Tuning .30 cal slugs with 600mm barrel

[Eddie00]

Hi guys, I'm will soon receive my Great White SCBA tank from Joe Broncato!! I am eager to start testing .30 cal nielsen slugs, but I always hear people saying you need a 700mm barrel, however I have the 600mm barrel. I hope to get input from you guys and see what you think about the difference between an extra 4 inches, I'm not trying to spend an extra $400 for and extra 4 inches of barrel lol. I hoping I can get the same results from my 600mm barrel. Can anyone guide me to what speeds you guys are shooting .30 cal nielsen slugs at? Possibly include reg pressure, hammer spring measurements, and valve measurements that way I have something to work off of. Much appreciated.

 

[Eddie00]

lol

 

[mtnGhost]

You don't need any specific barrel length to shoot slugs. Simplifying the origin if that myth - the longer the barrel, the higher the velocity for a given reg pressure + plenum volume.


You'd want more plenum volume the longer the barrel is, but it's a relatively insignificant requirement for shorter barrels, since that plenum volume is effectively filling the barrel bore chamber with pressurized air - driving the projectile. 


That's the rudimentary explanation, so I hope that makes sense!

 

[Eddie00]

Pretty much what I was thinking. So to clarify, I have the Impact Mk2 with the Power Plenum, so with 600mm barrel I think I should be able to achieve proper speeds for good accuracy?

 

[triggertreat]

The extra four inches will yield another 40 to 50 FPS roughly with all else the same. Regardless, just a little more speed. I chose 600mm for the .25 cal for the compactness and 700mm in .30 cal for the extra power. Ironically, mine will shoot 34gr at 960 FPS, same speed as the .30 cal shooting the 44.75gr.