Texan .308 with JSB .50 Grain Chrono String low Power.

[Shooting Targets]

I know the Texan is mainly a hard hitting 1 to 6 shot gun but I wanted to see if this can be setup to make a mid bore gun similar to an FX Boss, wolverine, or Hatasan hercules. Basically I am trying to make a high power Condor.

In talking with Niel the ammo supplier he mentioned on trying to shoot JSB 30 Cal pellets. In a quest to find light ammo Niel suggested the 30 cal jsb to see how they would react with the gun. I did not have time to hit the range but wanted to look at the chrono string. So in my garage with a chrono what I found was a total of 58 shots going from about 680 FPS to 1028 FPS While starting at 2500 PSI and ending at about 1000 PSI. 
So here are the rough numbers but you can see a trend. The gun was set on the lower power wheel setting but not at max low power. Sorry about the chrono errors its been a pain with me. 

2500 PSI 685 690 error error error 712 err
2200 PSI 696 717 731 716 747 695
210O PSI 717 731 err 758 err err 773 784 783 795 802

1950 PSI 838 793 805 805 833 819 838 err err err
1700 psi err 927 920 920
1500 PSI 955 err err
1400 psi 1028 err err err 838 821
1200 PSI 829 err err err err 940 err err
1000 PSI 955 Stopped shooting

 

[Willie14228]

looks like you will need to bring your starting pressure down to 2000 psi adjust your power wheel half of a rev up this should get your 858 up into the high 900 if it goes higher then increase your pressure to 2100 psi I think you will find your sweet spot in that 2100 to 1700 psi range, once you start pushing those jsb over 1000 fps they are going to start bouncing around your target board like jumping beans I think

 

[Shooting Targets]

Willie, thanks for the reply. Yes I am having a hard time figuring out the settings. I agree the first thing I noticed was the higher pressure looked almost like valve lock. So reduce the fill pressure to 2050 if possible and increase the power so I get in late 900s to early 1000s with some form of usable curve. Right now the pellets were jumping around in FPS all over. I agree not much over 1000 for JSB but at 980 to 1000 we are still looking at about 110 FPE which is well above the FX impact and Wolverine/hatsans. The nice thing is at 2100 psi my carry tanks has much more fills vs going to 3100 PSI. That said if i can get 10 to 15 usable shots within 100 PSI of each other that be very nice. I will keep you informed since you have played with these guns more. I was at a bit of a loss until you mentioned lower PSI and more power to get a traditional curve. 

Thanks and if you have any more info pass it along. 

Jared

 

[Shooting Targets]

Will i did another quick test for shot counts and chrono. I need to get a new chrono I think this one is about dead lol . 

anyway here goes the top 20 shots groin from about 2000 PSI. I turned up the power to about mark 2 out of the 5. or basically the first mark line. 

2000 psi
1. 818
2. 803
3. 820
4. 785
5. error
6. 811
7. 833
8. 833
1850 PSI
9. 855
10. 857
11 861
12. 895
PSI about 1750 to 1700
13. 855
14. 882
15 885
16. Error
17. Error
18. Error
19 900
1500 PSI 
20. 999

Friday i might have some time to play more and turn up the power wheel to about 1/2 way. and see what I get. Right now it is shooting about 75 FPE to 92 FPE over 20 shots. I am not sure if I can tighten up the FPS spread on those 20 shots ???? If I turn up the power some will the FPS on each shot tighten up but then get a sudden drop ? Your thoughts, as of now I am getting about 12 to 17 shots with 100 FPS.

Any suggestions ?
thanks again jay

 

[Prouzy]

Nick makes/is making some 60gr swaged slugs for .300, but Im thinking these and JSB probably will not be accurate due to larger bore in .308. But, you never know until you try. If you decide to continue, my suggestion that is easiest would be to obtain extra hammer spring and reduce coils by one at a time. Even if you increase power wheel to reduce slack at some point, hammer travel will be reduced, while being able to shoot at higher pressures; thats what is going to give you shot count. 

Another option, though it may not work because OAL may be too short for the twist, is to find light bullets. If I recall, Rick Morrill makes a 78gr .308. Could be a nice balance in fps/shot count to produce a mid bore. Efficiency will certainly improve with current set up. With your current ES, you really wont be able to make use of most of those shot beyond 50-75yd unless you have a good range card, eg holdover will be different at about every 2-3 shots at 100yd. You may also consider round ball, about same weight n BC of pellets, but may fit better in your bore.