GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: mb4859 on March 05, 2015, 09:24:37 PM
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Let me set the stage. I am using my new ProChrono Digital and it didn't miss a shot...
The pellets are H&N target 21.14 gr.. The first string I filled to 3100 psi on the pump.
2900 on the gun and shot down to 1900 psi.
1. 789 21. 836
2. 788 22. 837
3. 806 23. 837
4. 796 24. 842
5. 805 25. 849
6. 809 26. 846
7. 800 27. 839
8. 814 28. 836
9. 809 29. 838
10. 820 30. 836
11. 819 31. 840
12. 822 32. 834
13. 822 33. 826
14. 819 34. 830
15. 823 35. 823
16. 823 36. 822
17. 824 37. 819
18. 826 38. 818
19. 835 39. 803
20. 833 40. 803
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Forgot to list these.
Spring screw in 3 turns CW
Throw in 1/2 CW
Valve screw out 4-1/2 CCW from closed
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Seems to me you could lower the fill pressure, and shoot it down a bit further to finish out the bell curve - still get 20 shots, but with less extreme spread.
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From your first shot to your highest velocity, are the 21gr pellets hitting the bullseye? If so, leave it and have fun. If not, you still have some work to do to find what FPS those pellets like to fly at. Then tune to get more shots in that range.
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I didn't shot these pellets for accuracy, just looking at the fps. I probably should have.
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None of it makes any sense if you can't hit what your aiming at. You shot 20 shots then refilled the rifle, right?
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No I shot all 40 shots on one fill from 2900 to 1900 psi.
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That's the beauty thing about the Marauder, you can tune this way and that, more power, efficiency, whatever. If you get a hankering to tune again, try the A Teams B Tune as described at the other site. It worked well for me, I have just been fine tuning from those results since then.
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Let me set the stage. I am using my new ProChrono Digital and it didn't miss a shot...
The pellets are H&N target 21.14 gr.. The first string I filled to 3100 psi on the pump.
2900 on the gun and shot down to 1900 psi.
1. 789 21. 836
2. 788 22. 837
3. 806 23. 837
4. 796 24. 842
5. 805 25. 849
6. 809 26. 846
7. 800 27. 839
8. 814 28. 836
9. 809 29. 838
10. 820 30. 836
11. 819 31. 840
12. 822 32. 834
13. 822 33. 826
14. 819 34. 830
15. 823 35. 823
16. 823 36. 822
17. 824 37. 819
18. 826 38. 818
19. 835 39. 803
20. 833 40. 803
Looks like you are learning a lot about your rifle ;) :)
I would fill to the same pressure ( 3100 psi pump gauge ), then adjust the hammer spring ( 1/4" hex wrench ) CW 1/2 turn at a time ( see pic ), until the STARTING velocity is 819 fps. Being sure to refill back to 3100 psi every 2- shots, until the goal is reached. I would do this and not adjust anything else, for now.
Once the shot string is established, then test to see if this combination is accurate ;D
(http://i1365.photobucket.com/albums/r750/marauderrifle/IMG_2539_zps935b7b07.jpg) (http://s1365.photobucket.com/user/marauderrifle/media/IMG_2539_zps935b7b07.jpg.html)
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No I shot all 40 shots on one fill from 2900 to 1900 psi.
I'm an idiot, i only saw the first column of 20...added to the second column, not a bad string at all!
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Tim that's what I was thinking. I was just waiting for someone to confirm my thoughts. I'm thinking a little more spring pressure would open the valve a little better on the first few shots. But will it make the middle shots go higher also?
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Would tightening down on the valve screw bring down shots #25 and #26 or should I not worry about a couple high shots.
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A very good option would be to leave it as it is.
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Tim that's what I was thinking. I was just waiting for someone to confirm my thoughts. I'm thinking a little more spring pressure would open the valve a little better on the first few shots. But will it make the middle shots go higher also?
