The not cycling thread got me thinking. Before I begin a build, I spend at least an hour inspecting, measuring, test fitting and cleaning. Let’s keep this thread for lowers only. I am curious as what everyone does before building a stripped lower. I will outline my procedures.
I am no expert, but have built, repaired, stripped, rebuilt and replaced many parts. My guess is that I have been involved in over 50 builds from a stripped lower and many more from rebuilding etc.
The first thing I do is a visual inspection. I have seen grip screw recesses that wasn’t threaded. Had one that had plugs in the threads. Seen lowers that we’re not drilled for the bolt catch roll pin. Had four lowers from the same manufacture that were all out of spec regarding the distance between the front lugs. Etc.
If all looks good, I start test fitting. I have a set of all generation pmags and D&H and okay mags. They all need to fit and fall out. If so I install the mag catch and adjust and recheck. I test fit at least 3 uppers and check for fit and test fit both the pivot and take down pins. Then I test fit the bolt catch. Had a few that were out of spec and wouldn’t fit in the frame.
I always inspect the bolt catch plunger recess by installing two different plungers backwards. This is very important. If short drilled, I can remove the plunger via the nipple with needle nose pliers. Having had a short tapered recess that the plunger got wedged in and was a real bitch to extract, I consider this essential. Then I test fit the trigger pins and safety as well as the grip. Usually I have to work the grip off and on and remove some material while verifying the depth of the safety spring. Then check fit the remaining springs and detents.
Next comes the receiver etc. check fit the stock, spring, detent, castle nut and QD plate. Had a few plates and extensions that were defective. Then test install the receiver to the frame and check interface with the buffer detent. If all checks OK, I start my build.
That’s my preparation before I start to build a lower. What preparations does everyone else utilize?
on AR-15’s, if not already tapped, I tap the hole for the take-down pin detent & spring for 4-40 set screw. it’s a very common mod. Some AR-15 lowers come with that mod.
ETA: had incorrect screw size of 2-56, now corrected to 4-40. thanks to @M90A1 (below) for catching this flub of major proportions.
Thanks for the responses. They are bit different from what I anticipated. If I am understanding, folks don’t inspect anything before the build? My process can take up to an hour or as little as 15 minutes. I absolutely agree on buying quality. I do buy what I consider quality stripped and complete lowers as as well as parts.
This includes Sionics, SOLGW, BCM, FCD, Colt and a few others. However, on one occasion I bought a complete lower from a gun store. It is what is considered top tier. Therefore I didn’t check it over. It was out of spec and improperly built. I guess I prefer to do an inspection before the build to ensure all is good. Otherwise, I would have to strip the lower etc if I found a problem. That, to me, would be aggravating if it was towards the end of the build.
I have personally seen top tier products that were out of spec. I believe we have seen numerous people post about various issues. Perhaps the one I have seen is a lower that wasn’t drilled for the bolt catch roll pin, or improper grip screw and short bolt catch plunger hole and tapered.
Hence, my reasons for an inspection as set out above. Frankly, even top tier companies can put out lemons, so that is why I do a preventative inspection. Thanks, For the response.
I kind of like your idea, I might have to try it out on my next build.
The only prep work I do before assembling is to wipe it down with a lint free cloth and some degreaser if needed. Zev, SOLGW, and Aero have never given me fitment issues.
if you do this mod, you need to shorten the detent spring by about the length of the set screw. The set screws I use are 1/8" long, so I shorten the spring by that amount using a Dremel cut-off wheel. I just eyeball guesstimate on how much to cut off with the whiz-wheel, and then also use the side of the whiz-wheel to put a flat surface on the newly-cut end of the spring, “dressing” the end of the spring.
all of my lowers from Aero, Spikes Tactical, and PSA have been completely in-spec, uneventful. Yes, PSA. no surprises during the builds. including AR-10 builds on Aero M5 lowers.
Yes, this, Ive only 3 lowers right now but 1 lower was built and then striped at least 5 times at this point and everything ive done works just fine.
Its a spikes lower if that makes any diff.
I robbed parts from it a few times to finish my adm and aero lower and back, only issue I had was when originally building the spikes lower I mushroomed the bolt catch roll pin and one of these days I will get around to replacing it and the bolt catch.
Its a strike industries enhanced that works with the norgon clones well but the ****ing wobble they both have(other is on the aero) im afraid my a5 green sprinco will snap the ****ers when the bolt stops.
I think a 2-56 set screw is going to be too small for that hole. Are you sure you’re not using a 4-40? I’ve seen some companies using a 6-32 even. I’ve been using a 4-40 for 30 years.
@M90A1 you are absolutely right. I’ll edit my above post. I went and eye-balled the tap that I used, and lo and behold, it is indeed 4-40.
thanks for catching that. much appreciated.
The 2 out of spec lowers ive had were a kac and a geissele. I check everything similar to the op, mainly because i do enjoy it. Its frankly surprising that a forum that in general thinks so highly of itself would do so little qc, but i suppose “its never been an issue before” is good enough for most.
My only objective is to see how fast I can get this friggin thing done and move on with my life. It’s a chore, and I want it behind me as quickly as possible.
I never got the impression the forum members think highly of themselves, the impression I get is buy decent parts, shoot the piss out of the build, and avoid getting caught up in minutia. You buy decent parts 'cause upgrading cheap parts gets expensive.
That is my point. I buy “decent parts” as stated above. I have had bad parts, out of spec parts and receivers from top tier companies. Everyone can produce a lemon. The most screwed up Complete lower receiver I had–bought brand new was an LMT. I have had other out of spec parts from top tier companies. It happens. So, I buy decent parts, but sometimes it is impossible to “shoot the piss out of the build” because of these bad parts from decent top tier companies.
Imagine my surprise when I built a stripped lower from a decent company with decent parts, but the front lugs were oversized to such an extent that you could not fit a top end to the lower. If you wanted to beat the hell out of the upper to try to get the upper lug to wedge into the lower maybe. That was a waste of time. I ended up completely stripping the lower and starting over with a different lower, that I measured and test fit multiple uppers before the build.
Perhaps our definition of performing QC is different. Anytime I buy a new gun, I inspect it. This includes looking down the barrel to make sure there isn’t an obstruction. I generally clean and lube the gun before I fire it. This to me is just common sense and maybe some might consider it doing QC. I have to say I am a bit surprised by the responses. For instance, I am getting ready to build an upper. I have test fit the barrel to a few upper receivers and decided which one fit the best. I will check the headspace. I know most folks don’t bother to check the HS. I will test fit the gas block etc. So far, knock on wood, I have never had an upper that I built, malfunction.
For me, I just believe in checking certain items and doing some basic safety checks before I build or shoot a new gun.
This. The extra money for a non-gucci but good product pay themselves back in time.
I also get it done fast, so if something is oos, i find out asap with minimal time invested.
I used to do all the repairs to my own cars. I graduated from that, now its worth it for me to pay for it to be done… my free time is for doing what I want, not saving nickels.
For rifles, I know how they work. If its out of spec I need to find out asap and replace it. Inspecting 9 good parts for 1 bad is not a good use of time. Its more efficient to just go ham and find the 1 bad after the fact.
For my own personal builds I follow a similar course of action but when I was building for a shop,I would reject parts and the boss would give them right back and say “make them work”. You know you are working with crap when you get a case of lowers that are in a partial state of various part assembly.