Building a truck gun

[popinsmoke]

I am in the process of building a “truck gun” out of a Olympic Arms lower and a Century International Arms G.I. Surplus upper.
Some of you might a recognize this setup as the “Centurion” Rifle sold by Century Arms many moons ago. If fact that what it is. I purchased the rifle as a pile of parts from a local who thought he was a gunsmith. Normally I would run screaming from some one else hatchet job but this rife has a Honest to goodness G.I. Issue Knights Armament Rail system and 6 position buttstock.
I fired the rifle and it double feeds and jams every other round,
The buffer tube detent broke the upper and lower receivers are loose the accuracy is piss poor.
I am looking to rebuild the rifle and hopefully tighten up the accuracy I am not looking for a tack driver super ninja sniper stealth tactical rifle. Reliability is key it MUST go bang every time.
I have the Marine Corps Rife manual and the AGI video anyone point me in the right direction for a parts kit and what to look for as I am rebuilding the rifle?

[ColdMan]

I would look for a new barrel and bolt for starters. Changing a barrel isn't complicated but does take a few extra tools.

Have you tried different magazines?

What type of Jam every other round?

[dbrowne1]

It sounds like you bought somebody else's problems. And one piece of decent kit (the KAC foreend) is like lipstick on a pig.

You may have an out of spec lower if the fit is loose and the buffer retainer is getting mangled. That's bad news.

[RMTactical]

Well, I hope you bought it for a song because it's gonna take some money, work, and tweaking to get it the way you want.

[popinsmoke]

I bought the rilfe for $100. I have tried about 8 USGI mags that are known to function in my bushy M4.
I figured on a barrel and perhaps a bolt.
Are there any online spec for the lower so i can measure mine and see if it's out of spec?

[Washington,D.C.]

http://www.biggerhammer.net/ar15/cad/ar15_receiver.pdf

[Washington,D.C.]

Good source for parts,


http://www.usarmory.com

[Washington,D.C.]

http://www.ar15.com/content/manuals/lowerBlueprint.pdf#search='ar15%20blueprint'

[Washington,D.C.]

http://www.biggerhammer.net/ar15/cad/ar15_lowerblueprints_unknownorigin.pdf