Modify Crown mk2 stock for easy access to internal hammer spring adjustment.

[tor47]

Before you consider cutting into the stock, you might try the newer powerwheel first: https://www.europeairguns.com/en/repuestos-2/fx-airguns/fx19908
That will probably get you finer steps to adjust between each click

 

[MEC17670]

Thanks for the info.
I have the latest version of the power wheel , 1 through 24, unless I missed something.
The idea on modifing the stock was to access the internal pre-load adjustment while being able to fine tune groups, much like the micro tune on the new Impact 3. 1/8 of a turn on the internal pre-load could affect group size. Extremely hard to shoot groups with the stock off and to stream line the process would be productive.
Thanks for the input.
Mike

 

[jking]

I set mine Crown up so that at "Max" the micro adjuster is also at max. The factory wheel to me seems to have enough lowering setting to fill my needs and then it's just a matter the keeping the micro screw from backing out with a little loctite. I agree though that pulling the stock is a inconvenience and those pesky little steel balls. That 1-24 adjuster does look enticing though.

 

[LDP]

Yes, I know the 500mm will bring my velocity down, but if I could shoot 25.4 gr pellets... or slugs in that weight range @ 900+, I'd be happy. I'll get around to tryinging that tuning method because it has the potential. Thanks for the info.

I shoot the 25 gr. in my 380 mm at 800 fps and its not maxed out. I would think the 500 mm would hit 900 fps. Mine is a crown mk2 so if you have the first gen you might not see the same fps.

 

[LDP]

I set mine Crown up so that at "Max" the micro adjuster is also at max. The factory wheel to me seems to have enough lowering setting to fill my needs and then it's just a matter the keeping the micro screw from backing out with a little loctite. I agree though that pulling the stock is a inconvenience and those pesky little steel balls. That 1-24 adjuster does look enticing though.

I also have my pre load at max on max.

 

[MEC17670]

I set mine Crown up so that at "Max" the micro adjuster is also at max. The factory wheel to me seems to have enough lowering setting to fill my needs and then it's just a matter the keeping the micro screw from backing out with a little loctite. I agree though that pulling the stock is a inconvenience and those pesky little steel balls. That 1-24 adjuster does look enticing though.

1-24 adjuster is nice. I tore up my first one, my bad. Ran it it on 24 to much. Curve of the cam on 24 is thin, now I don't go beyond 23, but there it's very close to maxed out.
I have a stainless steel pw after market also. In order for the machinist to allow me to buy it i had to swear not to divulge my source, sorry. Haven't installed it yet but looks rock solid and has a solid flat little setting locations.
What are you running for reg pressure? OME spring, probe?

 

[huntr]

I shoot the 25 gr. in my 380 mm at 800 fps and its not maxed out. I would think the 500 mm would hit 900 fps. Mine is a crown mk2 so if you have the first gen you might not see the same fps.

Mine's a MK ll also. My regulator is at !20, but if I go higher I loose velocity. So I'm assuming there is not enough 'umph' behind the hammer to overcome the pressure on the valve at higher reg. setting. Am I correct?

 

[MEC17670]

Mine's a MK ll also. My regulator is at !20, but if I go higher I loose velocity. So I'm assuming there is not enough 'umph' behind the hammer to overcome the pressure on the valve at higher reg. setting. Am I correct?

How long is barrel and are we talking .22?

 

[MEC17670]

How do you have your internal pre-load set up, maxed at 24?

 

[MEC17670]

Reg, 155, tf H, pw 23. 29 gr slugs 953 fps. 6 shots. 57 yards.

 

[huntr]

How long is barrel and are we talking .22?

I have a 500mm , .22 cal. barrel and preload was adjusted on the low setting. Following the AEAC method. I started out, if I remember, at reg. pressure of 140 or 150. I had to keep backing it down until I got to 120 to get around 880 with 21 gr pellets or slugs. That's PW 23, TP high.

I definitely need to try setting the preload on the max PW setting to see if that makes the difference. Just time consuming, as you said, and I haven't taken the time to do it.

 

[LDP]

Mine's a MK ll also. My regulator is at !20, but if I go higher I loose velocity. So I'm assuming there is not enough 'umph' behind the hammer to overcome the pressure on the valve at higher reg. setting. Am I correct?

not from my experience. I ran my reg up to 150 and had no issue opening the valve with stock hammer and spring.

 

[MEC17670]

I have a 500mm , .22 cal. barrel and preload was adjusted on the low setting. Following the AEAC method. I started out, if I remember, at reg. pressure of 140 or 150. I had to keep backing it down until I got to 120 to get around 880 with 21 gr pellets or slugs. That's PW 23, TP high.

