6.5 20" barrel velocity?

[Froggy1129]

I have used the Hide Google search and regular Google searches. Can't quite confirm any data on this.

I am interested in getting a 6.5 barrel of some sort (.260 or creedmoor) for my AI AE. I shoot suppressed and would like to go 20". Looking on JBM it would seem if you can get 2700 fps that it would be worth doing ballistically. I have no experience with 6.5's so your input is appreciated.

If not, I can always stick with my .308

Be safe,

Justin

 

[SONIC SAAMI]

Re: 6.5 20" barrel velocity?

I get 2,730fps from the factory CM 140 A-Max load with a 24 inch barreled bolt gun.

 

[raptor99]

Re: 6.5 20" barrel velocity?

I cut a 26" barrel down to 22"s and lost exactly 65fps going down 4"s with my 260. I bumped it up a grain and was back to nearly where I was before I cut it down.

The rifle was more accurate but the one thing I did notice was that the groups would open up from 900 to 1000yds. Hope this helps!!

 

[Guest]

Re: 6.5 20" barrel velocity?

I would say that many more (relevant) factors should be considered before worrying about your barrel length. Getting the desired load and appropriate barrel twist would be higher on my list than a couple of inches of pipe.

I asked a similar question not too long ago and have a similar project in mind of putting a 6.5mm into a shorter AE platform.

I caught a bunch of shit for "cutting the legs out from under the horse" of a 6.5mm or 6mm pony in wanting to chop it down to 20". I say f*** that! Not 4 minutes ago, I just watched a guy hitting steel at 600y with a .260 pistol. I've also seen where fellas have pushed 6mm BR's to 1k in pistols.


Feed it right and drive it right, and 20" is more than enough.

 

[Big_Daddy]

Re: 6.5 20" barrel velocity?

Tag for future comments. I have a 20" .260 bolt gun in route so I am curious to see any other input here. From what I have noticed in reading other posts here and abroad the shorter barrels don't seem to lose as much velocity when you're talking higher end barrels. Maybe better quality, rifling & manufacturing reduce velocity loss? What I have read is mostly anecdotal. Of course some barrels are "faster" than others so I know it's hard to say X-length barrel will have Y velocity.

 

[fastford]

Re: 6.5 20" barrel velocity?

tag

 

[bm11]

Re: 6.5 20" barrel velocity?

I'd like to see more on this as well because a 6.5 barrel is in my future as well. I'd like to be able to run a 20", and on a .308 there is no reason not to- the tests I have seen show no difference in muzzle velocity between a 26" barrel and a 20" barrel. You only lose 20 fps or something like that going to an 18.5. Now on a .260, if I would lose a bunch of MV, it would be worth considering the longer barrel.

I would imagine that the type of powder used would make a difference, yes?

 

[LoneWolfUSMC]

Re: 6.5 20" barrel velocity?

I need to run the numbers again, but the last time I did it I seemed to remember I needed to keep the velocity up pretty good to make the 6.5 worthwhile over the .308 (when looking at wind drift).

I am interested as well because I would really like to keep a tactical rifle shorter for some stages.

 

[bm11]

Re: 6.5 20" barrel velocity?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body">I need to run the numbers again, but the last time I did it I seemed to remember I needed to keep the velocity up pretty good to make the 6.5 worthwhile over the .308 (when looking at wind drift).

I am interested as well because I would really like to keep a tactical rifle shorter for some stages. </div></div>When you get that data, please share it with me. I'd like to get a 20" 6.5 barrel to match my .308 barrel, and to make it more reasonable in length with my suppressor on, but not if I sacrifice the benefits of the smaller caliber in the process.

 

[LoneWolfUSMC]

Re: 6.5 20" barrel velocity?

Just run the numbers through JBM and take a look at the wind drift. See what velocity gets you the drift you deem acceptable.

 

[bm11]

Re: 6.5 20" barrel velocity?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body">Just run the numbers through JBM and take a look at the wind drift. See what velocity gets you the drift you deem acceptable. </div></div>How do I determine the velocity based on barrel length though? That's the variable I don't know.

 

[michael_aos]

Re: 6.5 20" barrel velocity?

I've got 22" & 24" rifles chambered in 260 Remington.

42.8gr H4350 gets me right at 2800fps (139gr Scenar) with the 22" barrel. The exact same ammo in the 24" barrel is 50fps less (~2750).

22" is a 1:8" twist Lilja with "match" chamber
24" is a 1:9" twist Krieger with a little looser neck

 

[JamieD]

Re: 6.5 20" barrel velocity?

I'm getting ready to build a project hunting rifle in a .260 and was conteplating the same thing. Likely going to go 22" but 20" seems like it would be handier in the woods, yet more than capable at a longer shot if needed.

JamieD

______________________________
Jamie Dodson
Wolf Precision
814-262-7994

 

[LoneWolfUSMC]

Re: 6.5 20" barrel velocity?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bm11</div><div class="ubbcode-body">How do I determine the velocity based on barrel length though? That's the variable I don't know. </div></div>

Exactly.

That is where I am stuck at as well. Only real world data will fill in that blank because different makes/styles/chamberings will result in different velocities.

I have a 20" Noveske .308 that is as fast as a 26" Remington .308. So it's all up in the air until you actually put it over a chronograph.

 

[Froggy1129]

Re: 6.5 20" barrel velocity?

.260 or Creedmoor to get the velocity needed for a 20"? I gather they are close.

 

[bm11]

Re: 6.5 20" barrel velocity?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Michael Aos</div><div class="ubbcode-body">I've got 22" & 24" rifles chambered in 260 Remington.

42.8gr H4350 gets me right at 2800fps (139gr Scenar) with the 22" barrel. The exact same ammo in the 24" barrel is 50fps less (~2750).

22" is a 1:8" twist Lilja with "match" chamber
24" is a 1:9" twist Krieger with a little looser neck </div></div>Interesting stuff right there!

 

[Guest]

Re: 6.5 20" barrel velocity?

Thought this might be relevant....although by the end it became a pissing match:

http://www.snipershide.com/forum/ubbthre...527#Post1742527

 

[bm11]

Re: 6.5 20" barrel velocity?

Good find, Pointblank.

 

[alf]

Re: 6.5 20" barrel velocity?

Just for reference,

I've got a X-P 100 in 6.5-284 with an 18" Broughton that runs 142 SMK's at 2740, which is exactly a 300 fps loss over my 31 inchers.

 

[Guest]

Re: 6.5 20" barrel velocity?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bm11</div><div class="ubbcode-body">Good find, Pointblank. </div></div>

Not too hard, i'm tight with the OP

 

[bm11]

Re: 6.5 20" barrel velocity?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pointblank4445</div><div class="ubbcode-body">Not too hard, i'm tight with the OP </div></div>I see that.