AT44 or BT65 in .22?

Forums PCP Airguns AT44 or BT65 in .22?

  • Views : 2556
  • Link

    JDShapp
    Participant
    Member

    A Bull Boss maybe in my future Bwalton, but that won’t happen until the fall. For now this AT44 .22 short is going to be the rifle I always carry with me in the Jeep.

    Link

    Bwalton
    Participant
    Member

    I also have a short in .22  They like to be shot at 880-890fps Reg if possible,With a good tune and bell curve you can get a 12fps-15fps es if done right. Need any help let me know.
     

    Link

    JDShapp
    Participant
    Member

    Right now I’m working on the bell curve. The useable shots appear to start around 170 to 180 bar by the gauge. Most of the shots fell in the 850’s and highest was 866.4fps. That’s with 18.13gr JSB. I want to wait till its above 50 outside though before I begin any hammer spring adjustments.

    Link

    Bwalton
    Participant
    Member

    sounds good keep us posted

    Link

    JDShapp
    Participant
    Member

    Figured I’d give an update here on the AT44. I got a regulator into it, and after tinkering at first with the regulator going as far as up to 130bar, and then working on the hammer spring I think I’ve managed to find a happy medium at 117 bar with the hammer spring adjusted to work in the 860fps area again. It’s not the magic 880fps area, though I did get that before unregulated, but its good enough to put the hurt on some starlings now.

    Link

    JDShapp
    Participant
    Member

    Got up this morning, did one tiny adjustment to the regulator, and made sure everything was clean. Did a few shots over the chrony and now I’m shooting in the low 880 to high 870fps range.

    Next up is getting some new groups and getting my tank refilled.

    Link

    JDShapp
    Participant
    Member

    Got a few groups tonight in. As I expected my POI shifted, and so did some of my grouping. Before with the JSB 18.1gr I was getting close to .32 to .35 inch at 25yds. Now they’ve opened up to 1/2 inch but at the same time my 40yd grouping tightened up to 1/2 inch. So I’m going to give the barrel a good cleaning since I’ve chewed my way through about half of the 500 count tin of JSBs and see how does. Also next time I go out I’m going to try to get chrony numbers in direct sunlight vs the LED method I was using in my basement.

    Of course the accuracy differences could just be me rather than the tune I’ve done on the rifle itself.

     

    Link

    JDShapp
    Participant
    Member

    Today I decided to give the gun a complete tear down, and check along with cleaning the barrel. Probably wasn’t one of my best moments, but I got a good look at the hammer and the grub screw inside used to adjust the hammer spring tension. Took my time realigning things, and went as far as to give the grub screw a complete turn out, and then back in. After everything was back in and I did some more fine tuning on the Huma regulator I just set it back to how it shipped to me and adjusted the hammer spring.

    From all my tinkering I know I can make it fire over 900fps now if I wanted to, but I settled for it in the 870’s. Tonight after work I’m going to check how my groupings are now and hope for the best.

    Link

    blackdiesel
    Participant
    Member

    I would check different pellets.  I recently got a bad batch of Jumbo 18 gr pellets.  If I didn’t know my gun shot them very well in the past I would have thought it was a problem with the gun.

    Link

    JDShapp
    Participant
    Member

    Glad  you mentioned that. Rechecked my JSB 15.8gr grouping tonight and it was one hole at 25yds, and at 40yds it was .34inch ctc. That hands down the best accuracy I’ve had yet at 40yds for any pellet. Air Arms 18gr were a close second again at .43 inch ctc at 40yds. Shot count wise I’m getting about 25 good shots before it falls off the regulator. Not sure if that’s bad for anyone else, but for me its acceptable.

    Now all I have to do is make sure that spring I posted about in another topic doesn’t come off on the trigger again and I think I’ll be good to do some serious starling exterminations.

    Link

    JDShapp
    Participant
    Member

    Got my trigger fixed up and reset my zero last night. Have a ProChrono coming in next week to check out my fps since my old chrony got on my nerves for the last time today. Also have 2 tins of 15.89gr JSBs coming.

    Link

    JDShapp
    Participant
    Member

    Got to work with the ProChrono today. 15.89gr were shooting at roughly 884fps for 13 shots, then dropped off the regulator. The regulator is set at whatever the huma marking is between 96 and 110 is, which is also what they preset it at. For now I’m thinking I have the hammer spring set to high. In any case I’ll have to wait for another day to do more tinkering. Still the accuracy is there even after it falls off the regulator. All in all its proving to be good practice before I try working on the .30 cal.

    Link

    blackdiesel
    Participant
    Member

    Something up with your tuning.  I have the AT44 long which has a smaller air cylinder than the BT65 and I get 40 shots at 896 +/- fps with the 18 gr pellets and 920 +/- 4 fps with the 16 gr AA pellets. I have my reg set to 110 bar with no hammer spring tension.

    Link

    JDShapp
    Participant
    Member

    Its got be the hammer spring then, but this is even smaller since its a short version. For now I’m just happy that I have some verified consistent numbers from the regulator. Tinkering around with it will give me something to do until spring hits and I can begin planting trees where I want.

    Link

    JDShapp
    Participant
    Member

    Got to tinkering today. Bottomed the hammer spring adjustment for decreasing power and set the regulator to 110. Got an average of 875fps using JSB 15.89gr pellets and it should be delivering over 20 usable shots easy now. Would have done a full string but my tank is running low and won’t allow a full 200bar fill, but I’m thinking that’s 30 consistent shots now. For AT44 short 30 shots on a regulator will be good enough for me at this point. I can deal with 27ft-lbs as long as it stays wicked accurate like it is.

    Link

    JDShapp
    Participant
    Member

    A little more progress. I tapped and set screwed the 3 bottom holes on the valve. I may go back and epoxy or JB weld that part in to make it smoother. Now I get to do more testing to see if that increased my efficiency a little.

    Have to say its still a fun rifle to shoot, and should be even more fun to use once I’m finished. Between this and my marauder I shouldn’t have any trouble in the years to come once the sapling hazelnut and pecan trees I’m planting begin producing.

Viewing 16 posts - 21 through 36 (of 36 total)

You must be logged in to reply to this topic.