Yes, you are correct. More spring pressure will open the valve more/longer and raise the velocity.
You could fill to 3100 psi ( use the gauge on the pump ) try 1- turn CW on the spring, then shoot about 8- shots across the crony and post the results.
61 fps difference between the high and the low is a bit much, unless you are shooting close in. How far away will your farthest shots be ? 25 yards ? 50 yards ? 75 yards ?
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Well when I'm squirrel hunting I'm sure 40 or 50 yards would be a long shot under ideal conditions but I love target shooting out to 75 yards or more. These guns aren't that much fun stacking pellets in a ragged hole at 20 to 25 yards. But I can narrow my shot string when I'm long distance shooting at the house. I'm not sure if I've mentioned it but I'm pumping the gun with a hand pump so I would like it to be efficient. Tim when I do this will this likely tighten the string or just raise the fps across the board? Either way I'll try it tomorrow. Oh yea thanks all of you for your help. I have really enjoyed shooting this pellet gun.
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Well when I'm squirrel hunting I'm sure 40 or 50 yards would be a long shot under ideal conditions but I love target shooting out to 75 yards or more. These guns aren't that much fun stacking pellets in a ragged hole at 20 to 25 yards. But I can narrow my shot string when I'm long distance shooting at the house. I'm not sure if I've mentioned it but I'm pumping the gun with a hand pump so I would like it to be efficient. Tim when I do this will this likely tighten the string or just raise the fps across the board? Either way I'll try it tomorrow. Oh yea thanks all of you for your help. I have really enjoyed shooting this pellet gun.
Well, looking at your avatar, I can see that you have the Gen 1 Marauder rifle, so unless you or someone else has changed out the transfer port, the one in the rifle should have an id of .125, which when combined with the 21.14 grain pellets, at the velocities posted is probably close to being maxed out, meaning the peak of the shot string should not get much if any higher. Also, the Gen 1 rifles have a less stiff valve spring in them, so the higher pressure end of the spectrum ( 3000-3100 psi ) will be your friend, meaning it will help to close the valve quicker, which should go along with a flatter shot string.
With your stated shooting goals, I believe a velocity difference between the high and the low fps of the entire shot string, should be no more than 40 fps - but that's just my
thoughts ;)
Anyway, tuning usually takes a bit of time and tweaking to arrive at an acceptable shot string that suits ones needs - but that's part of the fun ;D
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Don't mean to hi-jack your post, but just got done running my gen 2-22 Mrod across the chrono and with 14.3 CPHP I'm getting on average 828 FPS. Getting 40 shots from 3000 fill on my pump gauge down to 2000 psi. What can I do to increase FPS? I'd be happy with 30 shots per fill if I could boost FPS and FPE using the same 14.3 gr pellets. Again mb4859, sorry for hi-jacking your post.
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Ok Tim, I cranked the spring down 1 turn after pumping up to 3100 and was shooting too high so I ccw 1/4 turn and was shooting 329 so that is where I left it. Here is the 2nd string.
1. 829 21. 853
2. 832 22. 851
3. 833 23. 851
4. 835 24. 844
5. 835 25. 849
6. 833 26. 847
7. 840 27. 847
8. 843 28. 841
9. 844 29. 839
10. 846 30. 836
11. 848 31. 832
12. 848 32. 828
13. 850 33. 822
14. 852 34. 820
15. 856 35. 815
16. 854 36. 810
17. 853 37. 807
18. 859 38. 806
19. 851 39. 796
20. 858 40. 795
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On my 1st string I got 28 shots with a 30 spread.
On my 2nd string I got 32 shots with a 30 spread at 10 psi higher average.
