60 SHOT JSB STRING NEEDS A LITTLE HELP
This 60 shot JSB 15.8 gn .22 cal. string is a little ratty at the beginning and the end. Basically the FPS is all down hill from 1055 FPS to a low 0f 886 FPS. That’s a big spread but other than the ratty jumps in FPS the groups are reasonably good at 50 yards.
When grouped in 15 shots the SD is 16.6, 14.0, 11.4, & 45.9 with FPE of 37.7, 34.8, 32.2, & 31.6.
Even the last group of 15 gave me a reasonable 1 1/2″ group with 2 fliers.
FILL PSI 1760…ENDING PSI ABOUT 1095
1,055.17
1,054.34
1,051.60
1,021.34
1,041.46
1,049.04
1,011.53
1,036.11
1,043.26
1,033.46
1,028.81
1,001.81
1,024.02
1,018.85
1,016.96
1,006.98
1,013.90
1,005.23
998.34
1,004.14
1,006.48
1,001.65
997.77…..PSI 1518
996.04…..PSI 1507
989.04…..PSI 1496
977.78…..PSI 1485
977.86…..PSI 1474
975.73…..PSI 1463
973.22…..PSI 1452
973.69…..PSI 1441
967.23…..PSI 1430
969.87…..PSI 1419
969.40…..PSI 1408
965.30…..PSI 1397
962.69…..PSI 1386
962.24…..PSI 1375
952.62…..PSI 1364
957.44…..PSI 1353
952.92…..PSI 1342
949.85…..PSI 1331
947.03
947.25
938.80
940.11
935.68
901.00
926.87
922.63
999.58
912.96
994.41
982.06
988.00
904.57
989.39
984.62
998.10
887.78
895.73
886.74
My Condor likes JSBs 15.8 grain pellets better than the heavier pellets I’ve tried. I just ordered 25.4 gn JSBs.
I’ve locked the TH in place at 0.069-0.070″ with blue locktite.
I’ve moved the Condor added hammer weight to in front of the hammer spring leaving me with a 48.7 gram hammer and a little extra tension on the spring.
The Power Wheel is set at 6.
I don’t understand why this setup has not seen a rapid drop off in FPS. I figure if I can work out the rattyness in the beginning and end, it will even be better than I think it is now.
Your ideas would be appreciated.
All Replies
I find that if I hold the tank straight up and down and spin the rifle to get it threaded in it tends to take the same path and is consistent in where is screws in each time.
Pab,
I don’t think the 1st 3 shots of the 2nd string can be considered. I tried to explain that I had …(ugh) slightly cross threaded the tank after checking the PSI and lowering the PW by 4 (about 1/4 turn).
The valve probably took a hit at a very slight angle for the first shot of 925. Then my actual second shot didn’t register because it stuck in the barrel. I removed the tank and sure enough, NO Light at the end of the tunnel. I properly installed the tank and without loading another pellet I blew the stuck pellet out at 125 FPS. The next shot, 1005 FPS may be a little slow because of residue in the barrel. Then the Velocities picked up and make a consistent gradual decline.
I hadn’t lowered the PW for the 1st 15 shots from 1950. We need to see what that will do. Also, I need to shoot further down on the PSI to see if it has improved over the first day’s last string that started at 1265 PSI and ended at 1100. That group was ragged yet grouped OK and hadn’t started to dive in PSI or POI.
I’ll try 75 shots from 1950 PSI all at the NEW PW setting and hopefully not mess up the results again.
The Hill pump only takes 8-10 easy strokes to read the PSI between the groups of 15 shots. I wish the tank was held by more than 1 thread when in place. Someone aught to make a better collar threaded to the end and have several set screw indents for varying the position.
That 2nd string starting 1775 looks to be the better starting pressure. Odd little climb before it maxes out and starts the drop..We want a longer climb 😕 It points to too little pw imo. But more wheel is the wrong way at this pressure, but already the pw is too low and showing inconsistancy at the start.
Basically you want more psi and more wheel to get a good curve, but thats gonna put the pellet WAY over speed.
You really are pushing the envelope trying to tune for such light pellets..!
Getting the good old max fps 1st shot followed by the long drop is easy enough, but tuning for a good long flat string at these low pressures and low pw with a light pellet is gonna be a challenge..
Lol, a lighter hammer would do wonders with these light pellets… 😉 💡
SAVAGESAM,
I went back to the 1st string and entered what I had for approximate PSIs in the range of 1500.
That 1st string of 60 all appears to have used about 11 PSI per shot. The group of 60 string I changed the PW from 6 after the first 15 shots and the PSI per group began to vary slightly ❓ I am surprised that it didn’t seem to vary in the first bunch. I wonder if I did something wrong there ❓
I also calculate the FPE for all the shots. For these 15.4 JSBs at 1500 PSI it would be about 34. If you set a regulator at 1500 and pumped the tank to 3000 PSI you should get over 120 GREAT Shots.
