1891 Argentine re-barrel caliber?

[ronniet]

Well, I got my .375 Rimless Nitro Express (9.5x57 MS) from the Gunsmith about a week ago. It was built on a BSA (Herters U-9) Majestic action. The barrel is 25" long and I scoped it with a Weaver 4x with a crosshair and post reticle.

I have been formed cases from 30-06 brass. That isn't hard but it isn't as easy as running an 06 case into the full length sizer and trimming to length. I loaded 50 round with 235 gr Speer bullets with 46.5 grains of H4895, which is 1.5 grains under max as published by the Mannlicher Collector Association (MCA). I'm guessing that this load will push out at approx. 2300 fps. I loaded up 50 rounds with 270 grain Hornady bullets with 49 grains of IMR4064, which is one grain more the what MCA published. I'm guessing these will push out at approx. 2200 fps. I have fired these without any issues.

Once the weather gets nicer I post some results.

I am glad to hear it, I have all the parts now to go ahead with mine, using the 1891 Argentine as a platform with many custom upgrades to add, I have a reamer and headspace on order from PT&G but have not received it yet.
Am wondering how does its feed from your reciever ? any mods to help it?
I have a set of dummy rounds made up to check feeding but have to get the barrel on it first.
Also wondering about pressures and felt recoil from it.? how does that feel and look like on your cases?
I have a 9.3x62 I made a few years ago and cant bring myself to fire it anymore. The recoil and noise level was just terrible and only fired it 2twice with bruised black shoulder. Using factory Pruvi ammo @ 285 gr.
I will get my 375 Nitro together soon I hope, I had 3 other projects ahead of it and only finish 2 so far.
Good to hear from you update me when you can.
Ron

[CA Dude]

I went out today and shot my loads across a chronograph. My guessamations wasn't too far off. The 235 grain load produced an average of 2,376 fps for a five shot string. This load produced a spread of 118 fps (low 2308, high 2427). The SD was 42.8. In my rifle it produced 22.5 ft. pounds of recoil. Compared to 25.2 ft. pounds of recoil from a 7 pound 30-06 rifle. The 270 grain load produced an average of 2276 fps for a five shot string. This load produced a spread of 37 fps (low 2251, high 2288). The SD was 15.9. In my rifle it produced 26.6 ft pounds of recoil. Compared to 27.8 ft pounds from a 9 pound 300 Win Mag.

The cases for the 235 grain loads indicated zero case expansion. The 270 grain measured .0005 larger than a unfired cases.

I loaded four rounds in the magazine and they all feed without issue. My rifle required no modification to make it feed.

As for how loud it is? Well, it is hard to say. I remove my hearing aides, put in ear plugs, put on my ear muffs and then I talk very loud to everyone.

My rifle was chambered with a Reamer and headspace gauge from PTG. Both are ground to the C.I.P specs. If you have seen the old case drawing from 1910 you will note that the shoulder is shown at .455 in diameter. My reamer produced a .450 shoulder and that cause a very minor issue forming the brass.

My dies were made by CH and they are cut to C.I.P. specs. 30-06 brass can not be just ran through the sizing die and then trimmed to length. The 30-06 when formed in the sizing die results with a shoulder that measures .441 so the case has no resistance against the bolt as it is chambered. You have two options to make the brass so it can be safely fired in you rifle. One expand the neck and body to approx. 43 caliber so that when the case is formed in the die it will have enough shoulder to set the headspace. Or two, when sizing the case don't push the shoulder back so far. In my case I put a .030 feeler gage between the shell holder and the die, then tighten the die down against the feel gage. The first case could not be forced into the rifle enough to close the bolt. I kept doing this same process with thinner feeler gages until I had a .021 gage between the shell holder and the die. When set up like this I could close the bolt on the formed case. I then sized all my brass with this set up. The neck measured only .328 in length. When I fired the round it came out with a .350 length neck that matches the old case drawing.

Overall, I think it will be a very good round for hunting Middle Weight to Light Heavy Weight, non-dangerous game. My 270 grain loads still has 2080 ft. pounds of energy at 200 yards. I think I could harvest just about any animal I'm likely to run across in the woods of Arkansas.

