I hate when people give this typical answer so don't take it offensive, but I know there's a good forum discussion on this caliber if you do a search I remember seeing it not to long ago on here. It talked about the case structure and such, just look back a little ways and hopefully you'll find it. Sorry that wasn't a lot of help.
What do you mean by long range? The .375 H&H may be my all time favorite, a lot of good memories associated with it. Range finders, good ballistic info, and better scopes help it a little farther out than it used to. Those things also help a host of other cartridges that are probably better suited to stretching whatever range your thinking. Start with the specifics target size, distance etc. and run some numbers through the ballistic calculator at the top of the page, and compare it to other cartridges more commonly considered "long range". Why the .375 H&H?
I have been pondering "long range" use of the h&h for awhile myself.
I got rid of my .338 awhile ago, in part because there is so much overlap between the two out to about 400 yards. Frankly, my skills haven´t progressed to the point that I can use the superior long range qualities of the .338´s. As a bridge, I am looking to develop proficiency with my .375 out to about 600 yards. That appears to me to be the practical limit of the h&h case with the bullets currently available.
I must stress that I am still in the research phase of the idea. Based on some previous discussions on this forum, I plan to start by handloading with the Barnes 250g TTSX. If it does well in my rifle and performs well on game, I will stay with that load. If not, the 260g Accubond looks like a good alternative. I figure that I should be able to push either bullet to around 2900ish plus or minus a little bit. Having run the basic numbers on the JBM ballistics website, on paper that level of performance would appear to give reasonable performance to 600ish yards.
I plan to start the initial load work this fall, but I don´t think my schedule will allow enough range work to reach any useful conclusions until next fall. Will post my results when I have something worthwhile to share.
If anyone else beats me to the punch on this, I would be most interested in the results.
I also have been playing with my 375h@h wihitworth as to push some distance started a 300 yards and was near no hold over but far from long distance ,that was 18 mouths ago this week i pushed 700 yards and keep a 6inch group . i have a sheperd scope and shooting 270 gr bt . i am looking to start reloading this gun now and see if i can tighten up the group i like to push for the 1000yrd shot then try it in the field after i am confident .gun) now just to keep the wind out of the pic.
I stumbled on this thread today and was curious if either of you guys have done any more research on the subject??? I've been loading the 270gr spbt bullets that have a bc of .478 and pushing them at around 2700. It seems to be performing well, but the gun and load are both new to me. Anything you guys have found on the range as far as loads you like and longer range groups with the cartridge would be great.
Years ago Dave King put together a build similar to a Sendero in 375 H&H and shot 260 NAB's out to 1K with good results. Similar come up as the .308 Win. I shot mine out to 600. A search on this site should come up with something