This time I shot the dots for accuracy and it seemed I had slightly better grouping at 800 to 820 psi. I shot the string at 30 yards which is where I have sighted for zero. It looks like I had about a .5" high to .5" low so a 1" variance in elevation in the full range of psi. The wind was 10-15 mph so I'm going to try it again before I make any changes. I think next I want to try a 770 - 800 psi string and see how many shots I get with that setup. I bought me a better shooting rest yesterday to shoot for accuracy. I bought the Fieldpod from Academy. I think I'm going to like it. It's light weight and very portable and suits my shooting set up. My wife's tired of me leaving boxes and chairs set up on the front porch for my target practice every day. I'm going to make a mount for the front of it to mount the chrony to so maybe I won't shoot my chrony. I'm waiting on my grease to come in I ordered and I'm going to take my gun down and give change O-rings and give it a good lube. Sometimes it is really hard to cock. It gets almost all the way back and it seems to lock up. I want to do some polishing. I would appreciate any advise on where to start. And Worm all's good. We're just all trying to learn.
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I smoothed out the bolt on my rifle and pistol with a little graphite powder. I had to remove the hammer to get it all around the tube, but it is much more smoother now, and I rarely get the end-of-pull stickiness that i used to.
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One way to look at it is to look at the best-of-the-best (more about the plateau than the slopes leading up and down).
In the first tune, had about 14 shots inside of 2%. In the 2nd, have about 20 shots.
In the first, had 3 shots inside of 1%, in the 2nd have about 10.
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Ok Tim, I cranked the spring down 1 turn after pumping up to 3100 and was shooting too high so I ccw 1/4 turn and was shooting 329 so that is where I left it. Here is the 2nd string.
1. 829 21. 853
2. 832 22. 851
3. 833 23. 851
4. 835 24. 844
5. 835 25. 849
6. 833 26. 847
7. 840 27. 847
8. 843 28. 841
9. 844 29. 839
10. 846 30. 836
11. 848 31. 832
12. 848 32. 828
13. 850 33. 822
14. 852 34. 820
15. 856 35. 815
16. 854 36. 810
17. 853 37. 807
18. 859 38. 806
19. 851 39. 796
20. 858 40. 795
859-828=31
31/859x100= 3.6%
Shots 1-32 are looking good
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On my 1st string I got 28 shots with a 30 spread.
On my 2nd string I got 32 shots with a 30 spread at 10 psi higher average.
This time I shot the dots for accuracy and it seemed I had slightly better grouping at 800 to 820 psi. I shot the string at 30 yards which is where I have sighted for zero. It looks like I had about a .5" high to .5" low so a 1" variance in elevation in the full range of psi. The wind was 10-15 mph so I'm going to try it again before I make any changes. I think next I want to try a 770 - 800 psi string and see how many shots I get with that setup. I bought me a better shooting rest yesterday to shoot for accuracy. I bought the Fieldpod from Academy. I think I'm going to like it. It's light weight and very portable and suits my shooting set up. My wife's tired of me leaving boxes and chairs set up on the front porch for my target practice every day. I'm going to make a mount for the front of it to mount the chrony to so maybe I won't shoot my chrony. I'm waiting on my grease to come in I ordered and I'm going to take my gun down and give change O-rings and give it a good lube. Sometimes it is really hard to cock. It gets almost all the way back and it seems to lock up. I want to do some polishing. I would appreciate any advise on where to start. And Worm all's good. We're just all trying to learn.
Testing for the best accuracy at different velocities is a good idea.
Yeah, I should probably get me a nice shooting rest too.
If you do decide to disassemble your rifle, I have a customized valve cap with spring, that I have found to flatten out the shot string more than the ones that came with the Gen 1 rifles ( like the one you have ) and allows for better efficiency, vs adjusting in on the vas. If interested, shoot me an email at: contacttimhill@gmail.com
(http://i1365.photobucket.com/albums/r750/marauderrifle/IMG_3093_zpse58ylkfz.jpg)
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Don't mean to hi-jack your post, but just got done running my gen 2-22 Mrod across the chrono and with 14.3 CPHP I'm getting on average 828 FPS. Getting 40 shots from 3000 fill on my pump gauge down to 2000 psi. What can I do to increase FPS? I'd be happy with 30 shots per fill if I could boost FPS and FPE using the same 14.3 gr pellets. Again mb4859, sorry for hi-jacking your post.
