Home Forums Hunting & Shooting Ask The Gunwriters 24 inches to 18 inches 375 H&H

Thinking about building a 375 H&H with a threaded 18” barrel. How much velocity loss can I expect with a 270 grain bullet that would be loaded to give 2700 FPS to 2750 FPS at 24”?
Thanks

BTW: I already have a 375 Whelen AI 22” threaded rifle. Would it be worth it to build the proposed rifle?

Just a SWAG …..150 to 200 fps! A fast burning powder may mitigate a little bit of that loss……but, I doubt it! memtb

Having shortened and re-tested many barrels, including one .375 H&H, I doubt you'd lose 200 fps. Maybe more like 100 fps--which wouldn't make any difference in "killing power."

I cannot imagine what 18” gets you that 21-22” will not besides hearing damage!

That is the main thing. You shorten them any more than 20", and they are horrible. This coming from my gunsmith. He said he had one at 20", and "never again", was his exact words.. He said it was the loudest POS he had ever seen.

I cut a bunch to 18” and 20” for customers in Ak. Never cronoed any of them afterwards but never had a complaint or anyone bring one back to be rebarreled with a longer tube.
When I built mine I finished the blank at 20”. It would push 300gr Sierra SPBTs to 2550 using IMR 4831 with great accuracy and good brass life.

Here’s the thing. I can buy a pretty much like new 700 7mm RM with a synthetic stock on line for less than $600 shipped. Send it to Shaw and have a 375 H&H threaded SS barrel installed for less than $600. Their length limit for threaded for suppressors is 18”. I have a suppressor with the appropriate threads. Noise shouldn’t be an issue.
I’m concerned about going to somewhere where the authorities say the brass and the barrel have the same cartridge destination.
For about $1,100 I can have a new to me rifle I can play with and it would be acceptable in such places. I know there’s other cartridges that would likely work fine. But I like the 375 H&H. I’m not particularly fond of synthetic stocks, if I couldn’t get this combo to shoot well I’d put on a walnut stock - but I doubt that would be necessary.

'...I’m concerned about going to somewhere where the authorities say the brass and the barrel have the same cartridge destination.
For about $1,100 I can have a new to me rifle I can play with and it would be acceptable in such places...'

???????

Do suppressor s have an effect on muzzle velocity?

Flow through suppressors affect velocity very little, but a traditional baffled can actually will cause a slight increase in my experience.

I'm not saying you're wrong, because I don't know, but it is surprising to me that losing 1/4th of a 24" barrel wouldn't cause a 200+ fps velocity drop.

I think we all have read and heard about losing 50 fps or more per inch of barrel length. I shortened my 280AI from 24” to 21” and lost 60 fps total.

I believe MD. The bore to case ration is high. It’d be a lot different for say a 264 Win, I believe.
I appreciate the information though. I don’t want to waste the bucks if the velocity dropped too much.

A 26" Browning A-Bolt SS went from ~2700 fps firing 300gr Hornadys to ~2540 fps when cut to 22" from the same load. That's 40 fts per inch loss.

In addition, the increase in the blast factor should be a consideration without muffs or a can. My current .375 has a 22" barrel but was made that way. With better powders, I'm getting what I could from the .375 H&H with the 26" barrel. Different make with different results. It's impossible to predict depending on many variables including not only barrel length and make but powder, bullet and the handloader himself/herself. Some are more cautious and others push the limit. Those issues in total can easily make a difference of 200 fps.

Bob
www.bigbores.ca

If you look though the old post here, I posted a bunch of test some years back. Lots a calibers, 222, 300 Ultra, etc. If you are burning smokeless gunpowder, and have a good barrel, 25 fps or so is the loss or gain per inch.
Charlie

24" is my choice. If the brush is really bad, you have to hold your rifle in one hand and push it away with the other. It really doesn't matter in that situation.

Yep. I’ve owned chronographs continuously since the early 80’s, and an average would be 25fps loss per inch of bbl.

Magnums like the 7RM and 300Wthby lose more, others like the 308/7-08 lose less.

Have only chrono’d one 375H&H though.

Like Charlie, I have shortened quite a few barrels and tested the loss/gain with the same load, in the same barrel. Haven't seen anything, no matter the cartridge, that would indicate 50 fps per inch as anywhere near typical--especially with a cartridge with the bore/powder capacity like the .375 H&H.

Barrels on the US Missouri are 65’ long. Why is that?

I knew a guy who picked up a Sako Mannlicher carbine in 375 several years ago for a cheap price. He didnt keep it very long.......