Hi,

I have Black Rifle II, and it shows the bolt reliability kit in the M4A1 SOPMOD section.  I wanted to see if anyone had the specifics on the parts list? I have a good deal of information and also understand several companies make similar kits but I'm interested in the NSN kit that the military currenty uses for SOPMOD 

Bolt Upgrade: 

Viton Crane O ring
Milspec Extractor Spring Insert
Extra Power Extractor Spring - not in original kit/not sure if it's officially used?
Extra Power Ejector Spring
One Piece Gas Ring

This is what I have can anyone ellaborate on additional items and specific brand names or manufacturers?


Thanks!

Items in kits are identified by NSN and are unlikely to identify the manufacturer.
The same parts may have been supplied by different manufacturers as new contracts are offered.

That was a good upgrade 10 years ago, but wasn't 100% GTG in every gun.  I saw plenty of problems with the o ring and those junky McFarland gas rings.

Today, the better option is a Colt extractor with copper spring and black insert and a new set of Colt rings.

This is the truth right here.  Last time I ordered from Brownells, I just ordered a bunch of those along with my order so I have spares, or can help someone having malfunctions related to those parts.  Colt gold springs are like $5.

I have been using Colt bolts and gas rings and Sprinco extractor five coil springs with insert and viton oring.  I'm ordering some Sprinco ejector springs for all my bolts soon.  So standard gas rings, and the enhanced spring with insert is good to go?  I heard the McFarland one piece rings issues were due to the fact that folks would believe they were unservicable because they would not provide as much resistance when they did the BCG Inversion test? Can anyone ellaborate?  They currently cost less than Colt gas rings.  I found several different American made manufacturers selling them for $2-2.99 each.  

I use BCM extractor springs, but I think the point is to use HD springs vs. standard springs.
I do not need and do not use the o-rings in any of my AR’s.
I have never had a problem with McFarland rings and I have several sets in use some dating back to when they first came out.

The Navy found that the McFarland rings increased mean rounds between stoppages significantly.  It reduces friction and apparently when they shine is with heavy carbon buildup.  I  don't know if I'm convinced they are better than standard gas rings.. I  believe one major improvement is the enhanved extractor spring and a heavier CrSi buffer spring. Analysis of the military is that the springs don't get changed often enough.  If they did it's likely there would be fewer stoppages. 

I have been using Tubb’s flatwire CS action springs since they came out generally with heavier buffers.
The Tubb’s spring works with both rifle and carbine stock setups.
As long as you don’t let them rust CS springs should be good for the life of the weapon.
There have been posts about problems with Tubb’s springs and McFarland rings, but that is not my experience so I will continue to use them.

It was a stop gap upgrade until the Army finished testing the Colt upgrades.

I believe the Colt copper extractor spring + black insert, new gas rings, and ejector spring all finished testing in 2007.

I wonder what if anything they did to enhance the gas rings?  I have been using Colt rings and I have to say I'm happy with them.  My first set got cooked on my M4 back when I was using the civilian Breakfree CLP. Thank God I don't use that stuff anymore.  I used to scrape carbon for a while and still left the components coated with carbon.  Since I started using FrogLube liberally, the carbon is no longer an issue.  I started with the paste, and it works well down to zero degrees despite conflicting reports.  I now use FrogLube Extreme during the colder months and I keep a massive tub of paste handy.  I have had the Extreme out in negative 10 minus wind chill and it works just fine.  My 1911 didn't like the paste when it was new and uber tight but 4000 rounds later it's good to go.  I would definitely recommend Extreme for the arctic climates like mine to be safe.  I just wipe the parts off now, no more scraping.  You do have to apply liberally, if you go too thin with the FrogLube it will limit its effectiveness at dissolving carbon.  I paste up the BCG good and it dries, and as soon as it runs it heats up and wets.  The gas rings don't get caked and fused together like they did with CLP, and they get a good dose of paste as well.  I use Extreme liquid for all the dropper spots.  Still haven't tried FrogLube CLP on anything but a sample on my 9mm which worked very well for the short period of time I used it.  My Walther likes the Frog paste too, but per the manual it gets Extreme on a few spots per guidelines.