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.458 socom barrel throat issue

ffej ruedorb

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This seemed to be a good place for this question. I just got this second hand .458 socom Tromix upper. the throat appears to be bad. the picture is the throat with lands that shouldn't be there. 4 out of 8 lands go thru the throat. which of course has the bullet jamming into the lands where it shouldn't. does anyone have any suggestions as to a gunsmith that can fix. it's kind of a big deal as bullet setback from the lands is nfg. I looked up Tromix before i purchased and the price point and what I paid seemed like i was winning. I probably should see if I can get my money back

1698366323834.jpeg
 
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The bullet I am using is chunky and more likely to hit the lands than other designs. But as you can see the lands shouldn’t be hitting there. Seeing that was cause for getting the borescope out
 
It looks brand new, very clean and no outside signs of wear. Some copper on the lands so slight use I’m guessing.

There is a good chance of Polishing and some skinflint gunsmithing.
 
Tromix isn't known for crap, I've got a few builds with their barrels. Why don't you try giving them a call and see what they say? Even with good companies some crap still gets by QC. I bought a brand new PPK once and only half the barrel was rifled, granted it was when S&W was making them but still you would think a major thing like that would not get out of the factory.
 
Tromix isn't known for crap, I've got a few builds with their barrels. Why don't you try giving them a call and see what they say? Even with good companies some crap still gets by QC. I bought a brand new PPK once and only half the barrel was rifled, granted it was when S&W was making them but still you would think a major thing like that would not get out of the factory.
I am going to get a email together this weekend. With what I’m hearing about their reputation I wonder if it’s a legitimate Tromix.
The rear take down pin won’t fit into the upper either. The hole is not the rite size.
 
This seemed to be a good place for this question. I just got this second hand .458 socom Tromix upper. the throat appears to be bad. the picture is the throat with lands that shouldn't be there. 4 out of 8 lands go thru the throat. which of course has the bullet jamming into the lands where it shouldn't. does anyone have any suggestions as to a gunsmith that can fix. it's kind of a big deal as bullet setback from the lands is nfg. I looked up Tromix before i purchased and the price point and what I paid seemed like i was winning. I probably should see if I can get my money back

View attachment 810329
With out knowing the specs on the chamber its hard to say if that chamber is cut wrong?
It looks pretty good to me
 
Not sure if you came across this
 
With out knowing the specs on the chamber its hard to say if that chamber is cut wrong?
It looks pretty good to me
Three lands are visible in the pic
Two show a throat cut but the third extends all the way to the chamber.

That barrel should go back to the vendor.
 
Three lands are visible in the pic
Two show a throat cut but the third extends all the way to the chamber.

That barrel should go back to the vendor.
My eyes and shitty little phone screen are just not seeing it.
I might be tempted to send the barrel and a bullet back to the manufacture if they are willing to
Fix the issue?
 
My eyes and shitty little phone screen are just not seeing it.
I might be tempted to send the barrel and a bullet back to the manufacture if they are willing to
Fix the issue?
I zoomed in several times to see it.
Saw the land impressions on the bullet about 0.020 from the case mouth and that just doesn't seem right.
 
the upper is on its way to tromix with dummy round and sized boolit. Even though I bought the upper second hand tromix wants to make it rite. I’m not sure what that will mean yet.

@mac1911 barrel slugged out at .458
Bullet sized @.4595
 
Not sure if you came across this
I did not see this. Interesting read and something to consider when buying things and staying with certain brands.
 
Its update time ! Tony at Tromix was eager to help. I sent the upper to Tromix and he "rechambered" it with .030 additional freebore. he also sent along a (50$) slotted cartridge gauge at no charge. There is more freebore, But!!! the throat is still off with partial lands on one side of the throat and he basically said the MP462-420 bullet design is not suitable for 458socom and not even suitable for 45-70, take that however you want to. I may be a little to critical about the condition of the throat. to me it looks real sad. 🧐 This upper is just shy of 1000$ to buy on tromix website rite now.
WIN_20231120_17_12_16_Pro.jpg WIN_20231120_17_24_58_Pro.jpg WIN_20231120_17_24_52_Pro.jpg
 
