.25 Marauder Gen2 Bstaley Tune

[bill_dd97]

This afternoon I re-tuned my stock Gen2 Marauder to get a flatter shot string. I was going for a tune that would reach 100yards before I ran out of dots and stayed over 30fpe. I added in two 211 o-rings for a Bstaley tune. I set my Spring and Striker to 6 turns clockwise and velocity at 4.5 turns out. Starting at 2700psi it gets 24 shots down to 1900psi with a spread of 26.7fps averaging 803.9fps and 36.5fpe using AirArms Diabolo 25.4gr. ChairGun tells me at 100yards there is a 4.25 mildot holdover and it retains 624fps and 22fpe at 100yards.

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[ajshoots]

Very nice work Bill!! Amazing what some o-rings can do!! Is this a gen1 or gen2 gun??

 

[bill_dd97]

Gen2. I'll edit that into the original post. Today I hope to get the time to zero the scope and shoot some groups with sorted pellets.

 

[bstaley]

Nice tune, but unless the gen 2 is very different from the gen 1, with only 2 o-rings and 6 turns cw on stroke, the hammer isn't even hitting the o-rings.

 

[bill_dd97]

Previous attempts at tuning with 6 turns and no o-rings produced higher velocities and much lower shot count.

My previous tune required no more than 4.5turns on striker with no o-rings and spring at 3.5turns to get 24 shots from 3000psi to 2000psi with a spread of over 30fps at 40fpe. This tune is giving me 24 shots from 2700psi to 1850psi with 26fps spread using 2 o-rings, 6 turns on striker and 6 turns on spring. Pressure read from gun gauge.

I got to put pellets on paper today and was getting 30 shots before a noticeable vertical POI shoft.

 

[Helimech]

I'll have to agree with bstaley on this one. I tuned a gen 2 marauder last week without o rings for a friend and got almost the exact same results you did with o rings. It's still a great tune, so I wouldn't touch it. 

 

[ajshoots]

Haven't played with a bstaley tune for ever, but I was thinking with 3 oring you only had 2.75-3 turns in cw before you were no longer touching the orings?

 

[Bruce]

Is there a link to the bstaley tune?

 

[ajshoots]

https://docs.google.com/document/d/1Jn0RFfnH9YnFaEbT5ynizTnIyJ9DG6u5htJ_65R9P5g/mobilebasic?pli=1

 

[Bruce]

Thanks AJ.

 

[bill_dd97]

Took it back apart and did some measuring. The striker at 6 turns is 3/8" long. So, you were correct about the hammer not touching it. I added in a third o-ring, but I'm unable to test as my hand pump gave out on me during my last shooting session.