Why is does my French Berthier 8mm carbine have flyers always to the right

[rayg]

I just measured the diameters of the my two rifle's and carbine's barrel at their muzzles. The carbine barrel is .510 dia and the Lebel and Berthier rifles are .585 dia. So the rifles barrels are .075 thicker and I would guess that the thinner carbine barrel might flex more, you think? Ray.

[rayg]

Probably the low velocity cast bullets don't cause enough barrel flex and that's why they shoot to the right where the bore is pointed.
Would like to hear some other opinions or thoughts on this, Ray

[Wineman]

Shooting cast with AL2400 in a Swiss K31 (~1,500 fps) shoots low and to the right, either with iron sights or a scope. GP-11 and reloads with the same velocity shoot to point of aim. When I calculate the drop of a cast bullet it will not correspond with a sight setting for the same drop with a jacketed bullet. The rear sight must be much higher. The harmonics, recoil forces etc are different for cast vs. jacketed. I would try a slower powder like IMR4895 at around 32 grains and possibly a tuft of Dacron fiberfill under a 200 grain cast bullet and see if that changes the dynamics as that load should be about 1,900 fps and closer to the original 2,400 fps of the Balle D.

Wineman

[rayg]

Thanks wineman, I'm sure you're correct. A faster cast bullet would probable provide the movement/harmonics of the barrel to move the impact to the left. Low velocity cast bullets just don't have enough bang to flex the barrel like the full power cast bullets will. Ray

[muffett.2008]

Come on you lot, the original post was about flier's to the right, not the whole group, if it's harmonics or any other rediculous cause, it will effect the lot, not an intermittant shot.

[rayg]

You're right, I got side tracked when I bore sighted the rifle and saw the bore points right of the target and then saw the front sight is made offset to do that. The only expalination I can think of as to why some shots go to the right and the others are on target is maybe a slight difference in the velocities between the cast bullets was enought to change the harmonics between each shot otherwise I don't know the answer. I haven't fired full power loads in the carbine but I'm assuming the offset sights were designed because of the short thin barrel coupled with barrel flex/harmonics to shoot on target. Ray

[Wineman]

Good point on the flyers vs group. How about a fatter bullet to really fill up the throat? Have you tried to get a chamber cast or fill a case with lead to the neck and then upset a soft lead slug in the throat area by flattening it with a rod from the muzzle? Try 0.001 under the ID of a fired case for a bullet OD.

Wineman

[rayg]

What I've done without having to measure the throat is to begale the bullet mould, (furnace tape between the moulds face), to increase the size of the bullet until it can't chamber anymore, and then cast the bullets a bit smaller.
I think all I need to do is increase the powder/velocity and that might do it, Ray

[rayg]

Sorry I'm late in following up on this post. But a carbine was shot with full power jacketed bullets and it shot center target. In fact a hair to the right. Quite the opposite of the cast loads. So the thin carbine barrel shoots center dispite the off set front sight. As I suspected the barrel harmonics/flex was figured to center up according to the barrel length, Ray

[rayg]

I meant it shot a hair to the left!