[kansascity45]

Congruents on your new MCX!!

As you probably know, rifle break-in procedures vary greatly - from a lot of bore cleaning during the 1st 50 or 80 rounds, to shooting it like a zombie invasion was underway!!

Personally, I do a lot of cleaning on my bolt long guns, and less on my ARs. IMO, it's important to do a good initial inspection, cleaning and lube before going to the range. Also to not run your rifle too hot early on.

I pay particular attention to how smooth the cleaning rod feels running down to bore on that 1st cleaning, and how many patches it takes to get to a light gray/relatively clean patch. This will tell you how polished the bore is from the factory.

My indoor range has never had a problem with my cleaning rod, brush & patches out on the bench.

On my ARs, I'll stop after 5 round or so just to let her cool down, and do a bore cleaning at 10 rounds. Run a bore brush with solvent 10 passes, and see how many patches it takes to get to that light gray patch. If it's 15+ patches, I'll suggest another cleaning at 20 rounds, and again see how many patches it takes to get to a light gray patch.

I'd adjust the round count between cleanings by how quickly the patches become clean. You want to get to a reasonably clean patch in 6 or 8 patches. Then you know your bore is in pretty good shape.

AR barrels have muzzle devices and are difficult to actually see their bore, but here's a pic of a 300WM barrel at 70 rounds that has just reached 'copper equilibrium'. That's precision shooter's speak for a broken-in bore...

Oh, and since this is an MCX, you'll also want to keep an eye on the upper receiver's internal cam path - looking for any excessive gouging around the steel insert.

Yeah, we've seen problems there with these new carriage assemblies. Many of us have installed a roller cam pin from POF to avoid that issue.

Cheers

 

[MrMcGoo]

Before firing a new MCX, the barrel bolts" torque should be verified at 60 inch pounds. It may make zeroing a little easier.

Bill

 

[kansascity45]

Yeah, keeping those 2 T27 torx barrel clamp screws at 60 inch lbs is important. IMO the they're also one of MCX's caution points. Ya gotta be careful with those two!!

We've seen examples where these were over torqued and broken, stripped a head out and couldn't be removed, and the little spring loaded screw retention bracket was broken. Any of these pretty much disable your rifle, so like I said - be careful!

I've installed my MCX barrel with almost every cleaning - here are some suggestions that'll keep ya out of trouble.

Have your rifle in a secure, stable position. Trying to remove/install your barrel with the rifle balanced on your knee is asking for trouble.

Only use a good T27 screwdriver. No - your pocket knife isn't gonna work well for ya here!

When removing the barrel, backout one screw say half way, and then back the other screw out - keeping the retention bracket somewhat level. Be careful not to let the driver slip and strike the bracket. This bracket isn't a very strong part.

When installing the barrel, make sure the 2 indexing pins on each side of the barrel are fully inserted into their positioning detents. FYI it's actually pretty easy to install the barrel that's 1/16 to even 1/8 short of it's correct position - and that can't be a good thing!

I like to torque these screws to 40inlbs, and then go up to 60inlbs in a 2 step process. May take a few seconds more - so call me OCD!!

Cheers