I got a problem

[RM422]

Ok heres a long story. i have a crosman RM422. That was rated for 500fps and was doing about 530 out of the box. Then this may almost 2 years after I got it, it suddenly lost power. Poof just like that you could see the pellet flying through air. So I took it apart and saw that the spring had weakend a tad and the piston seal and piston head was worn. So I call up crosman they send me a new piston and a new spring etc etc all for free!! Because this rifle has been discontinued. So I get the parts and notice the spring they sent me is not the RM422 spring it was longer and much stronger than the old one. The coils were also spaced out way more. So I re-oiled and re-lubed everything. Then put it back together. With the new spring I swear it must have been doing almost 800fps. It had devastating power. Then this summer. Someone told me that spraying graphite lube on the piston and spring would make it more powerful. so I did that and it mucked up the whole inside of the gun. And actually decreased the power. So I took it apart cleaned it out and re-lubed everything like i did before. so I got it back to normal for a few months and then a few weeks ago it suddenly lost power again?? I think because it was diesling and it may have burned the piston head. But parts cannot be accuired for this rifle anymore and I was wondering if parts from any other break barrels would fit into it? If so please tell me because I really like this rifle and want to shoot it. It is my main hunting rifle and i don't really like using my 1377 and 760 because of all the pumping.

[Mulby]

I would say that your best bet would be to contact either D&L Airgun, or James Maccari to see if they have parts that may interchange with your airgun. HTH,

Mulby

[RM422]

Thanks Mulby. I think I might try that. I know for a fact that some of the beeman R9 parts will fit into it. Like the main spring but I'm not sure about the piston. The main spring from the R9 will get it to about 830fps. But I'm not sure where to get it. Like I said before It was doing about 800fps with that weird spring crosman sent me. All I really want is to get it back into hunting velocities again. Anything over 500fps is fine with me.

[RossB]

The Canadian Crossman Mendoza mainspring should be 36 coils of .100" wire with an OD of .790"
A Quest 1000 spring (35 coils of .117 wire with .764" OD) may fit.
Many other mainsprings could also greatly improve performance.
A suitably sized .128" wire mainspring spring would probly give highest fps but may need a tight guide, tophat and tar to minimize twang/recoil.
The piston ID should be .800".
The Guide OD should be .500" ( one can always change the guide).

[sniper]

I have RM422, with original spring on chrono does 460 fps to 480 fps using copper head wadcutter 14.3 gr. This gun would/will never make it to 800 fps., unless you change with a bigger receiver/cylinder as big as HW77 or D350, or use a very very light pellet, perhaps a longer barrel too but anyway the recommendation from JM, it's the R9 spring which I have now in it and now it's capable to do 500 with 16 gr. but the sound of heavy impact on the piston against the receiver, it's almost sounds like it does 1000 fps., I chrono it with cleaning pellets and does 855 fps.

[Parker_101_]

I chrono it with cleaning pellets and does 855 fps.

Haha.....Hey sniper .....I just about choked on my coffee when I read that.....gotta clean my desk off now........good one....

[RM422]

Well my RM422 was pulling some pretty big numbers. If it wasn't doing 800fps it was definately doing over 650fps with 14.3 gr pellets. The problem is parts can not be obtained for any of the RM series anymore. With I think is ridiculous because crosman is still making parts for guns over 30 years old. All the RM series rifles are only 2 or 3 years old. Even though mendoza made the RM series for crosman. Crosman still had their name put on the rifle which means it's their product and they should take full responsibility for it. So if crosman can't supply me with new parts for a 2 year old rifle then they should atleast send me a new gun close to my RM422 like the quest or something. I took my RM422 apart again this weekend to see what was wrong and the same problem again a chipped piston head. So I changed the spring again and went through all the used piston heads I had and put the best looking one in. It's not perfect but it will do until I either find new parts or get a new break barrel. I also re-lubed and cleaned everything. So I have my RM422 shooting acceptibley but not perfect. I had it putting a hole through a bean can from 75feet but it wont be good until it's going straight through and out the other side from 30 yards like it did before.

By the way RossB thanks for the spring measurements I may try it.