Building a BCG

I am assembling a basic M4 using parts from BCM, Spikes, FN, Colt and JP. The lower will be an 80% lower that I will complete. A franken gun, but quality pieces. Part of that is having the components to build a BCG.

This includes:
- JP enhanced bolt
- BCM gas key, firing pin, cam pin, retaining pin and extractor spring upgrade kit
- Colt carrier

I also bought this gas key staking tool from Brownells. https://www.brownells.com/gunsmith-t...prod29337.aspx

I guess what I am looking for is feedback on anything that I should pay attention to in assembling and/or any problems I may encounter when I actually run it in the gun

I like using the OCKS Carrier Key Bolts, those things are awesome. Forward Controls Design has them $6.50 for 2 and they were in stock about 5 minutes ago. I also think lapping & using a sealant around the Carrier Key and BCG gas port help's stop gas leaks around the mating surface. Hope everything goes smoothly for ya.

I suspect everything will be just fine. It looks like you chose quality stuff.

I use a Fat Wrench. I don’t know if its the best tool or not, just because I don’t know about that sort of thing, but my key does stay on. I’ve used regular wrenches with equal results. Like you, I use BCM keys, and they work. +1 for the OCKS recommendation. As for sealing, I use Loctite 518. I think @Markm said that he laps his instead. I might try that one day, just for the pleasantly tedious experience. Some people do neither.

Find a detail-oriented youtuber to show you, and then realize its only 25% as hard as it sounds.

Permatex Aviation was used on Uncle Sam's spec'd keys at one time. Perhaps this or whatever new and improved chemical. I've also seen Permatex Indian Head gasket shellac used without issue.

https://i.imgur.com/HajDBEV.jpg

Thanks for the responses.

Interesting to see that back in 9/20/78 they added spring pins to secure the gas carrier key screws. I wonder when they revised the specs to use staking of the screws.