Just about finished with this. Minor issue that should be fixed tomorrow...then maybe some range time middle of next week.

This thing started when I picked up a12.5" SPR WOA from ADCO to use in my MGI upper as a second barrel to complement the 7" DPMS Kitty Kat that I got from Spikes a few months back.  Spikes then did me big favor (really?) by having a sale on their lowers and uppers!  Thanks, Tom.  I needed another gun like a hole in my head, as my wife would say.  So with a barrel, upper and lower receiver, what was I to do, but make them one happy pistol!

Spec:
12.5" WOA SS SPR 1/7 5.56 Wylde chamber
YHM low profile gas block w/ WOA gas tube
YHM Phantom 5C1 flash hidder
VTAC-JP Enterprise Mid-length free float tube with a mid-length top rail
Spikes M4 upper receiver
Spikes SL15 lower receiver with the color fill
CMMG lower parts kit
Ergo Sure Grip
Magpul MBUS
Magpul Enhanced Trigger Guard
Primary Arms M3 multi-reticle w/ P.A.'s cant mount
CMT charging handle
ACE pistol buffer kit with standard carbine spring, but with H-buffer and QD sling mount
BCM M16 BCG (I may pick up a Spikes BCG soon to get the matching Spider logo BCG...what the hell, it's just money)

The lower and upper receiver fit perfectly together.  I have a CMMG rifle that I think has a very good fit, but the receivers I got from Spikes have the best tolerance I've seen on an AR15.  There is almost no movement between the upper and lower receiver. It feels like I have an accu-wedge in there.

The finish on the upper is slightly more matted than the lower, but it's not too obvious while it matches the VTAC parts almost exactly in finish.  The CMMG LPK installed very nicely.  I used a DPMS kit on a CMMG lower a couple months ago that seemed to have slightly oversized roll pins which made it tricky to get them in.  With the Spikes lower and CMMG LPK, the lower was built with no hassle what so ever.

The VTAC tube was easy to install with just an standard barrel wrench.  I didn't use Loctite on the outer barrel nut as the JP instructions said to do.  If you don't know, the VTAC uses an outer and an inner barrel nut. The outer is suppose to be loctite set onto the upper receiver and then the inner nut compresses the barrel to the receiver.  Some don't like the Loctite on the receiver, and neither do I.  So I used a drill bit in the gas tube hole of the outer barrel nut and the upper receiver to hold the outer nut in place and keep it aligned while torquing the inner barrel nut. Worked like a charm and 50 ft-lbs put a notch right where my gas tube had to go.

I had a bit of a problem with my gas block. The ID was a couple of thousandths too small than the .750" barrel.  Long story short, I heated it with a torch and it slipped right into place using the gas tube as a guide.

The WOA barrel is heavy in this application. I can feel the weigh on my left arm.  I haven't weighted it, but it's probably close to what my 16" rifle weighs. But I wanted the 12.5" barrel after seeing some chrono testing done by a few of the members.  I'm hoping this pistol will perform as well as my 16" rifle.  I want it to be my go-to gun, and my SHTF gun...of course one never knows, I keep adding parts to my stash of parts, so who knows what will become of the parts.

Anyhow, I think I've got my ideal pistol now...so I have to stop shopping  While I was taking pictures of some BCG for a post, my wife walked into the office and noticed the Spider....she didn't say it until I pressed her to explain her silent reaction, but she likes the Spider!  (I was surprised she didn't give me grief about another gun, but I don't think she knows I have more than one AR  . LOL!

Sorry for the long post, but here it is..."WAKIZASHI !"

WOW––thats excellent.  I often wondered why someone never developed a 5.56 round for pistols using powder with a different burn rate than the standard barrels, and a 77 gr bullet ? A good strong sling on that to counter pull will help with the weight . Looks like an accurate design.

Nice! I want one!

nice

Thanks guys. It was fun putting it together.  I'll try to get to the range soon and post some results...

