I need help

[Greg Mercurio]

I loaded some 400 grain cast boolits in both the .450 NE and .458 WM with Trailboss for a range session. Shooting both at 25 yards produced mostly keyholes, and I'm not sure what is going on. I use a similar Trailboss/cast boolit in my .416 Rigby and get cloverleaf groups at the same range. The only difference between the .458 and .416 loads is the .416 mic's at .417 and the .458 mic's at .458. Can .001 make that much difference?

Bullet too small? Bullet too long for the twist rate, velocity too low? I'm lost.

[bhn22]

What do your bores measure? Most 458s that I've seen prefer bullets around 460 or so.

[Greg Mercurio]

Unknown. I'm going to slug the bores later this morning.

[btroj]

Sure sounds like a fit issue to me. Was the bore leaded?

[Wayne Smith]

Do you know your relative twist rates? One rifle may stabilize at a low velocity where the other won't on the basis of rifling twist.

[quilbilly]

My 338 Winmag did similar. At an 80% TB load for an MV of 1450 all the boolits keyholed at 40 yards but when I went to a 95% load for an MV of 1640 it stabilized the boolits beautifully shooting well at ranges beyond 200 yards

[onondaga]

I shoot a lot of cast in .458 WM. My Colt Sauer Grand African .458 WM slugs at .4570" groove to groove. My boolits drop at .460" and I size them to .459"
My mold is a honed out Lee 457-340RNF, I cast with Lyman #2 alloy and tumble lube with 45:45:10 Recluse.

http://i30.photobucket.com/albums/c338/rhymeswithwhat/458Bal.jpg

http://i30.photobucket.com/albums/c338/rhymeswithwhat/coltsauer.jpg

Load:
Win Brass trimmed 2.495"
340 gr Lee sized .459, Lyman#2 alloy
LOA 3.125"\Crimp: Lee Factory Die
Primer: CCI 200
Charge: 53.3 gr H4895
Ballistic Filler: BPI Original to 1/8 inch of rim
1610 fps verified

This is my deer/bear load for New York State and recoil is less than a 30-30 lever rifle in my 10 lb scoped rifle. The load groups less than 1 inch at 50 yards and I have shot several groups less than 1.5 inches at 100 yards with weight matched boolits. Note that foot pounds of energy is over 1000 out to 200 yards.

I have tried 75% volume Trail Boss loads with this boolit and pressure was insufficient to expand brass and seal chamber. This leaves brass a charred mess.

Gary

[Greg Mercurio]

Slugged the bore today, the groove diameter is .458. Interestingly I had to upset a boolit fairly dramtically to get a good reading. I suspect I'll need to use either a .459 or .460 diameter boolit?

[MT Chambers]

You list 3 potential things wrong and any/all of them will cause bullet to be unstable.....find out bore dia. then make your bullets a bit wider, find out twist and if it will work with that bullet, finally try diff. speeds 'till your happy.

[onondaga]

I say go .460" sized. The .458 WM is a slightly tapered case, That makes sizing it for cast boolits very easy. If you back off the sizing die about 3/8 inch from the shell holder your .460 bullet will likely fit nicely without bulging the case. Full sizing with the die all the way down will cause case bulge when seating .460 boolits. That is not harmless either. full sizing will cause the brass to size the boolits to be undersize upon seating them. So, set your sizing die properly and the bullets will be OK and brass wont have a bulge. The +002" boolits should shoot very well for you.

If you haven't picked out a mold yet , the Ranch Dog molds he sells for the 45-70 are awesome for the .458 WM. Link at the top of the page to his products.

In a large bore like the .458 WM that .001" makes a big difference in accuracy. Go .002" over your groove to groove diameter.

My Lee mold is a plain base and over 1610 fps I lose accuracy but the Ranch Dog molds are for gas checking and with a 15 or higher BHN alloy can be pushed 2200 or so with the Gas Check and tumble lube.

I am waiting for the plain base gas check making tool for my boolits from PatMarlin and will check mine and bring up my velocity when he delivers.

Gary

[Greg Mercurio]

Thanks to all who answered. I didn't think the .002 was significant. Never too old to learn. :D

[Greg Mercurio]

Ordered a mold and sizing kit from Ranch Dog this morning. It shipped today. Fantastic Customer Service. Thanks again to all.

[onondaga]

I bet you will do fine with the RD mold. But if you haven't used a 6 cavity mold before they have a learning curve. The mold blocks need to be plenty warm and the usual procedure is to cast using only 2 cavities till the mold is warm enough to drop 2 nice boolits. Then start using the next and so on. Member CowboyT has wonderful videos on using 6 cavity molds, but these .460 rifle boolits are much bigger than the pistol bullets so the mold heats up even quicker so you will have to adjust your pace.

I use the 45:45:10 Recluse tumble lube thinned enough to be easily shakable once before sizing/checking and then twice after with all the tumble lube design boolits I shoot.

I shoot no full power factory loads in the .458 and all of my loads use fillers except some with 5744. I f you need any loading suggestions, PM me.

Gary

[MtGun44]

Not only is .002 significant, but in many cases it is a pretty massive difference, easily the
difference between success and failure in many cases.

Typically you want to be .001 to .003 larger than groove diameter for best results.

Bill