Thread: Barrel length vs speed

Can someone explain this to me like I’m a 5 year old please - if I was to chop a standard 22” 7mm08 barrell to say 18” how would that affect bullet speed and stability ?
Thanks in advance

Originally Posted by Nathan F

Can someone explain this to me like I’m a 5 year old please - if I was to chop a standard 22” 7mm08 barrell to say 18” how would that affect bullet speed and stability ?
Thanks in advance

Stability won't change, if done correctly accuracy potential will increase, you should lose around 150 fps depending on components used

Minimal effect on stability, and you might lose 100 or so fps.


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The reduced length of the barrel means that the expanding gases from the ignition of the powder have less time to drive the projectile forward so therefor the projectile will be travelling slower when it exits the muzzle than it would be if the barrel was longer. A practical way to demonstrate this is by using a pea shooter (e.g. a section of bamboo). Blow a pea through the shooter as hard as you can and have someone mark where it lands. Next cut the shooter in half and repeat. The second pea will fall short of the first.

Beautiful. Thank you all for the reply’s. Exactly what I was after. Cheers

Keep in mind the reduction in velocity does not mean you'll kill fewer animals.

I got my 7mm08 cut to 16" and it's a great rifle with plenty of killing power for short - medium distance (300yd or so) and I have found a few loads that the rifle seems to like a lot.

MV for the 139g interlock in front of AR2206H was 2700 fps as measured by chrono, but I am validating that with drops this weekend, assuming the forecast stays OK.

Originally Posted by Kiwi Greg

if done correctly accuracy potential will increase

how does this work?

Originally Posted by bang

how does this work?

Shortening the barrel can make it stiffer giving a more consistent point of exit for the projectile.

Originally Posted by bang

how does this work?

Greg has magic fairy shooting dust that he sprinkles on the barrel.

Originally Posted by sdogg73

Shortening the barrel can make it stiffer giving a more consistent point of exit for the projectile.

A long barrel may deflect more, but if the stimulus is the same it will react the same, so should still be as consistent. so would it be more correct to say that a shorter barrel is more forgiving for small variances in loads or heat?

I would be interested in obtaining some of that magic dust.... my shooting is atrocious

Originally Posted by bang

how does this work?

By shortening the barrel, it 'whips' less while the bullet is travelling down the barrel, less whip of the barrel means less inconsistency when the bullet comes out the end.

Same principle as a big heavy barrel on a target rifle.

As a general (approximate ) rule of thumb, for centrefires it is usually about the 50fps per inch when a barrel is shortened so the estimates of about 150fps would be within reason. As mentioned, in most rifles the projectile is accelerating rght up unto it exits the muzzle at which point the pressure behind it is released and it then relies on momentum.

This can be countered by using a faster burning powder that expends all of its energy in the time it takes to move the projectile to the muzzle, but to be hones, 100-200fps difference at the muzzle will not make much "real world" difference to most hunters.

If I run a basic calc with the Hornady white tail, instead of getting 2840fps at muzzle and just dropping below 2000fps at 400yds, it would be 2640fps at the muzzle and would drop below 2000fps at a bit over 300yds. If you are shooting eggs at 300 yards this might make a difference, but anything bigger than the 3" difference in drop and it wont matter....

Originally Posted by Rushy

Greg has magic fairy shooting dust that he sprinkles on the barrel.

How much per kilo?

Originally Posted by Max Headroom

How much per kilo?

Duh! It’s weightless. It’s magic. Ha ha ha ha.

Originally Posted by Rushy

Duh! It’s weightless. It’s magic. Ha ha ha ha.

Ok your Honour, i'll rephrase the question.

How much per cubic foot?