Tuning Hammer spring preload??

I have been trying to perfect my maverick .22 BT compact to shoot 25 grain pellets but for the life of me can’t get my Allen key to fit into the hole for the adjustment. So… can anyone please recommend what I should set this thing to? Ernest Rowe recommended 6mm in an old video about disassembly but what about actual tuning? Should I max it out and slowly adjust backwards? Kind of a pain until I get a new hex set. Currently set to 6.33mm and at 110 bar was shooting 18.13 grains at 880 fps

edit: have 3 hammer weights to chose from as well. 4mm 11.g 6mm 12g and 8mm 13g

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I think he shows on one of his videos what hammer weight you need to get to max power with heavier pellets. Also has dope sheets to each pellet weight, barrel length and caliber to make it even easier. Just sayin’…….
I have a .22 Maverick Compact and shoot 15.9 FX pellets and have “tunes” to go up to 28 gr. Need heavier hammer weight for the 28’s and 30gr.
 
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I changed my Maverick Compact 25 to a 22 600mm barrel. I put a stock 22 hammer weight in and went to work. somewhere in the forum I have an older thread about why wouldn't the gun shoot 25's at 900 fps. I ended up putting the 25 cal hammer weight back in with the 22 barrel to achieve decent speed with 25's keep that in mind.
With the short runway in your compact that issue will only be worse.
what size Allan wrench are you trying to use? hate to ask questions like that but I have made similar goofs. if it is 1.5mm then you may have to open the adjust ment hole up with a 2mm drill bit. maybe there is something obstructing the hole?
I would leave the IHJS where it is and adjust the 2nd reg to get to a speed of about 5-7% over your target speed. Then you can reduce your speed with the IHS.
 
I changed my Maverick Compact 25 to a 22 600mm barrel. I put a stock 22 hammer weight in and went to work. somewhere in the forum I have an older thread about why wouldn't the gun shoot 25's at 900 fps. I ended up putting the 25 cal hammer weight back in with the 22 barrel to achieve decent speed with 25's keep that in mind.
With the short runway in your compact that issue will only be worse.
what size Allan wrench are you trying to use? hate to ask questions like that but I have made similar goofs. if it is 1.5mm then you may have to open the adjust ment hole up with a 2mm drill bit. maybe there is something obstructing the hole?
I would leave the IHJS where it is and adjust the 2nd reg to get to a speed of about 5-7% over your target speed. Then you can reduce your speed with the IHS.
It’s an example of having imperial hex keys instead of metric so it’s .05 inch not 1.5mm lol I just need to buy the right one but I do have a 1.5mm bit that I use to tune it when the gun is disassembled. I put in the 6mm 12g weight that @Utah-Airguns sent me and shot a horrible string of 850 816 830 850 fps and was like EEK then realized I was running out of air and daylight… will continue with updates here but I think you’re putting me on the right track.
 
It’s an example of having imperial hex keys instead of metric so it’s .05 inch not 1.5mm lol I just need to buy the right one but I do have a 1.5mm bit that I use to tune it when the gun is disassembled. I put in the 6mm 12g weight that @Utah-Airguns sent me and shot a horrible string of 850 816 830 850 fps and was like EEK then realized I was running out of air and daylight… will continue with updates here but I think you’re putting me on the right track.
Best of luck to you. If you get stuck or frustrated there are quite a few people here with very good knowledge and experience with the Maverick platform
 
I've been researching like crazy but its hard for me to find the right resources when I myself don't know the terminology of exactly what I'm trying to do all the time. Like inletting???? never would've known that's the word I was looking for when I was messing with a custom stock. But I appreciate everyones help here and I'm glad to put all my knowledge that I gain over time out there so maybe someone finds it later on.
Best of luck to you. If you get stuck or frustrated there are quite a few people here with very good knowledge and experience with the Maverick platform
 
I've been researching like crazy but its hard for me to find the right resources when I myself don't know the terminology of exactly what I'm trying to do all the time. Like inletting???? never would've known that's the word I was looking for when I was messing with a custom stock. But I appreciate everyones help here and I'm glad to put all my knowledge that I gain over time out there so maybe someone finds it later on.
It is the point of the forum. Share what we know and learn to help each other. When I started here I knew nothing and learned plenty. Good bunch of folk
 
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I have the 25 BT so no real experience with 22. 110 bar seems really high for 18 gr out of a 600 mm though. You really can’t do anything until you get the 1.5 wrench as that screw is key to tuning. I personally do it opposite of what many recommend with this platform. I start with the screw turned way in clockwise and work my way up. If you seek to shoot 25 gr pellets like said above the 25 cal weight is probably the way to go. Just to ballpark for you my settings in .25 with the .25 weight are 115-117 bar and 33.95 are about 905 fps.
While I have no doubt the fancy tuning add on mentioned makes it more convenient the gun stock is super easy to tune very well.