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What's the shortest you could go on a 6.5 CM

L

Lofty

Gunny Sergeant
Full Member
Minuteman
Jun 14, 2008
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Lenexa KS
Without losing significant performance?

I was watching the video of Lowlights .260 from a few years back with an 18 inch barrel. It doesn't seem like he gave up much of anything in performance and gained the portability and usability of a shorter rifle.

I'm a sucker for short handy rifles.

I'm wondering if an 18 inch 6.5 would provide the same performance.
 
Re: What's the shortest you could go on a 6.5 CM

I actually just asked Frank this question last week. His answer is the 260 he shoots the most is 21". It is also his longest 260. I originally was going to go 25.5" but after talking to Frank I am going to go 22" and call it good. It is still handy but will help with the velocity a bit over a 20".
 
Re: What's the shortest you could go on a 6.5 CM

"cjgemm" on here has a Savage with 18.5" barrel and he's reported 2640fps with Hornady 140gr factory loads.

"RugerSlinger" has a 19" 260 and has reported 2650fps with 142 SMK and 43.0gr H4350.
 
Re: What's the shortest you could go on a 6.5 CM

I just had a new 21" Creedmoor barrel put on my gun, in fact the Cerakote is cureing now
smile.gif


I'll be shooting a 130 VLD loaded by McCourt Ammunitions and hopeing for 2820-2850 depending on what load out of the test packet it shoots best.

I will be running my Surefire on it so that's the only reason I went shorter, but if not running a suppressor I would have run a longer barrel to reach the same velocity but with the much higher 140-142 class projectiles.

If you got the money to throw around go for it but it seems you would be handicapping the cartridge by running such a short barrel, that's if you go with something in the 18" range.
 
Re: What's the shortest you could go on a 6.5 CM

I have a 22" barrel on my 260 and wouldnt consider going any longer. The more I shoot short barreled rifles, the more I love them and want to shorten all of my rifles.
 
Re: What's the shortest you could go on a 6.5 CM

Seems like most smiths say to go no less than 22" without any significant loss in performance. At least the smiths I've asked.

I'm having a 6.5CM built by Accurate Ordnance cut to 22" soon.
 
Re: What's the shortest you could go on a 6.5 CM

Fact is the shorter you go the more extreme velocity loss becomes. Whether or not it will still perform how you depends on your velocity expectations.
 
Re: What's the shortest you could go on a 6.5 CM

Like Boiler up was saying I am getting 2650 with 43gn of H4350. I bumped it up to 43.5 and I am still not seeing any pressure signs. I am just going to leave it as is because I don't shoot any further than 600yds. If I had to do it again I wouldn't change a thing, I love the 19".
 
Re: What's the shortest you could go on a 6.5 CM

Just in comparison, I am getting 2930fps with 43grns of H4350 and the 140 AMAX in my 26" 6.5 Creedmoor. Personally I wouldn't go shorter than 24".
 
Re: What's the shortest you could go on a 6.5 CM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lofty</div><div class="ubbcode-body">I'm wondering if an 18 inch 6.5 would provide the same performance. </div></div>It depends on how far you want to hit things with it.
 
Re: What's the shortest you could go on a 6.5 CM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Just in comparison, I am getting 2930fps with 43grns of H4350 and the 140 AMAX in my 26" 6.5 Creedmoor. Personally I wouldn't go shorter than 24". </div></div>

I would have to agree with Rob. I would even say you see the most flatline performance at 25" and 26" barrels. I am wanting to try a gain twist barrel soon from Bartlein and see what it does then.
 
Re: What's the shortest you could go on a 6.5 CM

As long as we're opining...

Seems like a 6.5CM or 260 @ 18" would only have a small ballistic advantage over an 18" 308. The trade off being ammo cost and availability, and barrel life.
 
Re: What's the shortest you could go on a 6.5 CM

I have a 22" 6.5x47 that launches 140s to 2820 and 130s to 2900.

I'm currently putting a .260 together and plan to run it at 24-26". I will mostly be running it suppressed, so I'm trying to decide which. In reality, how much handier is 2-4"?
 
