.475 sizer die info

[dubber123]

Hello, a new guy here, I have a F/A in .475 4-3/4 inch.  The problem I have is getting a lube/size die that is correct.  According to my measurments, a .4755 to no larger than .4760 would be perfect, but after two attempts, RCBS can only come to within .4765.  I know this is a small amount, but with the tight tolerances, my 440 gr. LBT's chamber very hard and cannot be ejected without firing them.  Accuracy is super though, best 50 yd. group was .810!  none worse than 1-1/4".  Well except for the occasional flinch.  I bought a .474 sizer, but accuracy and power is down.  Do I try to hone this die, or does someone sell what I need?.  Thanks!

[475/480]

I would hone it myself,I have done a couple,not to hard to do.
sandpaper,metal rod,double sided tape,3/8 drill.

Sean

[dubber123]

Thanks Sean for the response, I have been busy with a new gun and haven't had the time to mess with the 475 again.  The smaller size die cost me velocity and accuracy over my slightly oversized one.  Before I hone it out, I want to see if increasing the powder charge will help, any thoughts?  Thanks!

[MS Hitman]

I'm shooting the 400 and 350 LFN bullets that I cast.  If you lost velocity with a smaller bullet, you most likely are experiencing gas going around the bullet in the barrel.  Bumping the charge up may cause the bullet to fill out in the barrel and seal it.  You may want to check how trimming the case bacl a couple or three thousandths effects your situation.

[dubber123]

Hitman, good to hear from you.  I was assuming the same thing about the gas leakage, or the smaller bullet slipped through the cylinder throats easier, and killed the initial pressure buildup.  If it ever stops raining, I'll try more powder, and see if the power and accuracy return.  The mold I am using is an LBT, and the bullet is full diameter for over .140" outside of the case.  So I would have to trim ALOT to help with the sticking in the chambers problem.  Thanks for the help!

[dubber123]

I just honed out a die for another caliber, .512 to .513, and it wasn't nearly as hard as I thought it would be.  They do get pretty warm in the process though!  I think i'll go ahead and do the .475, and try to get the perfect (In my opinion) 1/2 a thousandths under cylinder throat size.  Thanks for your suggestions, any others are also welcome.

[Marsh1]

Are you using a roll crimp or taper. I've head the chambers are so tight a taper may be necessary. Dunno.
Marsh

[dubber123]

Marsh1, I roll crimp in my Hornady dies, and then I taper crimp them slightly.  I have to to get them to chamber.  It's not alot of taper crimp, just a slight "bump" in the die.  I started out with a heavy roll crimp, and later tried reducing it, thinking it would be easier on the cases, surprisingly on such a hard kicker, I had no problems with bullets jumping the crimp, and the lighter crimp actually produced a little more velocity, which is the opposite of what I normally experience.

[dubber123]

Marsh1, I roll crimp in my Hornady dies, and then I taper crimp them slightly.  I have to to get them to chamber.  It's not alot of taper crimp, just a slight "bump" in the die.  I started out with a heavy roll crimp, and later tried reducing it, thinking it would be easier on the cases, surprisingly on such a hard kicker, I had no problems with bullets jumping the crimp, and the lighter crimp actually produced a little more velocity, which is the opposite of what I normally experience.