Silly question time,

[rsc1960]

I have always wanted to ask this question, so bare with me, and I hope you understand what I am asking as I'm not a techy guy at all.

 

Eg: when I read some load data it will say that the bullet weight and amount of powder used was in a 24" barrel and we got such and such velocity,

 

Now if I was to load the same round of ammo and used it in a shorter barrel say a 20" barrel what is the possible results be,

 

Will there be a large lose of velocity

 

Will I have problems with pressure

 

Etc

 

Cheers

 

RSC.

[gbal]

Your question is entirely sensible,and relevant-many barrels are shorter,and some are shortened-say from a more trad 24 inches to 20 inches (tactical/tacticool) etc

 

The answer is that velocity is decreased by typical barrel shortening.How much is somewhat variable,depending on the cartridge and calibre (basically what the muzzle fps was), but very roughly linear,within the likely shortening lengths-at extemes,the loss may be more variable.

 

One decent study is by BLClark,University of S Florida "Effect of barrel length on MV".This used a Mosin Nagant 7.62x54R rifle (cheap-would you use a custom rifle?),and the barrel was cut two inches at a time from the initial 28.75 inches toa final 16.75 inches,and ten shots fired at each length;reasonable procedure and firing sample.(rifles may differ a little-even similar models,of course).

 

barrel 28.75 MV 2827 fps

 

barrel 16.75 2574

 

The loss was essentially linear within this quite wide length variation- MV loss was about 25 fps per 2 inch

reduction,or 12 fps per inch.

 

Google this topic ("barrel length v muzzle velocity": you will find the general picture is as above-though some find/claim on variable data somewhat variable fps loss per inch-as would be expected,with different lengths/cartridges etc etc.But the range is not very large (10-20 fps per inch would be ball park).

Clark also includes some data on accuracy;in general any effects are rather small/negligible,and can go either way- a long whippy barrel might be shortened and stiffened and a tad better....generally,very little change.

 

OK,10-20 fps per inch,but have a read-there is genuine variation around the ball park here,and with different cartridges.

 

Actual shooting data seems pretty well to confirm all this-though there isn't perfect control of all the variables-especially load data-and not very often before/after comparisons,which would be the best data,if enough of it.

Muzzle blast tends to increase-brake,better yet,moderator.Pressure is not of concern-chamber is not changed. Within the cartridges effective envelope shortening a barrel to say 20 inches typically does not seriously affect performance (100fps less in a 308 tactical rifle may well be worth it for increased handling,it won't be in a 1000y 308).

But that's all another discussion.

 

gbal

[rsc1960]

Goal

 

Thank you so much bud,

 

Very informative

 

RSC.