Regulator setting for .25?
I have a new 25 BP and was doing a string for a review and I noticed something strange. I can post the exact numbers later, but I got 30 shots from 240B down to 150B. The JSB Kings (25.39g) were shooting from 893 to 910 but when I got to 150B on the gauge, the fps dropped down to 881, 880 for two shots then jumped up to 915, 918, 915 for three shots and I stopped there. Is the regulator set too high?
The gun is very new and has maybe 200 pellets through it so far. The gun is also very accurate and I can live with the shot count, but I wonder if it can do better.
All Replies
Viewing 4 replies - 1 through 4 (of 4 total)
Thanks for the replies. I am very happy with the gun and how it shoots now, so I will probably put another thousand pellets through and then see how the regulator is doing. I just wondered about the strange behavior as it came off the reg.
that’s not right. a regulated pcp is the most consistent above the knee, i.e. where if you crank up the hammer tension higher it does not add any more fps.
think about it differently, if your hammer spring was binding it would not matter much because the power output would be the same. (if you are above the knee)
if you tune it on the knee or under, it will be more efficient (more shots) but consistency will suffer.
there is always a compromise between consistency and shotcount.
I think your reg is just too high. sometimes you cant just add more hammer spring tension then you have to go in and fiddle with the reg.
anyway, does the reg output go down or up over time? is it due to the deforming/getting weaker bellevilles or deforming seat/seal.
If you are asking if the gun can do better in terms of shot count I would say in my experience no, 30 shots is about normal for the .25 vulcan. If you are asking if the ES can improve yes I would say 17 foot per second ES is a little high. I would say for the .25 caliber bullpup (all models) an ES of 7-10 FPS is very acceptable. I have tuned a few vulcan .25s and it is my experience that the gun is most consistent with the regulator set at 150 BAR. The reason your gun is shooting 3 more shots faster is because your gun is off the regulator. What happens with some designs and HST settings is the gun when the internal pressure lowers in the plenum the valve dwell time increases. This only last for a few shots before the gun’s pressure is too low to evacuate the required volume of air in time in order to generate the speed witnessed on your string.
The most important step taken on any regulated airgun is to break the gun in before adjusting a regulator. I would say 1500-2000 rounds then take a closer look at the gun. The first step of tuning is to find the HST bell curve. Find the point where the speed decreases after increasing the tension. This will show the speed where the HST is at the top of the bell curve. This where the regulator will be most consistent.
Viewing 4 replies - 1 through 4 (of 4 total)
- You must be logged in to reply to this topic.
The spike after regulator cutting out point is not desirable. It means that your settings are suboptimal: