Trying to get some 500 grain loads going...
 

... for the 458 SOCOM.

The inter-web is big on questions but very short on solutions for this one question.

So far I have the option of 21ish grains of 4198 or 17ish grains of H110 for the 500 grain Hornady RN. Someone suggested Trailboss but there may be a problem with case capacity.

Let's get the ball rolling on this one - I think the bolt gun may give higher velocities tho'.

I load 26.3 gr of reloader-7 with a Lee 500 gr cast.

Are you looking for subsonic loads or something to get out there with???
I'd look at 2400 in the 18-25gr range. I've been using 28gr of 2400 with 605gr bullets in the 510. Thats a subsonic load. If you're looking for supersonics try 22gr and work up. I've also had good luck with 4227. Its been good for subsonics but really shines when going hotter.

Frank

First you need to state if it's for an AR-15, AR-10 or a bolt action. Are you loading to a 2.28", 2.8", or some other length magazine? There are lots of 500 grain and heavier .458" bullets but not all will work well out of an AR-15 magazine. With cast lead you have gas port clogging to worry about in a gas gun.

Bolt gun.

Subs assumed but a accuracy preferred.

Hornady 500 grain RN as basis.

You tell me the load that works and I'll try it!

I've been using 21.5 grains VV N110 and a 530 Outlaw bullet out of my 7" AR.

Function test (ie does the bullet make it out the barrel) went well with 18, 19 and 20 grains of H110.

Accuracy was good with all three but chrony the load next challenge!

Gas port clogging not an issue if:
1) you use an appropriately sized bullet-.001"-.002" over bore diameter
2) if the velocities exceed 1300fps or so, a gascheck is utilized

I can't tell you how many times this wives tale has been regurgitated over the years. There is another site/forum that has great information with not only AR's, but AK's and M1A's as well using cast. PM me for site info, as I'm not sure if links to other sites will upset the moderators here.

Respectfully,

Kevin

Results time.

All loads are 4198 and all velocities average. No test for accuracy.

a. 20 grains: 975fps

b. 19 grains: 925fps

c. 18 grains: 900fps

d. 17 grains: 840fps

The steep drop off in velocity at the 17 grain mark is very telling of a load that needs more love.

Looking like 21 grains will sit in the 1025fps mark and 21.5 about the 1050fps mark.

Penetration test - try over 2 feet of wet clay before I got bored digging!

21 grains of 4198.

Av Velocity = 1099fps
SD = 4.5

The higher the powder weight the better the consistency and lower SD.