308 cast

[fiver]

is this the LEE with the regular lube groove?
the one that has a T/L groove counterpart?
if so that's your problem.
the bullet itself has a very poor COG and wants to do the shuttlecock thing until it 'settles down'
IE the rpm monster rears it's head and controls the bullet.
[which you found out]

 

[rodmkr]

Fiver,
It is the single deep groove gas checked bullet
I cast them 3 years ago using 50/50 pure and clip on wheelweights waterdropped.
At the time of loading they measure BHN of 16
Sized to 309 the nose or front section of the bullet reads .301
They shoot great in another rifle so will just let this one shoot jacketed.

Out of the 30 or more regulars at the range I go to I am the only one that shoots cast so am kinda out there swinging on my own.


Jim

 

[fiver]

as are most of us.
all we can do is relay information or pictures and work through the steps until we get where we want.

I know [not IMO or maybe or probably,,, know]
your rifle has the potential to be a very good cast bullet shooter, and not at just 1500 fps.
you need the right design, and then need to help it with the proper impulse of pressure timing.
thinking outside the lines of the lyman/LEE catalogue, and not using old school methods of using fast shotgun powders is the way to do it.
your gonna have to use some slightly different loading techniques, and maybe even change your alloy some, but the potential is certainly there if your willing to pursue it.

 

[Ian]

That bullet has a tapered nose, best suited only to certain throats. If the leade taper is longer than the nose, the bullet is going to gimble. A scuff-fit, two-diameter bullet cast of a more resilient alloy might actually work better as long as the nose isn't so long that the lands can't support it. A bullet with a much longer, shallower nose taper with very little base in the case neck would work well with the 50/50 alloy.

One thing the Lee 312-160 lacks is lube capacity. Depending on the powder, pressure curve, barrel length, amount of jump, neck tension, bore finish, and velocity, it may not be enough.

A carefully measured and plotted chamber cast of each rifle, in addition to precise measurements of the bullet nose shape, would go a long way toward explaining why one rifle likes the bullet and the other doesn't.