Another stop on the CP1 co2 pistol journey.
Set myself a goal of a total of 300 foot pounds out of 1 12gr. with all shots inside of 3% varation AND something close to 5 foot pounds of energy. 60 shots at 5 foot pounds would be ideal, but I'd take 65 shots at about 4.6 foot pounds or 55 shots at 5.4 foot pounds (anywhere in that range).
Broke it in first, made a shroud, adjusted the trigger, found a reddot sight size I liked, and shot it enough to break it in.
Basically taking care of the little things while waiting for warmer weather for testing. Been 77-81F for all of the following tests.
HAve to pick some percentage of varation for comparison, and I really don't care if you pick 2%, 3%, 4%, 5% or 8%...so long as it's the same. Knowing co2's nature one's a rifle/pistol gets tuned up (when it drops off in speed, it drops off like a narcoleptic vulture) so I reworked the old tests with a 3% goal. (After all, what good is a low powered .177 if it's not accurate and consistant?).
To keep it kind of even, kept the same tin of 8.44gr. JSB's for all tests.
TEST #1. As issued (just well broken in):
3% for 42 shots...average ve. 509fps/ 4.86fpe / 204 3% foot pounds per 12gr.
TEST #2. Next serious testing, adjusted the striker spring tesnion down a little (by reducing the spring guide's "top hat" to the point where there was just a tiny touch of compression when the end cap went back on)and put a "buffer pad" on the face of the valve.
In retrospect, don't think the buffer did "jack".
3% for 48 shots...average 508fps/ 4.84fpe / 232 3% foot pounds per 12gr.
TEST #3. Got all serious about it and reduced the internal valve diameter by sleaving the inside. Basically restricting both gas flow and volume a little bit.
(you'll have to look up previous posts on that to get shot strings)
3% for 51 shots...average 508fps/4.84fpe/ 247 3% foot pounds per 12gr.
TEST #4. Went back inside and reduced the striker weight by 20%. Are those that say that 20% won't be noticed....but it hasn't worked out that way for me.
So with the striker reduced from 35 to 28grams (just picking 1oz/28grams as "good 'nuff").
3% for 59 shots...average 509fps / 4.86fpe / 287 3% foot pounds per 12gr.
DERN...so close....like 4% of goal close.
What I did notice in all of this is that the velocity didn't change. Thinking on that, can only conclude:
1. It's a gas hog in .177 as issued...squirting out more co2, mostly later than be used to drive the pellet. LArger bore (they do make it in .22...and in .25 in Europe) might make more use of that than a .177.
(To counter balance that, does seem (from other tests) this one is a bit fast compared to others. Just the random nature of acceptable tolerances of mass produced parts most likely).
2. After all the above, it's still shooting just as fast as when it started....so it might be time to look into strangling off the transfer port a little bit.
3. Looking at this shot count, think I rushed it a little and didn't let the pistol warm up to ambinat temp. Started slow, stayed a little slow until it found it's balance (warming up from outside temp. vs cooling down from shooting at a measured pace).
4. Likely, at back yard ranges, I'd have gotten to shot # 64-65 before noticing the velocity decline...just takes a lot of velocity change to be noticed at 15-25 yards.
SO....for that one reviewer that claimed +80 shots...my first reaction was "BS". Now I'm thinkin it "could be". Would be some "ifs". IF he was just plinking at short range and jusdging by the point of impact change (which would be pretty high....like 6-8%) AND if the pistol was spitting out pellets in the 4.0 to.4.3 foot pound range.
NOPe...still thinking BS.