KAK 458 SOCOM build and headache

Mikezito · March 6, 2015, 11:26 AM

Hey all,

This is my first thread on the FL forum. Ran into a very frustrating issue while throwing together my latest build, a KAK 458 SOCOM, and thought I'd post my findings with the hopes I can save others the headache I've had to endure.

I've been building AR's (5.56/300blk/.308) for a while now but am by no means a pro, just enjoy the hobby. I'm also a novice reloader with only a couple years experience.

This latest 458 SOCOM build was uneventful but once completed, I immediately ran into issues chambering rounds. The bolt would stick 1/4 inch from seating fully.

I'm using a KAK 458 specific bolt/barrel combo as well as factory Starline brass. As recommended, I resized the brass using Redding dies and loaded a handful of rounds using a light crimp. The chambering issue had me stumped and I set off online trying to identify what I was doing wrong.

Many threads talk about reloading mistakes and even poor spec barrels being the problem. I tried everything recommended, including resizing techniques, no crimp on the bullet and checked head space... nothing made sense.

Ultimately I narrowed it down to the bolt. More specifically, the extractor. After disassembling the bolt, I noticed a fairly hefty o-ring installed to assist the extractor spring. After removing the o-ring, rounds chambered and cycled easily without a single issue.

It looks like the o-ring was placing so much pressure on the extractor that the rounds were not able to seat properly against the bolt face. I've never had an issue like this with any other AR and haven't found any info online pointing to the extractor preventing proper chambering.

I hope my experience can save others the time and frustration troubleshooting this issue has cost me. Hopefully this is an isolated event, maybe the wrong o-ring installed?

March 6, 2015, 11:26 AM	#1
Mikezito Junior Member Join Date: August 8, 2014 Posts: 2	KAK 458 SOCOM build and headache Hey all, This is my first thread on the FL forum. Ran into a very frustrating issue while throwing together my latest build, a KAK 458 SOCOM, and thought I'd post my findings with the hopes I can save others the headache I've had to endure. I've been building AR's (5.56/300blk/.308) for a while now but am by no means a pro, just enjoy the hobby. I'm also a novice reloader with only a couple years experience. This latest 458 SOCOM build was uneventful but once completed, I immediately ran into issues chambering rounds. The bolt would stick 1/4 inch from seating fully. I'm using a KAK 458 specific bolt/barrel combo as well as factory Starline brass. As recommended, I resized the brass using Redding dies and loaded a handful of rounds using a light crimp. The chambering issue had me stumped and I set off online trying to identify what I was doing wrong. Many threads talk about reloading mistakes and even poor spec barrels being the problem. I tried everything recommended, including resizing techniques, no crimp on the bullet and checked head space... nothing made sense. Ultimately I narrowed it down to the bolt. More specifically, the extractor. After disassembling the bolt, I noticed a fairly hefty o-ring installed to assist the extractor spring. After removing the o-ring, rounds chambered and cycled easily without a single issue. It looks like the o-ring was placing so much pressure on the extractor that the rounds were not able to seat properly against the bolt face. I've never had an issue like this with any other AR and haven't found any info online pointing to the extractor preventing proper chambering. I hope my experience can save others the time and frustration troubleshooting this issue has cost me. Hopefully this is an isolated event, maybe the wrong o-ring installed?