Best BCG Coating?

[CPM]

Is there another reason why I have to hit the forward assist when doing a bolt lock reload to strip and chamber the first round from a full magazine? I have fresh springs and an H3 in my 6933. It starts lubed to the gills and 200 rounds in that top round will choke. Gen 2 PMags mostly.

[AndyLate]

Thanks for the origin story, gents. I always assumed markm was your son.

I honestly thought brother, because Mark is not young (not throwing shade, neither am I).

Back to OP - I envied the guys in Army basic who had chrome bolt carriers because they wiped clean. That was 1986, apparently chrome plating did not affect the service life of the carriers

Andy

[lysander]

Yeah, I saw that too. I had read it somewhere a while back, don't remember exactly. @lysander will be the guy to ask about this.

They have been working at this since 2016. It seems to work fairly well as a lubricant, but has some issues as a corrosion resistant layer, and the Army wants it to perform better in the salt-fog test. As you should know, the salt-fog test is a pretty harsh test.

Why do half measures? If you still have to apply oil to keep the steel parts from corroding, what’s the savings in having a permanent solid film lubricant?

As to bolt and carrier coatings . . . .

I would never recommend hard chromium plating (AMS2406), it is well known in the aviation industry that hard chrome reduces fatigue resistance by a good bit.

If you want a shiny silver bolt carrier group assembly, do what the original design did, and go with a thin dense chromium layer (AMS 2438). It is much thinner and resists fatigue better.

[SteveL]

I have a few NP3 that I've been happy with.

For those of you saying nitride, is your bolt made of 9310 or C158?

[1168]

Is there another reason why I have to hit the forward assist when doing a bolt lock reload to strip and chamber the first round from a full magazine? I have fresh springs and an H3 in my 6933. It starts lubed to the gills and 200 rounds in that top round will choke. Gen 2 PMags mostly.

Now you’ve caught my attention.

This is a regular H3, or an A5H3?

[CPM]

Now you’ve caught my attention.

This is a regular H3, or an A5H3?

Regular H3 with new carbine spring.

[Disciple]

Is there another reason why I have to hit the forward assist when doing a bolt lock reload to strip and chamber the first round from a full magazine? I have fresh springs and an H3 in my 6933. It starts lubed to the gills and 200 rounds in that top round will choke. Gen 2 PMags mostly.

Which lube are you using? Are you using one kind throughout or mixing types?

1168, wouldn't it really twist your noodle if he switched to A5 and the problem went away?

[1168]

1168, wouldn't it really twist your noodle if he switched to A5 and the problem went away?

Consider my noodle twisted already.

[okie]

Is there another reason why I have to hit the forward assist when doing a bolt lock reload to strip and chamber the first round from a full magazine? I have fresh springs and an H3 in my 6933. It starts lubed to the gills and 200 rounds in that top round will choke. Gen 2 PMags mostly.

I mean it's a known issue, which is why they recommend downloading to 28 rnds, but I've never had it happen, much less consistently. You would almost have to conclude that something somewhere is a little out of spec. One of the reason I really like Colts is they polish the feed ramps to where you don't get those hangups. I'm assuming your ramps are polished, making it even stranger, and more suggestive of something just not lining up quite right to let that round slide out of the mag. Honestly it sounds like the mag is sitting too low, which can be caused by a number of things in both upper and lower. I'm guessing stacked tolerances since it only happens on a full mag when the gun is dry.

Have you tried swapping parts out to see if you can isolate something?

[titsonritz]

I mean it's a known issue, which is why they recommend downloading to 28 rnds, but I've never had it happen, much less consistently. You would almost have to conclude that something somewhere is a little out of spec. One of the reason I really like Colts is they polish the feed ramps to where you don't get those hangups. I'm assuming your ramps are polished, making it even stranger, and more suggestive of something just not lining up quite right to let that round slide out of the mag. Honestly it sounds like the mag is sitting too low, which can be caused by a number of things in both upper and lower. I'm guessing stacked tolerances since it only happens on a full mag when the gun is dry.

Have you tried swapping parts out to see if you can isolate something?

"They" recommend downloading to 28 round so a magazine will reliably insert on a closed bolt, that is typically for the GI MilSpec aluminum mags, PMags are more forgiving in this respect and most can cram in 31 rounds, so with 30 rounds they still has a little more spring compression.