newer style 80% spec question

[Seesm]

THat is a Q-L lower right... From what I have done you will go a little thinner up front... if you need come on up I will help you out by letting you use my mill.

[ar15barrels]

It looks like you may be able to get the FC cavity within 0-.050" of center, and have it be the proper width, which shouldn't be a problem.

If you are 0.050" off center with the fire control pocket, you may have problems fitting the selector to the trigger.
Do it right or scrap it, start over and call it a learning experience.

[ke6guj]

yah Randall, I was just guestimating that it could be .050" off center and still be able to have the hammer make it into the BCG without issues. I wasn't thinking about the safety having to line up as well. And even that could be made to work, but it would take work.

I would mark the lower with Dykem and mark out what the FC cavity should look like and see if I could make it work. Looking at the small drill holes and then the divot of the larger one, it appears that the small drill holes may not be out to the final dimension, but since I haven't done a "drill out the FC cavity" build, I don't know.

Heck, looking at it further, I'd say that I'd probably mill out the FC cavity on center, and live with a couple vertical grooves on the right side, as long as the the FC pins lined up on the flat. But as I mentioned, I'd mark out where the FC cavity should be and see how off you really are.

[savs2k]

yeah its a q-l lower. There out of stock right now or id have another on the way and attempt to fix this without admitting failure. What i was going to do was use dykem and mark the correct pocket and mill it by eye and a micrometer. The smaller holes won't be too much of a problem. I can just make a 1/2" diameter hole in the center of the pocket and use the 3/8 end mill to clean it up. But the 3/8 holes that are done might be too far out. The FC cavity is really close to the red outline. at most .005 off either way.
The selector should be fine since i havent milled enough meat out on that side. I'm just worry about the the hammer not fitting right and not have clearance to strike the firing pin. Even after that if the side of the hammer isn't close to wall, can the hammer walk on the hammer pin and not line up with the trigger?

[goober]

looks salvageable to me. not pretty, but should be possible to build into a functional lower.

[savs2k]

I had a little bit of free time today so I decided to get back to work with the lower. It looks like it'll fit. I realigned everything to get it in spec. Ugly wall but hey it should work. So anyone who screws up by not reading directions at least once like me.... you can still fix it. I still need to do the trigger slot and trigger/hammer pin. Then i'll know if it's functional. I did a test fit and my upper has some slop to it. The milling adapter plate slot is a bit wider then it should be. I'll figure out a way to stop the play but its not bad i've had worse on lowers/upper i've bought. Anyways here is a single picture update. Thanks for the help guys.

[fabguy]

Who's lower is it? (manufacturer) and who's jig did you buy? I want to do one of these but not sure which jig to get that will work with which 80% lower. If I could get that info and try it out, I have a few friends waiting to get theirs. I guess they want me to be the guinny pig. I have a fabrication shop so I guess MAYBE I could host a 80% lower party here in So. Cal. ( for calgun members))if anyone is interested.

[Rule .308]

The jig and a whole lot more can be found here.

http://www.cncguns.com/

[goober]

Who's lower is it? (manufacturer) and who's jig did you buy? I want to do one of these but not sure which jig to get that will work with which 80% lower. If I could get that info and try it out, I have a few friends waiting to get theirs. I guess they want me to be the guinny pig. I have a fabrication shop so I guess MAYBE I could host a 80% lower party here in So. Cal. ( for calgun members))if anyone is interested.

both CNC and TM jigs will work w/ any mil-spec 80% lower.
but depending on what flavor of 80 you have, there may be different things left to do on it.
for TM 80's and others that need only the trigger & hammer pin + FCG pocket done, the TM jig has everything you need.
if selector, bolt catch roll pin or and/plunger, and/or mag release holes need to be done, the CNC jig has those covered as well.
assuming from your post that the "fab" in your username does not stand for "fabulous" (or at least not solely ), you should have no problem doing an 80 if you have a shop. you could even make your own jig if needed.

[savs2k]

the jig is a cnc jig from justin. the "cooler" looking 80% is a quentin. The other 2 80% are ar15plus. The quentin lower is really nice. You need to do the fc pocket, trigger and hammer pin,the rear pocket where the back of the upper goes,and the hole for the trigger its self to go into. The new style jig for a solid fc pocket does take alot longer to do but it's not too bad. If you have a mill you'll be able to knock these out within 10 mins. If you decide to do it on a drill press like i did... well have fun. If I had to do one more... sure I would on a drill press. But if I had to do 2 more..... i'm putting out the money for a decent mill.

[goober]

the jig is a cnc jig from justin. the "cooler" looking 80% is a quentin. The other 2 80% are ar15plus. The quentin lower is really nice. You need to do the fc pocket, trigger and hammer pin,the rear pocket where the back of the upper goes,and the hole for the trigger its self to go into. The new style jig for a solid fc pocket does take alot longer to do but it's not too bad. If you have a mill you'll be able to knock these out within 10 mins. If you decide to do it on a drill press like i did... well have fun. If I had to do one more... sure I would on a drill press. But if I had to do 2 more..... i'm putting out the money for a decent mill.

10 minutes is awfully optimistic on a mill. 30 would be more like the minimum, on a bridgeport-sized mill with a skillful operator.

[ar15barrels]

10 minutes is awfully optimistic on a mill.

I think he's talking about a CNC mill.

[goober]

even then w/ setup time 10 min would be just doable, w/o 4th axis

[savs2k]

i was talking about a manual. I'm lazy and would have just plunged to get it done. I don't find it practical to run a cnc for an 80%. But then again my cnc operator skills aren't the best yet. I wrecked a part i was running the other day on a hass vf-2. Dunno what the heck i did but it reset my g54

[savs2k]

i never look at the clock when im machining so you guys could be right. It might only seem like 10 mins to me but is 30 in reality. I'm also a newbie to machining so dont burn me too hard