I'm going to be having my 6.5 Creedmoor chambered this week. It's a M24 contour bartlein barrel and defiance action. I'm wondering if there is an optimal barrel length for this cartridge. By the way...It is an 8 twist. Thanks for any input.
- Thread starter Denny440
- Start date
Sorry should have stated that... Velocity Currently I'm planning on a 22" barrel.
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Well... the longer the barrel, the more velocity you get (to a point). I'm sure there is a point of diminishing returns. But if "optimal" to you = higher velocity, then go with a longer barrel. Most people tend to go with 26" I think. That's what I have (M24 contour too). I get 2818fps out of factory Hornady 6.5 Creedmoor, 140gr ELD-M loads.
We did some testing a few years ago with factory ammo and found 23" & 26" worked well and were in line with quick loads "accuracy node" If your hand loading then barrel length does not matter to a point, your going to tune for your barrel anyways.
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Thanks for the input.
Depends what you want for velocity vs how handy you need it. I run my rifles in PRS style matches and I run a 27" and a 28" plus the brake and have no problems getting around and get good velocities. Factory 140 ELD-M from the 28" is 2880fps. But if you wanted short and handy hunting rifle then you will give up velocity. A good all around would be in the 24-26" length.
Something to think about though is you can always get a barrel cut back but you can;t add length once you cut it short.
My 28" Creedmoor to give you an idea of length.
Something to think about though is you can always get a barrel cut back but you can;t add length once you cut it short.
My 28" Creedmoor to give you an idea of length.
It depends on the barrel as well as some are faster than others. As an example the same lot of factory 140 ELD that is 2880fps in my 28" barrel is 2825fps in my 27". 55fps is a good amount of velocity. Handloading I am running the 140s at 2850fps and the 147s at 2825fps in my 27". Again you can always cut it back but get a slow short barrel and you are stuck.
Someone did a limited test of cutting down a barrel to observe the velocity changes. That you might find to be helpful.
http://rifleshooter.com/2016/02/6-5...el-length-on-velocity-cutting-up-a-creedmoor/
As has been said though, different barrels have different properties, and unfortunately one barrel does not define a "standard"
http://rifleshooter.com/2016/02/6-5...el-length-on-velocity-cutting-up-a-creedmoor/
As has been said though, different barrels have different properties, and unfortunately one barrel does not define a "standard"
Depends what you want for velocity vs how handy you need it. I run my rifles in PRS style matches and I run a 27" and a 28" plus the brake and have no problems getting around and get good velocities. Factory 140 ELD-M from the 28" is 2880fps. But if you wanted short and handy hunting rifle then you will give up velocity. A good all around would be in the 24-26" length.
Something to think about though is you can always get a barrel cut back but you can;t add length once you cut it short.
My 28" Creedmoor to give you an idea of length.
What profile is that? Heavy palma?
Does barrel life have anything to do with the length?
No. Barrel life is really determined by throat erosion, which is caused mostly by heat.
Mark Kuczka
Accurate Ordnance
FWIW, out of my Tikka CTR 20" suppressed: hornady 120gr eld match avg = 2754fps, hornady 140gr hpbt match avg = 2530fps. Mind you this is only the first 30 rounds fired out of this rifle.
ETA: those are factory hornady loads.
ETA: those are factory hornady loads.
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Sorry, the reflection made it look tapered.
Thanks again for all the good info. I may end up leaving it longer. Like you say. I can always shorten it.
This is very good information. Thanks for posting it.
That test is BS. You don't gain velocity from a 27" barrel to a 24" barrel. Also the load is very slow to begin with. I would take that test with a grain of salt and I wouldn't use it to make the decision on barrel length.
It's an M24/40 contour Bartlein.
I run a 27" krieger with a modified mtu contour. By modified I mean I increased the length of the breach by a couple inches so that when I shot the throat out I could recut the chamber n get a little more life out of it. I'm getting just over 2900fps in summer temps hand loading but in -20 temps I'm down to 2750s. I have come to the conclusion that after 4K and chsnge rounds down this tube it's time for a new one though. I'm going to have some fun with it n chop a few inches off at a time and see what my velocity changes are though.
Hey Rob
I am the author. This is the second or third time I am aware of you calling my test "bs". Read the entire post and let me know which specific parts or conclusions you disagree with. I post data I record along with cautionary notes regarding sample size and correct conclusions to be drawn.
Thanks
Bill
Bill, how many rounds were put through the barrel prior to conducting the test?
