LPK, is there really much of a difference?

[Smith5361]

Curious because I just saw that PSA has a LPK for pretty cheap from P-Tac. Ive heard people say the best was colt, but does it really matter that much? What can the difference be, Tolerances?

[LRRPF52]

There are some pretty significant differences, though most users would never notice.

A lot of your lower parts are Metal Injection Moldings. The true Mil-spec calls for batch-tested magnetic particle inspection on several critical parts, like the hammer/trigger, and bolt catch.

I've seen bolt catches break from suppressor use. The increased cyclic rate is very hard on the bolt catch when your run to bolt lock.

Detents also are not the same as the Mil-spec, which calls for cadmium-plated detents. Civilian look-alike parts use cheap zinc-plated detents, which will corrode something horrible in humid environments. I have witnessed it personally when my Magpul 1st Gen MIAD grip fell to pieces in -27 C, high humidity weather. When I went to replace the grip with a spare, my selector detent looked like a corrosion party was in full-swing, where you could literally watch the chemical reaction happening in real time.

The Colt and other high-end parts will have inspection stamps and proofs on the trigger, hammer, bolt catch, safety/selector, and magazine catch. With most parts though, there is no way of knowing the chain of custody and what processes they went through. Are they made b Elisco Tool? Are they made in Taiwan?

That's the issue you run into with no-name or economy branded parts. It might not be a big deal for most people, but if you plan on any of the following, I would suggest being prejudiced about what LPK's you use:

* Shooting suppressed
* Competition
* High-volume
* Humid environments
* Extreme cold environments
* High priced hunting events

[keystone183]

SO, the question is...is it worth it to buy a Colt kit (this one http://www.brownells.com/rifle-parts...acturer_1=COLT) when a palmetto or other is much cheaper for a whole LPK? Putting together the components for a top notch build to include a lilja barrel, and want to know. Would fit/finish be worth the extra cash, as i suspect my rifle will never see salt air, or sub zero temps?

[LRRPF52]

If you are using a high-end trigger like a Geissele, you can't go wrong with those Colt lower parts, but I haven't seen any issues with pivot and take-down pins, for example.

To be honest, I have used the DPMS LPK- kits, where there are no fire control parts, then I add a Geissele, JP, or tuned RRA 2-stage.

You can add grease to the detents, but I would want a tested bolt catch if the gun is going to be used suppressed.

The thinking behind getting the Colt parts in lieu with the Lilja barrel makes sense, although you can get some of the DD or Stag LPK's for that same price. I don't know what QC Stag or DD goes through, but they seem to be regarded better than DPMS. Based on your stated uses, I doubt you'll ever notice the difference, as long as you install a good trigger.

[keystone183]

It feels good to say I have a colt kit in her....just don't know how much extra that is worth. The only two lpk's i have experience with are palmetto, and cmmg. Two of each, and although a small sample, the cmmg's, i thought, both produced a tighter fit/better finish. So, i suppose i'll have to dive into the money bin and see how many nickles i want to part with.....

[LRRPF52]

I've hears good things about:

* DD
* Spike's
* LMT
* CMT
* CMMG

I suspect that at least several of the above manufacturers source their LPK's from the same sources, as most big name companies do not have MIM capacity in-house. Bill A. would be a good one to ask about this.

[keystone183]

I suspect that at least several of the above manufacturers source their LPK's from the same sources, as most big name companies do not have MIM capacity in-house. Bill A. would be a good one to ask about this.

^^This. In my readings, it seems most parts are the same, just in a different package. But i haven't found to much reliable as to where/who from, and which particular ones would be best. So, i suspect i'll just bite the bullet and spring for the colt....

[cory]

I've personally installed the following lpks.

RRA
Spikes
JP
Palmetto

I've put them in the order that I feel they fell in quality.

I intend to buy a lpk from Prescision Firearms for my my 16" Lilja build. Once I can get my hands on a spikes billet lower receiver for a decent price.

[jurassic]

I agree, RRA makes good stuff. One of the things I've noticed is the use of roll pins instead of spring pins with the DPMS and cheaper LPK's. RRA lPK's come with them, most don't.

I've personally installed the following lpks.

RRA
Spikes
JP
Palmetto

I've put them in the order that I feel they fell in quality.

I intend to buy a lpk from Prescision Firearms for my my 16" Lilja build. Once I can get my hands on a spikes billet lower receiver for a decent price.