Zerodefect says:
How could it get more accurate with a piston bouncing around on the tip of the barrel?
Did you also add a free float forearm at the same time maybe? Or change to a better batch of ammo?
After some thought, and donning my flameproof underoos, I've decided to take a crack at answering this question.
I get asked this one alot by customers and potential customers who are confounded by the fact that my piston uppers outclass their DI setups. Now I am NOT a magician and the only thing up my sleeve is a smelly armpit. What I am is a tinkerer. I have, over the years, had direct user experience with most of the piston drives extent starting with my Dad's M1A that he brought home from Korea.
As a gunsmith one of the biggest parts to my work with the AR platform have been fixing problems caused by user error. Usually those errors are in cleaning/maintenance of their weapons. If you've ever been a gunbunny/cage monkey for a law enforcement agency or company armorer for a military organization you'll get what I mean. After a few trips down this road you start looking for ways to make your life and your customers life easier. This is what started my initial investigation into piston driven AR's and retrofit kits.
The trips been a long one with stops along the way to experiment with most, if not all, of the piston retro kits available. Adams Arms,Ares/Bushmaster,CMMG,Osprey to name the most, IMHO, reliable piston retrofit kits on the market today.
After LOTS of testing, on my own rifles, as well as customer weps, I've narrowed my retrofit choices to three. Adams Arms, Ares/Bushy,and Osprey with Osprey earning top spot for patrol rifles and Ares/Bushmaster earning top spot for SPR rifles that require narrow FF tubes like the ERGO or DD. (The Osprey won't fit under the ERGO for love or money. DD's have to be modded so that they'll fit.) Adams Arms gets my vote for building Suppressor equipped rifles, also SBR's The other two sometimes, not always, have issues with either overgassing or undergassing with all the attendant issues. So, for reliabilities sake, I chose to go with the AA kit for this class of rifle.
No, these are not perfect choices.. they're MY choices... go get/make your own!
If, in the future, someone points out a better product I'll probably use it. If, when,,,, maybe
.
The biggest reason I chose the Ares/Bushmaster and the Osprey Defense retro kits is the big two.. ease of maintenance and user confidence. They work, all the time, everytime and they are easy to clean and maintain. The reason I recommend them for patrol rifles is, believe it or not, officer boredom. If there's a button to push or a knob to turn someone is going to push it or turn it and forget that he/she did. This means that if/when the SHTF the weapon will not be in a ready condition. This is bad... very muchly bad! The nice thing about these two kits is that under normal circumstances the user, that bored guy/gal remember, can't readily get at the working parts of the piston drive in order to muck it up. This is known as a GOOD thing
. (At least to law enforcement administrators)
Ok, so what other benefit besides ease of maintenance does the end user get? How about reduced recoil? Yuppa,, unlike some piston drives these two systems do reduce, not drastically, the felt or subjective recoil noticeably. This is a major plus with smaller/less experienced shooters. It is my very strong belief that anything that increases shooter comfort and confidence is a GOOD thing. I am not into self abuse and most of the folks who I do work for aren't either. So, why make it worse by adding weight and increasing recoil? Seems kinda dumb to me.
If I'm building an SBR shorter than 12.5" I'll use the AA kit. Especially if the end user is going to suppress it. Yes it's heavier... yes recoil is slightly heavier than the other kits..but it IS adjustable and reliable. And, to be honest, most of the end users that get my builds actually go to a gym now and again and actually work at upper body strength so an extra 1.9 lbs isn't a big deal to them. I use Surefire or PWS brake/adapters only...my choice based on experience with them and other brands and not subject to debate.
Now the second part... yes, I always recommend free floating the forearm whenever it's within the POU (philosophy of use) for the weapon.
Patrol rifles have to fit into racks in squad cars and thus have to be uniform in the profiles in order to fit. The solution to freefloating these is simple. Compass Lake Engineering makes a CMP free float tube that "hides" under a normal set of hand guards. For a norminal fee they'll shorten their stock rifle length tube to carbine length and weld on the round carbine forecap and even mod your forearm caps for you. Nice people who are easy to work with.
Special Purpose Weapons,,,, IE, toys for SWATTIES/CERTS,ERTS and so on are generally very very mission specific and require lots of head scratching on the end user and smiths part. Too big a subject to go into here,,,, might start a different thread.