Being my 2nd post, going in head first again. I've built a couple more than a dozen AR-pattern rifles/pistols of all kinds at this point, but only recently considered trying a piston-driven build, and not for any practical reason other than I'd like to test it myself and see how I feel about it. I like the added benefits of course, but mainly for the helluvit. Not too sure it makes a lick of difference, but it's gonna be a retro-fit to an existing build, not a ground-up build.

This is the system I'm looking at is this;
https://suparms.com/collections/retrofit-piston-kits/products/copy-of-750-adjustable-piston-system-carbine-length-solid-melonited-low-pro-ar15

Over my first choice of AA's systems only because 5 adjustable settings vs. 30 settings was an easy choice. My concerns are fitment under my handguard, which I've got the specs for both, and the numbers run close, with a mere 0.085" of clearance. Is this too close, or will it just be a real close fit?

Also, any pitfalls, common issues, or things I should look out for or know ahead of time before I start this undertaking? I'm excited and very anxious to get this started, but a little hesitant due to a lack of experience. I understand how it works and the difference between long and short stroke piston systems, but what I know helps me very little on this project. Please advise, anything you'd think I should know would be greatly appreciated. Thanks again everyone, y'all are the best

I have that kit on a 12" Larue barrel. Works great. Rail is Geissele MK8. I keep my screw in interference mode rather than bleed off. Some minor pros and cons each way but equally effective from a functional perspective.

-Stooxie

I'm using the SA piston kit with a Strike Industries Strike Rail.  Fits great, goes on and off easy for cleaning.  If you've built other AR's you won't have any problems using a Piston System.  Follow SA directions for tuning your cycle.  Takes a little time and ammo.  Your SA bolt will be clean because all of the dirty gas will be at the piston block.  I pop my rail off ( one pinch bolt) and clean her up after a few hundred rounds.

https://www.strikeindustries.com/shop/products/ar/strike-rail.html

I have two piston rifle brands, LMT and a PWS

The systems are great, I really like them.  You will read people saying this is not the original design, don't go with a piston. But I have to say this platform is really nice.

The LMT and PWS are two different designs, one a short stroke LMT and long stroke PWS.

As far as shooting, and my the LMT gods forgive me, but I am leaning towards the PWS for feel and overall shoot ability, for lack of adjectives to explain.

I am considering SBRing my LMT, as it is a MRP upper that makes barrel swap easy.

One thing to add, the LMTs and PWS are set up to shoot suppressed, the PWS with adjustable gas block makes a big difference.  Also, shooting suppressed, the PWS stays cleaner, don't know why....after 200 rounds suppressed, the PWS BCG looks new.   The LMTs will need cleaning

But in terms of overall long term reliability and durability, IMO, the LMT will win

77

I don't think either or will outlast each other...I think both are built rock solid...cant go wrong with LMT nor PWS...both have great reputations...

Thanks everyone for all your hands-on experience and thoughts, all exactly what I was looking for. I still do have a few things rolling around the head though.

I've no clue what those terms refer to, other than obviously a setting on the gas block. I pretty much got the rest figured out, as to date I've built 17 AR's from the ground up, and a handful of mods to existing guns for friends, and all in less than 2yrs. I've more or less dedicated ALL my spare time to the AR platform, learning all that I can, so though my years of experience are nothing compared to a lot of y'all here, I can at the least say I know my way around an AR15 better and more intricately than the city I live in, LoL.

Here's my biggest thing, short stroke vs. Long stroke. Although I haven't found a reteo-fit kit in long-stroke, only short, any idea as to why this is? From the research I've done in to the 2 systems, I agree with your conclusion, and am leaning towards the long-stroke system. As they both have their particular sets of pros and cons, guess it really boils down to personal preference.

If anyone knows of a reteo-fit long-stroke kit available, please LMK who and where, I do appreciate it.

As far as handguards, THIS is the part that about drove me mad. If the dimensions of the corresponding gas block are less than those of the internal diameter of the handguard, would it work fine, or should there a certain amount of clearance between the two? Check this link and you'll see why I ask...

Proposed Piston System and Handguard Combo

I would just get a factory piston upper.

That's you though, and that route is too simple and costly for me. I'm more hands on, learn the hard-way kind of guy. Besides, there isn't much gratification buying a complete upper. Also factory choices are getting better, but still lack some things I would like in an AR.

But if the piston system has clearance, even very minimal, would it be alright, even if the clearance is only 0.085"?

Thanks again everyone for your help and responses, I greatly appreciate it

I have two rifles setup with that Superlative Arms kits. They both are installed on Mega Arms MKM AR15 uppers. Clearance is pretty tight but they work perfectly fine. As long as the op rod is not interfered with, I don’t see an issue with having minimal clearance between it and the hand guard. You just want to make sure you can insert the Allen wrench into the adjustment screw so you can set it up or tweak it as needed. For me that means I have to remove my suppressor. If you want I can post some pictures.

I’m thinking of doing the sup arms piston kit on my ar pistol.  They say that some modifications may need to be made to the barrel nut to fit the piston.  Just a simple file down I suspect

The biggest problem with clearance will be the same as a DI system, accuracy while load bearing the rail. If you shoot off barricades, for instance, you can flex the rail slightly, contact your gas block, and thus slightly flex your barrel. I've tested this out to 100yds while intentionally flexing barrels off barricades for my own education. Mixed results, barrel profile and length plays a role, but inside a rail (rail rigidity will also play a role) I would tell you I'm not worried about missing man sized targets at 100 because of minimum clearance with the possiblity of contact with load bearing.  

The way the SA piston is housed, even if you contact your gas block, it won't interfere with the action of the op rod. At worst, you're no longer free floated. That's pretty much it I'd say.

I say go for it.