Hi
that barrel was new- it's in the post. Some are shot a lot. I'd argue the relative gain in velocity over those initial rounds is negligible but who knows definitely. Notice the 123 shows different than the 142.
There is another study looking at barrel pressure versus velocity on different barrel lengths of 5.56- M855 ammunition and showed similar results where velocity can be observed to fluctuate over different lengths and not display a consistently upward trend relative to increasing length.
www.dtic.mil/ndia/2010armament/WednesdayCumberlandPhilipDater.pdf
And this looking at the 6BR. Smaller variation but still not always a linear path.
http://bulletin.accurateshooter.com/2011/12/barrel-length-and-velocity-barrel-cut-down-tests/
It doesn't really matter to me to worry about the length, beyond- Does the overall length of the rifle work for my needs (and weight)? Am I getting an acceptable velocity out of my barrel for my purposes without under/over-pressurizing the load? Am I able to tune my load to see if I can maximize the burn rate to achieve a 99-100% optimized burn rate using a program like Quickload? Is the load accurate with a wide enough pressure node to stay consistent in the temperature ranges I generally shoot in?
I still feel that the general rule of the longer the barrel, the faster the velocity applies if you tune the load, but even if it doesn't, and the rifle still works with for the more fundamental points I mention above, who cares if the bullet is a little slower than it could be. I'm certainly not willing to cut up a bunch of barrels to see what that happy place is.
I'm also happy to follow the lead of the top shooters and copy what they do to an extent that works for me: http://precisionrifleblog.com/2015/11/21/precision-rifle-barrels/
www.dtic.mil/ndia/2010armament/WednesdayCumberlandPhilipDater.pdf
And this looking at the 6BR. Smaller variation but still not always a linear path.
http://bulletin.accurateshooter.com/2011/12/barrel-length-and-velocity-barrel-cut-down-tests/
It doesn't really matter to me to worry about the length, beyond- Does the overall length of the rifle work for my needs (and weight)? Am I getting an acceptable velocity out of my barrel for my purposes without under/over-pressurizing the load? Am I able to tune my load to see if I can maximize the burn rate to achieve a 99-100% optimized burn rate using a program like Quickload? Is the load accurate with a wide enough pressure node to stay consistent in the temperature ranges I generally shoot in?
I still feel that the general rule of the longer the barrel, the faster the velocity applies if you tune the load, but even if it doesn't, and the rifle still works with for the more fundamental points I mention above, who cares if the bullet is a little slower than it could be. I'm certainly not willing to cut up a bunch of barrels to see what that happy place is.
I'm also happy to follow the lead of the top shooters and copy what they do to an extent that works for me: http://precisionrifleblog.com/2015/11/21/precision-rifle-barrels/
That's what I was suspecting, Bill.
Since I purchased a magnetospeed 3-4 years ago Ive tracked every new barrel I've gotten. From the first ten rounds down the barrel, again at 50 after a cleaning and again around 100 and a second cleaning. I've found that by 100-120 rounds down the bore and two cleanings, the same load will have gained between 1.5 to as much as 5% more velocity. That includes my last three 6.5 creedmoor barrels. But in those all I've used were 140 weight bullets so I can't offer any insight on the behaviour of lighter projectiles.
Since I purchased a magnetospeed 3-4 years ago Ive tracked every new barrel I've gotten. From the first ten rounds down the barrel, again at 50 after a cleaning and again around 100 and a second cleaning. I've found that by 100-120 rounds down the bore and two cleanings, the same load will have gained between 1.5 to as much as 5% more velocity. That includes my last three 6.5 creedmoor barrels. But in those all I've used were 140 weight bullets so I can't offer any insight on the behaviour of lighter projectiles.
I plan on doing some more work on how barrels speed up. Were all those data points at the same temp?
We've done broken in barrels with a few thousand rounds down the tube and observed the same slowing in 223. Unexpected but that's the data we got.
I'm running a 24" WIN tactical (Bartlein blank i believe) out of my AI. It's shooting Prime 130's anywhere from 2835 (30*F) to 2905 (70*F). I have to due some testing to see if the velocity change was due to temps only or because I had cleaned the barrel just prior to shooting on the 30*F day.
I'm thinking it was a combination of the two but some thorough testing will sort that out in the coming weeks and months.
I'm thinking it was a combination of the two but some thorough testing will sort that out in the coming weeks and months.
