458 Socom - Help needed

[lksmith]

Good morning folks!
Been tinkering around with my socom and am trying to figure out a problem/load.
I have about 500 copper washed 405gr WFN and 250 hard cast 300gr FN bullets that were in a lot of loading stuff i bought from a guy. he loaded 45-70, so had a bunch. Having those bullets is one of the reasons I went with 458socom over 450bushmaster for a big bore AR15. Problem is I can't get them to group for crap! Due to the chamber on my rifle, I have to seat them pretty deep so they don't stick on the bore diameter part of the bullet (thinking short throat).
Tried some 300gr yesterday and they were minute of posterboard at 25yds, 405's not much better. I had thought that maybe I swaged them under diameter by seating them deep since they almost seemed to be keyholing.
Pulled a few and they measured .4585 and .4580. Granted not .459 but should be enough to stabilize.
The thing that really has me baffled, is that my 500gr cast 3r bullets seem to do pretty good. I run all 3 through the same sizer so size should be uniform across the designs.
I know the "most logical" thing might be to melt the smaller ones and recast to 500gr, but seems silly to me to melt 700+ bullets just to cast when I have something that uses that size.

I thought about getting some sort of reamer to lengthen the throat to allow me to seat them longer, but not sure if that would help or where to find the right one.

Thoughts?

[btreanor]

Interesting. If the bullets are very hard then they might not obturate enough at .458 SOCOM velocities and the .4585 or .458 sizing might make a big difference. Have you slugged the bore on your gun? What powder(s) are you using? I've used Reloader 7 with 300 to 400 grain bullets and it's worked very well but my bullets were sized .459.

[lksmith]

Velocity is in the same range as 45-70.
300gr with Re7 is ~1600, with Lil Gun is ~2000FPS
405gr with 1680 is ~1300fps
500gr with 4198 is right at 1000fps (sub load)

I have not slugged my barrel. Was assuming since 500gr does well, and the bore diameter section is seated in the case, that sizing wasn't my issue.

[DDriller]

No one I know has had a lot of success with accuracy with the .458 socom trying to push it very fast. Gas checks help along with PC or HiTech coating. Shoot some jacketed and see how they group. If you are getting 2000 fps with LilGun you are way over the 37,500 psi pressure.

[Gatorhunter1313]

I shoot a 525gr hard cast in my socom and I can shoot it out to 150 yards accurately. If I go down to 300gr cast my accuracy is even better. I’m loading them with reloader 7 and I have never had an accuracy issue. I’m running a tromix 16” barrel. If they won’t shoot well it could be a sizing issue of a barrel issue. There are a lot of barrels out there that are just not made right

[dh2]

which twist rate is your barrel, one twist rate is for subs and one for lighter bullets, trying to make one do the other will give poor results'
I am pushing a 325gr slug sized at .460 with good results

[Gatorhunter1313]

which twist rate is your barrel, one twist rate is for subs and one for lighter bullets, trying to make one do the other will give poor results'
I am pushing a 325gr slug sized at .460 with good results

That’s a good point. There’s a few different twist rates put into 458 socom barrels. Where did your barrel come from?

[lksmith]

No one I know has had a lot of success with accuracy with the .458 socom trying to push it very fast. Gas checks help along with PC or HiTech coating. Shoot some jacketed and see how they group. If you are getting 2000 fps with LilGun you are way over the 37,500 psi pressure.

No pressure signs at all on brass or primers. QL puts that load at 32,804PSI.

I didn't think about powder coat being the difference. the 405's and 300's are factory lubed, the 500gr is powder coated. All were run through the same sizer to ensure uniform sizing.

[lksmith]

That’s a good point. There’s a few different twist rates put into 458 socom barrels. Where did your barrel come from?

barrel came from Delta Team Tactical/Davidson Defense. Twist is 1:8

[DDriller]

No pressure signs at all on brass or primers. QL puts that load at 32,804PSI.

I didn't think about powder coat being the difference. the 405's and 300's are factory lubed, the 500gr is powder coated. All were run through the same sizer to ensure uniform sizing.

QL is way off on the pressure with LilGun. I shoot a lot of it.

[TyGuy]

Maybe it’s just me but 1:8 twist seems really fast for the .458. What length barrel?

[lksmith]

Maybe it’s just me but 1:8 twist seems really fast for the .458. What length barrel?

16"

[lksmith]

QL is way off on the pressure with LilGun. I shoot a lot of it.

I know QL isn't the bible, but wouldn't I have pressure signs on the primers if over pressure? Especially using pistol primers with softer/thinner cups vs rifle primers.
I have never seen over pressure loads that didn't show some pressure signs, but I haven't seen it all either

[Gtek]

If truly 1-8 and with that alloy with a shorter bearing area on the 405 and 300 even at slower may be stripping. The 500 may be able to overcome with length and alloy possibly being different. Playing with this round only with jacketed and 1800 was about the wall with multiple powders. Flattened primers happened real fast when bumping into top side.

[Castaway]

Maybe 1:18 instead of 1:8?

[Gatorhunter1313]

Ideal twist for a 458 socom is 1:14. 1:8 is really fast twist. And I’ll have to check some other places but the delta team barrels were not true 458 socom spec reamers. There’s a very short list of people who have the correct specs for the true 458 socom dimensions. Tromix, Wilson combat, rock river arms…… most other producers are out of spec and have issues

[lksmith]

You're right it is 1:14, I must've been thinking of one of my other rigs.

[Gatorhunter1313]

Being 1:14 it should stabilize most any bullet. I have 6 different 458 socom rifles and I can shoot everything from 100gr aluminum bullets up to 525gr hard cast bullets. With cast bullets it’s all about size. I slug all my barrels and make sure I use the right bullet for the right barrel. When I shoot cast through my 458 I only use gas check bullets. I can push lighter bullets as fast as possible without going over pressure and I’m still accurate. I would start with slugging your barrel and make sure you don’t need to bump the size up. Like I said before though, that barrel is most likely a reverse engineered reamer. Could just be a bad barrel from a cheap seller

[Sailormilan2]

Have you slugged your barrel yet? I have two 458 SoCom barrels, and they have different bore sizes. The Bear Creek barrel is very tight, at about .457, and the Tromix is right at .458.

[lksmith]

Have you slugged your barrel yet? I have two 458 SoCom barrels, and they have different bore sizes. The Bear Creek barrel is very tight, at about .457, and the Tromix is right at .458.

I'll have to load up and fire a bullet into my bullet trap to "slug my barrel," my round ball mold drops, only other sizes I have close are my 500gr and my 50 cal molds. the 500gr has too much bearing surface for me to drive it and the 50 is too much larger.
my bullet trap leaves the bore area pretty much as fired, especially if loaded light