I recently bought a Tell 2 that is shooting 125 fps. Just curious what they normally did?
I recently bought a Tell 2 that is shooting 125 fps. Just curious what they normally did?
Funnily enough I investigated this myself in a previous thread (http://www.airgunbbs.com/showthread....ght=twist-grip). Using Milbro waisted pellets, average weight 5.74 grains, and resizing them by pushing them through the barrel, I obtained a fairly consistent 200 fps. This was using a very good condition, little used Tell 2 pistol.
Interesting, lightest pellet I have is a 7 grain hobby, and never thought about resizing. I’ll have another go.
Interesting physics problem, your pellet is about 20% lighter, does that correlate to reducing your speed 20% to equate to a 7 grain?
Good afternoon experiment, sizing a 7 grain and seeing if oil has helped the seal? Not sure this makes any difference but this is what we do. Lol
Last edited by 45flint; 18-02-2018 at 04:49 PM.
No doubt resizing is the key here: thanks much for that idea. I had to push pretty heavily to get a 7 grain hobby into the barrel. Resizing put my fps up to 160. Given the lighter pellet above the math would put this just about equivalent? I think this pistol would be better with a thin skirted pellet. Crosmans come to mind I’ll see if I have any around.
Value of the forum, not sure I would ever thought about resizing?
Last edited by 45flint; 18-02-2018 at 05:44 PM.
Actually there is not a simple inverse relationship between muzzle velocity and pellet weight. So if the pellet weight is increased by x%, the velocity does not go down by x%.
The pellet velocity is actually proportional to 1 over the square root of the pellet weight.
In my example, a 5.74 grain pellet gave 200 fps. If I were to increase the pellet weight to 7 grains this should theoretically give a muzzle velocity of 181 fps, all other things being equal.
In case you think I am a mathematical genius, I just plugged the numbers into one of the many available online calculators: https://www.airgundepot.com/airgun-c...s-article.html