828 fps av; What is the Hi and the Lo, of the 40 shot string ?
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The low was 815 and the high was 840 through 40 shots. I was able to get my velocity up, but now the bolt is very hard to cock espeacialy at the end. I'm sort of lost here. I did the same tune as my 25, but the first shot string today was in the mid 500's. I started out with VMS@4, HT@6, HS@3. After adjustments I got it shooting in the mid 800's. Like I said, now the bolts is very hard to cock. Am I going to need to take it apart and deburr the insides. After adjustments the tune is VMS@5, HS@5.5, HT@4.5 with a low of 809 and a high of 885. What can I do to smooth up the bolt short of taking it apart? Is it a forgone conclusion that I'll have to take it apart to smooth of the bolt?
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The low was 815 and the high was 840 through 40 shots. I was able to get my velocity up, but now the bolt is very hard to cock espeacialy at the end. I'm sort of lost here. I did the same tune as my 25, but the first shot string today was in the mid 500's. I started out with VMS@4, HT@6, HS@3. After adjustments I got it shooting in the mid 800's. Like I said, now the bolts is very hard to cock. Am I going to need to take it apart and deburr the insides. After adjustments the tune is VMS@5, HS@5.5, HT@4.5 with a low of 809 and a high of 885. What can I do to smooth up the bolt short of taking it apart? Is it a forgone conclusion that I'll have to take it apart to smooth of the bolt?
Gen 2 .22 cal. rifle
Try:
Fill pressure 3000 psi ( using the pump/fill station gauge )
VMS 4 ( make sure to remove the set screw first, make sure the VMS does not move move/turn when you tighten down the set screw )
HT 0 ( fully CCW )
HS 0 ( fully CCW )
Then, adjust the velocity as needed, using the HS ( 1/4" hex wrench )
Try to get a velocity range close to 868 - 900 - 868
If the rifle does not cock any easier, send me an email at: contacttimhill@gmail.com
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I was wondering how to keep the set screw from turning the valve screw. Just snug it up a little? I filed an angled notch in the stock to be able to get to the valve screw without having to take the action out. I've got to get supper started for the kids. Seems they never stop eating. LOL I'll give your recommandations a try tomorrow. I appreciate the help.
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Got it all set up, but ran out of light and the chrono wouldn't register the shots. I'll try it as soon as its warm enough to get out.
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Got it done today. Used Tim's start out tune. 3000 PSI on pump gauge, 3200 on rifles gauge. First shot was 764 FPS last shot was 889 FPS. Getting around 24 FPE. Got 50 shots from 3200 to 2200 PSI (rifles gauge). Tune is VMS@4, HS@1/2 and HT@0. Bolt is still a little stiff, but is a lot easier to cock then it was yesterday. Shooting 14.3 gr CPHP. At 25 yards shooting sub 3/4" groups. Think it would be a lot better with a better shooter and scope. I appreciate all the help. Any suggestions Tim on smoothing up the bolt? Half afraid to open the rifle up, but will if necessary.
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Apply moly powder ( lightly ) to the bolt assembly and the inside of the breech, where the bolt assembly slides and to the bottom of the hammer. Make sure the "bolt stud" on both the hammer and cocking bolt are secure.
BP1764S-W BP2264S-W_EVP.pdf (https://support.crosman.com/hc/en-us/article_attachments/201593690/BP1764S-W__BP2264S-W_EVP.pdf)
I have some small packets of moly powder, if interested send me an email at: contacttimhill@gmail.com
(http://i1365.photobucket.com/albums/r750/marauderrifle/IMG_3119_zpscuhrzjys.jpg) (http://s1365.photobucket.com/user/marauderrifle/media/IMG_3119_zpscuhrzjys.jpg.html)