Tuning Crown .22 tightening my SD

[madeintheuk]

I haven’t done much tuning with it yet, but I’d like to have my expectations set first before I go too far.

I currently have it tuned for jsb monsters at 870fps with reg at 120 bar and hammer maxed out. They are pretty accurate so far to 50 yds, but I did notice my SD was a little higher than I prefer. I know it’s not terrible, but I know I can get it tighter. It’s currently at 8.5. I had this gun shooting 18grain at 960 with an SD of 2, so I know it’s possible.

My question is, before I go too far, are the factory hammer weights strong enough for me to go higher on the reg than it is currently? Or do I need to order a heavier weight and stronger spring?
I’m asking current crown owners/tuners for advice before I either ruin my current tune, or spend money I really don’t need to spend.

Thanks in advance.

 

[starlingassn]

i think backing off the hammer a little would help tighten the e.s.

especially since you said you have it maxed.

 

[Scotty1]

I think you will likely max at around 130 bar with the stock hammer, in my limited experience.

 

[madeintheuk]

i think backing off the hammer a little would help tighten the e.s.

especially since you said you have it maxed.

I backed off, and it got worse.

 

[Bigragu]

An 8.5 Extreme spread is dang good. Your SD should be right around 2-3.

I’ve had at best an extreme spread of 2 in a string of 36 shots, and up to 14 FPS in a string of 96 shots. But we’re they accurate? For hunting yes, for target no.

I’ve noticed I’ve gotten my best accuracy with spreads in the mid teens. My rule of thumb is if my spreads are 15 and less for a regulated gun I’m happy, as long as they’re accurate and consistent.

 

[dcr540]

I have the 1st version Crown, before the amp reg and before the Continuum or MKII models. I set my regulator to 150 and soften the hammer to 3 or 4 and this gives me a 4-5 SD with either pellet the JSB 18.1 or 25RD. (18.1 895ave 25RD 865ave) also I screwed in the hammer travel adjustment, I keep the TP on 177/22 I get plenty of pop for pellets with a high Reg and low Hammer, 4-5 SD with these one reg rifles is a good goal too.

 

[Bigragu]

I have the 1st version Crown, before the amp reg and before the Continuum or MKII models. I set my regulator to 150 and soften the hammer to 3 or 4 and this gives me a 4-5 SD with either pellet the JSB 18.1 or 25RD. (18.1 895ave 25RD 865ave) also I screwed in the hammer travel adjustment, I keep the TP on 177/22 I get plenty of pop for pellets with a high Reg and low Hammer, 4-5 SD with these one reg rifles is a good goal too.

Are you meaning 4-5 FPS EXTREME SPREADS or 4-5 STANDARD DEVIATION?

If it’s the latter, then that’s not good. I’m hoping you mean 4-5 ES. If it is a 4-5 FPS EXTREME SPREAD then your SD should be at somewhere between 1.5 to 2.5

 

[dcr540]

to clarify if I mixed up the definition of the terms, I'm sorry" I thought Extreme Spread is the first shot of the string to the last shot of a string.
example shot 1 is 900FPS and shot 15 is 875FPS, 25FPS is the Extreme Spread (right?) Standard Deviation is the difference between shot to shot (right?)
4-5 FPS is not a bad difference is what I'm saying for a moderate PCP. I agree the lower the ES the better the SD will be" to have a 1.5-2.5 SD is a very efficient regulator found on the high-end rifles. (Sorry it took a while to get back to ya)

 

[dcr540]

You can go crazy with modifications, heavier hammer, springs, etc. these lead to problems down the line, if it's not in the rifle when you bought it, when you put these things in you might not get the Increases you desire...