Crosman Mk1 Upgrade?

deadman

deadman

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I've got an old Crosman .22, and have a hankering for a bigger bore. I haven't spent any time in this forum, so please forgive me if this has been covered before. Realistically, what is the most I can expect to gain from this pistol without major alteration? I'm not concerned about an increase in the CO2 consumption, but would like to maintain the use of the standard cartridges. Also, is there anyone around that does this kind of work?

Thanks.
 
Dennis Quackenbush used to sell a .25 caliber conversion kit and MAC1 does valve work and barrel changes that approach 600+ fps...........Track of The Wolf sells barrel blanks and ships to Canada [.25 ACP works fine]............Harold
 
You run out of room for the barrel bore diameter, a little over .30 caliber, unless you are willing to permanently hack your frame.

You want to get familiar with a couple places on the web. Mach1 Airguns site, is the first. If it can be done reliably to a Cr.Mk1/2, he's done it.

The Crosman Forum on Network 54, the Yellow Forum, and the Canadian Airguns Forum, are also good places to do a search at.

Realistically, clean up the Mk1, shoot it as-is, or build it into an accuracy gun. Get a 2240 to #### around with and mod. It is a more modular built airgun, and is not die cast zinc. The valve is easier to work on, and there is a loooonnggg track record for big bore mods.

Cheers
Trev
 
I have done a few Crosman Mk I big bore conversions to as large as .30 cal. and 9mm cal. The .30 cal is a breech loader, using a modified tap loading system, while the 9mm was a muzzle loader. Some of my modded Mark I pistols can be seen on Todd Cooper's website. (link in above post by sunray).

There is a lot of machine work involved in such conversions, and thus, unless you have the capabilities to do the work yourself, the cost in doing so would be prohibitive.

I'd suggest that you enjoy the gun in it's stock form, and perhaps learn more about the airgun hobby, before laying out some major funds to get a custom airgun made up.
 
deadman said:
As for the airgun hobby, how is it different from a real gun hobby?
Click to expand...
Actually airguns are as much "real guns" as any powderburner - just for clarification.;)

With airguns, the powerplant can play a much greater part in hold sensitivity, and follow-through than most firearms.
Some airguns can be virtually recoilless, while others, such as heavy magnum springers, can produce a hefty "kick" that requires great care in controlling to obtain any sort of accuracy.

Many folks find it a bit difficult to transition from shooting powderburners to shooting airguns - especially springers. I recently had a fellow bring me an air rifle that he simply couldn't shoot worth beans - he was certain that the gun was defective, as he couldn't get better than a 6" group at 20 yards. He asked me to check it out and do any repairs to get it shooting accurately. I tested the gun with various pellets, and found nothing wrong with the gun - it would shoot 1/2" groups at 20 yards, no problem.
When the fellow picked up his gun, he couldn't believe the targets that I showed him. After chatting a bit, I discovered what he was doing wrong - he was resting the forend on a rest, same as he would his .22RF - which just doesn't work for a springer. After a bit of tutoring on the "DOs & DON'Ts" of springers, his airgun shooting has improved dramatically.

Learning the intricacies of each of the different airgun powerplants is all part of the fun.
 
I don't find accuracy with the Mk 1 a problem. Growing up with both airguns and .22 rifles etc, I have never noticed much difficulty in transitioning between the two.

My original question was because I just thought it would be neat to have a big bore air pistol, specifically my Mk 1. I don't want to do it if it means having to hang a tank on it, or swap a long barrel on. Basically keep the current configuration, just lobbing a bigger piece of lead. Not interested in modding up any others, just wanted to do it to this one.
 
It can be done.

Got a metal lathe? Makes it easier. Cheaper too. Even after buying the lathe, to judge from the amount some seem to be spending on parts.

Valve mods are a bit tetchier on the Mk1/2 than on some others. The Mac1 valve gets, among other things, a second O ring around the body to reduce or prevent blow-by between the port and the valve body, as well as ( I have been told) the valve body being glued in to the frame (retaining compound, maybe?). There is not a lot of meat to carve up on the Mk series valves. If you can get hold of a spare or two, it'll pretty much take care of the need for having spares as insurance, but to be able to return to the original state is good, too.

I might have a .30 or .32 cal tube I made up, around here somewhere. I'll look.

Cheers
Trev
 
Found the tube. Want it for postage?

It is machined to be a close fit at the breech of an unmodified frame. Really needs a support built to replace the barrel stub and the hammer spring retention/adjuster.

Bore is a little rough, but not horrible. Was a .32 cal Marlin barrel in a former life.
Pretty sure I had thought it a good size to use buckshot in.

Cheers
Trev
 
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