how does shorting a barrell change the performace of a air rifle?

[howie1a]

I am thinking of shorting my air rifle barrell about 4 inches that would leave me with a 14 inch barrell will my fps go up since their is less friction of the rifleing to the pellet and how will it affect the accuracy?  what is the adverage barrell length? any help or imput will be a help. thanks howie

[Big_Bill]

Hello Howard,

First we need a little more information, like what make, model, and type of air rifle are you considering doing this to ?

I will say that a shorter barrel will be stiffer, and produce less harmonics in the barrel. Harmonics are vibrations that whip the barrel, sometimes causing inaccuracy. Some free float the barrel so not to interfere with the harmonics, while others, glass bed or custom stock the barrel to help dampen the harmonics of the barrel. This applies even pressure along thelength of the barrel that is in the stock.

If the power plant of the air rifle is powerful,shortening the barrelmay reduce the fps of the air rifle. PCP and CO2 air rifles may loose velocity because there could be enough of an air charge to propel the pellet all the way through the barrel. While weaker air rifles may only propel the pellet through a portion of the barrel, causing the pellet to begin to slow down, after the air charge is reduced below the level able to accelerate the pellet.

If were to do this, I would remove 1/2" - 1" segments of the barrel at a time, and then check the velocity to see what, if any effect the cut had made.

I hope this helps.

Bill

[howie1a]

i am  thinking of shorting my fast deer to reduce weight and make it into a carbine, I would have thought in a springer with a steel barrel you shouldn't have a problem with harmonics, maybe in my Gamo a magnum rifle with high reciol and twang, but a lower fps rifle that is smoother,I don't know I have shortned b3's after takeing off the front sight just to get rid of the rabbit cut in the  barrel for the sight, mostly for looks,my thoughts is in shorting the rifle singe we are not dealing with power burning while the bullet is still in the barrel adding push, while the push is only at the start of the shot,my thinking is  is that the friction of the rifleing  will be reduced and you should gain some fsp and if the their is enought rifleing the accuracy shouldn't change.  also their are a lot of springers with shorter barrels than 17 inches.what think you.

[daved]

This is hearsay, but I've heard 12" is all the barrel the typical springer needs.  Several high end springers have barrels about that short hidden inside their shrouds.  Of course, a really short barrel on a break barrel can make cocking a bear, and with a fixed barrel, what do you do with the cocking lever?  Maybe Vince will jump in, I think he's chopped the barrel on more than one.  Good luck.

Dave

[howie1a]

the cocking lever is not a problem since the rifle I am changeing to a carbine is a side lever.

[SDale]

You might just gain a few more FPS by shortening it up a bit. The Fast Deer isn't a very powerful rifle and may benefit from the shortening. Just remember to recrown the barrel after you cut it unless you want a scatter gun :D

[howie1a]

I got the deer from south summint and they say it has a fps of 850  I really don't know but it will put a waddcutter into a solid cardboard target 3/4 " deep which is what my big cat does so who knows also they say that the barrel length is 15.5 " long but mine was 18 " long when I got it now it is 14 " long and it shoots fine dead on I did fire lap the deer when I got it and did a full tune up and put 3 spacers at the end of the spring and reworked the trigger sear polished it as well as rehardening  it the trigger is still a little hard to pull but nice and smooth I had to rework the safety switch so it would stop acting like a set trigger if you pulled the trigger when the safety was on you had a hair trigger . now their is no play in the trigger when the safety is on. I also   recrowned it then and when I made the barrel shorter it now has a 14" barrel and weights 7.5 lbs with the scope on it, the balance is better too. it looks ok as a carbine so I will leave it this way .It shoots with a snap sound and is able to put 5 rds in one hole at 10 yds. which is what is what I was looking for. I don't have a chrony so I can't get any numbers as what the fps is.

Howard, if you get a chance and have the inclination, take a couple pics of it. It would be great to see what she looks like with the shortened barrel.

Bryan