Should I change the velocity of an archaic CO2?

[Ed Hall]

Hi Everyone,
I am in posession of a borrowed Walther CP2 CO2 AP. I, of course, will be contacting the owner to see what his recommendation will be as well, but I thought I'd ask the TT crowd for some opinions. The gas adjustment is apparently a factory sealed screw on the Walther CP2.
Most of my targets show a terribly trashed and torn penetration. The last match I shot you could hardly tell where the real hit was so I thought I'd check the velocity which seems to vary more than my Daisy 777 did before it started having serious troubles.
I started with the gun directly from storage in a cooler room and checked the velocities for ten shots. I came up with an average of 414.3 fps and spread of 28.72 fps for the first ten. Since the gun (cylinder) was cold I warmed them for a while in a heated room and checked ten more velocities. This time I got an average of 383.8 fps and spread of 19.51 fps. The velocity appears to be heading in the wrong direction with warmth. It has been suggested that I increase the velocity to around 480 fps. What does the learned body of TTers suggest?
Take Care,
Ed Hall
<a href="http://www.airforceshooting.org/">http: ... ng.org/</a>
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[yana]

you say your targets are severely damaged; sounds like
your pellets aren't stable in flight, maybe turning
maybe a real dirty barrel;than the pellets don't get their
necessary twist cause the grooves have slipped up
maybe power problem...than power should be really low I guess
isn't it leaking somewhere?
CO2 reacting to temperature changes in itself is perfectly normal though
hwtyger-at-hotmail.com.46779.46773

[Spencer C]

What type of target?
What type of pellet?
380 - 400 fps should be giving a clean hole in a quality target and sound in the correct range for this type of pistol.
.46781.46773

[Spencer C]

What type of target?
What type of pellet?
380 - 400 fps should be giving a clean hole in a quality target and sound in the correct range for this type of pistol.
.46782.46773

[Wally Edmunds]

Ed,
I have a CP3 Match-MV which I assume is very similar in design. I have adjusted mine to shoot at 520fps with H&N pistol match (7.4gr). With heavier H&N rifle match (8gr) it does 495fps with a spread of around 9 fps. This may be a little on the fast side. Walther says 140 - 150 m/sec is right. (460-490fps).
When I got the pistol the velocities were low - around 430 with a large spread. I could not adjust the speed any higher.
The gun had not been used for a number of years. Replacing o-rings supplied by Walther cured the problem. The adjustment screw (striker spring tension)is now around the middle of its range.
A dirty barrel may also have a lot to do with low/erratic velocities.
Nice clean holes now depending on target quality.
Good luck.

squid-at-mweb.co.za.46793.46773

[Ed Hall]

Thanks for all the info. Here's more from my end. I'm not positive, but pretty sure the targets were National Target brand. I was using RWS Meister Kugeln Extra 530 pellets. There's a very light impression on the box that reads 20060 4 50. I took this as a lot number and size (4.50). There were lots of other types of guns being used at the event and I could see no other targets that were trashed like mine. Thanks again for all the help.
Ed Hall
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ed_ka2fwj-at-juno.com.46801.46773

[fred]

If an older gun such as this were mine and was giving this type of clearly sub-par performance, I would simply pack it up and send it to a good airgunsmith for a complete seal replacement and adjustment. The unexpected velocity decline when it got warmed up would seem to show that a simple velocity adjustment will not do the job. A properly sealed and adjusted CP-2 should give reasonably clean holes even in one of the American made targets.



: Hi Everyone,
: I am in posession of a borrowed Walther CP2 CO2 AP. I, of course, will be contacting the owner to see what his recommendation will be as well, but I thought I'd ask the TT crowd for some opinions. The gas adjustment is apparently a factory sealed screw on the Walther CP2.
: Most of my targets show a terribly trashed and torn penetration. The last match I shot you could hardly tell where the real hit was so I thought I'd check the velocity which seems to vary more than my Daisy 777 did before it started having serious troubles.
: I started with the gun directly from storage in a cooler room and checked the velocities for ten shots. I came up with an average of 414.3 fps and spread of 28.72 fps for the first ten. Since the gun (cylinder) was cold I warmed them for a while in a heated room and checked ten more velocities. This time I got an average of 383.8 fps and spread of 19.51 fps. The velocity appears to be heading in the wrong direction with warmth. It has been suggested that I increase the velocity to around 480 fps. What does the learned body of TTers suggest?
: Take Care,
: Ed Hall
: <a href="http://www.airforceshooting.org/">http: ... ng.org/</a>
: <a href="http://www.geocities.com/ed_ka2fwj/">ht ... ka2fwj/</a>

frbauer-at-msn.com.46804.46773

[Raymac]

The velocity of your CP2 should be close to 500fps. Increase it by turning the large screw at the rear of the action colckwise. You may find that the loss of velocity is because the hammer spring behind the screw is collapsed and needs replacing [a common fault]. Earl's Repair in MA. is the best source of Walther parts. The spring for the CP2 is #244 35 46. The spring for the CP2 MATCH is #248 07 47. You may want to get valve repair o-rings from him at the same time. I can give you the part nos. if you need them.

mcdougall.imports-at-shw.ca.46823.46773

[Ed Hall]

Thanks again for all the help. I replaced the seals and three more tests gave almost identical results to the first two. Then I tried to increase the velocity and put four complete turns on the screw. The velocity only increased about 30 fps. Any further turn of the screw impeded the cocking operation. I'm going to check into a new spring next. (Thanks for the part#, Raymac.) I already had the o-rings and an extra set.
Ed Hall
<a href="http://www.airforceshooting.org/">http: ... ng.org/</a>
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ed_ka2fwj-at-juno.com.46827.46773