❓ How to slug a barrel?

[JungleShooter]

With NSA soon producing slugs of a wide range of diameters — .216 — .2165 — .217 — .2175 — .218 — I finally see a good reason to follow the advice of so many slug sages: "Go and slug your barrel, so you know which slug size your barrel will like."



Good, I will do just that.

Can you explain to me HOW??



▪(1) Do I use a slug or a pellet?

▪(2) I push the projectile thorugh the barrel, all the way (shroud removed) past the choke — with a cleaning rod — right?

▪(3) I need to take the barrel off the gun for that, right? (P15/Skyhawk)





▪(4) How in the world do I measure such tinzy-winzy differences in size?

▪(5) What instrument do I use? (I have 15-dollar digital calibers with more digits than the diameters....)



▪(6) Where do I measure that which I'm supposed to measure? And how do I make sure that when I measure that I don't just dent the soft and measure much more than the actual size?



Thanks for helping me out with this. To some of you this might be rudimentary, but hey, we all started somewhere....



Matthias

 

[jwrabbit123]

push 6 pellets threw barrel past choke and measure and get ave of 6 this is smallest part and add .0005 this would be ideal size ,

or

or take an old jag put it in choke and melt bismouth in barrel it will make an exact cast of your choke measure and add .0005 and this is size of slug



once you got size , then tune gun to shoot your slugs ,



OK stability , check your twist rate and your fpe ,

then match ammo by twist rate and your power to get ideal shape weights for your set up



to get a very rough idea

go here enter in things and see how stable it is ,

https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

 

[elh0102]

Or....shoot'em and see. Let the target make the decision. Whatever you might measure, you will second guess it anyway, so just get a variety for testing. Slugging the barrel is an interesting exercise, but don't expect it to be absolutely definitive of the best performing size. When I was casting bullets for metallic cartridge reloading, I would slug barrels. But the best shooting diameter would vary in different barrels of the same measurement. It would probably be realistic to expect the process to narrow your test group to three sizes.