Hacking the CP-2

[George Schmermund]

Here's a shot of the set screw that holds in the rubber ball. It's a 4x3 mm screw. I've had no luck getting any email response from Mrodair about spare parts, so I guess we're all on our own.

Luckily the set screws are easy to find at the hobby store. The rubber ball can be substituted with a small slice from an o-ring that will fit into the screw hole. If you get the bolt section apart it's worth while to polish the bolt and all of it's contact areas and then apply some grease.

Another thought is that the set screw doesn't need to go in through the bottom. It could go in from the side and then be adjusted after the gun is reassembled.

[Wayne52]

Today I opened up all the ports in my CP2, I've got the long barrel on mine right now along with the carbine stock.  It was giving me about 9.5fpe and opening up the ports it brought it up to 11.5 - 12pfe. with 16 grain Air Arms pellets.

[cobalt327]

Here's a shot of the set screw that holds in the rubber ball. It's a 4x3 mm screw. I've had no luck getting any email response from Mrodair about spare parts, so I guess we're all on our own.

Luckily the set screws are easy to find at the hobby store. The rubber ball can be substituted with a small slice from an o-ring that will fit into the screw hole. If you get the bolt section apart it's worth while to polish the bolt and all of it's contact areas and then apply some grease.

Another thought is that the set screw doesn't need to go in through the bottom. It could go in from the side and then be adjusted after the gun is reassembled.

Thanks for the photos and details on the bolt adjustment.

FWIW, you can order parts from SPA. No barrels or grips but most other parts should be okay:

Julie at SPA airguns for parts
email- sales@china-airrifle.com
•   Request China post if available for best shipping rate
•   ~ 2 weeks delivery wait

[George Schmermund]

Yesterday I started to play with the .177 pistol using the 8" barrel and decided to record a before and after muzzle and breech treatment test. The lathe and Dremel tool were used as described in previous posts. I was more aggressive with the Dremel on the breech this time and the improvement in smoothness of loading dramatically improved. I'm starting to think that a good crown job will only get you halfway there without doing the breech, too.

The photos show the before and after performance using the same RWS .177 Basic Line 7.0 gr. pellets from the same tin. Shooting was done using the bench vise and the targets were at 15 ft. Each group is 10 shots. I'm pleased with the outcome even thought one pellet in the "after" group tried to express its individuality by attempting to become a flyer.

[AmBraCol]

Looking good!

[George Schmermund]

I've been thinking about the recent post that showed the 'before and after' results of machining the CP2 8" barrel. While staring at the 'after' group and trying to decide how large it actually was I put a pellet from the tin into the main group's hole. It was quite amazing to me that the skirt of an unfired pellet could support the whole pellet if I picked the target up.

This inadvertent test leads me to believe that these barrels (post machining) are forsooth worthy of competition shooting on some level. The other interesting thing from this group is that the rogue pellet was shot #9. Shot #10 fell back into the same hole where the first 8 pellets went. Nothing in the setup and testing changed except for the pellets. I'll leave it as food for thought as to why the #9 pellet deviated from its brethren. Hints: Weight? Head diameter? Ovality? Unbalanced axial precession? Damage? ........

The photo shows an unfired pellet placed in the group's center with the target raised.

[AmBraCol]

The other interesting thing from this group is that the rogue pellet was shot #9. Shot #10 fell back into the same hole where the first 8 pellets went. Nothing in the setup and testing changed except for the pellets. I'll leave it as food for thought as to why the #9 pellet deviated from its brethren. Hints: Weight? Head diameter? Ovality? Unbalanced axial precession? Damage? ........

The photo shows an unfired pellet placed in the group's center with the target raised.

Most likely a problem with the head, although an uneven skirt will also throw them out.  It's interesting what can be done with carefully sorted pellets, although how one would improve on that grouping is a question worth contemplating.  The main idea behind sorting is to eliminate the odd pellet that falls outside the main group by ensuring as much as possible that each pellet has as close as possible the same dimensions as all the other pellets.  It'd be interesting to see how well it groups at a standard 10 meter competition distance.

