I just finished my BO pistol.  I'm running a 10.5" barrel, but with just a bare KAK Gen 2 pistol tube with a crutch foot on it and a YHM phantom flash suppressor, so no braking or compensation happening, and I would say the recoil is amazingly light.  I have to add I'm running an AA piston, so not sure what effect that has on the pistol recoil, but I would say it's not even as bad as my 18" 5.56 that weighs a good 3 lbs more with 3-9 x 40 Leupy glass, a Rainier medcon barrel, and a considerably heavier handguard and the full AA gas block piston vs the XLP i put on the pistol.  I've only shot supersonic 125g FMJ BTs through it thus far, but it's exceedingly comfortable to shoot.

Finally finished the 300blk lower

Soaked in acetone overnight this time. Most of the previous GK is removed, but not all. Didn't think I needed to since GK was going back on...





This time I did not warm with a heat gun between coats and I like the results better. Not as rough of texture. I also did fewer coats and put more on with each coat.
After baking 1.5 hrs...







The hammer pin nicked off a little GK again. At least it's small this time. I might go back and touch up later.






Well that project only took 8 months to complete... geesh!

I have a Kineti-tech brake with shroud I might just put on this to see if it helps me stay on target better than the BRT linear comp.

I have 2 more lowers still  to finish. I think I'll look into the process of Cerikote or maybe dye them black after anodizing. I'm not really sold on the GK after this experience.
One will build with a 10.5" Wylde 223 (already came) and the other a 7.5"  7.62x39.

Last touches

Foam tube cover bought from here. Can't beat the price at $3.50 ea. I picked up 3 since the shipping was more than the PVC grips. So it came out to $8ea with shipping and got them in 2 days.



Nice and thick padding. I cut it 1/2" longer and could have gone 3/4" I think. Wanted a little extra at the shoulder to provide some extra cushion.



Have to cut the tube down from 18". They do have a 6" but it would not have reached the shoulder of the buffer tube.





The brass was getting dinged at the case mouth so I added a little Velcro to the deflector.



Just loaded up 400 rds of 300blk with 110gr 30 carbine copper wash bullets using 20.0gr W296 at 1.845 COL. This fills the case up to where the base of the bullet seats.

For the trigger job:

Before anodizing I threaded the pistol grip screw hole all the way through to the fire control pocket. Installing a 1/4" long 1/4-28 allen head set screw to where it touches the bottom of the trigger tail to reduce/optimize the reset.It then needs a shorter pistol grip screw so it doesn't bottom out on the set screw. Also installed JP yellow springs and cut the rear protrusion of the hammer off. Still have to lap the trigger/hammer sear with 600grit lapping compound. I'll do that this weekend.  

And the parts list:

Barrel - 7.5 mid weight 300blk eBay - $110
Rail - 7" carbine free float w/nut 11.8oz  eBay - $27  
Gas block - low profile eBay - $15
Stripped upper - PSA - $50
LPK - PSA - $40
JP yellow springs - Joe Bob's - $5
Ergo grip - eBay - $17
Aluminum trigger guard - $4
Comp - BRT linear - $50
Optics - Burris F3 - $256
forward grip - Mako FAB Def PTK + VTS - $28
Buffer tube - Guntec Model 4/15 Sig Tac extended - Amazon $32
Buffer tube foam cover - Gympart.com - $8
Rear plate with sling loop - Amazon - $17
Castle nut - Amazon - $4
Charging handle - eBay - $14
Buffer and spring - already had it
Bullet Button (damn thing) - reversible BB (Raddlock knockoff) eBay - $15
Other small items like pistol grip screw/set screw - $5
Lower - 80% Tactical Machining - $72 lower ea + $80 jig and all the other stuff = way too much!! Probably avg over 5 lowers, $200 / lower

Total minus lower = $697
with lower = $897 and 8 months in the process.

Definitely the least expensive way to buy/own a legal pistol in CA these days is to go this route.

300blk Lee die set with factory crimp  Amazon - $36

Hopefully my trials and tribulations will help someone out on their build.

Trigger job in case someone is interested:

Applied a little 600 grit diamond lapping compound to the sear engagement and pulled the trigger catching the hammer just after release 20+ times. Reapplied some more compound and repeated the process a couple more times. I think I could have gone with a higher grit. maybe 1000.
Back of hammer bobbed.



Removed the hammer and trigger to clean the compound off and then used a dermal with buffer wheel to polish a bit more.
Here you can see where the trigger sear has been honed.





JP Yellow springs installed

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Bobbed the hammer spur off with a dermal. Hacksaw had a hard time because of the hardened surface. Used a little Aluma Black to darken the white steel back to black.



Pic showing the 1/4" 1/4-28 set screw in position. It was screwed from the bottom of the receiver and a little Loktite dabbed on the threads.



You need to back the set screw out some to get the safety selector installed. Then turn the set screw in until the trigger will not reset, then back out to where the safety selector will turn and the trigger will just reset. Oil the sear and check the engagement.
It should be a lot better than what you started with. I compared 3 of these trigger jobs to a RRA 2 stage trigger and the RRA was better, but this was about $70 less expensive.

For a AR pistol it is fine for me. For a rifle I like the RRA 2 stage. Also have a one piece Wilson 2 stage with a lighter trigger and nice break I like even better than the RAA.

I'll get a chance to check accuracy on this weapon next weekend.

Very nice!  I use flitz to polish my trigger/hammer and it has worked well for me for years.

All it's missing is a Hammer & Sickle...I like the etching idea though.

Is there a particular Flitz polish you use? Seems to be both a liquid and paste,

I used this

Forgot I left that place holder. That's what happens when you spend over 8 months on a friggin project. The etching came out better than I ever imagined.

I have 2 more lowers to finish.

 One I'll do in honor of my father who was USMC and spent his first tour on the USS Colorado and searched for Amelia Earhart.   Etching a battleship should be a good challenge. Almost have it finished in the design program  Also drawing out the USMC emblem for etching.

 Second I'll do for my father in Law who fought in Patton's 3rd Army during WWII. Plan to etch a tank and the 3rd Army patch.  

Went to accuracy test the 300blk 7.5" with the 110gr 30 carbine copper coat and 20gm of W296. Not impressed with the results. First thought it might be the Burris F3 walking around. Then tightened the mount more and installed backup iron sights. Still rounds were not consistant even at 25yds. These might have been too hot for this bullet.

I'll load up some match bullets and see where they land.

I use the stuff in the grey tube. I have also used permatex valve lapping compound first, followed by flitz if the trigger feels really gritty.

Thanks, I'll try the grey tube flitz. There's still a hitch before the gitty up after the 600grit lap.