[samari46]

How about the 9.3x57??. Make brass form 8mm cases. Open the necks to 375 then slowely resize in a 9.3x57 die but leave a slight shoulder so when you close the bolt you get a slight crush fit. Headspace wasn't all that great. 286 grain round nosed bullet at 2100 -2200 feet per second and with about 45 grains IMR 4895. pressures are low about 44.000 psi so no barn burner. I measured the twist on mine and get 1x14".You can go slightly faster with the twist say 1x12" Really nothing fancy. Frank

[ronniet]

I went out today and shot my loads across a chronograph. My guessamations wasn't too far off. The 235 grain load produced an average of 2,376 fps for a five shot string. This load produced a spread of 118 fps (low 2308, high 2427). The SD was 42.8. In my rifle it produced 22.5 ft. pounds of recoil. Compared to 25.2 ft. pounds of recoil from a 7 pound 30-06 rifle. The 270 grain load produced an average of 2276 fps for a five shot string. This load produced a spread of 37 fps (low 2251, high 2288). The SD was 15.9. In my rifle it produced 26.6 ft pounds of recoil. Compared to 27.8 ft pounds from a 9 pound 300 Win Mag.

The cases for the 235 grain loads indicated zero case expansion. The 270 grain measured .0005 larger than a unfired cases.

I loaded four rounds in the magazine and they all feed without issue. My rifle required no modification to make it feed.

As for how loud it is? Well, it is hard to say. I remove my hearing aides, put in ear plugs, put on my ear muffs and then I talk very loud to everyone.

My rifle was chambered with a Reamer and headspace gauge from PTG. Both are ground to the C.I.P specs. If you have seen the old case drawing from 1910 you will note that the shoulder is shown at .455 in diameter. My reamer produced a .450 shoulder and that cause a very minor issue forming the brass.

My dies were made by CH and they are cut to C.I.P. specs. 30-06 brass can not be just ran through the sizing die and then trimmed to length. The 30-06 when formed in the sizing die results with a shoulder that measures .441 so the case has no resistance against the bolt as it is chambered. You have two options to make the brass so it can be safely fired in you rifle. One expand the neck and body to approx. 43 caliber so that when the case is formed in the die it will have enough shoulder to set the headspace. Or two, when sizing the case don't push the shoulder back so far. In my case I put a .030 feeler gage between the shell holder and the die, then tighten the die down against the feel gage. The first case could not be forced into the rifle enough to close the bolt. I kept doing this same process with thinner feeler gages until I had a .021 gage between the shell holder and the die. When set up like this I could close the bolt on the formed case. I then sized all my brass with this set up. The neck measured only .328 in length. When I fired the round it came out with a .350 length neck that matches the old case drawing.

Overall, I think it will be a very good round for hunting Middle Weight to Light Heavy Weight, non-dangerous game. My 270 grain loads still has 2080 ft. pounds of energy at 200 yards. I think I could harvest just about any animal I'm likely to run across in the woods of Arkansas.

CA Dude ,
glad you made the rifle and I commend you in the collection of the data,
I copied all your data to use when I finish up my 375 Nitro. Thank you
I think it would be a great addition to the calibers
Ron

[CA Dude]

Ronniet,

I shot my loads for groups yesterday. My rifle seems to like the 275 grain bullet. 49.0 grains of IMR 4064 produce 1 1/4" groups. The 235 grain loads not so well; 2 to 2 1/2" groups. If I had a different reticle I think I could bring the groups size down some. The post covers about 2" at 100 yards. I think that is fine for hunting but a little course for grouping.

I have checked out the 375 Raptor cartridge and they are getting the best velocity by using Rel 10x. I ran 10x through Quickload and I'm going to give it a try. I have no intention of running to the same pressures of the 375 Raptor even though my rifle could handle it. According to the Prowley Computer 49 grs. of IMR 4064 produces 51,000 psi (44,900 CUP). The max load as given by MCA of 48 grs of IMR 4064 produces 49,000 psi. I was a little surprised that Quickload and Prowley came in very close when comparing this load.

I'm looking forward to using some cast bullets and my paper patched bullets soon.

CA Dude