I have three Sakos in 375 H&H and I am looking to rebarrel or possibly just rechamber one of them. Not sure what I want to do yet, but I am considering using the factory barrel and just rechambering to 375 Ultra. My question is: what modifications need to be made to bolt face, feed rails, etc.? Also, is 24" enough barrel? Any help would be appreciated.

[ 08-30-2003, 03:11: Message edited by: DOCTOR LOU ]

I've had it done to an extra Ruger Express in 375 H&H.
1) Measure your chamber dimension (375 H&H)
2) Get proper reamer that will clean up the belt when reaming
3) Open the rails as the 404 brass are a little fatter
4) The bolt face doesn't have to be opened as both cartridges are within a few thousandths depending on make of brass
5) This the last part that I am waiting for, a drop box magazine (pregnant floorplate) to accomodate 4-5 cartridges in the magazine.
I hope this encourages you to experiment as I think this is a great round to play with. I haven't shot anything big with it yet, but have done quite a few groung squirrels and other varmints or other targets of opportunity. Jon Sundra made up the first published 375 Ultra when the 300 Ultra first hit the market. His articles are worth looking up.

475guy, thanks for the info. Lou

Of course a 24" barrel is enough but make sure the rifle has some weight to it. That cartridge really kicks. I suppose one can shoot it well but everything has a cost.

Doctor Lou,

Have you considered going with the excellent 375 H&H improved? This is one caliber which benefits a great deal by being improved. The velocity gain is exceptional as is the "across the board" performance. This is a simple set back and rechamber job. And hey, if you're out in some remote location and you lose your ammo, you're not likely to be out of luck. You can damned near stumble and land on 375 H&H ammo. It is everywhere...

Good luck,

Malm

G. Malmborg, just started thinking about it today. Not sure if I should go improved or Weatherby. What's your opinion of the two? I really don't want to set the barrel back because I don't want to move the sights or lose the factory stamping. Is it mandatory to do this with the improved? I understand it's not necessary with the Weatheryby. Dr. Lou

[ 09-15-2003, 02:02: Message edited by: DOCTOR LOU ]

Dr. We rechambered a Mark X 375 to 375 weatherby without setting the barrel back. I had the reamer made so the throat is normal. I also bought a model 70 that was rechambered to 375 ICL which is just an improved 375. The work was done by an outfit in Reno or close by. This one holds a little more powder than the Wby and drives the 300gr.partitions at 2825 about 75fs or so faster.Both are 24" barrels. I don't know if the barrel was setback on the Win. but it doesn't appear to have been. The Win is a beautiful rifle and people chew me out about rechambering it but it was done before I got it.Mark

Doctor Lou,

The .375 H&H Imp and the .375 Weatherby are virtually identical and loading data is said to be interchangeable. You do not need to set the barrel back to make this "Belted Mag" conversion for this Ackley improved version, however, anytime something can be done to close the sloppy factory belted headspace setting, I will always recommend that.

Keeping the sights aligned is a breeze provided your gunsmith knows how to correctly mark and set the barrel exactly 1 turn. I don't think you would lose any factory lettering. 1 turn would equal 1/16 of an inch. I don't remember the lettering being that close to the receiver. I may be wrong, but you can measure and see.

I will occasionally build me a .375 H&H Ack Imp just because I like them so much. I have a hard time hanging on to them as friends will come along and whine until I sell it to them. I've seen these things chronograph around 2950 fps and slightly higher using the 300 grain Sierra bullet. The 250 and 270 grain bullets can zip along well over 3000 fps.

Good luck,

Malm

The less alteration to the rifle that is necessary, the better.

On that note, definitely go with the .375 Imp. or .375 Weatherby. Personally, I'd lean more toward the .375 Weatherby. Why? No good reason, it's just my current inclination.

I have had the H&H and the weatherby and the ackley version and now the ultra mag.Go with the ultra mag more capacity and seems to be very accurate.The recoil isn't terible with a 300gr nosler @ 2840.I have never had luck getting a 300gr @ 2800fps with the ackley or the weatherby and I would not even want to know what the pressure it would take to get it there.

DOC LOU

If you want to run the line all the way out, get a 375G&A or 375-404. Downside with the ultra mag is poor quality of brass and who knows how long remmy will keep it alive
A normal 375 is fine too

/ JOHAN

Does anyone here have experience with the improved version of the .375 H&H called the .375 JRS? This is a cartridge based upon an 8mm Rem. Mag. necked up to .375 with no other changes. I believe it was designed by writer Jon R. Sundra (hence the name) in the late '70s. It, too, can fireform brass by shooting regular H&H cartridges in the chamber, or else by necking up 8mm Rem. brass.

As far as belted .375s go, it sounds like it would be a very practical cartridge. Does anyone have any comments?

Thanks for all the info. I can't wait to get started on the project. I have already contacted my gunsmith so that he can order the reamer.

Doctor Lou,

Got 3 x .375's as well; one Sako & 2 Win 70 classics one Chrome Moly for a custom & one stainless. The stainless is being converted to .375 RUM hopefully ready by this weekend.

I'd defintely recommend you to the .375 RUM as opposed to the improved .375 H&H cartridges. The latter oprion is probably the cheaper way to go & the performance difference is not noticeable. But, selfishly I want a larger user base with which to trade data & ideas. Its not exactly setting the world alight in popularity is it. But out of all the RUM this one is very well balanced cartridge & from the reload data definitely not over bore.

I'm hedging my bets slightly & mine will be a single shot initially till I get a chance to use it & am happy with the cartridge, then I'll have the feed looked at. Main concern here is with recoil but I think that can be managed. Its also a reason I picked the Win to convert as it has a much heavier profile barrel than my Sako L691. Also my Sako shoots tiny 1/2 inch groups with 270gn Woodleigh PP's so I aint't touching that one. Sakos are great out of the box aren't they?

As far as I know the .375 RUM reamer will clean out the .375 H&H chamber & no barrel set back or bolt face work is required.

You're lucky in the US you can get the .375 RUM brass cheap & loaded ammo too. Here we get Winchester ammo at reasonable prices but the RUM ammo is only one rung down from Weatherby Ammo. We pay $130 for a box of 20 - Remington Ammo with the 270gn Hornady SP & the A Frame stuff is not even brought in.

Keep us posted on your .375 RUM project.

The 375 JRS was designed around the 8mm Rem Mag brass because Jon saw the 8 RM brass as already pretty much "improved" over the old 375 H&H. He would therefore eliminate a fireforming step. Ballistically, it is the same as the 375 H & H AI, or the 375 WBY. - Dan