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3 May 2010, 14:52 #1
Osprey Defense OPS-416 piston retrofit kit
(I posted this review on some other forums starting in early March. I put some more rounds through this set up last week at the range. I humbly offer my review/experience on this unit thus far here for the WEVO members.)
Though the system is designed as a retrofit, I decided to put it in an upper I built from parts I had on hand. The barrel is a Daniel Defense chrome lined 1/7 twist 16" M4 profile (carbine length gas system). I used a YHM clamp on front sight/gas block and the standard end cap, barrel nut, and delta ring set up. I also used the Midwest Industries MCTAR-17P drop in type rail system design specifically for piston systems. The upper receiver is made by DSarms. The bolt, firing pin, firing pin retainer pin, and cam pin are all from Stag Arms. I had an LMT tactical charging handle lying around, so I used that and a Midwest Industries low profile flip up sight to finish the upper build.
The upper is on a Spike's Tactical Lower:
Installing the piston kit itself had some challenges that I imagine get easier once you tackle the job a few times. Like other kits, you must insert a bushing into the upper receiver that the op-rod rides in..to be honest, I used a tool from another manufacturer's piston kit in order to install the bushing:
By far, the hardest part was installing the "groove pin" that secures the "piston chamber" into the front sight base/gas block. As the directions suggest, I used a 5/64 punch to get the job done...but it took a lot hammering. I caused some damage when the punch slipped off of the pin:
Another challenge was installing the "retaining clip" through the left side so that it clips upward as the directions suggest. Cory (Osprey Tech Support Guru) later told me that I could have installed it the other way. In fact, they now have a redesigned clip. However, I was able to install the kit following the directions exactly:
The one piece bolt carrier that comes with the kit requires installation of the bolt, firing pin, cam pin, and firing pin retaining pin:
The Osprey bolt carrier does not have a built up rear section to prevent possible "carrier tilt":
I ran the kit using a standard carbine buffer as Osprey suggests:
RANGE TESTING - FIRST TRY:
On my first trip to the range, the rifle would fire, but the bolt carrier would stop about half way back across the magazine...it was short stroking. I fired several shots with the same result on every pull of the trigger. So I tried my upper on two other lowers. The other lowers both had notched hammers...but the result was the same.
I checked the barrel nut to see if the op-rod was moving freely. I found that the op-rod was rubbing slightly. I thought I had found the problem, so I disassembled the upper, and re-aligned the barrel nut so that the op-rod moved without any rub.
Back at the firing line...I had the same short stroking problem.
It was back to the shop...
ENTER CORY THE OSPREY TECH SUPPORT GURU:
I called Osprey and spoke to Cory. Cory was pleasant to deal with and eager to fix my problem. He looked up the date that I had purchased my order of kits, and found that it was prior to a slight design change they had made in the piston itself. He told me he would send off a new piston for each of the kits I had in-stock. They arrived inside of a week...unfortunately, so did record breaking snow falls.
I replaced the piston...but another range visit had to wait a few weeks...
RANGE TESTING - SECOND TRY:
I loaded a mag with just six rounds. I had inspected the new piston, and could not see any real difference between the old piston it replaced. So I did not expect improved performance. However, I pulled the trigger the first time and the weapon cycled without a failure. A second trigger pull...a second no-malfunction cycle. I finished the six rounds with no malfunctions.
I loaded up three more 30 round mags and decided to let it rip. I fired all three mags as fast as I could pull the trigger (semi-auto) and reloaded. 90 rounds later I still had ZERO malfunctions. I guess I should be more of an optimist, because that was all the ammo I brought that day. Like I said, I wasn't really expecting the unit to work for me.
I realize 96 rounds is not a real performance test, but I was feeling pretty good about the unit at that point. Once back at home, I took this picture of the inside of the top rail where the gas exhausts:
On my next trip to the range I had an opportunity to put another 240 rounds through my test weapon. The rounds were fired in the following manner. The first 120 were in four 30 round magazines fired as quickly as I could pull the trigger and reload. I then reloaded the four magazines and fired three of the magazines (90 rounds) in the same manner. I then had about a 10 minute brake while a buddy of mine took the rifle and finished off the final 30 rounds. He fired his 30 rounds more slowly than I had, but at about a shot-a-second cadence.
The rifle had zero malfunctions. Examination of the YHM bolt on front sight/gas block showed no evidence of any movement (yet?). So at this point I had 336 rounds through the system.
Here's a photo of the piston afterthis day's range session:
Inside of upper rail:
The BCG had the slightest evidence of wear:
I could see no real evidence of buffer tube damage from any carrier tilt:
With a visit to the range last week, I've got 570 malfunction free rounds down range. The bolt on gas block/front sight is still holding in place well too. I'll get some updated photos ASAP showing any additional carbon build up.
This piston system, like others, has slightly more felt recoil than a DI carbine, but it feels much lighter than other piston systems I own...thought that isn't a very sientific conclusion.
I'm not completely sold on this piston system just yet. I like that it does not use any springs (that wear out) and seems to have a more simple design. However, the fact that very few rail systems (thus far) work with the OPS-416 hurt its marketability.
5 October 2010, 13:22 #2
Sorry I haven't put an update on this yet...
So far, I have just shy of 1000 rounds through this test rifle without malfunction. I haven't cleaned or lubed anything either.
That said I'm still not completely sold on this system yet. The rounds I have through the rifle are what I would call "easy" rounds: Shot a few hundred at a time on nice weather days with no real stresses on the weapon. I'd like to see how it would survive an intensive carbine class, but I'm not sure that I'll have an opportunity to put it through one.
Though I used a bolt on gas block set up, I would not recommend using this system with anything other than a pinned gas block/FSB. A serious blow to the side of the gas block could move the entire system out of alignment and render it inoperable. Just the slightest misalignment would make the system malfunction.
Freedom of movement of the piston rod is the biggest concern in the system. A canted gas block/FSB or rubbing on the barrel nut will prevent full movement of the piston rod causing short strokes.
On the plus side, the OPS 416 adds very little weight so it would work well on a light-weight build. As I mentioned before, the lack of springs means less parts to worry about wearing out. I guess another plus is that the installation of the OPS 416 is completely reversible. So if you donít love it, you can go back to your DI system.
Osprey Defense has a new Nickel Boron coated version out that should make everything run smoother and make cleaning easier.
Some quick pics at 996 rounds:
The inside of the upper rail where the gas vents...
5 October 2010, 13:28 #3
19 October 2011, 20:51 #4
Im gonna be that Necropost guy.
Looking at putting together a 11.5" SBR with a piston kit.
Shooting mostly suppressed.
I was hoping to use a 11" troy text rail I had, but all the piston kits either have huge gas blocks that prevent anything longer than carbine handguards.
or this ops 416 which needs a huge rail. If I go with this kit, a Spikes BAR is on the agenda.
how has this kit been for you?
20 October 2011, 05:50 #5
20 October 2011, 08:35 #6
I'll hit you off-line with a related topic that might help you out though.
27 October 2011, 07:07 #7
Please keep us posted.