This is a tune by a member from GTA which is the standard tune for the .30cal. I find that the platform is great for power and accuracy. I also found that the 44,75gr JSB has better accuracy over the Daystate 50gr, and the 50gr JSB pellets in this case. the best speed for shooting the 44.75gr has been 928-933fps. I sent the BT65.25cal off to Steven Cochran
for a stock.
here is the numbers.
After everything was lubed and assembled, I was very anxious to see what kind of performance I would get. The max preload is 10 turns, where 1-3 turns the spring is loose and 4-10 turns the spring is in tension. The stock spring is in tension at 0 preload. I filled the tube to 200 BAR and shot the following 2 shot strings, I used the gauge on the airtube to record a rough idea of pressure drop. It matched to my tank @ 200 BAR.
10 turns: 1006 (112 FPE) / 997. (End pressure of ~180 BAR or .68 FPE/ci)
9 turns: 968 /987 (End pressure of ~185 BAR or .97 FPE/ci)
8 turns: 906/923 (End pressure of ~190+ BAR or 1.2+ FPE/ci)
This gave me all the information I needed to know. I decided to shoot a full string @ 8 turns, or 4 turns past no tension. One thing I did notice was how much quieter the gun was shooting compared to before. A short snap is the best I can describe. The BT has an anti-hammer-bounce device that uses a mechanical stop to keep the hammer from opening the valve twice, which was smoothed and polished were needed.
On to the full shot string starting at 200 BAR @ 8 turns:
906/923/939/934/948/958/957/951/959/960/957/962/949/950/947/952/948/950/934/923/908/905
If shot to within:
4% of max: 20 shots avg. 946 fps or 99.4 FPE, 39 fps ES. Fill to 190 BAR refill @ 105 BAR. 1.3 FPE/ci
2% of max: 14 shots avg. 953 fps or 101 FPE, 15 fps ES. Fill to 175 BAR refill @ 110 BAR. 1.4 FPE/ci!!!
The chronograph is a F1 chrony, which is in my basement with a 100w halogen light 6ft above it; I get no errors this way. The muzzle was ~3 ft. from the chronograph.
for a stock.
here is the numbers.
After everything was lubed and assembled, I was very anxious to see what kind of performance I would get. The max preload is 10 turns, where 1-3 turns the spring is loose and 4-10 turns the spring is in tension. The stock spring is in tension at 0 preload. I filled the tube to 200 BAR and shot the following 2 shot strings, I used the gauge on the airtube to record a rough idea of pressure drop. It matched to my tank @ 200 BAR.
10 turns: 1006 (112 FPE) / 997. (End pressure of ~180 BAR or .68 FPE/ci)
9 turns: 968 /987 (End pressure of ~185 BAR or .97 FPE/ci)
8 turns: 906/923 (End pressure of ~190+ BAR or 1.2+ FPE/ci)
This gave me all the information I needed to know. I decided to shoot a full string @ 8 turns, or 4 turns past no tension. One thing I did notice was how much quieter the gun was shooting compared to before. A short snap is the best I can describe. The BT has an anti-hammer-bounce device that uses a mechanical stop to keep the hammer from opening the valve twice, which was smoothed and polished were needed.
On to the full shot string starting at 200 BAR @ 8 turns:
906/923/939/934/948/958/957/951/959/960/957/962/949/950/947/952/948/950/934/923/908/905
If shot to within:
4% of max: 20 shots avg. 946 fps or 99.4 FPE, 39 fps ES. Fill to 190 BAR refill @ 105 BAR. 1.3 FPE/ci
2% of max: 14 shots avg. 953 fps or 101 FPE, 15 fps ES. Fill to 175 BAR refill @ 110 BAR. 1.4 FPE/ci!!!
The chronograph is a F1 chrony, which is in my basement with a 100w halogen light 6ft above it; I get no errors this way. The muzzle was ~3 ft. from the chronograph.