That is utter awesomeness!

Beautiful build!

What is your opinion on the PA sight? It doesn't make much sense to me that you put a $70 optic on such a pretty rifle.

Thanks.  As for the P.A. optic...in short, I'm a cheap SOB.  

So why didn't I just build a pistol with cheaper parts?  Well, the long of it is that I feel the functionality of the weapon is more critical than anything I can hang on it.  So I would rather spend money on the function critical parts.  The WOA barrel, coupled with a good BCG is what I believe forms the heart of the weapon.  I probably could have gotten a comparable BCG from a different shop, but I hadn't purchased anything from BCM yet so I wanted to give them a try. They also HPT the bolt, so I figure what the heck...spend another $10 bucks and let's see.  

Why didn't I spend more on the lower and upper receiver then?  Well, I don't think some of the more expensive receivers offer a big enough advantage, if any.  Not everyone will agree, but as long as I have well machined receivers made of good forgings they would be more than good enough for reliable function and longevity.  It was fortunate timing for me when Spikes had their sale on the upper and lower. The receivers fit together like they were machined buy the same machinist on the same day.

With those four critical parts, I felt everything else could be compromised a bit.  I really don't like the Magpul MBUS that much, but I had them in my parts stash.  I will probably go with some irons later.  The rest of the parts to complete the build were from my parts bin too, including the P.A. optics.

I bought one of the PA M3 multi-reticles for my rifle which already had irons sights that I was comfortable and competent with, so the optic was just gravy.  I was a few mouse clicks away from buying an Aimpoint when MidwayUSA had them for $398 or so, but then I started looking at mounts for it.  I realized I'd be well over $500 for the Aimpoint and a mount.  I read some good reviews of Marshall's red dots, and I thought they were more than justs the usual $20 wholesale Chinese products you see selling for $70 or more with high promises.  Marshall even broke one open to show that the thing was put together well (epoxied internal, not taped).  He didn't try to over sell the optics and was very honest about them. A lot of the early buyers were very pleased wth them, so I went for it.  I bought a maginfier with the red dot too. So for about $200, I had optics and mounts.  I figure if it crapped out after a year when the warranty runs out, I'd have gotten my money's worth while the magnifier and mount could be used with an Aimpoint.

When I got the PA equipment, I was satisfied enough with the money spent that I bought a second one for my other pistol, $89 for mount and optic on a range toy, why not.  The quality of the PA M3 is very good.  The dials have a feel of quality to them and everything was solidly assembled. One of the early buyers even said he prefered his PA over his Aimpoint.  Now I don't have an Aimpoint to make any comparisons, but as a mechanical engineer with design and manufacturing in my past, I feel the optics is of much better quality than the price would indicate. The red dot is really not a complicated piece of equipment, so it isn't like there are 20 parts in it that could go bad.  The new M3's have a longer battery life ,and I have the same CR2 batteries in the white light that I use, so I will always have spare batteries.  Sure the 10000 hrs of the Aimpoint would be nice and the proven ruggedness of the Aimpoint would be nice too, but I'm not in the Service and I'm not an LEO...so my uses for the optics is less abusive and critical.

Now..to be honest...with my busy work schedule and the kids, I haven't had a chance to go to the range with the PA stuff yet! Ain't that something?  Go ahead and laugh.  But plenty of guys have reported rock solid performance at the range.  

When I got the first one, I mounted it and did the best I could to shock and break it without running over it with my truck.  My own flavor of NDT was to shock it enough times to see if anything shifted (compared to the irons aimed at my back fence post) or if it would fail. I figured my flavor of NDT (although not equivalent to 1000's of rounds fired) was good enough testing for a $90 red dot.  And if it fails, well that's what my irons are for...to make up for the gravy when the gravy is gone!  

Sorry for the LOOOOONG post.  I got bored after disassembling and cleaning one of my lowers

good info tho!