Optimum velocity for medium weight pellets?

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  • #898
    benzin
    Participant

    The only pellets i can get in my town, are medium weight ones, like crossmans, gamos, etc.
    So i adjusted the top hat on my condor, so it will fire them at arround 1000fps (acording to softchrono).
    I get a lot of shots, and velocities seem consistent, the only problem is…
    The accuracy stinks!
    No kidding, i get better groups at 30 meters with my CFX!
    i suspect too much velocity is the problem.

    So the question is…
    What speed do you guys consider optimum for medium weight (say 15grain) pellets??
    the idea is to shoot them as fast as possible, while preserving nail-driving accuracy!

    Thanks!

    #28375
    colinb
    Participant

    as far as i can tell as close to the speed of sound without breaking through it is the optimum velocity for a diablo shaped projectile

    as the laws of physics stay the same until you hit that barrier then up is down and down is up and shock waves cause havoc

    id probably guess its something else causing the accuracy problems

    but the only way to tell is to turn down the power and see if it helps

    #28377
    teflontron
    Participant

    Most people say that about 850-950 is best for absolute accuracy, but like all things it really depends on multiple things and comes down to your own testing.

    #28382
    daved
    Participant

    I think you’re going to need to be below 900 fps before you’ll see anything close to acceptable accuracy, and lower might be better. I can get away with Kodiaks at close to 1000 fps, but even they do better at 900-950. Most of the mid weight pellets I’ve shot in other guns seemed to be best between 800 and 850 fps, I’m still experimenting with my Talon. Good luck.

    Dave

    #28389
    benzin
    Participant

    Thanks for your answers.
    The reason i suspect excesive velocity is the problem, is that i can see no other reason for this poor accuracy.

    Heres my “checklist” for accuracy (if im missing something, please let me know)

    1- Shooter (me), i stink, but im using the bipod 😆

    2- Consistent velocity, according to softchrono, i do get it, variation from shot to shot is little (most arround 10fps)
    I did this by installing my heavy hammer, setting the PW on 10, and regulating speed with my top hat instead of PW.

    3- The right pellet, ibe tried about 5 diferent medium weight ones, and i get the same results.

    4- Barrel quality, well, i tried cleaning it, no improvement. The crown seems OK, no visible “bumps” or damage of any kind.

    5- Enviroment, most testing was indoors, and the outdoors ones, were made with no wind.

    6- the right velocity?? im shooting 14.3 crossmans starting at about 1050fps ~ 1030fps

    7- “Other” causes? i had a home made LDC installed, it was a 1.5″ PVC pipe with and end cap. and a rolledup piece of rug inside it. I removed it, same results ( just to be shure, i wont do any more accuracy testing with it attached to the gun)

    I can see no other reason for the terrible accuracy, except for too much speed.
    If anyone has any additional hints or sugestions i would really appreciate them.

    #28394
    walkonking
    Participant

    No matter what I shoot I keep the velocity around 950fps or less. I have found that accuracy is so much better and consistent. I stopped chasing power a while ago. My career can through kodiaks at 1300 fps and I still only use 950fps and less.

    My Talon is set up perfect now with a 16″ barrel from Tony and vented bushing with one of his shrouds. The valve is tuned and it shoots Premieres at 956fps with amazing accuracy at 100 yds and it is quiet. That is what I want from an air rifle. Anymore and I reach for a firearm.

    #28420
    benzin
    Participant

    I re-adjusted the tophat, now i get arround 920fps with 14.3 crossmans, and accuracy has improved A LOT 🙂

    I havent done long range testing with this new setting yet, only 10 meter grouping, but results look very promising.

    At this range, (10 meters), i got about 1/2 ~ 2/3 inch groups before, after slowing the gun down to 920fps, i get only 1 hole groups 🙂

    thank you guys!

    #28427
    benzin
    Participant

    Just one more question please…

    What kind of accuracy, can i expect at say, 50meters (about 55 yards)?
    I need some kind of reference point, so i can accurately judge if the gun is performing OK or not.
    What kind of grouping do you guys get at this range? im not saying you “absolute best groups” just your “average”

    #28429
    teflontron
    Participant

    I think that you should be happy with sub 1 inch 5 shot Groups at that range if it’s on a regular basis.

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