I’m figuring on 60 fairly consistent shots with a 2″ gradual drop at 50 yards.
Went to the range this afternoon. It was busy…
I had raised the fill to 1950 and it didn’t shoot faster than shit, the first 15 shots were SHIT:
PSI = 1950
0.00
979.76
1,059.60
1,001.90
999.75
980.79
992.13
957.44
1,043.17
962.46
1,037.54
1,034.96
1,034.61
1,031.44
1,048.86
PSI CHECK = 1775
So, turned the PW down 4 (about 1/4 turn)
I was trying to co-ordinate with other shooters and after checking PSI I started to shoot the second string of 15. 1st shot was SLOW at 900 FPS and the 2nd stuck in the barrel. When I unscrewed the tank I found it wasn’t seated. Dam Dummy! Re-installed tank the right way and blew the pellet out at 125 FPS.
Here is the second string:
900.46
125.58
1,005.89
1,045.06
1,041.10
1,037.80
1,036.29
1,028.28
1,031.44
1,029.51
1,022.89
1,018.50
1,019.10
1,017.22
1,012.37
PSI CHECK 1590
3RD STRING:
1,014.07
1,007.07
1,005.31
1,003.14
1,003.31
999.58
995.39
989.77…….approx PSI 1501
985.42…….approx PSI 1489
984.54…….approx PSI 1476
974.71…….approx PSI 1463
976.44…….approx PSI 1451
966.69…….approx PSI 1438
964.15…….approx PSI 1425
963.69…….approx PSI 1413
PSI CHECK = 1400
4TH STRING:
964.07…….approx PSI 1400
964.00…….approx PSI 1390
952.54
949.55
943.41
945.62
945.55
945.99
941.06
936.84
933.45
931.29
933.95
928.22
921.58
PSI CHECK = 1250
I would like to have shot 15 more to compare the approximate PSIs with the previous outing where the last 15 were real ragged by still grouped ok BUT, I had to get Mom to Bob Evans Restaurant for a late supper.
SAVAGESAM,
Do the above figures, where I indicate the ‘……..approx PSI’ help?
The PW is truned down a little from before.
I’m trying to check the PSI every 15 shots and chart out the PSI drop per shot on the average for that group.
In the 3rd string the avg. drop was about 12 PSI where as in the 4th group the avg. drop was about 10 PSI per shot.
It’s rough estimating looking at the scale from both side angles of the needle but it appears to work. If I used 10 shots the margin of error would be much greater and if I used 20 or more shots it doesn’t seem to me to show a trend.
I need to pump back up to 1950 with the lower PW setting and see if that string will flatten out. And, I need to shoot 15 more on the low end to see how the lower PW setting effects that group that was the worse ragged group the first day out.
Pab and Edward,
I have 43 fairly consistent shots today with the PW turned down by 4 and it seemed to smooth out the upper end that was a little bumpy before.
Can you tell if I’ve turned the PW to much or not enough ❓
Lurker, out of pure curiousity, try a starting pressure of 1500 and shoot ten shots the way you have it set up now please. I’d like to see that string. Your low pressures make me think good thoughts about hill pumps and exercise lol. 😀
Aw dang it, I ordered 25.4 gn JSBs from Pyramid Air on Sunday with 3-5 day delivery (the cheapest way) and they got here early this afternoon. Ya’d thunk they’d know I didn’t want them until at least Friday.
That’s what I get for living in the same state as Pyramid. Because of the same state I even got gigged $0.02 for state tax? Of course I donated $0.22 to NRA. Total bill$34.37 for 800 pellets.
= 4.3 cents/shot.
Oops, I’ve hijacked my own topic 😈
Pab,
I had checked the PSI before the last group of 15 and it used about 165 PSI. Figuring at a higher start PSI it will use more than the 165, I’ll increase by 180 from 1760 to about 1940.
That could allow 60 shots and drop the last group that gave the worse jaggies of FPS. Roughly figuring I should end up with around 1265 PSI in the tank
😆 😆 😆 Does it ever turn out like you figure ❓
If the first 15 shots are higher but to erratic, I can check the PSI and either lower the PW a little and shoot 60 from there or pump it back to 1940 and decrease the PW to shoot a full 60 shots.
Like you said:
“I’m thinking hes at the top of the curve, judging by the more erattic shots at the beginning. Hopefully, a bit more air will start the fps lower and climb a little.
Or it will just shoot fast as shit… Laughing”
If it starts lower, I’ll just shot out the 60 rounds to see if they are all good enough to keep.
On the other hand…We may find out just how fast shit can fly :11
I’m thinking hes at the top of the curve, judging by the more erattic shots at the beginning. Hopefully, a bit more air will start the fps lower and climb a little.
Or it will just shoot fast as shit… 😆
Probably a combination of a bit more air and a little less pw, which will also yield more shots.
