I've had my Bushmaster lower, Bushmaster lower parts kit, and LMT SOPMOD kit for some time now. I ordered a punch set from Bushmaster, and it was taking a while to come in. So, I went to Home Depot and picked up a Stanley nail set with three punches covering the range from 1/32" to 3/32". The sizes didn't match up with those specified in the lower assembly guide, but I decided I'd give it a try anyways.
Everything was easy except for the trigger guard roll pin and bolt catch roll pin. The trigger guard pin required a surprising amount of force. I protected the pin with a few cleaning patches and started it with a hammer. About midway through, I noticed that the hammer was beginning to deform the pin, so I used a punch the rest of the way. Since the punch wasn't really big enough, the deformation continued, but I was able to "tuck" it in.
Trigger guard roll pin (55KB)
As for the bolt catch pin, I protected the receiver with a cleaning patch and got to work. I started the pin with a hammer, then used a punch the rest of the way. I was nearly done and feeling pretty good, but then I lost my concentration for just a second.
Bolt catch (56KB)
Overall, the build was easy, just like everyone said it would be. I think next time, when I have the correct punches, I'll be able to minimize damage. The exposed, dinged metal sure screams amateur! have1) The safety action is very gritty. Quick transition is hindered. Is this normal or should I just lube it up really good?
2) The trigger does not always reset by itself. The disconnector kind of binds to the hammer I guess. Will lubricant fix this? The parts aren't totally dry, I just wiped off the excess oil it came with.
3) The back of the Tango Down Battle Grip is not flush with the receiver. Is this normal? I know Tango Down parts have the reputation of requiring exacting tolerances. Which part is the wrong size here, the lower or the grip?
Receiver/grip transition (55KB)
If it helps any, I have worse mangling than that on a Colt, as received from the factory.
Couple things to check and a general comment.
selector grittyness: take the grip back off and remove the spring and detent (check to see that the detent is not backwards) remove the selector and examine the detent fit to the channel milled 90 degrees around the selector. check for burs, add a smear of lube to the channel and to the lower (left&right side holes), reassemble, and work the grease in a while.
With the selector out, remove the hammer and trigger pins again.
Check to see if you have the small spring between the trigger and the disconnector in properly
reassemble and put a few drops of CLP on the parts. Make sure the hammer and trigger springs are oriented the right way as well.
During a function check the hammer should "klunk" off of the disconnector when you release the trigger, having pulled the trigger to drop the hammer and then cycled the bolt with the trigger still depressed.
I don't have experience with this grip, so no comment.
In the future, use a pair of full-sized vice grips to install both roll pins. Tape the jaw that touches the lower and control the "press" with the adjustable jaw handles. Much easier.
Tapper the inserted end of the roll pin with a small file and use a drop of CLP in each hole.
No impact to deform anything, no smashing the lower with a hammer or slipped punch.
Cheers, and good luck,
Another thing good to do is put a layer of duct tape against the side of the receiver to protect against erant hammer strikes.
Safety Detent selector cant be installed backwards.
Good job on the build. One day I will post a few things I do now to keep the oppsies from re occuring.
I just put my first lower together today, and did pretty good I think, though I'm having a similar issue with the disconnector. Ameetec lower, RRA parts kit. Mine started by not releasing the hammer at all after the trigger was released. After a few cycles it started to let go, and at present it just hesitates a second before letting go. I pulled it back apart, and the spring is properly seated. I suspect the disconnector needs a hair shaved off it to get everything clean, or perhaps light polishing on both mating surfaces,but a little lube and a few zillion more cycles might do it just as well.
No marring surprisingly. I started the roll pins with needle nose pliers, with the appropriate areas on the lower and the jaws of the pliers wrapped in 3 or so layers of masking tape. When it came time to drive the pin for the bolt release, I wrapped a rag around the rear of the reciever, wrapped the rest in tape, and taped the end of the punch as well. Excessive? Not if you knew my usual track record with handtools I actually used the punch out of an AK cleaning kit I had banging around, worked out fine. Got to chase the pivot pin detent and spring a few times 'till I stuck the whole damn thing in a bag and made my dozen or so remaining attempts in there before it clicked home.
I had the same problem recently. I had an M&A parts kit (not sure where their lower parts come from). The disconnector was either cut at the wrong angle or not cut down enough or something, but it would catch on the top inner hook of the hammer and not let go. I would have to manually use a screw driver and press down on the back of the disconnector to get it to release it. I took another disconnectory I had and put one on top of the other. The new disconnector was definitely longer on the top. I put in the other disconnector from another AR and the hammer would release properly, even when pushed all the way back. Popped the "new" disconnector in, it would stick. I ended up ordering a replacement part which solved the problem.
i looked at the dings-
i would suggest alumiblack. when you use the stuff, i would recommend pouring a small amount into a water bottle cap or something. i used a q-tip to apply some to little marks on my receiver and dipping the q-tip back into the bottle tainted it a littl. one supid ass thing i noticed is the plastic coated paper and aluminum seal is a really stupid idea. i wasn't able to get 100% of the seal off and didn't think i needed to. a week went by before i opened the bottle up again and the alumiblack totally reacted with the exposed aluminum on the seal. talk about "tainted"