Rifle barrel reduction test.

Antelope_Sniper · Jun 30, 2010

http://www.accuratereloading.com/223sb.html

Here's an interesting article about barrel length. Guy started with a 22" barrel and kept testing and cutting until he made it down to 11".

Now he might be ready for a rebarrel! :grin:

bteate · Jun 30, 2010

that is very interesting, indeed. I kind of figured the velocity would drop off a tad more, but the accuracy was still pretty good even with the barrel cut to 10". That would be an awesome truck gun!

DrMike · Jun 30, 2010

Interesting. The data is pretty old. I wonder if the fellows did any other studies. The accuracy was about what I would have expected, and the velocity loss was right in line with others who have conducted similar experiments. They don't say if they were crowing the barrel after each cut, but maintaining accuracy as they did, I would assume that they did so. Did you notice that there was a "sweet spot" with each load, after which the groups began to open up again. For instance, 22 g. H322 tightened up significantly at 18 & 17 inches, and opened up again as more barrel was removed. Fascinating. For people looking for a brush gun, this data should encourage them not to reject a rifle out of hand because it is short-barreled.

1Shot · Jul 1, 2010

That is with a 223. It really depends on the caliber that you want as to what the velocity loss will be when you chop the barrel down. Most round based on the 308 case do pretty well with a shorter barrel but when you start in to the 06 and mag cases barrels shorter than 20" really loose velocity in my experience. I saw a test done with different calibers from 7mm mag down to 308 like this in a shooting magazine a number of years ago just to see what the velocity loss would be. If memory serves me right they found that in the 7mm mag they lost right at 50 fps with each inch cut off and about 40 fps with 30-06. I might still have that magazine someplace but it would take me months to find it. :lol:

Elkman · Jul 1, 2010

I have always used the 40fps per inch rule. I use this to help me figure out where my gun may be in comparison to published ballistics, and based on ballistic computer runs I am fairly close.
A same discussion came up on another forum site not long ago and that seemed to be the most popular estimate. I have also read similar studies over the years and remember that same figure. I really don't think the 10 fps one way or the other is that critical unless of coure you are cutting 10 inches off of a 20" inch gun.
I believe that (I am not big on this stuff) if you cut your rifle barrel down past 16" that you have created a pistol and of course the laws and regulations regarding those are different in many places than those for rifles. I could be wrong as I frequently am.

Antelope_Sniper · Jul 1, 2010

Elkman, you and I always figured about the same. One a .270 Win I always figured 100 fps per 2" of barrel. You are also correct about cutting off the barrel. If the length goes below 16" it's considered a short barreled rifle and required a tax stamp from the ATF. SBR's are typically considered a class 2 item, and requirements for the stamp are similar to a silencer.

Big Squeeze · Jul 7, 2010

Antelope_Sniper":37zxogfi said:
http://www.accuratereloading.com/223sb.html

Here's an interesting article about barrel length. Guy started with a 22" barrel and kept testing and cutting until he made it down to 11".

Now he might be ready for a rebarrel! :grin:

...................Kinda reminds me of Steve McQueen`s shorty lever rifle he used on his 50s TV show. The show`s name escapes me.

From the shorter barrels, certain cartridges, such as in the family of shorter cases such as the 300 WSM, 7mm/08, 308, 260 Remy and others, can and do retain a closer percentage of velocity loss (fps per inch) in comparison to their longer barreled counterparts. Full sized cartridge lengths like the 270 Win, 30-06, 7mm Rem and others, seem to lose more fps per inch of shorter tube length.

Chrony tests using my 16.5" barreled 300 WSM Ruger Frontier carbine vs other 24" 300 WSMs seem to bear this out. A 16.4 fps to a 19.5 fps velocity loss "per inch" of shorter barrel length, or a 4.2% to 5% of overall loss were my results using the same loading components. This also applys to other accounts I`ve read that included a 16.5" 7mm/08 Frontier, retaining 95% of a 24" barreled 7/08.

Some cartridges can retain a higher percentage of velocity from the shorter barrels, while others seem harder pressed to do so. The only way to be extremely accurate for comparison`s sake, is to cut the same barrel down in 1" increments and record the velcocity findings as you go as was done in the above example.