Hi edward,
Good to hear from you ❗
No, don’t have a scuba, just a great reliable Hill pump with DryPack. I found that some of my groups tightened up when I shot at lower PSI, especially with Baracudas’ and better yet now shooting JSB exact Jumbos 15.8 grain. Do you think the recoil was too much for me? …. .. …. .. I have lowered the hammer weight to 48.7grams and increased hammer spring tension by about 2 1/4 turns by repositioning the added Condor weight to in front of the spring just behind the PW. The Top Hat works best for the lower PSI at about 0.070″. I had it lower but it needed to be increased to about 0.070″ for the 21.14 grain Baracudas and 32.4 grain Eun Jins. I’m shelving the Eun Jins for now because they never give me a tight group at 50 yards. Since my Condor seems to like the 15.8 grain JSBs I’ve ordered some 25.4 grain JSBs to see how they do.
This 60 shot string stayed fairly tight so I’m rethinking what pellets to use. With 2100 PSI I was shooting 20 x 32.4 gn EJs @ 880 on down to 840. I think that was to slow for best groups but they are a pain to load and probably don’t have the best BC with the pointed nose.
Like I told Pab, I was thinking wrong about which way to adjust the PW. So, after I try a bit more PSI I may have to reduce the PW like both of you suggested.
Overall, I hope to continue with PSI below 2200 and if possible a single PW setting while shooting a combination of pellets stepping down the weight as the PSI gets on the low end for the heavier ones. I’ve had limited success with 3 different pellets shooting 55 shots @ PW = 6 but the groups of the heavy EJs has never been what I want.
Don’t tell anyone… this is a secret just between you and me… I can’t afford a scuba tank or new tank and regulator right now because I dropped my rifle and slightly bent the scope, so I am trying to come up with The POOR MAN’S COMPROMISED SELF REGULATOR METHOD.
The above 60 shot string of JSBs maintained good groups at 50 yards with a gradual POI drop about 2″ from PSI 1760 ending 1100. The FPE went from 39.3 to 27.8 for the last shot. The last 15 shots FPS jumped up and down a bit but the group was acceptable considering they were the last 15 of 60 shots on one fill.
If a slightly higher starting PSI or slightly lower PW setting will settle it down, the gradual lowering of POI by 2″ or less at 50 yards for a string of 60 shots won’t be a problem.
What amazed me is that there wasn’t a steep drop of FPS and POI 😮
Like you said, edward, the lighter hammer works for the lower PSI fill. And, my Condor is shooting plenty fast with 15,8 gn JSBs at up to 1055 FPS on a 1760 PSI fill. I attribute the good speed to the Polished Valve Stem, bore polished last fall with FLITZ Anti-Tarnish Formula, pellets lightly lubed with FP10, and consistent pellet seating with the ball end of the Beeman Pellseat.
I’ll let ya’ll know what results I get as soon as I can get a good day to get to the range.
BTW, edward, they are doing more improvements at the Lima Sabres Shooting Assoc. range. They are building up the backstops on all the ranges. It is an impressive improvement to the 300/200/100/50 yard range. Mostly I use the Small Bore 50 yard range because in the afternoon when I can get there, there is shade for my Chrono. I need to get back to the 100 yard range but the shade there is in the mornings and since I retired off of 2nd shift 5 years ago Mom and I still only do afternoon hours. Wow, I haven’t been late for work for 5 years ❗ …. .. …. ..
Pab,
I’m glad I asked. I was thinking of going up on the PW. The PW setting of 6 works best with my Baracudas’ and I am hoping to achieve one setting so I’ll try a little more PSI before lowering the PW.
Thanks for the help ❗ Sometimes I don’t get to the range for a couple of weeks while sometimes I get there in between storm fronts. Your expert advice eases my worry about which adjustment to make.
that is fast, for that pressure and pellet, i think that you are on the bottom of you curve, i guess it depends if you want to shoot at that low pressure all the time or is your sucba low. well if you want to shoot at that low pressure, i would lower you hammer weight and back off the power wheel and turn in the top hat and tune from there. if you had more pressure your gun would shoot fast as shit.
Looks like at the moment you are wanting either a bit more air in, or a little less power wheel. Maybe you have happened right upon the edge of the curve with those settings.
Your arm runs out of energy real quick when you are lobbing bricks. When you are throwing pebbles, the arm still gets worn out, just at a slower, less perceptible rate.
Thanks Pab, that’s a clear explanation ❗
If I add more PSI will I get an upside of a curve Or, would an increase in Power Wheel help even out the bumps in FPS at the beginning and end of the string ❓
Not as much back pressure to hold the valve open too long with those lighter pellets. So the drop in fps/psi is much longer and more gradual.
Your arm runs out of energy real quick when you are lobbing bricks. When you are throwing pebbles, the arm still gets worn out, just at a slower, less perceptible rate.
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benneeb0y,
I believe you are absolutely correct ❗
That’s how I prefer to do it but when I don’t have the range to myself, for some stupid reason I change up.
Thanks for bringing this to my attention. Hopefully I won’t make that mistake again.