That's a Bartlein
Actually it's been more than that every time it comes up on facebook. Look at the 142 chart. You don't gain velocity going from a 27" barrel to a 24" barrel. Sorry. Doesn't happen. If that barrel did then it's an anomaly or the loads were mixed up or like you said the barrel wasn't properly fouled but even that would only effect a few of the first rounds but guys are posting your test up like it's the only fact out there in barrel length. They miss the small part where you add about a new barrel and fouling in the Q&A. Sorry if you put a lot of time into it but the results are not what I have seen from shooting the round since 2008 in multiple barrels and talking to a lot of people with different barrel lengths. I don;t want people seeing that, spending their hard earned money and making the wrong decision on a barrel and not being happy.
Not to mention people posting that the 6.5 Creedmoor is "running out of gas past 24". They are new to the round and don;t know it was developed around a 28" barrel but they scroll down and look at your test and say there is the proof! Again sorry if my wording is too harsh but I stand by my opinion the test is flawed and doesn't show the truth about the barrel length and velocity. Also as I posted before, I don't think this is due to any malicious intent on your part.
Hi Rob,
I appreciate your response. The ammunition wasn't mixed and I published the results I obtained, that is how "science" works (and I use that term loosely). You record the data you get, not the data you want to get. The lighter load did speed up, heavier didn't. A better argument would be based on sample size (number of rounds fired and barrels (1) my background is in stochastic modeling- I actually wrote models for far more complex systems and we would test them against empirical data sets, when the model didn't match we would work on making a better one) or the quality (or lack of quality) of the barrel. I don't disagree that you would think longer barrels go faster, I do too. What you have is called an anecdotal account based on your experience, which is certainly valid (guys like me and you have access to far more resources than most shooters). Have you ever cut the same 6.5 creed barrel with the same ammo at the same temp? What does that data set look like? As far as people misinterpreting what I write (or you write), well, that is the internet. For what its worth we had similar diminishing returns over a mix of different cartridges and barrels.
For a little bit of history on why I started those posts it was to prove an article in a print magazine wrong. If you want I'll PM you the article, but basically someone claimed NO velocity gain in a 300 WIn Mag over 20" IIRC.
I guess we will agree to disagree.
Thanks,
Bill
No Bill I have never cut down a perfectly good barrel as I actually would rather shoot them and don't honestly care to do science for people. I have had 3 barrels in 6.5 Creedmoor and have data from those barrels, 2 28" and 1 27". With the same factory lot of 140 ELD-M, as mentioned above, I am getting 2880fps from the 28" barrel and 2825fps from the 27" barrel. That right there shows one of two things, varying barrels and speed and that the round is still gaining velocity. Not super high tech science but data from two barrels.
Yes we can agree to disagree but from my experience with the round the data you gave doesn't hold true for general use of the cartridge. Maybe it happened in that barrel but that was the exception and not the rule.
Yes we can agree to disagree but from my experience with the round the data you gave doesn't hold true for general use of the cartridge. Maybe it happened in that barrel but that was the exception and not the rule.
I have to disagree. Barrel life can be affected by barrel length, the reason is say you want to achieve a specific MV and you have two barrel lengths. With the shorter barrel length, you are going to have to load the round hotter to achieve the same MV as a rifle with a longer barrel. A hotter load means faster throat erosion.
Something else I will throw out there for people to think about. Hornady, who originally designed the 6.5 Creedmoor around a 28" barrel, used to list the 28" velocity on the boxes. But a few years back they went to 24" as people were using it in rebarrels and also more companies were making rifles in that length than 28". Below are the 28" and 24" velocities for the same ammo that they listed on the boxes from their test barrels.
140 AMAX
28"- 2820fps
24"- 2710fps
120 AMAX
28"- 3020fps
24"- 2910fps
Just something to think about when looking at barrel length and velocity.
140 AMAX
28"- 2820fps
24"- 2710fps
120 AMAX
28"- 3020fps
24"- 2910fps
Just something to think about when looking at barrel length and velocity.
I don't disagree with most of what you are saying. In that spirit, I'll make you an offer. I'll provide a 31" HV Bartlein, thread and chamber it, you provide the ammo and I'll follow any test protocol you want.
You don't have to do anything to satisfy me. I know about the cartridge and barrel length and how it effects velocity. If someone else wants it done then I am sure they would appreciate.the time, cost and effort and maybe they will provide some factory ammo for the test. Should only need a couple hundred rounds of 140s and 120 ELDs.
