SOLVED: .458 SOCOM upper not cycling

[RooftopKorean]

As the topic says I'm having issues with my .458 SC upper not cycling. I fire one round and it does not eject and chamber a new round. I am not sure if the ammo I purchased from LAX ammo is the culprit or if it is something else.

I am using the upper on my SCR and I have even tried it on my friends AR lower and it still has the same issue. The only thing I can think of is the gas block/tube. I am ruling out the buffer system because the SCR doesn't have a buffer and my friends AR works fine with his .450 BM upper.

I checked to make sure that there was no block in the tube by passing air thru it and made sure to line up the hole in the gas block with the port on the barrel.

Before I spend money on a new gas block / tube does anyone have any suggestions?

 

[That_FNG]

Does it have an adjustable gas block and if so is it turned off? If not, does it fire and then fail to fully extract the spent case?

 

[RooftopKorean]

Does it have an adjustable gas block and if so is it turned off? If not, does it fire and then fail to fully extract the spent case?

No it does not.

 

[Acer-m14]

my friend had issues with his 458 socom AR .. it was from using the 223 mags ,.. he is in bed now so can't ask what the full issues he was having ..
just know he had a issue using 223 mags

 

[Edwardteach72]

Who made your barrel? What size gas port? What gas block is on there

 

[dsdmmat]

Because you are using an SCR lower you will have to make all adjustments in the gas system. Might as well buy that gas block now.

did you try different magazines and different types of ammo?

 

[redtail]

Does the upper have an enlarged ejection port?

 

[RooftopKorean]

Does the upper have an enlarged ejection port?

Yes it does.

 

[RooftopKorean]

Because you are using an SCR lower you will have to make all adjustments in the gas system. Might as well buy that gas block now.

did you try different magazines and different types of ammo?

I haven't tried different ammo, unfortunately most shops around me do not sell .458 socom and I don't want to pay a transfer for one box.

I bought a Supurlative Arms adjustable but it was too big to fit into my handguard so I returned it. The gas block it came with is a non-adjustable.

 

[RooftopKorean]

Who made your barrel? What size gas port? What gas block is on there

I'm not sure, I bought it off GunBroker from Alex Lasurdo (some Long Island guy who sells various uppers). The guy himself was a piece of work which I found out after the fact.

Tried to charge me $45 to return it to him to have him look at it because it wasn't cycling. Also didn't include the BCG and CH when the auction clearly depicted it and charged me $90 after the fact for it. When I was going back and forth with him via e-mail he also swore that he tests all the uppers he builds/sells.

Edit: I guess this wasn't the case considering I had to drill out the hole in the gas block. It seems to have had a layer of metal with a hole no longer larger than a roll pin.

It was a shit show from the start. I'm about to cut my losses and buy a Bear Creek .50 Beowulf upper.

 

[RooftopKorean]

Who made your barrel? What size gas port? What gas block is on there

I will take pictures of the barrel when I get home. The gas block has no branding on it. The only thing I can tell you is that the diameter is .875

Update: the barrel has no branding, its simply marked .458 SOCOM 1:14 USA

 

[turbobike]

My 458 did the same thing, it needed the gas port drilled to .102”...simple drill bit and I enlarged it...now it cycles and drops spent cases 6-8ft in a nice pile...

 

[RooftopKorean]

Hrmmm I'll use calipers and check the hole diameter and report back.

 

[RooftopKorean]

My calipers say 0.1150"

 

[RooftopKorean]

I found the issue!! This gas blocks internal hole diameter is smaller than the diameter of a roll pin!

I took apart my 5.56 upper and took a look inside the gas block and it was wide open.

I'm gonna drill that now out and take it to the range sometime this week to test it out.

I'll report back.

 

[RooftopKorean]

Here are the before and after pictures. One looks significantly different then the other because I didn't think to use a flash light when I took the before pic.

Huge thanks to Turbobike for getting me headed in the right direction.

BEFORE

AFTER

 

[redtail]

Nice.
Good when you can DIY..

 

[Twogunwilly]

What a PIA to have to do to a new upper

 

[RooftopKorean]

What a PIA to have to do to a new upper

After being able to troubleshoot/fix the problem with the help of the forum I didn't have to build another upper. I just had to drill the gas block hole some more.

 

[turbobike]

After being able to troubleshoot/fix the problem with the help of the forumit I didn't have to build another upper. I just had to drill the gas block hole some more.

I’m glad you solved it! May I recommend dedicated C-Products 458 mags, and your upper may be happier with a minor buffing of the feed ramp...YMMV

 

[RooftopKorean]

I’m glad you solved it! May I recommend dedicated C-Products 458 mags, and your upper may be happier with a minor buffing of the feed ramp...YMMV

Yeah, I am going to look into getting Lancer L5 AWM 4 round mags.

 

[redtail]

Tromix is the go to guy for bb stuff.

 

[Edwardteach72]

Tromix is the go to guy for bb stuff.

This this right here

(Tromix also has 7 and 10 round mags for ban states)