velocity question /barrel effect

[MYCAR47562]

What would my velocity drop be if i took a 30-30 from 20 inch to 16 inch? and if you use a program can you tell me which load you used please?

 

[sniperpeeps]

Your velocity drop would depend alot on your type of powder and projectile. You could expect somewhere around 20-30 FPS per inch you take off of the barrel, but every barrel and load is different. It would be best if you could chronograph before and after and experiment with various loads. Also, if you are hand loading, the type of powder will effect the velocity change as well. The reason that a longer barrel acheives more velocity is because the burning powder has more time to completely burn off and more time to push the bullet. As the barrel shortens, the powder has less time to completely burn and less time to push the bullet. The bullet is accelerating in the barrel and as soon as it leaves the barrel, drag and other weather conditions begin to slow it down. We experimented with some .300 WinMag that was loaded long through a 20" barrel, which is really short for that cartridge. We were getting equivalent velocities of standard loads out of a 24" barrel, but we could not get it any faster. However, the difference between the velocity deviance between the two loads in the short barrel was much smaller than the deviance in the 24" barrel. We were getting around 150 FPS faster with the hot load out of the 20" barrel but out of the 24" barrel we were getting almost 200 FPS faster, which we attributed to all of the powder completely burning off before the bullet left the barrel. I am no ballistics guru, but I hope that helps explain things a little.

 

[sniperpeeps]

I updated that post with a little more info, hope it helps

 

[MYCAR47562]

i have read that the 30-30 round(factory load) burns most of it's powder in the first 14 inches of the barrel, can you or anyone else confirm that?

wish i was hand loading but im not yet, just using (right now) core-loks

 

[sniperpeeps]

I wouldn't know for sure but that sounds about right, it's a slow moving round. My knowledge pretty much revolves around .308, .300, and .50. I would take an educated guess and say that dropping your barrel length really wouldn't make a noticeable difference in the performance of your rifle. Yea, you will have a little bit slower muzzle velocity, but you aren't shooting any long range competitions with a 30-30. If you are just using it for hunting and such, I don't think you will notice a performance difference at all.

 

[MYCAR47562]

thanks, hopefully i will be able to borrow a chrono before i start the modifications, i would really like to see the hard numbers but i don't know of any outside of paintball chrono's and i doubt they would work.


this deffinatly will not be a long range comp gun lol this will be more of a wall hanger range fun toy for me and my father

 

[sniperpeeps]

Check with your local gunsmiths or your local range, somebody will have a chrono.