Please take the offer and do a small collaboration test Rob, if only for your entertainment. At least give him the protocol you want followed. It will give us an article that you can spit to anyone that misinterprets and quotes the original 6.5 article. You can also have a more real world test that anyone can hopefully learn from rather than the "flawed" new barrel test that are currently out there. While I take your word based off of your results and knowledge here, we all know of new shooters that want numerical "proof" when dropping the serious coin involved in this sport sometimes.
Sorry but not looking to get into the testing and providing ammo for it.
The protocol I would follow would be:
Use the same lot of factory ammo in 120 and 140grn weights
Shoot at least 100 rounds through the barrel before testing, 150 preferred so that there is no barrel speed up during test.
Then clean it really well and foul it with 15-20 rounds.
Then start the test shooting and barrel cutting shooting 5 rounds of each bullet weight at each barrel length.
That is how I would run it and if anyone else has any other ideas then add them as I am sure Bill would like to hear it.
I'd say keep the barrel as long as you can, considering the extra weight and lost maneuverability the longer you go.
I cut mine to 24" and am getting 2800 FPS with 140 AMAXs (although it still seems to be getting faster, since it's still got a low round count).
Rob01's advice is sage, go long, you can always shorten it if it's unmanageable, but you can't make it longer.
I cut mine to 24" and am getting 2800 FPS with 140 AMAXs (although it still seems to be getting faster, since it's still got a low round count).
Rob01's advice is sage, go long, you can always shorten it if it's unmanageable, but you can't make it longer.
My 27" M24 8-twist Barltein shoots great for my 6.5 Creed. I am reloading and pushing Berger 140 hybrids at just a hair over 2,900 fps. measured with a MagnetoSpeed.
Do you mind sharing your load to get that velocity? How Are your primer pockets holding up?
Thanks
A real scientific test would involve multiple barrels. Any study of any type with what we call n=1 is always suspect. Realize that would be crazy expensive but just putting it out there. The other thing would be a parallel set of control barrels, same age and seasoned with the same number of rounds and then shot side-by-side with the cut barrels but retaining full length. You can see why we would do that control. Of course again this would make this even more prohibitively expensive but that is the reality of testing that is statistically significant and controlled.
I run 6.5 CM in 24, 26, and 28. I like them all, but if I had to get rid of 2 of them, the 24 inch stays. Great balance and good velocity.
Yeah you should do like you said if you wanted to spend that much time and money and cared that much about the outcome. My list was an easier way to try and take out some of the variables but it is still just data from one barrel. I don't feel the need to do any test as I know what the results will be from owning and talking to people since 2008 about the cartridge not to mention gathering data from people's posts on this and many other forums. But if Bill wants to do another test then all the power to him. I just gave my thoughts on how it should be done.
I am with you. Don't need that information to spend a small fraction of what it would cost to do a proper study - just putting it out there.
Can you share the data that you've gathered? That kind of thing would be edifying for the person deciding on the barrel length of a new rifle. You could make it a sticky in the bolt action rifle section. Probably plotting the data would be best, and restrict the data into categories of factory ammo, reloades, bullet weight, and so on...
Let me just start by saying I have no experience reloading and only shoot factory ammunition at this time. Perhaps I am missing something with the barrel length discussion but doesn't the amount of contact surface of the bullet play into the velocity out of a particular barrel with a fixed charge? I understand that when reloading the charge can be tailored to the resistance of the bullet in the barrel and the length of burn available in the length of the barrel but with factory ammunition aren't these things fixed? Wouldn't a bullet with less bearing surface (in this case the lighter bullet) in the barrel produce higher velocities? Isn't this why I hear the Berger 215 Hybrids produce higher velocities than the 210 VLD/s? It would seem completely plausible to me that the fixed burn of the factory powder load would reach a point of diminishing returns. This point would obviously vary depending on powder burn rate, resistance of the bullet, etc. Because the debated barrel length test was using a fixed factory load that was not tuned to the varying barrel length each time it was cut would it not simply show the optimal barrel length for that exact load (lot number, powder, bullet, etc)? Clearly if max velocity is reached with a particular charge and bullet out of say 24 inches of the barrel, to utilized the potential velocity of more barrel length the load would need to be modified, would it not? The way I understand it the optimal barrel length then would be different for a reloader than a factory ammo shooter. Maybe I am missing something but that is what seems logical to my untrained ear.
I have not written any of it down so no exact numbers to plot. I give my recommendations on my learned knowledge so that is all I have to offer.
