I am building another double rifle. This one will have two sets of barrels: (1) .375 H&H flanged magnum and (2) .38-55 McPherson (2.125" case with chamber size/length by Manson reamer. For the .38-55 barrels I will proof them at 50,000 psi.

I wish to duplicate the circa 1899 2.5" H&H flanged N.E. cartridge ballistics in the .38-55 McPherson, which does not appear a difficult issue as Buffalo Bore "Heavy" .38-55 cartridges almost do that currently. Of course, there is a bit of disconnect here as the 2.5" H&H flanged .375 was originally offered in 270 grs and 300 grs projectile loads--255 grs is close, however.

The new .38-55 chrome molly barrels are in hand with .367" bore/.377 groove as well as the reamer and cartridge cases. Both sets of barrels are to be mounted on "shoe lumps" via brazing (if you are not familiar with shoe lumps visit YouTube and search for Verney-Carron and Heym videos). I have made the .38-55 shoe lump and plan to fit it to the barrels and prepare them ready for later brazing this week if time permits.

With that introduction to the project here are some questions that I have of you .38-55 shooters:
(1) I have load data for propellants H4198 (31.0 grs) and RE-7 (32.0 grs) using jacked 255 grain projectile that produce 2,000 fps at muzzle--how accurate are these loads?

(2) Do any of you have better loads that produce velocity of about same or greater and maybe the pressure data as well?

(3) In the past I have called Buffalo Bore and they quoted the pressure max on a cartridge that they sold. I do not know if they continue to do that. Does anyone know the pressure max of the Buffalo Bore heavy .38-55 loads and what propellant they use?

Thank you;
Steve

Why the .38-55, if you don't mind me asking. Imho your handcuffing yourself to a limited variety of bullets. I would have gone with the .375 win.

I am pleased that you asked this question as others may have a similar, although incorrect view. The .38-55 McPherson case is longer than the .375 Winchester case. And also the .375 Win. case is made of thicker brass at the rear. Both of these case issues with the .375 Win cases limit propellant capacity to where these cases cannot contain as much propellant as the .38-55 McPherson case. I can use more of different propellant to produce velocities that I want without the high pressure of .375 Win cartridges.

Using the .377" grove diameter barrels that I am using with the longer .38-55 McPherson cases increases the number of bullet choices and diameters I can use. I can use both the .377 and .375 diameter bullets. However, very few bullet manufactures produce bullets in the .375 diameter of the weight that I want to use that will expand upon contact with game flesh/bone at 2,000 fps velocity--most .375 bullets are manufactured to expand at .375 H&H Flanged and Belted magnum cartridge velocities. I will likely use Hawk bullets in .377" diameters. The .375 Win case is 2.060" length; the .38-55" McPherson case(made by StarLine) is 2.125" in length.

The .38-55 McPherson is going to be fun to shoot. When I want or need a really quick bullet I will use the .375 H&H Flanged Magnum barrels.

Having said all of this, I believe the .375 Winchester would be a great cartridge for the bush.

My .38-55 McPherson will be used as a wild hog rifle.

Thanks for your excellent question. Can you give me a favorite .38-55 loading that you have?