Tight .458 Socom load

[Ike Clanton]

My first attempt at 458 Socom. Tromix 10.5 upper. 400 grain GT Bullets hollow point powder coated then sized to .459 in lee sizing die. Long story short they are hard to extract. Almost have to mortar it to get a loaded round out of the chamber. Got the Tromix case gauge and determined it the Bullets tight fit. Is this normal since cast Bullets are suppose to be .001 oversized? Or should I just get a .458 sizing die since I probably have a tight bore.

[Aguila Blanca]

Have you slugged the bore?

[Shadow9mm]

depending on the shape of the bullet it could be seated out too far causing the bullet to engage the rifling and get stuck. what some shooters would consider JAM for bullet seating.

[44 AMP]

To be clear, your bullets are not sticking in the rifling, they are sticking in the chamber throat?

In an AR type rifle.

A gas operated rifle designed to shoot jacketed bullets....

And, you're doing what the books say you should do with lead bullets, .001" over bore diameter, so the rifling gets a good grip.
And your bullets stick in the chamber...
Is that about right?

the first thing to try is to use smaller diameter bullets. Jacketed .458 is what its made for. Lead and coated or plated probably can be used, but some adjustment to the normal loading practices due to your rifle's characteristics may be needed.

Just did some checking with a friend who had a .458 SOCOM upper (though not the brand you mention) and he recalls that the owner's manual said it wasn't a good idea to use cast bullets. The didn't expressly prohibit them, but they recommended they not be used.

These guns are made for jacketed bullets and because of that they are "tight". It's normal. Also, ARs are not very cast bullet friendly. Extra care and inspection is needed to ensure they don't clog the gas system.

Also, full Socom speeds are in the upper range of cast bullet speed, not the very top end but in the range where extra care is needed to ensure the proper alloy and sizing for the 18-1900fps speed. Get something just a bit "off" and you can get leading, and/or poor accuracy from bullets stripping in the rifling. reduced loads can solve some of that, but then you have issues with the rifle cycling. Its a balancing act between several different factors. Get things right, they work, but get one thing a little off, and you'll probably be unhappy with the results.

I'd shoot jacketed bullets in that gun. If you're determined to use the cast bullets you have, I'd size some to .458 and then see if they perform properly or have issues before doing all of them up as loaded ammo.

Be aware that there are some combinations that just won't work well together no matter what you do, and be open to selling or trading stuff that proves it just won't work as well as you want. Someone else, doing something else will be happy to be able to get what you can't use.

[Ike Clanton]

Wow thank you guys I feel dumb now. The bullets were engaging the rifling because I was using OAL data for a 405 gr jacketed bullet. I just seated the bullet a little deeper and it passes the case gauge and is no longer hard to extract or load. Thanks again! PS these are subsonic loads to be used with a suppressor which is why I chose a soft cast powder coated option. Designed to expand at pistol velocities.

[Unclenick]

You may still want a gas-checked design. The issue is gas streaming into the gas port can cut a little of the soft bullet material off the base and carry it into the gas system as it passes the port. That cutting would also tend to imbalance the bullets a bit, which won't help accuracy. There are tools for making gas checks from aluminium cans that are thin enough that you could probably press them into the powder coat with a sizing die.

That said, if you try them as they are, see if you can recover a few from the target berm to look at the edges of the bases for signs of that happening at one place. If there are no signs of it and if you have confidence in your ability to clean out the gas system, there's no reason not to see if you can get away with it.

[44 AMP]

The bullets were engaging the rifling...

Yeah, that'll do it.

Since that issue is solved, no need to size to .458" unless shooting results indicate it might be needed. (unlikely).

Do keep an eye out for buildup in the gas system, not just from the bases as Uncle Nick mentions, but from the rest of the bearing surface as well. Any "roughness" at the gas port, which is ignored by jacketed slugs can shave tiny amounts of lead and bullet lube off, which can build up in the gas system. Conventional bullet lube is the worst at that, I have no idea if powder coated bullets will do it or not, so I say keep an eye on it, until you're sure, one way, or the other. I hope you have no further issues, but keep an eye out for them, sometimes they sneak up on you.

[TX Nimrod]

… Do keep an eye out for buildup in the gas system…

“Keep an eye out” means using a bore scope, or pulling the gas tube periodically to check it. Or dig bullets out of the backstop and look at them. Or wait for action problems…





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[Ike Clanton]

Sounds like a good excuse to buy a bore scope. These 400 grain pills go pretty far into my backstop so finding one will be hard.

[Unclenick]

The inexpensive Teslong Bore Scopes on Amazon work surprisingly well. I won't say the image is quite as sharp as my Hawkeye, but it is really very good for something under $100.

Recovering bullets from dirt is shovel work.