I bought a Bushmaster for a good working example, and now I'm building a couple more ARs.

This one I'm working on now is going to be a mixed breed, mostly Rock-A-Lite, but I try to match some parts in logical ways.  E.G. bolt and carrier from same manuf., yet I'm not sure there's a NEED to do that.  Opinions?

What are your favorite combinations -- best match, worst pairing?  What's been your best frankenrifle?  What didn't work?

Although I know it'll be terrific functionally, I think I've been brainwashed into thinking purebreeds are better somehow.  Is this the fault of reading too many postings by the Colt true-believers?

How many of you can't remember who's parts you've got it what gun?

Wouldn't it be great if we could build our autos this way?hacko.gif

I've really only truely built one Rifle. And it is somewhat of a Frankengun. The project was to build a rifle as light as I could, without compromising on quality/reliability, as cheaply as I could. Most of the items were bought used from the E.E. The result has been great. It contains the following;

Lower;
Preban Oly lower. I have no clue who made the stock, but the buffer and buffer spring are Rock River. The safety and trigger are Bushmaster. The Disconnector is Oly. The ttigger is Colt. All other lower parts came in the gun, so I presume are Oly.

The Upper;
The upper is a Colt contracted M16A1 upper. The complete Bolt and Carrier assembly are Colt. The charging handle is Colt. The barrel is a 16" Colt lightweight. The handguard is a carbon fiber freefloat tube from Hyperform.

There's some other accessories here and there but they dont much matter, like the Reflex site, Surefire light or GG&G light mount. As you can see, the lower is all over the place, but I tried to stick with Colt for the Upper. Bushmaster would have suited me just fine, but when I got it, I couldnt get a Bushmaster lightweight barrel, and I wanted the Colt carrier because it is machined more and is lighter. I didnt get any off brand parts at all and wanted to stick with what I believe were quality manufacturers.

When I first built it, I was having trouble with the rifle doubling. The disconnector was worn and Oly replaced it. After that, the result has been very, very good. It's been through 2 classes and and several FDCC courses, and has never had a malfunction. On top of that, minus the Reflex and Surefire, I built the base gun for a total of $1100.

This is my only experience, but I think if you stick with good parts, you can mix a lot of the lower stuff. I was more concerned with keeping the upper half pure, especially the Bolt and Barrel. Give it a try. I had a lot of fun.

Ellery, great question! Although I can't even remember how many I have built there is a frankengun that sticks in my mind. Usually sticking with Rock River and DPMS components I did the "I am going to clean up all these loose parts" speech to my wife and decided to build from whatever was closest including new and used. I went with a Les Baer lower, a Rock River upper (A4), Wilson 20" varmint, used bolt carrier, new bolt, And our custom red handguards (free float) aluminum.
Went with a Rock River two stage trigger. I put a variable 6-24 power blazer scope (low end) that has target turret knobs 1/4 moa.
This was a rush, slam together job and the damn thing shot under 1" at 100 yards. It actually matched well with the color and went together without problems.
Worst problems I have ever had???/ Has to be assembling a stainless DPMS lower to a RRA upper
Did 2 of them with the same problems, alignment to pivot take down was incredibly tight (Too tight) and the lugs were almost at interference. I had binding when I charged a round, nightmare!!!!
Robert

My favorite mongrel is as follows:

Bushmaster lower with JP enterprises trigger

American Spirit Arms Flat top upper, Dpms Carry handle. Armalite green Furniture.

Oly arms Stainless 20" With Armalite Stainless Weaver gas block. Armalite removable front site.

Bushmaster Bolt Carrier With Smith Enterprise Hard Chrome Cam pin

The last three were Rock river lowers and Bushy uppers.The fit often requires the use of the swiss pattern file on the rear takedown extension of the bushy upper.
This makes 'em TIGHT!

All three used bushy barrels 1 std. 20" and the other two were M4 profile civillian legal jobs.

Fire controlls were 1 rock river std.1Rock river match,and 1 Accuracy speaks.
Rock river makes a great trigger and fire control setup.Accuracy speaks is my second "Go To".

I like Bushy for it's consistent quality and dimensions.

I really want to get my paws on some Cav arms components and give them a shot on a lightweight project,but time is short these days.

Good luck!
S-28

Another one of my favorite mongrels:
Post Colt lower with Fulton Armory internals.

USGI A-2 furniture

Bushmaster A-2 upper with Bushmaster Dissapator barrel and Armalite front sight.

Rock river arms bolt carrier and DPMS charging handle.

my current M4 project is a frankenrifle:

DPMS 14.5" chrome lined
Century stripped lower
Colt fire control parts
Bushmaster bolt carrier group
no name numbered flattop upper
Cav arms M4 furniture set
DPMS charging handle
Bushmaster detachable handle

My Franken-4 was for my wife:

RRA Lower
DPMS lower parts kit
FN A4 upper, Wilson M4 14.5" chrome-moly barrel
Wilson A2 muzzle break (now 16" barrel)
DPMS bolt/carrier
Cav-Arms pink CAR furniture
Cheap Blazer Red-dot.


She loves it, and it works great. I did have to polish the chamber to get it to extract reliably.

The whole thing came in at around $600 - maybe less.

Mostly Bushmaster lowers with one PWA lower, all with Bushmaster trigger group.  Colt upper with Colt barrel, Bushmaster upper with Colt barrel, Bushmaster upper with Georgia precision barrel, bushmaster upper with bushmaster barrels, front sight gas block, or bushmaster front post. all Bushmaster bolt group and charging handle.

I don't have one single pure breed, and all my guns work flewlessly.

Hey all!

I don't have a "purebred" rifle in my stable, either... although they're all built using BM stripped lowers.

1) Colt 9mm postban upper assy, BM lower with Model 1 "generic" .223 guts (hammer modified for 9mm), Wolff Xtra power buffer spring, JRW mag blocks pinned in place, converted UZI mags. Runs great!

2) Model 1 flat-top upper & bolt assy, BM lower, BM 14.5" M4 barrel + KKF A3TB, DPMS 4-rail float tube and stand-alone A2 rear sight, RRA ribbed tele-style stock, RRA match trigger kit. A real mutt, and my favorite!

3) RRA M4 flat top upper assy, match trigger and ribbed tele-style stock, BM lower, Colt M4 HGs, Cav Comp, Hogue pistol grip, unknown detach carry handle w/ Alcoa forge mark. Had to do some work on this one; barrel index pin was loose, barrel nut was under-torqued. Haven't shot it yet to test the fix.

4) Model 1 20" stainless bull upper assy, BM lower, RRA match trigger, USGI A2 stock and pistol grip with "Clip Grip" attached. Tack driver!