Short Barrel Ballistics

[kenneycrockett]

Seems impossible to find any credible information on this topic.
I have a 7mm-08 with a 22inch barrel, im wanting to cut it down to make a better bush carrying rifle. The question is how can I work out where my new limitations will be depending on the length I go to. "Aparently" you lose about 50fps per inch... but what does that actually mean in practical terms? How can you work out how much energy/velocity the bullet will have at certain ranges when coming out of a different barrel length. What does it mean when your talking about an animal thats getting hit by a bullet at x amount of distance? How about trajectory? Is there any practical difference when something gets hit by a bullet from a 24inch barrel and something getting hit by a bullet from a 18inch barrel?

any links providing info on this topic would be appreciated!

cheers

[McDerry]

You won't find any realy credible information. There is to many variables.  You will loose some speed by shortening up the barrel.  Inturn you'll loose some energy and some range.  You would have to chronograph the new muzzle velocity after shortening the barrel to calculate the energy.  The critters won't know the differance.  Cut an old enfield down from 25" to 16.5" a few years back and it still drops whitetails like sacks of potatoes out to a couple hundred yards, mind you it lost 300 fps in the process.

[Bigeasy]

Buy a cheap chronograph to check your velocities.  Most reloading manuals (Speer for example) have a chart that lists bullet BC.  Look up the BC of the bullet you are using, and the velocity.  It will give you down range velocity and bullet drop for that load.  Most manuals list the formula for figuring energy based on bullet weight and velocity.  If you don't want to invest in a chronograph, a good rule of thumb for non magnums is about 25 to 50 fps per inch.  Lots of stuff out there if you Google it, including the info I just gave you.  My 7mm/08 Ruger has a 16 inch barrel.  Kills deer just as well and as far as my Kimber in the same caliber with a 22 inch barrel.

 Heck, I even attached a couple links..

www.firearmexpertwitness.com/customguns/calcnrg.html

http://www.google.com/url?sa=t&source=web&cd=8&ved=0CDEQFjAH&url=http%3A%2F%2Fwww.handloads.com%2Fcalc%2F&ei=qLRrTO_uC4P7lwebrLjzAQ&usg=AFQjCNFVe8pOXCAn9HsThcoFUvmE0va46A

Larry

[chutesnreloads]

You mentioned"bush" carrying rifle.If you're hunting in the bush you probably aren't shooting far enough to make any difference in the velocity loss.

[gunnut69]

The loss of velocity will cause a lessening of the energy delivered and the amount is variable lossly based on the cartridge. The higher the intensity rounds uch as the 22-250 lose more than say a 30-30. Still velocity lost is energy lost. If the remaining energy is sufficient to the task at hand all is well. Also faster powders lose less velocity as the barrel is cut than the same cartridge loaded with a slower powder, although usually the slower powder will generate higher velocities for a cartridge, of course this can vary by load and individual rifle.. Measure what you end up with, used the balisitcs tables to calculate energy at range and concentrate of shooting well. Remember a bullet only works if its put in the right place!

[grdad45]

My Ruger Compact rifle in 308 has a 16 1/2" barrel. I shoot 150 gr PSP bullets, and it hammers whitetails as good as my 22" 280 Rem. I wouldn't hesitate to shoot out to 300 yards with it, so if you want a short barrel, go for it!