Re: What's the shortest you could go on a 6.5 CM

I too was asking my self the same question about 2 months ago. I wanted a short 6.5 (18' or 20") for competitions and after talking to my builder i went with a 26" 6.5 Creedmoor heres why. The shorter i would go the more loss in performance to push the lighter bullets. Thats were there .260 and 6.5 Creedmoore really shine. It's there ability to push lighter bullets really fast and use high BC bullets. My builder recommended that if i was looking for a short rifle to go with a .308 but understand the limitations that i was going to have (distance i would be able engage targets and loss of energy at impact). There are lots of people that have short barrel rifles on here and it seems that the round they have gone with is the .308. just my +2 and IMHO
Good luck
 
Re: What's the shortest you could go on a 6.5 CM

500' ASL elevation, standard atmosphere, 1000 yards w/ 100yd zero

260/6.5 Creedmoor, 142 SMK @ 2700fps: 9.3mil drop, 2.1mil drift
308 Win, 175 SMK @ 2500fps: 13.0mil drop, 3.2mil drift

Is this considered "small" ballistic advantage?

Even with the 175 SMK @ 2700fps (unobtanium from a <20" 308?) you'd still have 10.8mil drop and 2.8mil drift.

At the 650yd max I have available to shoot, the difference between the 142 @ 2700 and the 175 @ 2700 is 0.4mil elevation and 0.4mil drift; the 175 @ 2500 gives up 1.8mil elevation and 0.6mil drift to the 6.5mm.
 
Re: What's the shortest you could go on a 6.5 CM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BoilerUP</div><div class="ubbcode-body">500' ASL elevation, standard atmosphere, 1000 yards w/ 100yd zero

260/6.5 Creedmoor, 142 SMK @ 2700fps: 9.3mil drop, 2.1mil drift
308 Win, 175 SMK @ 2500fps: 13.0mil drop, 3.2mil drift

Is this considered "small" ballistic advantage?

Even with the 175 SMK @ 2700fps (unobtanium from a <20" 308?) you'd still have 10.8mil drop and 2.8mil drift.

At the 650yd max I have available to shoot, the difference between the 142 @ 2700 and the 175 @ 2700 is 0.4mil elevation and 0.4mil drift; the 175 @ 2500 gives up 1.8mil elevation and 0.6mil drift to the 6.5mm. </div></div>

According to the short barrel 6.5mm velocities reported in this thread, 2700fps is an exaggeration. The reports were 2650.

According to my personal experience with an 18" 308, I get 2600fps from a Hornady 178hpbt, which has a BC of .53

So, at 1000 yards:

19" 6.5mm drops 8.1mrad and drifts 2.1mrad (140 hornady match G1BC=.58)
18" 308 drops 9mrad and drifs 2.4mrad

To me, yes, that is a rather small advantage, and it would be hardly worth the trouble... And we're not even comparting apples/apples exactly, because of the 1" barrel length difference...but whatever.

YMMV
 
Re: What's the shortest you could go on a 6.5 CM

FIrst off who says you have to shoot heavies and slow, (under 2750) and why is it always compared to 1000 yards...

If you look at a lot of people's shooting it is actually inside 1000 yards, and even in the a wide cross sections of the tactical competition world, usually only 1 stage out of 20 stages is at 1000 yards. So where you're not gaining a whole lot at 1000 yards, you are still better off. <span style="font-style: italic">(not to mention many rifles have issue with Hornady Superformance especially in summer)</span>

Many 308 rifles with standard barrels are far below 2600fps at 18" -20" most hover around 2500fps with a 175gr ammo. So exaggerating it 2600fps using the best possible 308 bullet is a little misleading as they don't all work that way. In fact MOST don't.

A 130gr VLD is easily moving pretty darn fast and I know my personal short barrel using these sends the 139gr Scenar plenty fast and the 130VLD just as well 100fps faster. So there are some advantages to be had when put in the context of reality vs the best possible alternative.

While drift and drop seem like a small variation, I can hold 3" groups with my 260 at 800 yards, holding that with a 308 is much tougher, I figure 1 MOA at 800 yards with a 308 is outstanding, yet .5 MOA with a 260 is typical. That is huge advantage.

If the goal is simply drift and drop, and that putting a single round on target, ok, the advantage is small, but putting that together with accuracy. The 260 wins.

I shot my 21" 260 more so than most other rifles, and it is night and day different from shooting my 308 of the same configuration. Heck I shot out 1000 this weekend with my 20" 308 going 2645fps and while I was able to score consecutive hits on steel the groups were nothing to write home about. My 260 impresses every time.

Flawed thinking if you ask me ... especially when you actually go out and shoot it
 
Re: What's the shortest you could go on a 6.5 CM

Frank, you make several excellent points, namely:

How many shots out at 1000 are you taking?
How easy is it to shoot accurately?
Who says you have to use the heavyweight bullets?

Obviously, a short/handy 6.5mm is not an ELR rifle. It's a handy rifle that works well.

