Crown tuning question.

[srtmat]

So I decided to see how good the factory tune on my Continuum was. I recorded hammer spring adjuster measurement (16.4mm) I then maxed out my hammer spring.

I setup the crony and started shooting and backing off adjuster each shot. So here is my graph. Where would you guys turn the adjuster back too? Looks like it was real consistent from shot 7 to 17. Any advantages to being closer to one end or the other? Is 17 about at the “knee” or is it at shot 22?

Thanks

Mat

 

[Long_Gun_Dallas]

Try 12 and see how consistent it shoots there. Being a bit behind the curve isn't bad either. (10) either way, if accuracy and consistency is there... It's all gravy. Can always listen to the shot, too. That'll give you some feedback, too. Generally a balanced tune is a good bit quieter (on the muzzle end) than if it wasn't balanced.



As always, field results are what we want. 

 

[tor47]

If you want to know what is the most accurate on target, you should preferable shoot trough the chrono at a target. Sometimes the lowest ES does not necessary mean it will be the most accurate on target.

 

[srtmat]

Thanks 

I put it back to 11 then I checked the hammer spring adjuster measurement.

Factory - 16.4mm

Maxed out - 15.16mm

Set back to 11 - 16.1mm

It looks to me that the factory setting would have landed at about 13 or 14 which looks like it was right in the middle of that nice plateau. It appears it was in a pretty good state of tune from the Factory. I think as long as your in that range you’re good. I may test within that range but for now it seems happy.

Tested a bunch of weight and sorted MKI’s and MKII’s w/700mm. This “A” pellet liner did not impress with either. 1.25” groups at 75. I then shot 10 5 shot groups w/25.4’s which this liner was made for, a little better but still not great.

To be sure I didn’t mess up I put the 380mm back on PW 4 zeroed and shot a .600” 5 shot group at 75yds. So I shot 10 more 5 shot groups for an average of .841” same kind of groups it was shooting on factory tune. Pellets straight from tin. I’m going to sort some and see if we can shrink even further. Pretty happy with this 380 liner.

No need to throw anymore pellets down the 700mm liner. I’m getting a slug liner which is really what should be in here.

 

[mtnGhost]

Looks like you're having fun! I'm with the others, finding the knee doesn't necessarily translate to accuracy. I'd go with the manufacturer's velocity recommendations for the pellet you're shooting, then just experiment and shoot at closer range until your groups touch. Then stretch it out further and see if it's still happy. From there, you can fine tune.

Just be aware that if you have success / accuracy at velocity X, it doesn't mean that you will have equal success with a different configuration to achieve the same speed (e.g. high pressure + lower HST might yield you hole in hole at X FPS, but that same X velocity might be a 4" group with low pressure + higher HST). You're rifle will talk to you and tell you it's preferences eventually  

 

[Dairyboy]

If I'm reading right the first shots (1, 2, 3) are with the hammer spring near max? Cause then you'd ideally want to be around the 22 range. You'd get much better efficiency and lower hammer spring tension which should translate to a smoother shot cycle.

 

[Long_Gun_Dallas]

Sounds like you're making good headway! The main bonus from sitting behind the curve is increased shot count. But, being its a bottle gun, that's not a huge concern.

But as mtnghost said, higher pressure and less hammer may work well, too. I havnt gotten to do a lot of shooting with slugs yet, but I can tell you the jsb 18.13s are not picky at ALL about the tune thru the 380mm. Not mine anyhow. Factory setting was 130 bar, and peak efficiency seems to be right at 131 (balance between hammer, pressure, volume, and power) my gun is .22 though, I know most people are shooting 25 these days

 

[srtmat]

Dairyboy 

You are reading that correct. hammer spring adjuster is maxed at 0 which was 15.16mm.

I like your thinking. If I can get max speed with less hammer spring all the better I would think. I’m going to back it out a bit this week and do some testing.

Mat 

 

[spyde82]

I never really understand how that graph works if you only shot one shot how can you see if it is consistence? Mine need a couple of shoots to set when i adjusting the hammer spring

 

[srtmat]

I was a little confused about the graph at first too.

I tried a few shots at 0 on the graph, “hammer spring adjuster at “Max” and there is no consistency from shot to shot. That’s why you have to keep slowing backing it out 1/4 turn at a time until you start to see it flatten out.

I don’t think you will see any consistency in the 1-7 range no matter how many shots. 

I’m still testing but I’ve adjusted it to “11” then up to 16-17 and now I’m back to about “13” 16.4mm which is pretty much right at the factory setting. It’s shooting it’s best 50yd groups with the 380mm here. Groups were really pretty good across the whole plateau.

I’m shooting 9 5shot groups and was averaging .560” - .600” and on the current setting .534 and if it wasn’t for a couple flyers on one group out it would have averaged .481

Testing at 100yds is starting today. Not sure the 380mm has enough power to keep them stable at distance but I’ll run some through the 700mm as well and try some different speeds.

 

[srtmat]

 

[Cheytac]

17 I let at that velocity. If you go to 22 it may shoot all over.²

 

[srtmat]

I think 22 and bit beyond will still be consistent but power will drop off pretty quick.