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Any Credibility to this? 20" same velocity as 26"?

groundhogbuster

groundhogbuster

Sergeant
Full Member
Minuteman
Jul 20, 2012
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Western NC
http://www.tacticaloperations.com/SWATbarrel/

I haven't ran any numbers with my new 20" 5R, but it seems to be more accurate than the 3 other 24 inchers that I shot this past weekend. I only got it due to hunting, and being easier to transport, as there isn't much weight difference, but when they said the 20" was getting the same velocity with Fed Match Kings as the longer ones I was stumped! Any one ever cut a .308, and ran the #s? Thanks again guys, gun's doin awesome esp for an off the shelf gun
 
Re: Any Credibility to this? 20" same velocity as 26"?

Some barrels are faster and some slower. Maybe your 20 is a fast one and the longer is a slower one? Goofy chronograph readings maybe?

Not a normal situation at least from what I have seen. My longer barrels always run the same load faster than my shorter ones. Just more tube to work with.

Length and accuracy are not going to be related unless you are using irons (length and velocity go together though). My shorties shoot just as well as the longer ones I have.

Velocity on 175 smk with 43.0g varget for me ranges from 2620ish in the 26 down to around 2425 or so with the 16 incher. Never had a shorter barrel outpace a longer one. I have had chronographs be goofy, but using actual drop at known distances it has not happened yet.
 
Re: Any Credibility to this? 20" same velocity as 26"?

Must of been Red Jacket that made the claims.

Topstrap
 
Re: Any Credibility to this? 20" same velocity as 26"?

I just re-barreled my .308 match gun from a 24" Hart to a 20" Rock. I'm shooting the same load (43.5 grains Varget, and 175's). I got 2685 out of my Hart and I'm getting 2560 out of my Rock. 4" made a pretty big difference in my gun.
 
Re: Any Credibility to this? 20" same velocity as 26"?

I haven't clocked anything, just talked to a well known Barrel Maker of Pac-Nor, I'm sure he knows what he's talking about. He said the rigidity of the shorter barrels helped with accuracy, and depending on the caliber sometimes they lost very little speed. This was just a SWAT write up I posted, and is a good read. I do however know 1st hand that a 6.8SPC in a 16" isn't much faster than a 20" at all. Why? I guess like the article says, alot depends on it, and no matter how long the barrel is the propellant only pushes it so far, then it will atcually start slowing down in a barrel long enough. (Dunno how long that would be) but, the last shoot I shot in I saw alot (80%) of people were shooting 26" tubes, and the last shoot I went to, to watch, there were a whole lot more 18's and 20"s being shot. I'd like to know the exact difference, and will get a clock on the 24" vs the 20" next time we shoot, but look what "Longshot just said, he lost 4" of barrel, and with the same load only 25fps. Now that's a swap I definitely would take. I know their different brands, and have to have some effect, but WOW! READ THE LINK, it is interesting to say the least.
 
Re: Any Credibility to this? 20" same velocity as 26"?

Not sure what numbers you are questioning but, 48 grains of 2000mr/175 smk would go 2650 from a factory 20" Rem LTR. Actual come ups to 1k verified the speed.
 
Re: Any Credibility to this? 20" same velocity as 26"?

308 generally tolerates shorter barrels better than say, a 243 or 22 250. Some actually perform better in shorter tubes (within reason of course) like 300 blk or 22lr.

Shorter barrels are inherently more ridged than a longer one of the same profile, but I highly doubt you would be able to shoot the difference. I can't at least.

I take the longer barrels when I like the extra velocity or sight radius. I take the shorter one pretty much EVERY other time, especially if I am going to be carrying or maneuvering the rifle. For me, trading off a bit of velocity for a handier weapon is worth it.

Cut a 26 to 18 once, but it has been a while and I do not remember the specifics off the top of my head. I do remember that it was totally worth it. Gun was handier, and when suppressed was comparable to just a plain 26 inch tube. Running the suppressor is where the shorter barrels really shine; a 26 inch standard config rifle is very long suppressed.
 
Re: Any Credibility to this? 20" same velocity as 26"?

Given everything the same except barrel length a shorter barrel will have a lower velocity. It's simple physics.

However when comparing factory barrels that are mass produced and have rougher tooling marks versus custom hand lapped barrels you can achieve the same velocities. I had a 17.5" cut rifled Brux barrel that would achieve the velocities factory Remington 20" would.

Like others have said, some custom barrels in the same length are faster then others, don't know why, they just are.
 
