Sig Sauer MCX/MPX

[camracer]

I just picked up this new semi-auto repeater 30 round pellet rifle last week.
This is the .177 MCX version. Sig is releasing these first only in .177 cal. The .22 cal version will not be out for a while yet. They are powered with 90 or 88 gram CO2 right now, but HPA versions will be available next year sometime.

For me, that is too long to wait. But what can you do? ....convert it to HPA!

[camracer]

I made this simple adapter on my lathe:



I did not even try CO2 with the rifle. As a matter of fact, the first thing I did when I got it was to disassemble it.
The first shots I too with it were just around 1300 psi. I found that the opening of the valve was weak at this pressure. The "bolt" (striker/hammer) is actuated with a spring loaded plunger of sorts. Not sure what to call it, but the spring is weak and tuned for CO2. I am changing out the spring for a stronger one today. That should solve the issue.

I have a bunch of photos of the mechanical inner workings, as well as exploded photos of the valve assembly. The valve is very similar to that of the Drozd, but bigger. It will flow very well for HPA application. I'm sure it was designed with that in mind. I see no need to port it for better flow at the moment.

I will post the rest of the photos later, since Photobucket is loading way too slow at the moment. Check back tomorrow.

---Cam

[TBK]

Cool.  Can't wait to see the guts, especially the mag.  When I got the emails from AGD and Pyramyd I went to buy one but read that 22 caliber wasn't available and that a pcp version would come out.  Were you able to use a coupon as well?

TBK

[Parellax]

Awesome! I have been waiting to see one. Thanks for sharing. I can't wait to see where you take it!

[camracer]

Cool.  Can't wait to see the guts, especially the mag.  When I got the emails from AGD and Pyramyd I went to buy one but read that 22 caliber wasn't available and that a pcp version would come out.  Were you able to use a coupon as well?

TBK

Yeah, I wanted the .22 cal, not the .177, but decided to go ahead anyway.
 I can see that the innards won't need to be any different for the .22 cal version other than swapping the barrel and the pellet belt inside the magazine.

I was playing around with the "Bolt" spring assembly. Figured how to disassemble it without destroying it! My thought was to just replace the spring inside with a stronger one for more power to open the valve. Then I had a thought that the "bolt" may not cycle/reset properly If I do. The bolt has to reset itself, like the action on a "blowback" action CO2 pistol. I am trying to understand exactly where the air exits the valve to do that, as there is no hole for air to escape to allow that to happen. I am thinking that air must move around the valve stem to do that, somehow.
Another issue I found was with the bolt striking the valve. It only can move the valve about 10 thousandth's before it will not travel further. .......Hmmmn. That pretty weak! I need to lengthen the bolt's striker and grind away a bit of metal to allow for the bolt to travel further.

I wonder why Sig designed it that way. Most likely to keep fps low to comply with laws like Canada has, I assume.

[camracer]

Here are more photos of the innards:

[camracer]

BTW, I just posted those photos realizing that we DO NOT need Photobucket to do it!!! That is awesome!! You can simply upload a photo straight off your photos files on your computer. Sweet!!

I LOVE this new forum's format.

Oh, BTW, you can load four photos at a time per post.

I have a bunch of photos to upload, so that will save a bit of time!

[camracer]

Set #2

[camracer]

Set #3

[camracer]

Set #4

In the first, second, and third photos you can see a black plastic part that sits behind the "bolt". That is the buffer spring.
It collapses like a telescope when compressed

[camracer]

Set #5

In the rest of the photos I had  the buffer removed.

[camracer]

Set #6

[camracer]

Set #7

Here's the valve assembly taken apart. I am holding the the valve showing the valve's inlet hole:

[camracer]

Set #8

The part in the middle of the last photo is what I will call the "breech plug" for lack of a better description. It moves forward and seals itself against the back of the magazine in contact with the pellet feed belt.

[camracer]

Set #9

First photo is the back of the magazine