80% build tips

[Tully Mars]

When I'm dremel'ing metal with carbide cutting bits, I try to get the speed right so the material doesn't heat up too much and stick in the flutes. It still happens some no matter what, though. Keep a small jeweller's screwdriver on hand to periodically scrape the flutes out, and you'll find the going much smoother and the bits last a lot longer. It's much easier to clean than you'd expect the first time.

If you dip your cutter in kerosene when cutting/milling aluminum it will keep the flutes clear. I have been using it for 30 years. Tip was shared by an old machinist that was teaching me all those years ago. I keep an old soup can with a magnet in the bottom half full of kero near my mill. I use an acid brush to keep my tooling coated with the kerosene.

 

[11Charlie]

If you dip your cutter in kerosene when cutting/milling aluminum it will keep the flutes clear. I have been using it for 30 years. Tip was shared by an old machinist that was teaching me all those years ago. I keep an old soup can with a magnet in the bottom half full of kero near my mill. I use an acid brush to keep my tooling coated with the kerosene.

I'll have to try this out!

 

[turbo_vanner]

I'm a fan of polymer lowers, no finishing work needed. I work with aluminum all day, and wouldn't trust bare pins holes for anything long term. A DIY anodizing and cerakote will do the trick though.

 

[11Charlie]

I'm a fan of polymer lowers, no finishing work needed. I work with aluminum all day, and wouldn't trust bare pins holes for anything long term. A DIY anodizing and cerakote will do the trick though.

Ok explain yourself brother. Why wouldn't you trust bare aluminum?

 

[turbo_vanner]

its a lot softer than the steel pins sitting inside them. How long it lasts will also depend on how often pins come in and out, how much the rifle is used. Corrosion could also be an issue, but both would take quite awhile. Either way, if something were to happen to those trigger pin holes, the whole lower is worthless.

I have a few 80%'s in case something were to happen to my serialized lowers, or all serialized lowers in general, so I got something that wont degrade over time. I can't say polymer lowers won't have their troubles 20 years down the road, but they wont dent or corrode on me.

 

[Tully Mars]

I have a lot less faith in the poly lowers than the time proven aluminum ones.

 

[turbo_vanner]

are there examples of time proven unanodized lowers though?

I haven't found anything to dislike about the poly lowers, been running a few personally for years. As long as the rifle functions well, it should outlast most of the metal parts.

 

[notazombie]

I use this one:
RIDGID 5.5 Amp Corded Compact Router-R24012 - The Home Depot

I have used it on over 3 dozen lowers with zero problems. The lowers finished with the above look virtually the same as the ones finished on my milling machine. I hear it does a good job on wood too

I have that same router. Like it a lot.

 

[Tully Mars]

are there examples of time proven unanodized lowers though?

I haven't found anything to dislike about the poly lowers, been running a few personally for years. As long as the rifle functions well, it should outlast most of the metal parts.

The first 80 percenter I finished is about 4 years old. It has well over 10k through it.

 

[turbo_vanner]

good to know

 

[Ura-Ki]

I havn't run into any issues with in coated areas of the lowers due to wear or corrosion
I believe the heat treat of the material and work hardening fix any issues with that. Corrosion could be an issue with some steel parts, but if your like me and use stainless, it's likely not going to corrode! If your really worried about it, have it coated ether your self, or professionally in the coating of choice! Hot tip. You can make bronze bushings for inserts to your lowers, ther are many styles and types, I recommend "Oil Lite" automotive bushings to do this, bonus is they will correct any wear and play and restore a upper or lower to new condition. Done properly with a press, and new pins, I have found this to actually increase life span over factory set up by quite a lot! For a steel on steel joint, or steel on aluminum, this is a Super neato upgrade, and cheap to do!

 

[turbo_vanner]

I just meant corrosion on the bare aluminum spots like the trigger holes.

Good point on the bushing inserts, I forgot about those. A bit of a PITA, but definitely works.

There are also anodizing shops out there that do good ole boy deals, but you would have to ask them, preferably not over the internet.

 

[11Charlie]

Well if you all want to get technical a smith is not allowed to touch your lower once it has been milled out with out putting a serial number on it. Then he has to log it in if he is keeping it over night. So if you want to keep your 80's then I suggest doing something yourself.

 

[turbo_vanner]

well yes, technically.

 

[Tully Mars]

. You can make bronze bushings for inserts to your lowers, ther are many styles and types, I recommend "Oil Lite" automotive bushings to do this, bonus is they will correct any wear and play and restore a upper or lower to new condition. Done properly with a press, and new pins, I have found this to actually increase life span over factory set up by quite a lot!

I've not done this on a firearm but have thought about it. I've made this type of repair on many tractors and pieces of heavy equipment over the years. Just align bore the part oversize, fab a bushing for a press fit. Freeze the bushing, add a bit of locktite and let set. Align hone the bushing bore for proper pin fit and at least good as new!

 

[Ura-Ki]

I did this to an ultra High end FAL, Forged steel upper, Forged Aluminum Lower! The hinge pin area needed a little extra luvin so I fabbed a bushing pair and its nice and tight!

 

[Tully Mars]

What is the upper of which you speak?

 

[Ura-Ki]

Sadly, they don't make them any more! It was an 80% upper which was more like a 50% upper, but forged! Took a ton of mill work to carve the outside profile, drill, broach, ream, and thread both barrel and gas piston, and finish the bolt races, and finnish machine the bolt! But, it's perfectly blueprinted, every thing indexed off the fireing pin centerline!
Also has a 21 inch meloniteed 4 grove match grade medium heavy barrel and oversized closed ear gas block! 1/4 moa with good ammo

 

[kott0n]

The front rail on the P80 full size v2 is bowed in the middle. Slide won't function at all.

Smooth as butter before installing front rail. After the cant in the rail is too steep with the bow in the middle bowing up.

I emailed P80 so let's see what they say.

 

[kott0n]

Alright I got a little hasty and didn't stop to think for a minute. So my tip is to sand and polish then again and again on those front and real rails.

I got the slide on. She is crunchy feeling but functional. I'll do some more polishing this weekend to clean it up but I got it close enough that it doesn't feel like fail.