Quick question on issue with WCBT tune

[lbmalleo]

Hi guys, first of all I wanted to thank all of you that helped me tune my Impact MK2!
I am now in the process of tuning my Wildcat BT .22, 600mm Barrel, trying to shoot a 27 grain slug at about 950fps (target speed), slug power kit.
The slight problem and consusion I am having is that I’m trying to reach the highest possible speed at dial #7. I get close but only if I take all of the pre-load off the hammer adjustment dial, in other words I get the highest speeds with the dial all the way in instead of out, every time I move it back it drops in speed and I get the highest speeds on lower dials. I watched Ernest Rowe’s vids and he talks about setting the 6mm screw off the hammer adjustor, I’ve done it and the speed is super low, only when I set the screw to 0 is when the speed gets there. I’ve tried between 120 Bar all the way up to 135 Bar and the results are similar. So at 128 Bar I was able to get 950 on dial number 5 but not on 6 or 7.
Do I need a little more hammer weight to open the valve or a tighter spring? I do have a set of Humas.
Sorry to bug again and thanks for the patience!

Lucas

 

[Headshots]

It sounds like you have too much hammer . I would turn down your hammer to find max fps on pw7 . Then slightly back off your hammer for best efficiency.

 

[lbmalleo]

Thanks for your help, should I try a lighter hammer?
L

 

[Larryt]

My Maverick .22 700mm, which is essentially same gun, different chassis, with H&N 27gr HP Slugs:

2nd Reg 130 Bar
PW #7
IHS - 3/4 - 1 turn out
Slug Power kit with 13g hammer weight
FPS: 990

What gauge do you have for reg? The analogue gauges can be as much as 15 BAR out. I use Huma and Sekhmet so I am confident on my reg pressure reading being closer to shown value.

Hope this helps you??

 

[lbmalleo]

It sounds like you have too much hammer . I would turn down your hammer to find max fps on pw7 . Then slightly back off your hammer for best efficiency.

I have the hammer adjustment setting all the way down, that’s when I’m getting my highest speeds, I can’t back it off any more and whenever I put hammer on, the speed drops. In other words, the system is working backwards for me.
L

 

[lbmalleo]

My Maverick .22 700mm, which is essentially same gun, different chassis, with H&N 27gr HP Slugs:

2nd Reg 130 Bar
PW #7
IHS - 3/4 - 1 turn out
Slug Power kit with 13g hammer weight
FPS: 990

What gauge do you have for reg? The analogue gauges can be as much as 15 BAR out. I use Huma and Sekhmet so I am confident on my reg pressure reading being closer to shown value.

Hope this helps you??

Thanks, I’ll keep those numbers in mind.
I’m not having troubles finding my speeds, I just want to have the whole ”range“ possible. Im getting the speeds on dial #5 or #6 but can’t find the highest speeds at #7. I only reach high speeds when the adjustment dial is all the way “in” instead of “out”. Can’t seem to find the balance!

 

[Trucker3573]

I know it sounds dumb but Rick eutsler did it in his mk3 video…..are you sure you are looking at the scale correctly on the wheel ? The actual number it is set on is at the bottom not the top.

If this isn’t the issue it’s a simple fix. Set your desired reg pressures, turn the wheel to adjust, turn that internal screw way in, set the PW to 7 and slowly work that internal screw back out. Check velocities at each adjustment until it doesn’t increase anymore.

 

[Headshots]

I have the hammer adjustment setting all the way down, that’s when I’m getting my highest speeds, I can’t back it off any more and whenever I put hammer on, the speed drops. In other words, the system is working backwards for me.
L

That's telling you need more reg pressure or a lighter hammer. I would up the pressure then try again on #7

 

[lbmalleo]

I know it sounds dumb but Rick eutsler did it in his mk3 video…..are you sure you are looking at the scale correctly on the wheel ? The actual number it is set on is at the bottom not the top.

If this isn’t the issue it’s a simple fix. Set your desired reg pressures, turn the wheel to adjust, turn that internal screw way in, set the PW to 7 and slowly work that internal screw back out. Check velocities at each adjustment until it doesn’t increase anymore.

Hi, yes, I’m aware of the reading, learned the hard way though!
I did exactly what you suggested and I’m getting the highest velocities right off the bat, as I dial back the velocities decrease instead of increase.
L

 

[lbmalleo]

Guys,
I changed the hammer weight to the lightest of the Huma pair, then slowly crept up the Reg Pressure and voila, it worked like a charm so thanks to everybody for their suggestions.
I do have a couple of questions, do I need to dial down the hammer spring tension about 10fps in order to get better efficiency or can I just dial down to 6 or 5?
Another question, when do you need the heavier hammers?
Thanks again,

Lucas

 

[Headshots]

Guys,
I changed the hammer weight to the lightest of the Huma pair, then slowly crept up the Reg Pressure and voila, it worked like a charm so thanks to everybody for their suggestions.
I do have a couple of questions, do I need to dial down the hammer spring tension about 10fps in order to get better efficiency or can I just dial down to 6 or 5?
Another question, when do you need the heavier hammers?
Thanks again,

Lucas

I would leave it on 7 and back off the hammer a little, 10 fps would be enough imo. With your chronograph you can fine tune for the best standard deviation.

Your dialing in for your main ammo , but turning down the power wheel down will help with lighter pellets or slugs . You don't get the best SDs but it does work.

You use a heavier hammer when you run out of hammer spring adjustment on your desired slug or pellets FPE or fps . You will hit a point where the reg pressure will be too much for hammer . Then go heavier.

 

[lbmalleo]

Thanks so much!

 

[weevil]

Just curious - we’re you originally using a Tungsten hammer or just the heavier Huma brass hammer?

 

[HogKiller]

Thanks, I’ll keep those numbers in mind.
I’m not having troubles finding my speeds, I just want to have the whole ”range“ possible. Im getting the speeds on dial #5 or #6 but can’t find the highest speeds at #7. I only reach high speeds when the adjustment dial is all the way “in” instead of “out”. Can’t seem to find the balance!

Not to sound like a total jerk, but, unless you know the overall length of the HSA you've got no starting point or a reference point, you have to pull the thing and measure, then when you finally get it, take it apart and measure, now you have something repeatable.

 

[lbmalleo]

Just curious - we’re you originally using a Tungsten hammer or just the heavier Huma brass hammer?

I was using a 13g hammer, switched to a 12gram.

 

[lbmalleo]

Not to sound like a total jerk, but, unless you know the overall length of the HSA you've got no starting point or a reference point, you have to pull the thing and measure, then when you finally get it, take it apart and measure, now you have something repeatable.

I understand, I took it out 2 times and measured 6mm on it and it wasn’t until I screwed it in that the velocities started to climb. After switching the hammer weight I forgot to measure, what I did was started to back it up until the velocities didn’t climb anymore, that way I assumed it reached its max power at 120Bar. Gun tuned very well after that!