FX Testing different slug diameters…same tune?

[carlos_hathcock]

All right, I can already hear the shouting from the back row that your mileage IS GUARANTEED TO DEFINITELY vary because your rifle is like the fingerprint of some enigmatic person you've never met, but here goes. Please put down the pitchforks, torches, hot tar & feathers.

When testing different slug diameters, can one find the best tune for the first diameter, then use it to test the other sizes to find which diameter is best?

I'm interested to hear if the white lab coat wearing, scanning electron microscope wielding, decades of experience luminaries here would generally say yes or no. Or do I leave instructions for my headstone to read, "He devoted his life to airguns, went bankrupt on ammo, and got 13% of the way home".

(At work, missing my rifle)

 

[bdzjlz]

I have seen situations in my testing where velocity will vary for the same slug weight and series but different diameters. I think there is a correlation to how tight the slug fits into the bore.

I don’t know that I ever changed the tuning characteristics because of it.

 

[nervoustrig]

A fixed state of tune will seldom provide a useful test bed for evaluating different slug diameters. At least not when testing at distances, say, 50 yards and beyond.

Why? Changing the slug diameter changes bore friction, sometimes dramatically. Friction affects its acceleration (read: dwell…how long it spends in the bore). Therefore, valve dwell needs to be adjusted accordingly, otherwise the shot-to-shot consistency will be negatively affected. In other words, producing a poor extreme spread and contributing to greater vertical dispersion as distance increases.

 

[darknes]

why change the slug diameter. it's simple, it's a used barrel. if the barrel has a hard chock, it is a good idea to use a smaller slug diameter. I myself use fx dynamic.25 slugs with an average of 6.33 instead of 6.35 and it is a lot to know how it helped. if the barrel does not have a chock, it is better to use 6.35, also tested by buying an 800 liner and shortening it to 700mm and thus canceling the chock. so yes a different slug diameter will help a lot in certain cases. and in terms of accuracy it is actually better than the full average.

 

[Vetmx]

I think what a lot of guys battle, then it puts them behind the eight ball is Christmas syndrome. When a grown man receives all his little boxes of fun, he just wants to play with them all as fast as possible. And in the case with slugs, is hoping to stumble quickly into a jackpot winner. Personally I start with one slug and do every trick in my bag to see if it works. Fortunately I have tested so many, it doesn’t take very much for me to know it’s not going to give me the results I want. Then I move to the next slug. You absolutely cannot get ahead of yourself. It will cost you money and time. Instant gratification is for pellets and powder burners.

 

[darknes]

I tested all the slug manufacturers and in the end my own design of slugs won, which work best for me, they have better Bc than what I can buy in the store and most importantly they cost me 35% compared to the ones I buy and that's counting the cost of development and production of the matrix, lead wire, and the time I spend on production . I make about 80 of them per hour. as soon as I produce 9000 pieces, the price will drop to 15% per piece because I will have paid the costs that I put into it.