Getting to the same place from different directions.
I found for me, going to 23 then adjusting preload so there's no movement up to 24 then backing off a tiny bit. Then go to 21 on the pw and start increasing reg pressure till i get close to the velocity I'm looking for with the heaviest projectile i want to use. I then shoot for groups.
This post was started to find away to fine tune the internal pre-load in an attempt to find that sweet spot where harmonics are balanced, matter of dwell, imo. Equal forces acting opposite but equally, while being able to shot groups. As the Crown is manufactured, love the gun, this is extremely hard to due because you have to take off the stock to tweek that pre-load. Yes, it takes loads of time and help. Lots of help here, the rest is up to you.
Have fun, take good notes and pictures. You'll get just right for you.

I definitely need to try setting the preload on the max PW setting to see if that makes the difference. Just time consuming, as you said, and I haven't taken the time to do it.

 

[LDP]

I have a 500mm , .22 cal. barrel and preload was adjusted on the low setting. Following the AEAC method. I started out, if I remember, at reg. pressure of 140 or 150. I had to keep backing it down until I got to 120 to get around 880 with 21 gr pellets or slugs. That's PW 23, TP high.

I definitely need to try setting the preload on the max PW setting to see if that makes the difference. Just time consuming, as you said, and I haven't taken the time to do it.

set the power wheel on max which is 23 on my mk2 then take the power wheel and safety off and remove the stock. Put the power wheel back on and adjust the preload so its almost bottomed out. You dont want to bind the power wheel at max so just enough room to hit max on the wheel and not be jamming the wheel binding it. You should be able to run up to 150 bar. Mine is currently set at 145 and with a 600 mm barrel I am getting 865 fps with .25 cal 25 gr. JSB with the power wheel on 8.

 

[MEC17670]

set the power wheel on max which is 23 on my mk2 then take the power wheel and safety off and remove the stock. Put the power wheel back on and adjust the preload so its almost bottomed out. You dont want to bind the power wheel at max so just enough room to hit max on the wheel and not be jamming the wheel binding it. You should be able to run up to 150 bar. Mine is currently set at 145 and with a 600 mm barrel I am getting 865 fps with .25 cal 25 gr. JSB with the power wheel on 8.

Sounds right on, what's your transfer port set on?

 

[LDP]

Sounds right on, what's your transfer port set on?

I leave mine on high for all my fx rifles.

 

[MEC17670]

I leave mine on high for all m fx rifles.

I move mine to medium when shooting 25.39 pellets. If not I'll shoot to fast at a reg pressure of 155. Power wheel set 15 , 910fps.
I'll double check that info later for fair comparison when the ambient temp raises.

 

[Bigragu]

You won't be able to get the long end in, I don't think. Didn't take the stock off to actually see. From memory, the recess in the action where the adjustment is, isn't long enough to do that. Try it with the stock off and see if you can do it.

A cut out, like Revoman referred to, might work if you beveled the bottom edge to allow more swing room for the hex. But, you're opening up that access point for dirt and debris to more easily get in. How many times are you going to make that adjustment? It's not a routine adjustment, like changing the HS

I agree. Unless retuning for different Ammo I’m a set it and forget it guy. I think about way back when when folks drilled out the back of their wildcat MK1 MK2 stocks to access the hammer screw adjustment, and I always wondered why? Set it, locktite the adjustment nut, and call it good.

I think with guns like the impact, that boast easy caliber changes and tunes on the fly, I see more folks rather than do caliber changes or even Ammo type changes, they just pick up another impact and set it for a certain caliber and certain Ammo type. Not everyone is going to be into note taking and busting out calipers to pull measurements of adjustment settings.

To the OP- I think once you find your “perfect” setting, I mean so perfect enough you’re not going to want to mess with it, you’re going to regret the notch out on your stock. Just my opinion

 

[LDP]

I move mine to medium when shooting 25.39 pellets. If not I'll shoot to fast at a reg pressure of 155. Power wheel set 15 , 910fps.
I'll double check that info later for fair comparison when the ambient temp raises.

Ya I have power wheel set on 8 for the 380mm barrel and the 600mm barrel. I dont know how fast it will shoot set on a higher power wheel setting at 145 bar I have never tried it. My 700mm barrel runs a reg pressure of 130 bar and pre load set about half with power wheel set at 23 for about 900 fps with 34 gr. JSB

 

[MEC17670]

Ok Guys,
You talked me into not cutting my stock. Already set the pre-load pretty close to as much as I can with out binding. Loktite it in the last time I was in there.
953 with a 29 gr . slug. Will do unless I fool with the reg pressure again. 44 shots per fill, and carry extra 480 air vessel. 88 shots while hunting should make for a good day. If I need more, I have my larger vessels to fill from.
Those 29gr. Neilson slugs gives me sub moa accuracy when I do my part.
Been a great stock modification post.
Seems we got into different tunes for our Crowns. What do you folks think about the adjustable seating depth pin probe?