[George Schmermund]

Something else to consider in the overall scheme of things is that I haven't choked the muzzle yet. Choking may be all that's needed to ameliorate the recalcitrant behavior of pellet #9. Its deviation from the herd is quite small.

[George Schmermund]

Since I had the .177 dismantlement to machine the hammer's sear ramp and do some polishing as was done on the .22 gun I decided to deal with the main tube end plug mod, too. This is the plug that holds in the hammer spring and it's guide. The nib on the plug that is used to secure the gun into the grip stock on the CP2 had to be removed in order to use a CP1 wooden grip. I had been using only the screw under the pellet loading tray to keep the bolt housing secured onto the tube while the feasibility of the grip conversion was evaluated.

Now that I know the conversion is doable and highly desirable it was time to get the rear of the bolt housing securely fastened to the main tube. As the photo shows, the plug was drilled through the axis to allow a screw to be added that fastened the new wood grip to the main tube's plug. The plug's side hole that provided for the original screw was enlarged to 1/4" to allow the head of a shorter screw to pass through the plug and sit in a counter sunk hole in the opposite side of the original hole. This allowed a new, shorter, screw to pass by the center hole in the plug, but still have enough material left to clamp the main tube tightly to the bolt housing.

The axial screw can now pass through the new wood grip and into the drilled and threaded plug. For now I'll just leave this screw recessed in the wood and keep it tight for clamping purposes.  It will be easy to convert this screw to adjust the hammer spring tension in the future.

[George Schmermund]

The more time I spend tweaking these CP2 guns the more I like them. The paradox is that the more things that are improved, the more other things become obvious. Right now I'm back to the trigger. Using the pistol version is now focused in that direction. Not the trigger action, I love the way that's coming along, but the trigger blade (?) itself. I've removed the trigger guard and that helps to a large extent, but the actual trigger blade is like pressing against a piece of barbed wire. Well, maybe there's some hyperbole there, but then you should talk to my finger! It's now time to start thinking again about modifying one of the Vigilante triggers into a shoe. I'm wondering if I'll remember this as a project tomorrow. I'm sure it will all come back to me the next time I shoot the guns the way they are.

[AmBraCol]

Here's something else to play with - or not - once you get your other mods going.  An air stripper.  Attached is a picture of one done by Maverick airguns, it's for the ubiquitous Crosman barrels, but no reason why one couldn't be made up by someone for different barrels.  What it does is allows for turbulent air (or CO2) to be diverted from the skirt of the pellet as it is released from the barrel.

[cobalt327]

The more time I spend tweaking these CP2 guns the more I like them. The paradox is that the more things that are improved, the more other things become obvious. Right now I'm back to the trigger. Using the pistol version is now focused in that direction. Not the trigger action, I love the way that's coming along, but the trigger blade (?) itself. I've removed the trigger guard and that helps to a large extent, but the actual trigger blade is like pressing against a piece of barbed wire. Well, maybe there's some hyperbole there, but then you should talk to my finger! It's now time to start thinking again about modifying one of the Vigilante triggers into a shoe. I'm wondering if I'll remember this as a project tomorrow. I'm sure it will all come back to me the next time I shoot the guns the way they are.

Good thread!

From a CP1 thread:

I took the sharp edge off the CP1 blade and polished it. It’s comfortable to shoot now but that might not be enough for your trigger. The pull is set to 15 ounces, so being thin isn’t as much of a problem than if the pull were heavier.

[George Schmermund]

For those CP2 owners that find the trigger and guard arrangement to be as untenable as I do here's a partial fix. I was going to use a more destructive procedure, but since the trigger guard is plastic It seemed reasonable to exploit it thermoplastic properties.

The guard was uninstalled from the gun and then clamped in a vise along with some spacers so that the jaws could get a good grip. The guard loop was then carefully heated with a hot air gun and softened to the point where a 7/8" socket could be pressed through. The socket was left in the loop until the parts were cool and then removed.

