Has anyone ever converted their 375 H&H to an Ackley Improved? I have a 6.5x55 AI and have found that the brass does not grow. From the data that I have seen there does not seem to be a lot of gain in velocity but to get the brass to last longer and get the shoulder headspace seems to be a benefit.

sorry, i am still typing onehanded, but there is no problem w/ 375hh brass stretching. it head spaces on its rim or, after 1st shot, on its shoulder.

mine generally dies from split necks. kudude

The velocity gain for the 375 AI is a much higher percentage than that from the 6.5 x 55 to 6.5 AI because the Swede is already fairly fat whereas the 375 H&H has a pronounced taper.

And if you go there, do a 375 Weatherby and call it that on the barrel so you can get headstamped brass. Case dimensions are nearly identical and load data is interchangeable.

I've recently had a 375 Ackley Improved 40 made on a 300 WM R700 action with a 26.5" barrel (Krieger finished 0.8" at the muzzle). No free bore. Jewel trigger. I put it in a HS Precision varmint stock. It shoots nicely achieving 1.0" 3 shot groups at a 100 yds with full-bore loads.

It's ~10% increase in case capacity over the standard 375 H&H. I like slow burning powders and get the best accuracy with Sierra or Speer BT bullets. I like using slow burning powders, especially with the 300 gr. Sierra BT Game King. I'm using 94 grs of Norma MRP and getting ~2900 fps (Oehler and Pact) with this 300 gr. bullet - no pressure and no loose primer pockets after 4 reloadings. I haven't shot them a 5th time, but plan to soon.

It's amazing that people don't use the newer slow-burning powders with these cartridges. They perform well, just like they perform well in the bigger case capacity guns such as 378 WM.

I've tried the 260 gr. Accubond, but can't get it to shoot well - poor groups. Anybody else have problems with 375 Accubond?

quote:

Originally posted by Rasp65:
Has anyone ever converted their 375 H&H to an Ackley Improved? I have a 6.5x55 AI and have found that the brass does not grow. From the data that I have seen there does not seem to be a lot of gain in velocity but to get the brass to last longer and get the shoulder headspace seems to be a benefit.

I have a MK-X in 375 AI & like it. Do a search for 375 AI there are some good posts / info on the cartridge here somewhere!

The long sloping design of the 375 H&H makes it feed well. And also requires frequent trimming.
I set my dies up on shoulder and forget about the belt. Do like the idea of the Ackley for longer case life & less trimming.

quote:

Originally posted by Rasp65:
Has anyone ever converted their 375 H&H to an Ackley Improved? I have a 6.5x55 AI and have found that the brass does not grow. From the data that I have seen there does not seem to be a lot of gain in velocity but to get the brass to last longer and get the shoulder headspace seems to be a benefit.

I believe this would be very similar to the .375 Weatherby except for shoulder shape....

If the .375 H&H isn't enough to satisfy you then why not go the the 375/404 that Saeed uses or the Wby..

Both of those calibers are extremely effective on everything that walks, talks, swims, crawls or breaths...

quote:

Originally posted by Rasp65:
Has anyone ever converted their 375 H&H to an Ackley Improved? I have a 6.5x55 AI and have found that the brass does not grow. From the data that I have seen there does not seem to be a lot of gain in velocity but to get the brass to last longer and get the shoulder headspace seems to be a benefit.

Any cartridge that is precision headspaced by custom chambering will show increased case life.

The caselife increases are not related to geometry of the case. Give the standard cartridge the same treatment as an AI and you'll see.