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Old November 25, 2009, 01:58   #1
callahan318
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shorten barrel - effect on velocity ?

What kind of muzzle velocity do you get out of an 18" FAL using M80 Ball?

What kind of muzzle velocity do you get out of an 16" FAL using M80 Ball?

I am considering this for how short of a barrel I want my FAL to have, so any responses would be great!

ALso, the 21" barrel spits out M80 Ball at 2750 right?

Thanks!
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Old November 25, 2009, 05:55   #2
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In theory, yes, 2750. Some barrels are faster than others, even with the same length and ammo. I have seen 2640-2830 with the same ammo, same length barrel, same day.

I'd plan on 2400-2500 with a 16" depending on the powder used. 2550-2650 with an 18", again dependent on the propellant.
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Old November 25, 2009, 09:13   #3
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I remember the general rule of thumb is 75fps per inch cut off.

A 16" would not be my first choice for anything past 300 yds.
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Old November 25, 2009, 10:39   #4
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velocity isnt the problem .its cutting into a barrel with TIR ya didnt check for that causes accuracy problems ...30 100 fps ...pishawww ....magnum prime will give ya that back ....
short barrels arent inaccurate ...just the smiths who cut them down and dont re-line bore the tube ..and get it concentric on both ends ...
if they are processed like they do at the factory ...they shoot good .


tip of the day ..leave it alone
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Old November 25, 2009, 11:05   #5
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http://www.loadammo.com/Topics/October05.htm

and

http://www.chuckhawks.com/rifle_barrel.htm
"The Remington Catalog 2003 includes a "Centerfire Rifle Velocity Vs. Barrel Length" table that shows the following velocity changes for barrels shorter or longer than the test barrel length:

MV 2000-2500 fps, the approximate change in MV per 1" change in barrel length is 10 fps.
MV 2500-3000 fps, the approximate change in MV per 1" change in barrel length is 20 fps.
MV 3000-3500 fps, the approximate change in MV per 1" change in barrel length is 30 fps.
MV 3500-4000 fps, the approximate change in MV per 1" change in barrel length is 40 fps."

and

http://www.thehighroad.org/showpost....4&postcount=21
" 308 velocity from 16-n bbl
Posted here:http://www.tacticalforums.com/cgi-bi...;f=78;t=000956

(from latest SGN, platform was a FAL)
By projectile weight:

Hornady TAP 110gr 2894fps
Santa barbara surplus 146gr 2611
Horn. Spire point 150gr 2635
Black Hills Boattail 150gr 2643
Horn. TAP 155gr 2567
Rem. Nosler Ballistic tip 165gr 2573
Sellier&Bellot Match 168gr 2419
Black Hills Match 175gr 2378"
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Old March 24, 2012, 17:33   #6
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7.62x39mm 16" vs 12"

I compared two Romanian AKM rifles with 16" barrels and one AMD 65 with a 12" barrel. The AMD 65 has a Tapco 4" muzzle brake to make it legal length. I tried a variety of different ammo.

The 12" barrel averaged 123 fps slower than the 16" barrels. That is consistant with the long-established rule of thumb of allowing 25 to 30 fps for inch of barrel length.
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Old March 24, 2012, 19:28   #7
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That really only applies to the 7.62x39 cartridge. The volume of the case in relation to the bore size is why the 7.62x39 loses very little velocity when the barrel gets shorter, compared to other calibers such as 7.62x51.
I love my 8" & 12" AK's. I get slightly less velocity as a 16" in a lighter & handier package.
My 16" Mini-G averages 2500 fps with 147-150 grain ball loads.
As far as accuracy goes,shorter barrels are actually more accurate than longer ones. They are stiffer & flex less as the bullet passes down it's length. Where I think people make the mistake that they are less accurate comes from the loss of velocity. The shorter the barrel, the less time the powder has to burn completely. That's why they have a larger muzzle flash. Short barrels are just as accurate, if not more but you have to aim a bit higher to compensate for the lower velocity & bullet drop at longer distances.
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Old March 25, 2012, 13:10   #8
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Delta-3, what is a Mini-G?

You are correct regarding accuracy and short barrels. With all the available information out there, it is surprising to me that so many people still ask about how much accuracy they will lose if they shorten their barrel.

25 to 30 fps of velocity loss per inch of barrel removed is fairly consistent for most calibers and typical rifle barrel lengths. Anything less than 16" would probably not be considered typical rifle barrel lengths.
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Old March 25, 2012, 18:01   #9
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A Mini-G is a custom "tanker' Garand (if you will) made by Tim Shufflin at www.shuffsparkerizing.com
Instead of the 18" barrel with the stubby chunk of wood, Tim cuts the Mini-G down to 16" & eliminates the extra wood piece.
If you would like more info, check out the link. If I explain it, I'll be writing Tim's praises all day! He really builds/modifies a fantastic little rifle. I've had a few of my Garands converted by Tim. This is the latest & is the Mini-G I was referring to in my previous post. It's a mag fed Mini-G in 7.62mm that uses regular m14/M1A magazines. I really like it alot. It only weighs 7-1/2 lbs empty. It's much lighter & handier than a full sized Garand & I prefer the 308/7.62 round over the '06.

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Old June 21, 2012, 17:23   #10
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Quote:
Originally Posted by TideWater 41009 View Post
I compared two Romanian AKM rifles with 16" barrels and one AMD 65 with a 12" barrel. The AMD 65 has a Tapco 4" muzzle brake to make it legal length. I tried a variety of different ammo.

The 12" barrel averaged 123 fps slower than the 16" barrels. That is consistant with the long-established rule of thumb of allowing 25 to 30 fps for inch of barrel length.
The relationship of barrel length to MV is not linear. That is, the loss of velocity going from 21 to 18 inches is less than the MV lost going from 16 to 13 inches. For the typical non-SBR FAL, the rule of thumb seems to be more like 20 fps/inch; this increases as you get into SBR territory.

I think this is overrated. The SCAR-H has a 16" barrel and is fit for military use when additional range and penetration are required. The ballistics of that rifle can't differ much, if any, from a 16" FAL. If it's good enough for Marines fighting insurgents, it will certainly work for the rest of us.
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Old January 23, 2014, 18:56   #11
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Quote:
Originally Posted by ggiilliiee View Post
velocity isnt the problem .its cutting into a barrel with TIR ya didnt check for that causes accuracy problems ...30 100 fps ...pishawww ....magnum prime will give ya that back ....
short barrels arent inaccurate ...just the smiths who cut them down and dont re-line bore the tube ..and get it concentric on both ends ...
if they are processed like they do at the factory ...they shoot good .


tip of the day ..leave it alone
Any good smith will properly re-crown the barrel using a pilot centered in the bore. The best choice for a re-crown would not be the stock 90 degree cut but a 11 degree target crown. You may even pick up some accuracy with a properly crowned, 11 degree, 18" barrel. Shortening the barrel will make it a little stiffer and the 11 degree crown will make it more accurate than the factory crown.
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Old February 10, 2014, 23:28   #12
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My 11in OSW averages 2500 with LC 88 M80 ball ammo. The 21 in FAL same day same ammo same day was getting 2850. Oddly enough, 24 in M700 5R was 2850, and the 20 in AR10 with 1-11 krieger was 2950... You can guess all you want but you don't know until you know.
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Old August 09, 2014, 16:55   #13
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You can guess all you want but you don't know until you know.******** ***************** ***************************************** width="1" height="1">
Couldn't agree more. I just learned that the hard way today. I wish I found this thread earlier, anyway no big deal.
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