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Shooting & Reloading - Mausers, Big Bores and others >> Rifles
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vegard_dino
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Reged: 05/03/09
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Loc: From Norway, but living in Swi...
A short barrel, how much fps do you give up??
      #207129 - 16/04/12 02:25 AM



Hi all.

A rifle with a short barrel is handy. But, how much FPS do one end up giving away for that handy handling?
Thinking of a rifle with a 24" and one with a 20-22" barrel? The caliber I am thinking of is 8*57IS.
Are there nay program to figure it out?

Thanks

--------------------
Cheers all, Vegard_dino

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Sville
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Reged: 23/03/10
Posts: 1189
Loc: Sweden
Re: A short barrel, how much fps do you give up?? [Re: vegard_dino]
      #207139 - 16/04/12 04:28 AM

Normally 2-3 m/s for every 10 mm you cut off. You canīt do it with all calibers, but a 8*57 with a short barrel will not be a problem. To my Blaser I have a .308 and a 9,3*62 barrel. They are 520 mm because of the silencer, standard they are 577 mm. /Staffan

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vegard_dino
.333 member


Reged: 05/03/09
Posts: 262
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Re: A short barrel, how much fps do you give up?? [Re: Sville]
      #207142 - 16/04/12 06:07 AM


Thanks for the info

--------------------
Cheers all, Vegard_dino

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kuduae
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Reged: 13/01/10
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Re: A short barrel, how much fps do you give up?? [Re: vegard_dino]
      #207151 - 16/04/12 07:59 AM

The old RWS handbooks contain tables about barrel length and velocities. Here are the numbers for the still current standard load of the 8x57IS, a 12.7g round nose listed at 790m/sec from a 68 cm test barrel: 60 cm barrel = 767 m/sec, 50cm barrel = 733 m/sec.

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vegard_dino
.333 member


Reged: 05/03/09
Posts: 262
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Re: A short barrel, how much fps do you give up?? [Re: kuduae]
      #207184 - 16/04/12 04:44 PM



Thanks for the information

--------------------
Cheers all, Vegard_dino

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DarylS
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Re: A short barrel, how much fps do you give up?? [Re: vegard_dino]
      #207202 - 17/04/12 01:07 AM

Efficient ctgs. like the 8x57 will normally lose about 20fps to 25fps per inch they are shortened.

Larger case, smaller bore sizes will lose more - up to 40fps per inch.

Once you get below 20", the numbers can really start to drop off, expecially in large ctg. capacity rounds.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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vegard_dino
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Reged: 05/03/09
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Re: A short barrel, how much fps do you give up?? [Re: DarylS]
      #207210 - 17/04/12 04:06 AM



Thanks for the info

--------------------
Cheers all, Vegard_dino

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tinker
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Reged: 12/03/05
Posts: 4835
Loc: Nevada
Re: A short barrel, how much fps do you give up?? [Re: vegard_dino]
      #207221 - 17/04/12 08:19 AM

I have a winchester mod70 in 7mmRM, it has a 24" barrel and runs Remington Core-Lokt factory ammunition at 3010fpsMV

Factory claims 3100fpsMV from that ammunition.
Likely tested in a 28" barrel, also likely optomistic velocity claim for their ammunition.





Cheers
Tinker

--------------------
--Self-Appointed Colonel, DRSS--



"It IS a dangerous game, and so named for a reason, and you can't play from the keyboard. " --Some Old Texan...

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zimhunter
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Re: A short barrel, how much fps do you give up?? [Re: tinker]
      #207458 - 21/04/12 12:42 PM

Remington used to show an explanation in their Ballistics Information section for this loss. They start with a 24" barrel as standard and divide the lose by Muzzle velocity range.
2000-2500 10ft/sec per each 1" below 24"
2500-3000 20ft/sec per each 1" below 24"
3000-3500 30ft/sec per each 1" below 24"
3500-4000 40ft/sec per each 1" below 24"
Remington in their literature states that these values were determined in test barrels in the lab but should represent the approximate lose in performance in actual rifle barrels. I personally don't know much game that can read ballistics tables where it would make very much difference in thefield. I kinda believe if the chronograph had never been invented there would be many MORE satisfied handloaders. Never having used one or seen the real necessity I am probably jaundiced in my view.