I'd like to point out though, that in comparing drop/drift @ 1000, it exaggerates the ballistic advantage of the 6.5 over the 308.

That said, a 308 is an "adequate" 1000 yard cartridge - and the 6.5 is a decent improvement.

Another thought is that many matches are UKD, and the flatter trajectory of the 130s can be a sizable advantage.

Good post!
 
Re: What's the shortest you could go on a 6.5 CM

It does appear to be a small advantage with the shorter barrels but, when you shooting unknown distance and small moa targets that small advantage can pay off big time.

From some velocities on here I'm now hopeing to get 2850+ with my 21" barrel. If I can get that with a 130 VLD that's a significant advantage to my 17.5" 308, and I wasn't doing TOO bad with that short barrel.

Hope to have an update and pics of my stuff within the week. Suppresed and unsuppressed results, just to see if I pick up any velocity. I know on my shorty .308 I was consistently picking up 30-40fps.
 
Re: What's the shortest you could go on a 6.5 CM

My 21" Creedmoor load is a 140 Amax at 2730. I got pressure signs at 2750. It's still an improvement over a 308 of the same length. Better drop/drift, with less recoil. Will be switching to 130's soon, and there will be an even bigger improvement.
 
Re: What's the shortest you could go on a 6.5 CM

davis, what's your set-up and what brand barrel do you use?
 
Re: What's the shortest you could go on a 6.5 CM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Just in comparison, I am getting 2930fps with 43grns of H4350 and the 140 AMAX in my 26" 6.5 Creedmoor. Personally I wouldn't go shorter than 24".</div></div>

How is your brass life Rob? I have just been duplicating the Hornady factory load and have been getting 2830 out of my 26" Brux. If your getting at least 6 reloads I may have to work up higher. 2900+ is pretty damn impressive.
 
Re: What's the shortest you could go on a 6.5 CM

28 inches!!
 
Re: What's the shortest you could go on a 6.5 CM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Captramrod01</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Just in comparison, I am getting 2930fps with 43grns of H4350 and the 140 AMAX in my 26" 6.5 Creedmoor. Personally I wouldn't go shorter than 24".</div></div>

How is your brass life Rob? I have just been duplicating the Hornady factory load and have been getting 2830 out of my 26" Brux. If your getting at least 6 reloads I may have to work up higher. 2900+ is pretty damn impressive. </div></div>

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NOMAD</div><div class="ubbcode-body">28 inches!!
</div></div>

2930 @43 gr out of a 26" is def strokin

For the record, im gonna stick with 26" i'll take that speed/pressure/portability ratio
 
Re: What's the shortest you could go on a 6.5 CM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pusher591</div><div class="ubbcode-body">davis, what's your set-up and what brand barrel do you use? </div></div>

I've got a Bartlein 8 twist Med. Palma on a Tikka T3 action. It's also nitrided, but that has not seemed to affect velocity.
 
Re: What's the shortest you could go on a 6.5 CM

I got 8 reloads on some of my brass and it's still fine. Of course the barrel will have effects on the speed as some are faster than others.
 
Re: What's the shortest you could go on a 6.5 CM

With my 28" Kreiger in 6.5 CM with an 8.5 twist, I am able to get 2765-2787 using 41.5 H4350 with 140 SMK. It shows no signs of over pressure. The other thing I haven't seen much of a difference between using IMR 4350 or H4350. If anything I might have a bit tighter group with the IMR powder.
 
Re: What's the shortest you could go on a 6.5 CM

I am getting 2900 fps out of my Krieger 20" 1-8.5 twist custom AR 10 with the factory 120 grain A-Max.
 
Re: What's the shortest you could go on a 6.5 CM

22" Lothar barrel 2800 fps 142 smk and 2980 with a 123 amax
 
Re: What's the shortest you could go on a 6.5 CM

Hummerdawg, if you don't mind what load you running, those ate great numbers.
 
Re: What's the shortest you could go on a 6.5 CM

H4350 44.3 with 142 smk
H4350 46.0 4ith 123 Amax

primers look good cases on 4th reload
 
Re: What's the shortest you could go on a 6.5 CM

22.5" Hart 8tw

140 Amax @ 2.815 over 43.5gr H4350 2825fps
140 OTM Hornady @ 2.760 over 41.5gr H4350 (very soft load) 2635fps
140 Amax @ 2.810 over 41.5gr H4350 (again, soft load) 2630fps
130 JLK @ 2.875 over 44.1gr H4350 (est 55ksi) 2875fps
120 GMX factory goes 3080fps
 
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