Hi guys,

I recently purchased a used PWS MK114 upper with less than 500 rounds. I've shot them before from a couple of friends who owns them but I wasn't as attentive shooting theirs as I was when I was shooting mine. Today at the range I came across two interesting issues or it's probably nothing but I want to make sure.

So you know my setup, it's a PWS MK114 upper on a Aero lower with CMMG lpk and a VLtor mil spec buffer tube. I have different types and weights of buffer and buffer springs and I've tried all of them but still got the same results. I tried different ammo as well, the ones I was using were American Eagle red box, XM193, Tula, UltraMax, Black Hills and Winchester  my casings were flying off towards the 1 - 3 o'clock. First I had a sprinco red buffer spring with a ST2 and the Tula landed 2 inches from the gun, the Ultramax and American Eagle went 1 o'clock, Black Hills and Winchester went at 3, the 193 went towards 1. I found it strange that none went towards 5 or even 4. I changed the buffer towards a standard weight mil spec buffer and had a more consistent 3 on the mayoralty  but nothing behind that. I then later changed to a standard spring and ST2 and everything  went 1 except a few Tula that went towards 5. This caught my eye but I guess it was just those two the rest went towards 1. I changed the buffer to a standard weight and shot 3 xm193 and stopped because it felt like a hammer was hitting my shoulder also went towards 1. By this time I thought maybe it was me and my shooting stance so I gave the rifle to a friend of mine and again changed the spring to a Sprinco blue and ST2. I started to see more of a 3 o'clock on the mayoralty of the ammo except Tula which went towards 1 o'clock and left it at that because I thought I was never going to hit a 5.

Yes I know what y'all are thinking and gonna say "did you check the gas adjustment screw and made sure it was on O". The answer is yes, the position on it was always on O. It was the first thing I thought was the problam. After I shot all those rounds (5 rounds of each brand on each setting) I saw something interesting on the rifle and on my hand. My left hand had a black smokey spot on it, I found it wierd and checked the area I was holding the rifle. I found out there was carbon build up on a few places on the gas block. First was on the adjustment screw and also on the piston tube matting with the gas block. The tube didn't seemed to be properly seated on the block. I had a good 1/16 of space between them. I don't know if the tube needs to be fully seated or if this is normal. On the adjustment screw, the carbon was mostly leaking towards the top. I have Ergo rail panels on the top rails and saw deformed marks on that area.

I don't know if I'm putting too much thought into this or if this is a problem I should look into. I just find it strange this is happening to my upper. All my DI uppers throw the casings from 4-5. I've never had one do a 3 on me. So I find it hard to believe a piston would do this. I'm not saying PWS doesn't work or anything. I've shot a few of them before, it's just I've never noticed this on any of them.

Can anyone help me on what should I do or at least tell me if all this is okay.

Thanks

When the gas drives the piston back to operate the bolt and it compresses the spring the gas has to be released so the bolt can return forward and back to the chamber. That is accomplished by relief holes in the gas tube and thus when it vents it can get on your fingers.
It does this to mine and yes when it first happened i too wondered WTF but it is supposed to do that

I have a PWS Mk110 that I run suppressed pretty much all the time. I have the gas setting on #4 (OOOO) because I shoot full power NATO 5.56 loads. I get ejection that is 1-2 o'clock and only a foot at best constantly. I'm running the "Red" Sprinco recoil spring and an H3 buffer. I'm changed to lighter springs and buffer combos and it's still 1-2 o'clock ejection pattern. Haven't had any issues and has been 100% reliable.

I know it has to come out of the vent hole but I had carbon build up on the gas block to tube joint. Just like a DI gas block, sometimes the gas tube is a bit loose in the gas block and you get a little fouling where the tube sits in the block


Now on my PWS I get the same thing but more. Also the tube is not fully seated.

You don't see the build up now because I cleaned it before I took the pics. I always clean my guns after a range day. I should have left the carbon on and taken the pics but "Oh well". It also had build up up top where the the adjustment screw mates with the block, I also cleaned there before the pics.

Here's some carbon on the rail covers I haven't cleaned. Third rail from the top

Both my Mod 0 and Mod 1 MK114s eject between 1-2:00.

BG, if you feel that is more than normal send those pix to PWS CS and get an opinion from the horses mouth

duplicate.

you' ll get 3 to 3:30 shell ejection with the correct spring and a PWS H4 buffer ,   anybody who gets  1 to 2 ejection does not have there rifle correctly set up .

I've tried every combo you can imagine (suppressed and unsuppressed) and it's still the same. PWS states that their H4 buffer is for dedicated suppressor use only, so I use the H3 so that I can use my PWS unsuppressed if I want to.

So what would be the best spring combo with an H3 buffer?

With my Mk110, I've used both the Red and Blue Sprinco springs with success. If you're not shooting suppressed and plan on using a mixture for crappy and good ammo I'd go with the Blue. Personally, I only use NATO power ammo (mainly M193 55gr) and use gas setting #2 for unsuppressed and #4 for suppressed use. Since your barrel is 14.75" rather than 10.75" like mine, you may experience different results since the back pressure is different (less) on the Mk114. If the Blue spring doesn't allow for 100% function when shooting the ammo you want to use, then I would go with the standard carbine recoil spring (White from Sprinco). If you still have problems then switch to an H2 weight buffer. If you are shooting NATO 5.56, you should NOT be having to use gas setting #1 (wide open) for proper function.

BTW....I've tried every crappy ammo brand you can imagine through my PWS (Tula, Wolf, etc) and there was only one that would not function 100%...ZQI. It's made in Turkey and sold at Walmart and is complete shit. Stay away from it. Everything else is good to go.

I just got back from the range and I did some testing with the spring/buffer combo. I shot 5 rounds of each brand (american eagle red box, tula, xm193, ultramax and remington) with each spring and buffer mix.
Sprinco red w/h2
Sprinco red w/st2
Sprinco red w/std

Sprinco blue w/h2
......
You get the idea. Out of all the combos I would say I had a slight tie with sprinco blue/st2 and sprinco red w/st2. Both through brass at a consistent angle from 2-3 o'clock and both performed smoothly. But I would have to give the win to sprinco blue w/st2. Why you say, because this combo through everything i bit further back than with the red spring. Third place would have to go to sprinco red w/h2. Standard mil spec with all 3 buffers sucked big time. Nothing went close to 2 o'clock and the standard weight buffer with all the springs also did poorly.

I also kept having the same gas leak at the gas block. This time I took pics before cleaning it.





Remember guys this gas is not coming from the vent hole, it's coming from the gas block. Is this normal? Does anyone else experience this?

Mine does vent gas at the gas block/valve, but I'm not sure it's that much. Send those pics to Stacey @ PWS and see what he says. [email protected].  

I did, this is what they wrote back.