Need suggestions for 8mm Berthier carbine loads

[rayg]

I shoot my French Lebel and Berthier long rifles with loads of 16 grs of 2400 powder behind a cast 205gr unsized, approx. a .331 dia bullet and get a little over inch groups at 50yrs. Which are ok for my eyes. However when I used the same load in the shorter barreled Berthier carbines, some of the shots are on target and othes fly way to the right almost off the paper.
I'm assuming I need to try either a reduced or incresed power charge or a different powder entirely. Is 2400 the wrong powder to use for the shorter barrels? I have other powders I can use like Unique, 3031, 4895, 4227, 4064. Hope I got those numbers right. Any ideas? Ray

[Oldeyes]

Two things to consider here, how is the recoil on your carbine compared to the rifle? My good 1892 carbine kicks like a mule...... and I flinch a tad, throwing some shots wild.... and the bore is mint from a 1927 rebarrel.
Secondly, I recommend a careful examination of the muzzle for cleaning rod wear. The early carbines were originally equipped with cleaning rods that were sometimes used vigorously. My 1892 dated barrel Chattelrault has some wear on one side of the muzzle rifling, plug gauges show about 5 thou of rifling wear mostly to one side...the right....
And a third item comes to mind- the early carbines did not have recoil lugs and the stocks took a beating. How well does the action fit the stock at the tang?
I might as well add that the sights are a bit...odd.... and that short sight radius is not helpfull!

[rayg]

Those were some good points to check. The carbine is an early all matching except for the original cleaning rod and it has an excellent tight bore. I miked it at the muzzle and further in the bore about three inches and there is no different in bore dia. so no additional muzzle wear. It has tight stock recoil bolts and fit.

It's possible that the shorter barrel needs more the 16 grs of 2400 powder to stabalize the bullet. I'll try upping the powder to 18grs or a bit more. There was no kick with the 16grs so no flinching on my part.
I imagine a regular full jacketed load would let you know you fired it, Ray

[rayg]

Well forget the powder, I just bore sighted the carbine and the sights are off. With the sights center on target, the bore is right of the target which would cause the right hand shots. I also bore sighted my Lebel and Berthier rifles and the sights are right on. Maybe the sights were set different for the carbines shorter barrel to compensate for drift using full powder issue loads? Ray

[1Shirt]

Ray, if every thing went exactly the way we think it ought to, it would be a dull world. Now you know! Keep us posted on results.
1Shirt!

[JeffinNZ]

I would have thought 2400 in a carbine barrel would be the better bet. Did the wee rifles wear a bayonet much? I know some battle rifles are regulated for bayonets with regards the sights so when the blade is not being worn the rifle shoots off.