Stoeger XM1 Ranger tuning

[V5CVBB]

My 25 cal Ranger has maybe 150-200 pellets through it. I pulled the shroud off and decided to tune it bare barrel, and then go from there. It had been shooting close to 1inch at 50yds with shroud and just under an inch without.

Broke out the Pact chrono yesterday. Hadn't used it in 20 years and forgot how sensitive it to lighting changes. Factory hammer spring setting had it shooting JSB King 25.39 at 910fps at 3yds, which seemed to be around max velocity. Adjusted down to around 868fps, max minus ~4-5%, shooting steel. Looked better so I tried a group.

Both groups at 50 yds. Left pic is 10 shots. First 3 in red, then 7 through remaining hole. Reservoir pressure was down to maybe 170 bar, regulator at 160. So I tried another 5 shots, right pic. First 3 in red, then 4 and 5 were lower as it dropped off regulator.

Out of air, daylight and time. I was well pleased at my first attempt tuning a PCP. Thinking of trying a little less hammer spring next time I get to play with the tune. Regulator is not externally adjustable, plus I'm still using a hand pump.

My son is home from college this weekend and wants to shoot, so it'll be next week before I get to shoot it again.

 

[Shaky2]

My 25 cal Ranger has maybe 150-200 pellets through it. I pulled the shroud off and decided to tune it bare barrel, and then go from there. It had been shooting close to 1inch at 50yds with shroud and just under an inch without.

Broke out the Pact chrono yesterday. Hadn't used it in 20 years and forgot how sensitive it to lighting changes. Factory hammer spring setting had it shooting JSB King 25.39 at 910fps at 3yds, which seemed to be around max velocity. Adjusted down to around 868fps, max minus ~4-5%, shooting steel. Looked better so I tried a group.

Both groups at 50 yds. Left pic is 10 shots. First 3 in red, then 7 through remaining hole. Reservoir pressure was down to maybe 170 bar, regulator at 160. So I tried another 5 shots, right pic. First 3 in red, then 4 and 5 were lower as it dropped off regulator.

Out of air, daylight and time. I was well pleased at my first attempt tuning a PCP. Thinking of trying a little less hammer spring next time I get to play with the tune. Regulator is not externally adjustable, plus I'm still using a hand pump.

My son is home from college this weekend and wants to shoot, so it'll be next week before I get to shoot it again.
View attachment 596930

Very good shooting at 50yds

 

[JimD]

It's grouping pretty well but if you do not need all the fpe you might try lowering the regulator. I have SPA bullpups and it is neither super easy or very hard to change their regulator. But you do have to completely degass it and partially disassemble. I can do it through either end of the airtube but I've been going in through the end closer to the trigger, what I call the back end, lately so I can measure the total regulator length as a way to have an idea of the setting. With the air tube depressurized and off the gun, unscrewing the nut on the end of the airtube will reveal the regulator but if it does not come out with the nut you may have to push it out from the other end of the airtube. Then loosen a 12mm nut and turn a straight bladed screw head a small fraction of a turn. In reduces the setting, out increases it.

But for now I think you have the right idea. Play with the hammer spring and see what it wants to do. Sometimes small hammer spring changes can change group size significantly.

 

[V5CVBB]

It's grouping pretty well but if you do not need all the fpe you might try lowering the regulator. I have SPA bullpups and it is neither super easy or very hard to change their regulator. But you do have to completely degass it and partially disassemble. I can do it through either end of the airtube but I've been going in through the end closer to the trigger, what I call the back end, lately so I can measure the total regulator length as a way to have an idea of the setting. With the air tube depressurized and off the gun, unscrewing the nut on the end of the airtube will reveal the regulator but if it does not come out with the nut you may have to push it out from the other end of the airtube. Then loosen a 12mm nut and turn a straight bladed screw head a small fraction of a turn.

But for now I think you have the right idea. Play with the hammer spring and see what it wants to do. Sometimes small hammer spring changes can change group size significantly.

Thanks for the regulator info. I had planned on researching that. I was making half turn adjustments to hammer spring to get in ballpark. I'll fine tune going forward. Have you found it takes a few shots to settle after adjustments?

 

[JimD]

Sometimes it seems to move a little but that is more typical for scope adjustments and I blame the scope. Just turning the hammer spring it might go up slightly along with velocity but doesn't shift otherwise.

I like the little inexpensive Chinese chronographs which are not light sensitive. There is a clamp on that is available on Amazon, I think, for around $30 and a tripod mount I got from Alliexpress for about the same price. They have rechargeable batteries. I prefer the tripod mount because it doesn't touch the gun. I just put it on the bench in front of the muzzle and it almost never misses a shot. If it misses one, it will be cause I did not have it well centered.

The velocity may move a little as it settles into the new setting, however.