Most reliable = SP1 or modern retro build??

Assume the retro build was done properly & not by a drunken angry monkey, but which SHOULD be the more reliable AR = a probably 30+yr old Colt SP1 or a modern retro A1 build using mostly OEM parts??

Thanks, Bill

Unless the SP1 has a bazillion rounds through it, they should be equally reliable. Especially with mostly OEM parts in the modern retro.

Agreed

Totally depends on the build and parts used. I've seen Frankenguns that run like a bat out of hell and new factory guns that just jammed all the time.

Agreed with BOTH above ^^^

Good thing about an AR is you can tune it. Bad thing about an AR (if your not familiar with them) is you can "un-tune it".

If you use true Milspec M16 barrels, & BCG's, you're well on the way to an extremely reliable gun.

The gas port will be cut to the right diameter, the barrel steel and chrome-lining will be to some of the highest industry standards.

The bolt will be MPI/HPT Carpenter 158 steel, and the carrier key will have been sealed with a high-temp aviation-grade gasket before the key and fasteners are attached to the right torque spec, then tool-sstaked, not peened.

For a rifle build, it's pretty hard to screw up the BCG, gas system, and recoil system if you use surplust parts that didn't see a lot of use.

If they did see use, a simple armorer-level maintenance of the ejector spring, extractor, and extractor spring will put the bolt assembly back into order, unless the bolt has cracks or pitting.

I've used surplus bolts and BCG's in modern builds, and I have yet to have a malf in any of those carbines so far. I don't shoot any less than 300rds per range session with my 5.56 carbines either.

My factory bushy m4 jambs, my home built 7" piston sbr runs like a top
No logic to it

Bushmaster is notorious for not assembling BCG's in the manner I described above. They actually have great barrels, being 4150 CMV chrome-lined with 5.56 chambers, but the BCG's, gas port diamters, carrier weight & buffer all conspire to make a jam-o-matic often. There have also been questions raised about the ejector and extractor spring sources, which Colt has spent years on refining in the early 1960's, and upgrades being adopted for the Carbines in this area (springs).

A 16" barrel with a carbine-length gas system is a lot of dwell time to put on a 5.56 blaster, especially after lightening the bolt carrier, and using a 2.9oz buffer. That is a recipe for a faster cyclic rate if there ever was one, and resulting reliability issues with FTFeed, FTE, Double Feed, etc.

Tame the Bushy down if it's a 16" by using a heavier buffer, and M16 carrier, with properly-attached carrier key. Use brass-cased ammo, good lube like Slip2000.

Thanks. I was just a little leery of the SP1 due to the age,

Sure there is. Your 7" piston SBR was hand built by some one that gives a damn, and your M4 is a factory built Bushmaster.

I've got several 20" rifles built with Bushy barrels, and they all work great. Its one of the few parts that I liked to source from them because they were the best "bang for my buck" when I wanted chrome lined 20" A2/Gov't profile barrels with 1x9 twist. I did buy a complete rifle from them. It worked great, but it was a 20" A4, so it didn't suffer from the many carbine related problems you mention, and I took it down pretty far and rebuilt including re-staking the gas key.

The brass cased ammo is important, at least for 20" rifles. I've had a few (2-3) "Bolt over Base" malfunctions where the gun didn't pick up a new round, and a few (2-3) times it failed to lock open on the last round, using some rather lightly loaded (but still brass cased) .223 spec match ammo. Using steel cased ammo in my 20" rifles, I fired 15 rounds from a box of 20, and I had 14 short-strokes and a stove pipe. I left the other 5 in the box on the bench for anybody who wanted to waste their time with them...Haven't tried it in a carbine, so, hey, it might work...But I'll pass.

I usually shoot the Prvi Partizan M193, or the Federal M193 or XM193 or XM193F or anything with the magic number "193" in it, and all of my guns run 100% on that.

As for lube, I've used wheel bearing grease, surplus LSA, Hoppes brand gun oil, Rem Oil, CLP, Tetra gun oil, and PL-S. I like the grease and the LSA best becuase they don't fly around too much. All of the other stuff worked, but seemed to want to go everywhere rather than staying put. Just make sure you use enough of whatever you use, and apply it in the right spots.

I would say unless you know all about the parts used, the builders skill and maybe are allowed a test fire, choose the sp1.

Oh snap!

My first two AR15's that I purchased were 11.5" pre-ban Bushmasters back in the early and late 1990's. I was used to the Colt AR15A2 Sporter from the late 1980's and my issue M16's/M4's, and as far as I knew back then, there weren't many differences.

Boy was I wrong.

That said, my two 11.5" guns ran like champs, and I don't recall a single malf with either of them. I sold them both during the ban for more than I paid for them new.

During the ban, and after, I saw a lot of Bushmaster "M4's" that had loose bolt carrier keys. They would run for a few hundred rounds, then all of a sudden, short-stroke, short-stroke, FTFeed, FTE.

Most assemblers don't know and don't seem to care that the way to secure a gas ket to the carrier is to degrease it bone-dry, roughen up the surface interface of the carrier and key, use aviation-grade Form-a-seal compound to make a permanent gasket, torque the US-made fasteners down to 35-40 inch-pounds, then stake them with a compression, not peening method.

Fail-Zero is one of the few companies that does the above steps on their Nickel Boron BCG's, and they run like champs.

BCM BCG's also run like champs. A lot of the manufacturers are getting on-board with this critical area, while others don't seem to care. It's why I will nevr buy a complete blaster off the shelf again, unless it's a collector's piece, like an SP-1 or something rare.

This is why I buy Colt BCG's almost exclusively. Not a Kool-aid drinker, just like quality. The barrel to BCG relationship is the single most critical issue if you ask me. You get that right, you are there. I buy Colt parts whenever possible - have a 6933 upper I was going to tear apart to make a a733 - but even though it's a Colt receiver I'm having a hard time with tearing apart a nice Colt upper that is known to be reliable. BM bolts aren't MP checked either IIRC. I do like Bushy barrels - they seem to do that well.

+1

Thanks for all the imfo on this. That's exactly how the rifle runs.
Ive never paid attention to the carrier , I always assumed it was
Crap ammo.

All of the above replies covered the details pretty well in terms of component quality.

Beyond those elements, I'd like to boil it down to the "other" basics:

Proper gas pressure

Lots of lube

Good ammo

Good mags


In my experience those 4 things are the main reasons an AR won't run.

And I've personally seen 100's of malfunctions with Colt and other military M16's on Army ranges.

If NDS made BCG's I'd buy one in a heartbeat. Everything I've seen from them is as good as Colt or better quality -wise. This is why I only use NDS lower receivers.

Any quality AR that is lubed properly and using quality ammo will be perfectly reliable.

Issues arise when the rifle is bone dry, mags are going bad or you have bad ammo. For example, wolf tends to be under powered and can cause issues in some rifles. It is also dirtier than german scat porn.

Dude

A buddy of mine shot at least 1000, maybe more rounds of wolf before cleaning his bushmaster. His bushmaster had reliability problems before I convinced him that he should run it wet. It now runs fine.

Anyway, I never knew a firearm could get that dirty. I thought he'd need to use a chisel to get that crap off.

VHAT IST GOING ON HEARRR?!


But yes, Wolf is dirty crap. It's an inferior communist product. You get what you pay for.

Learned that one the hard way, couple-three times: Never, never, never, EVER! tear down a truely reliable rifle to build something else with it. A rifle that always runs 100% is one of life's true joys and a gift from God, regardless of configuration.

As to the Bushy barrels, yup, in the pre-Brick days, had 45Bravo cut down a lightweight 16" Bushy and attach one of his modified Bushy extended flash hiders for a XM177E2-forgery. It ain't as right as a Brick faux moderator would be, but it's also a lot more accurate than it ought to be and I'm not messing with it. It's a 1:9 twist and conventional wisdom says those won't shoot 77-grain bullets. But, this one doesn't know that and seems to work just fine.

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