1322 ACP setupFebruary 11 2012 at 12:10 PM
|Mike (Login 2289hunter)|
Crosman Forum Member
from IP address 220.127.116.11
Well, I am off to the range in 30 mins for some testing (on the 1377 contest gun). Its snowing slightly but it is 4 degrees C out so I probibly wont get a warmer day for a while. With the cloud cover and snow on the ground the light is pretty evenly dispersed (not a point source)so hopefully the chrony readings will satisfy steve.
I took another gram off the hammer yesterday (down to 35g) but added almost a gram by making a new metal hdd. It is thin steel with a brass weight in the frint end to help it lock with inertial forces. So overall the hammer is 36 grams. It started life at 40.5 grams. I also trimmed another coil off of the hammer spring in anticipation of a RVA. With these changes it has bumped what seems to be the optimum pressure down to 1500 psi with 4-5 recharge strokes. In light of this im expecting lower velocities, but this will be the 'low power' setting. The HDD might need more tweaks but seems to work better than the poly tube versions I previously made.
I will update this in the evening with the results and some pictures.
So I got some chrony readings but ended up getting snowed out. Got 20 shots off and then it started blizzarding so I packed it in. Went to take some pics and the battery was dead. Kinda dissapointed about that because the snow in the trees looked beautiful.
To start, Velocity at 1500 psi is 560 fps (.22 CPHP). I didnt record any values, but if I got it as close to 1500 psi as I could it was +- 10 fps max. Takes 4 pumps to recharge almost every time, yeilding 2.5 fpe per pump. One thing I noticed is that if I put one too many pumps in by accident, Velocity was in the high 400's. At 1400 psi it was shooting ~590 fps but required four and a 'half' strokes to recharge. This makes me think perhaps the sweet spot might be a tiny bit lower than 1500 psi. It might also benefit form increased valve volume. I will have to investigate that next time I am able to get out.
One thing is for sure, this thing is QUIET! I can hear the pellet ripping through the air. I feel like im not shooting anything really. The report sounds as if the HDD is doing its job, but there may still be gains to be had. On the second shot I had the pressure drop by twice the usual ammount but had the same velocity, so there was one glitch out of it.
Although I definately need to make a rear velocity adjuster, this has proven that it works at the very least. I will have to put some more tension on the hammer spring and see what higher pressures do with some more recharge strokes.
|This message has been edited by 2289hunter from IP address 18.104.22.168 on Feb 11, 2012 3:46 PM|