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Its update time ! Tony at Tromix was eager to help. I sent the upper to Tromix and he "rechambered" it with .030 additional freebore. he also sent along a (50$) slotted cartridge gauge at no charge. There is more freebore, But!!! the throat is still off with partial lands on one side of the throat and he basically said the MP462-420 bullet design is not suitable for 458socom and not even suitable for 45-70, take that however you want to. I may be a little to critical about the condition of the throat. to me it looks real sad. 🧐 This upper is just shy of 1000$ to buy on tromix website rite now.
View attachment 818942View attachment 818943View attachment 818944
It was nice of him to do the work but I really think that the main issue isn’t the throat but non centric bore
 
Its update time ! Tony at Tromix was eager to help. I sent the upper to Tromix and he "rechambered" it with .030 additional freebore. he also sent along a (50$) slotted cartridge gauge at no charge. There is more freebore, But!!! the throat is still off with partial lands on one side of the throat and he basically said the MP462-420 bullet design is not suitable for 458socom and not even suitable for 45-70, take that however you want to. I may be a little to critical about the condition of the throat. to me it looks real sad. 🧐 This upper is just shy of 1000$ to buy on tromix website rite now.
View attachment 818942View attachment 818943View attachment 818944
Looks more like the chamber/bore/lead/throat is out of round to what ever reamer/cutter he used.
Do you still get land contact?
Im a little ignorant to 458 socom
Does it even have saami specs?

Might have to just use a throat reamer ? Wont help much of the
Bore is not concentric with the chamber
 
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From tromix:

I spent some time today with your upper and your ammo.

I rechambered your barrel with the current spec reamer which has .030" additional Lead/Freebore.
The area directly in front of the chamber with no rifling is the Lead/Freebore. This distance on the 458 SOCOM is .080" (U-V on the print).
After the .080" Lead, starts the Throat which is the tapered section where you see the rifling go from nothing, tapering up to full rifling.
This distance is .267" (W-V on the print) The diameter of the Lead is .459" so you have a bit of a press fit with your bullet sized to .459" as it enters the Lead and you have no room for the full bullet diameter once you go past .080" and enter the Throat.

I also chucked up one of your dummy rounds that looked like it hit the rifling on one side, and I was able to get the case body run-out just behind the shoulder down to a ¼ of a thousanth (.00025) I was surprised it was that perfectly round. Then I moved the indicator over to the bullet and found there was .005" runout there. So your bullet either is not round, or it is not seated straight, or both.

I also pulled the SAAMI print for the 45-70 to see what kind of Lead/Throat it is running. Oddly, it has zero Lead, and only .091 Throat.
Then I pulled the SAAMI print for a more modern cartridge, the 6mmARC and found that it has .090" Lead and a .220" Throat. Keep in mind, that cartridge was designed specifically to dangle long ass bullets way off the front end of the case.

Anyway, I cycled your dummy rounds through your barrel and they seem to chamber and eject without hanging up, but the bullet is up against the lands with the current seating depth.
 
I was looking here at some ammo choices. Looks like all the bullet profiles taper right to the case mouth?
Sometimes some bullet profiles just dont work well.
 
I was looking here at some ammo choices. Looks like all the bullet profiles taper right to the case mouth?
Sometimes some bullet profiles just dont work well.
I expected to run into some adversity with the ogive on what I thought would be a
Perfect boolit I have on hand. But if you look at some of the 500gr heads in the Lyman book they looks to have a pretty close ogive to the MP462-420
 
I expected to run into some adversity with the ogive on what I thought would be a
Perfect boolit I have on hand. But if you look at some of the 500gr heads in the Lyman book they looks to have a pretty close ogive to the MP462-420
I ran into issues with cast in the K31
 
I ran into issues with cast in the K31
Was the K31 a similar issue?
the .458 socom isn’t really an accuracy round. Although One thing I enjoy as a caster reloader is getting more performance in accuracy and ability to shoot more. I will give this upper a try and see if it’s fine. The throat looks sad but should be ok and may run cast without issues.
As I am typing this out i keep thinking of the lands and basics of a barrel. and second guess my thoughts of it being ok the way it is.
He should have re barreled the upper.
 
Was the K31 a similar issue?
the .458 socom isn’t really an accuracy round. Although One thing I enjoy as a caster reloader is getting more performance in accuracy and ability to shoot more. I will give this upper a try and see if it’s fine. The throat looks sad but should be ok and may run cast without issues.
As I am typing this out i keep thinking of the lands and basics of a barrel. and second guess my thoughts of it being ok the way it is.
He should have re barreled the upper.
IDK, Lehigh used to have a 300gr match solid bullet that was pretty accurate but they don't seem to make them anymore, they were real spendy though. I have one box of them left.
 
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