Inside the Mrod CP-1M

April 14 2017 at 6:49 PM

cobalt  (Login cobalt327)

I received my CP-1M last week. I went with .177 cal. First thing was to clean the barrel. It was fouled with a dark greasy deposit that looked a lot like moly grease. Not heavy but there, nonetheless. After cleaning the barrel and giving it a once-over, I shot it over the chronograph w/a fresh cartridge, 5 shots were made to equalize the cartridge before recording the MV:

10 SHOTS, CPHP 7.9gr 75°F
HIGH 481
LOW 457
AVG. 473 fps / 3.93 foot-pounds
ES 24
SD 6

The MV is maybe a little low compared to other guns w/o any power mods, but I’d say it was within manufacturing tolerances.

I used a few more shots to sight it in. After sighting it in, I used the rest of the cartridge plinking. The targets set up in my BY range from 10 to 30 yards. I didn’t shoot any targets for record but the accuracy seems pretty good.

For me the grips are awful. There’s plenty of wood there should I decide to rework them but hopefully someone will be making replacements, or possibly I can find one of the early grips to buy (Mrod doesn't have any). Also hoping a carbine stock will become available, like was mentioned when Mrod released their CP-1M.

Speaking of replacement/modification parts, I was hopeful this gun would catch on enough so that aftermarket parts would be made for it. But I’m thinking that if it hasn’t happened by now the chances aren’t very good. Now I'm wondering if anything will be coming down the pike from Mrod. I need to buy a couple spares of each O-ring to have on hand before I take the gun down again to do some modifications. I am going to email Mrod to order them, I’ll report back with the outcome.

So after shooting the first CO2 cartridge, I took grip back off and removed the trigger and sear for some attention. This is one very simple trigger. And it comes with a lot of gritty pretravel along w/a ton of overtravel. I adjusted the sear to get rid of as much pretravel as I could, while keeping the gun safe. BTW, I have seen where some people have adjusted the trigger set screw to have the set screw bear against the sear instead of the trigger cross pin. After trying it both ways, the photo below shows how I adjust the pretravel screw so it rides against the cross pin behind the trigger- not against the sear. Besides making the pretravel shorter, this also causes the trigger to move rearward in the trigger guard- which gives more room inside the too-small trigger guard.

[linked image]

The as-machined sear is rough from the wire EDM process (or whatever is used), and to a lesser extent the same for the contact area of the trigger. Both contact areas were smoothed using progressively finer wetordry paper on a piece of glass before polishing w/a felt buffing wheel and polishing compound. Then the factory sear spring was replaced w/a lighter one. Pull w/the lighter spring before polishing the sear and trigger was 20 ounces and notchy. After polishing the pull is 15 ounces and much smoother.

[linked image]

Then I turned to the trigger blade. The sharp edge is uncomfortable to me and needed smoothing. The trigger is flash plated; this will not be very durable. Just a FYI. I used a dremel sanding roll followed by a Cratex point then polished w/a felt buffing wheel and polishing compound.

[linked image]

Next I took the barrel off the receiver to see what things looked like. I’m glad I did because there was some fairly significant misalignment going on in the TP between the barrel and receiver:

[linked image]

The center set screw locates on a dimple drilled into the barrel that holds the barrel in position (the other set screws don’t have this- just the center one). There are several ways to go about correcting the misalignment but I decided to simply use a small piece of solder dropped into the center set screw hole. When the set screw is tightened the soft solder conforms to the off-center dimple and when all’s said and done the barrel is held securely in the correct position. This left the front sight tipped to the right so I recentered it.

So that’s it- for now. I still have more things to do and/or try. A few of them:
• Grip!
• Trigger over travel limiter
• Straighten trigger blade
• Deburr, detail and polish the hammer and polish sear hook
• Open up trigger guard a little
• Polish leade if needed
• Carbine stock for occasional use

i'll post results as they become available.

This message has been edited by cobalt327 on Jun 23, 2017 1:14 PM

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