The resulting extra room is now a luxury. The trigger blade still not worthy, but that's for this afternoon's project. I've cut down one of the Vigilante triggers and now have to figure out how to attach it so that it can be made adjustable.

The photo shows where things are at this point.

[WhatUPSbox?]

George,
Since you have machining resources, have you seen this page? http://anotherairgunblog.blogspot.com/2015/09/new-trigger-guard-for-cp1-m-pistol.html

I do like your quick heatgun mod

[George Schmermund]

The trigger mod turned out to be much easier than I thought. The Vigilante 'shoe' was considerably softer metal than the CP2 trigger, which was very hard. After taking the picture of the trigger in the milling vise I realized that I'd need a carbide end mill to do the job.

The shoe can now be adjusted to the proper position for my first approximation of the feel I'm after and will be temporarily affixed to the CP2 blade. When everything feels right I'll epoxy it in more permanently.

I'm pretty sure that if I'd started off with a 2240 I wouldn't be getting the same satisfaction from modding it. My friend Dave is into the Crosman pistols and has a fair assortment of them. He's a machinist so he bought them to make custom parts. After showing him what the CP2 is capable of he's now on the verge of becoming a convert!

[Rob M]

looks excellent George.. Having a 2240 and the cp1 , I have to say the airmax guns are 10 times the quality for about 20 dollars more ( cp1 is 79.99 shipped

[George Schmermund]

Trigger feel to your finger is as important as the grip feel is to your hand. This is only news to me, I'm sure, but I'm coming along in the target shooting arena. The new Vigilante shoe conversion for the CP2 is working nicely. It's a rough lash-up that uses hot glue to put the 2 pieces together. The hot glue allows me to mate the floating shoe to the CP2 blade and still have time to squeeze the trigger to set the 2 together. I'm finding that the shoe is now offset to the blade in a way that combines the grip position to where my finger wants to be at the same time. The broad surface of the shoe significantly reduces the apparent pressure needed to break the second stage. This is all in the testing stage.

The usual trigger position in most of the entry level match pistols I've been seeing is vertical and at a right angle to the axis of the barrel. The more expensive pistols have an exotic looking trigger arrangement that I assume is designed to pivot to the angle of the shooter's finger. I'm guessing at all of this.

[AmBraCol]

Here's a look at one type of target trigger.  One can move it forward or backward.  The trigger "shoe" can be moved up or down AND it can be twisted so as to meet one's finger at a wide variety of angles.  Put one on my IZH 46M and am tickled pink with it.  It's much better than the original trigger, and even better than merely covering the trigger with a shoe.  Of course, the trigger target shoe is MUCH better than a thin blade, it makes the trigger feel lighter and tends to improve one's trigger control.  Of course, a trigger like the one posted here is even more better.  I've no idea what it'd take to adapt one or something similar to your CP-1, but it's something to think about.   

[George Schmermund]

I decided to get another start on some measurements. This test is to get the hammer strike to trigger the scope on channel 1 using the accelerometer and time the pellet's exit with the force transducer on channel 2. Ch1 is red, ch2 is yellow.

The photo shows that the transit time is just over 2 mS using the .22 cal 8" barrel. This is just a setup test. Next is to use the 18" barrel and overlay it's transit time onto the barrel harmonics testing.

[George Schmermund]

Now that there is an accelerometer for the o'scope triggering signal I got sidetracked back to doing the pressure measurements. As the photo shows there is a perfect place to install the transducer right into the valve cavity itself. The screw that secures the front of the trigger guard and clamps the grip onto the main tube is semi-compatible with the 10-32 thread of the pressure transducer. It's a blind hole from the factory that goes into the valve body and can be drilled further as a through hole into the valve and then tapped for a true fit with the transducer.

I did the same thing with the Vigilante valve, but it was not nearly as simple as this. It's as though the DP2 was designed to be hacked to make these measurements.