Alright. As requested, here are some pix of the areas which I polish on all my BCGs to enhance smoothness and reliability. This particular carrier is an LMT Enhanced Carrier (gen 4) with a std LMT bolt (not the enhanced bolt). It has an NIB cam pin from WMD guns, so please note that I did not polish the cam pin.
The areas, as seen from various angles, that are to be polished:
The bottom ‘pad’ of the carrier where the hammer rides
Each of the carrier rail ‘pads’ (which are actually uninterrupted rails on std carriers except for the portions that span the cam pin track on the top)
The flat sides of the gas key.
I also will buff the phosphate on the rear of the carrier (where it telescopes into the RE), but I won’t even remove the finish. Just some very light polishing to the usually very-rough phosphate finish in this area.
This has a sheen of FireClean on it that I did not remove for the photos. Also, LMT uses MIM carrier keys on their enhanced carriers and these are already decently smooth from the factory. I did some polishing to the sides of the carrier key, but it was minimal compared to what I did to the actual 8620 carrier itself.
I used an AC Dremel tool on LOW (approx 12,000 RPM) with very light pressure. I let the Dremel and the bit ‘do the work’. Don’t manhandle the bitch or it WILL walk on you and probably mark-up some other part of your carrier. Go ahead and ask me how I know that.
It has polishing compound and lubricant impregnated into the wheel itself. It’s slow going, but this is good and it doesn’t leave a metric sh*t-load of jeweler’s rouge laying everywhere like using a normal wheel+compound setup. I got my 520 wheel at WalMart for under $5. It also comes in their $12 “polishing kit”.
As Jaxman has said, sandpaper is also appropriate in the finer-grit varieties as long as it is by HAND and not via a dremel or other machine. The goal is to remove the phosphating and to polish the metal underneath on critical contact points, NOT to re-profile the damn thing. The goal is not to remove any metal…just knocking the jagged edges of the surface finish down. So go SLOW. I know it’s right when I see a dull luster and can drag the edge of my finger nail over the polished area and it feels very smooth. It doesn’t have to be a mirror finish as there will still be some elements of the phosphate finish in the little valleys of the metal. Now for pix.
Yeah… not too bad. I know Pappabear was going to loan me an LMT Enhanced carrier for a gun. It was so rough, I put it in, took it back out and gave it right back to him.
Mark, I’d be lying if I said the lack of smoothness of the finish wasn’t part of the reason I initially did this. I came directly from a FailZero NiB BCG to the LMT carrier and, DAMN, it was rough when I first got it
Same here. The two I got earlier this year were pretty good, but one of them is chewing up my buffer due to a small burr on the end of the carrier. No big deal.
This one did he same thing. it doesn’t show up well in the photo, but I polished the ever-lovin-sh*t out of the rear of the carrier and that fixed. It put what looked like several thousand rounds of wear on the buffer face in under 4 magazines. It was crazy, but the burr was not readily apparent upon a visual inspection.
Good to see a thread on this Buford. This thread led me to take pics of 2 of my carriers that I’ve polished in that past. Unfortunately I actually had to break down and do a rare full cleaning.
On the 2 carriers the top one is a BCM and lower is the LMT E-Carrier and I must say that before polishing the E-Carrier (by hand as Buford has mentioned, no power tools used) it was VERY rough.
I will say that this was all Bufrod T’s idea. I just followed his idea…and it was a good one. Also part of the smoothness comes from a well worn upper receiver to match the smoothness of the carrier. To achieve this smoothness on one of my newer Vltor uppers I coated the bearing surfaces of the carrier that was to be used in that particular upper with automotive valve lapping compound. After a couple of hundred hand cycles this helped wear in the upper much faster than just shooting it. Next I cleaned the carrier and upper with brake cleaner and reapplied Froglube. I also use that same lapping compound to polish the feed ramps of my handguns.
I’m not trying to be a smartass, but why not just shoot it and let the weapon lap itself in? This is what Les Baer does with their 1911’s, and an AR is not like a Baer 1911 that won’t function reliably until the break-in is performed (per Les Baer’s staff when I owned one). It’s good to go out of the box, and just gets better with time as it laps itself in. I would think it would do a better job, as well, hitting only the spots it needs to.
A few years back I did get an enhanced carrier with a burr on a rail that ate through the anodizing fast. I can see breaking the corners and taking off any high spots and just run it.
Good question. Answer: for all the thousands of rounds I’ve put downrange, none of them have ever gotten this smooth by themselves. Plus, i get to keep all the dry lube inside the upper intact.
That is completely different. If you don’t break in pads correctly, you will end up with hot-spots on the rotors where the deposits are un-even on the rotor and pad. Pad material MUST transfer to the rotor for brakes to correctly work. Fail to effect this transfer evenly, and you will have issues. Further, some brake-pads need to be properly broken in to avoid “green fade”. My Z06 was sortof like that, and the ZR1 and Z07’s with ceramic brakes were CERTAINLY like that.
By the time you have zeroed the weapon and shot a few drills with it, things should be polished nicely. At least, that’s how all of my rifles have been.
I think I would just degrease real well and apply a thick coating of moly lube before taking off any parkerizing or finish. How rough are those LMT bolts? The MIM carrier key keeps me away. I cannot recall a single malfunction ever with my Spikes and BCM BCG’s. They run no problem from the factory,as they should.
I would be concerned about removing the finish as well. I’m also concerned with polishing the sides of the gas key - removing burrs is one thing, but considering the number of case-hardened MIM and investment cast gas keys floating around, I’d be too afraid that I’d remove the hardened layer, leaving a soft-sided gas key which doesn’t sound like a good idea. Are most carriers through-hardened or case-hardened?
thanks
