re crowned in tests. Done a few on different calibers. Venture what you lose to what you gain. I chopped a 300 win to 22" and haven't had any deer complain after they drop, but sure do love how compact it is jumping in and out of trucks, added a folding mono chassis as well.

I will send him a note to see what he can do in doing this test with a 375H&H and see what he says. I think he'll say it may hurt too much to shoot all those different lengths, but it would be nice to see chopped every inch.
 
After looking at some ballistic charts I'm seriously thinking about cutting off 2" and having the barrel recrowned (recessed target crown). McGowen is just down the road from me and they can do it the same day but I'm hoping that they can chuck up the barrel without me having to remove it from the receiver. 20" would look weird with the stock that I have but 22" would look good and make the rifle a little more svelte. I can live with 24" but 22" would be a good compromise.
 
The other option would be a 375 Ruger with a 20" barrel, which would give you the ballistics of the 24" 375 H&H barrel with the handiness of the 20" barrel. One could take this too far I suppose, a 16" 378 Weatherby would probably beat the ballistics of a 24" 375 Ruger, but I wouldn't want to shoot that :eek:
 
A 16" .378 wby would be like a stick of dynamite going off in front of your face. I bet it would turn heads at the range though.
 
UPDATE:

I had the barrel cut down to 22" today and had a recessed target crown cut into the muzzle. I removed the barrel band along with the front/rear iron sights and used red loctite to screw in the rear sight screw. I'm going to grind the screw head down then use a file to blend the threads with the barrel. After that I'll lap the bolt lugs and then screw the barrel back on. Head space is extremely tight at the moment (will only close on a go gauge with considerable force) so a couple of thousandths off the back of the bolt lugs should be fine. I've added a front sling swivel stud to the stock, and the rifle will be going out to be dipped early next week. This is how it looked prior to all the work being done. I'll post a few photos in a week or so to show the finished product.

kimber_talkeetna_01.jpg
 
I chronied my BRNO 602 .375 H&H before I cut its 25" barrel down to 20".

I shot two loads (270 gr Federals and 300 gr something else) and IIRC the averaged velocity loss was around 90 fps.

That's not a lot of velocity lost considering how much handier my work rifle became for bush/transport use.

IMG_5483.jpg

Accuracy wise it was still fine after shortening. I shot this group off of the bench with only a front sandbag with the 100 yard leaf at 100 yards.

S5000033.jpg
 
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UPDATE 2: The barrel has been cut down to 22" and crowned, the hole for the rear sight has been filled, the barrel band has been removed and the bolt lugs have been lapped to give close to 100% lug to receiver contact. The bolt now closes easily on a GO gauge with no perceptible movement of the bolt when closed on the gauge. The bolt won't even begin to close on a +.003" NO GO gauge. Also, a front sling stud has been added to the stock. I'll be shooting the rifle tonight before it goes out for dipping tomorrow. I'll post photos of the rifle tomorrow as it now sits along with more after dipping.
 
My 20" M-70 in .375H&H pushes 270 gr TSX's at a reliable 2650 to 2700 FPS depending on the powder used.
 
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