Re: Any Credibility to this? 20" same velocity as 26"?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body">I just re-barreled my .308 match gun from a 24" Hart to a 20" Rock. I'm shooting the same load (43.5 grains Varget, and 175's). I got 2685 out of my Hart and I'm getting 2560 out of my Rock. 4" made a pretty big difference in my gun. </div></div>

Bump that charge up to 43.8-44 grains and I bet it will be just as accurate and you should gain 20-30 fps, maybe more.
 
Re: Any Credibility to this? 20" same velocity as 26"?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body">I just re-barreled my .308 match gun from a 24" Hart to a 20" Rock. I'm shooting the same load (43.5 grains Varget, and 175's). I got 2685 out of my Hart and I'm getting 2560 out of my Rock. 4" made a pretty big difference in my gun. </div></div>

Those are the exact same numbers I have too, and load. I was using a 26inch krieger instead of a 24 inch one though. I don't really care increasing the velocity as this load had the best es/sd
 
Re: Any Credibility to this? 20" same velocity as 26"?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pusher591</div><div class="ubbcode-body">Given everything the same except barrel length a shorter barrel will have a lower velocity. It's simple physics.
</div></div>

is there friction between the bullet and the bore? what happens when the expansion is done and there is still bullet/bore friction left? diminishing return? worse?
 
Re: Any Credibility to this? 20" same velocity as 26"?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pusher591</div><div class="ubbcode-body">Given everything the same except barrel length a shorter barrel will have a lower velocity. It's simple physics.
</div></div>

is there friction between the bullet and the bore? what happens when the expansion is done and there is still bullet/bore friction left? diminishing return? worse? </div></div>

Diminishing returns? sure. Actually getting slower with a longer barrel....that is well beyond a 30" barrel.

Go to any long-range type of match and talk to grizzled veterans. Almost all the ones I know have tended to lengthen their barrels for the added "free" performance. Working guns....different subject with different needs.
 
Re: Any Credibility to this? 20" same velocity as 26"?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TNtrg.300</div><div class="ubbcode-body">I read he lost 125fps, not 25 fps </div></div>

Sorry left the 1 off, my bad
 
Re: Any Credibility to this? 20" same velocity as 26"?

In my application, I don't think it would matter like the article says. Heck even in Law Enforcement Applications. I used to be "BAD" anal about speed, and I'd pick the best/fastest load I could get, I have since learned, after my custom 6mm, that that whistle pig really doesn't care if it's comin at 3500 or 3,00fps. Same in Archery, my bow only shot 386fps, (due to my 28" draw) and everyone else was shooting well over 300, but the deer died, and fed the family just the same.
 
Re: Any Credibility to this? 20" same velocity as 26"?

It varies from rifle to rifle. IIRC LL has a tight bore .308 at 22" getting 2770fps on cor-bon 175gr. My 24" 5R even with max loads only peaked at 2640fps.
 
Re: Any Credibility to this? 20" same velocity as 26"?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Scooter-PIE</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pusher591</div><div class="ubbcode-body">Given everything the same except barrel length a shorter barrel will have a lower velocity. It's simple physics.
</div></div>

is there friction between the bullet and the bore? what happens when the expansion is done and there is still bullet/bore friction left? diminishing return? worse? </div></div>

Diminishing returns? sure. Actually getting slower with a longer barrel....that is well beyond a 30" barrel.

Go to any long-range type of match and talk to grizzled veterans. Almost all the ones I know have tended to lengthen their barrels for the added "free" performance. Working guns....different subject with different needs. </div></div>

Are you implying that any caliber will be faster at 30" than it would at say 16"? Just making sure "simple physics" is really simple and blanket statements are safe to make.
 
Re: Any Credibility to this? 20" same velocity as 26"?

Started shooting a custom 308 today, I have 3 308's, 2 of em are 20"s. The factory is an SPS tactical. Same load and scope bases rings, and scope so I know its not that. Rem 700 on custom too. So the only thing different is the barrel, best I can tell there is a 30 FPS difference from the factory bbl to the Broughton. So, the length is a deff velocity, different barrels of the same length can have different velocities. Good luck
 
Re: Any Credibility to this? 20" same velocity as 26"?

It's not a blanket statement. No not every caliber may be faster at 30" vs. 16" but I was basing the statement off of the standard. Most people consider the .308 round to be a standard. I also based the statement off of length. The average length you see THE MAJORITY shooting is 18"-26". I think most would agree with those statements. Even the most popular calibers would fall into the same category. Everything being the same, yes it is simple physics.

Maybe I should have been more detailed, but common sense has the play a factor when you take advice from a forum, apparently everyone doesn't use common sense when posting here.
 
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