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DarylS
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Re: A short barrel, how much fps do you give up?? [Re: zimhunter]
      #207487 - 22/04/12 03:35 AM

Too - the lack of knowledge kept man in the Dark Ages for centuries.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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vegard_dino
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Reged: 05/03/09
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Loc: From Norway, but living in Swi...
Re: A short barrel, how much fps do you give up?? [Re: DarylS]
      #207491 - 22/04/12 05:06 AM



Thanks for the information.

--------------------
Cheers all, Vegard_dino

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zimhunter
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Re: A short barrel, how much fps do you give up?? [Re: DarylS]
      #207492 - 22/04/12 06:30 AM

One should really read more about the 'dark ages' to understand that it referred more to changes in the religious standards of the day from Catholicism to Protestantism and not from research or scientific knowledge. It had little if anything to do with the lack of knowledge.

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Grenadier
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Reged: 20/02/08
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Re: A short barrel, how much fps do you give up?? [Re: zimhunter]
      #207493 - 22/04/12 07:44 AM

There have been many people who have chronographed shots out of a barrel as it was cut back a little bit at a time. People in the USA should be wary of duplicating these tests because once the rifle barrel is cut shorter than 16" an unlawfully manufactured Class III "short barreled rifle" is the result.

A most comprehensive test was performed by someone who posted his results on Accurate Reloading. The report was followed up by a reader who graphed and discussed the AR data. Here are three of several tables from the discussion:












It is interesting to note in the first chart that for the .223 tested there appears a flat spot in the velocity curves at around 16"-17" barrel length. If you look at the second chart you will see accuracy hit a "sweet spot" when the barrel was approximately 17" in length. This suggests that there may be an ideal barrel length for efficiency. Perhaps there is an inherent ideal for each caliber and/or bullet. The third chart seems to support this as well - note how and where the lines cross. I would much rather shoot a bullet a little slower and get the ultimate accuracy than push it to maximum velocity with accuracy be damned.


The AR data is here: http://www.accuratereloading.com/223sb.html

The full report of the above data with more charts is here: http://www.varmintal.com/alite.htm#BarrelLength

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tinker
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Reged: 12/03/05
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Loc: Nevada
Re: A short barrel, how much fps do you give up?? [Re: Grenadier]
      #207494 - 22/04/12 08:03 AM

When I lived on the coast and pretty much all of my hunting happened inside 100 yards, there was much less need for chronograph comparison of bolt rifle loads

Here in the high desert, where 100 yards is pistol distance and 300 yard shots on game are considered close, it's more important to know what any given bullet is doing out of the gate so that I can better know how it's doing down range -- and for exactly how far I can expect a bullet to be effective on whatever I want to pierce with it.


With respect to load development and selection, I'm much more of a charts and graphs guy than I'd been before. I'm sure as I become accustomed to the relatively new surroundings and conditions I'll settle on whatever the new known-good combinations are.
Until then I'm keeping a good relationship with my chronograph.

FWIW I had no idea how my new 7mmRM would do with the cheap 150gr Remington ammunition.
They'd claimed one thing, I got something else across my chronograph.
At least I know.




Cheers
Tinker

--------------------
--Self-Appointed Colonel, DRSS--



"It IS a dangerous game, and so named for a reason, and you can't play from the keyboard. " --Some Old Texan...

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Grenadier
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Reged: 20/02/08
Posts: 570
Loc: North of the Columbia, USA
Re: A short barrel, how much fps do you give up?? [Re: Grenadier]
      #207495 - 22/04/12 08:09 AM

There is another interesting report here. This one regards barrel length vs velocity in a Mosin-Nagant 7.62x54R Rifle:

Effect of Barrel Length on the Muzzle Velocity and Report from a Mosin-Nagant 7.62x54R Rifle

--------------------
~

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