Barrel Length + Contour for .308

[ballisticdaddy]

I have an older Remington 700 Mil Spec that is in an AICS chassis and wanted to get a new barrel for it so I can shoot F-TR. Leaning towards a Bartlein barrel but not sure what length and contour. Is it really a disadvantage if it were 26" in length as far as MV as opposed to a 30"? With weight being a concern was thinking about heavy varmint contour and wanted to see if I was on the right track?

 

[raptor1ronin]

Hi,
If your going to shoot FTR the minimum I would do would be 30" Finished. This way you will be able to take full advantage of the .308 cartridge out to 1000 yards. I use a 1-10 twist Kreiger HV 30" for FTR and im pretty sure that 98% of FTR shooters use 30" barrels.

 

[Wildcats]

In a 308,i would keep it around 26",the extra 4 is not going to give a significant MV advantage and the rifle will be better balanced specially with a HV contour barrel.

 

[watercam]

Your competition will be using 30" or longer barrels to squeeze every last fps from the heavy bullets they use. 185s and up. Most that I have seen are straight contour around 1.25" but I have seen larger diameter. Balance is not much of an issue when shooting with a bipod and rear bag. A shorter barrel can get them there but it will take a tad longer and the wind will be pushing them for the entire flight to paper. The X-ring is 5" at 1000 yds. on an F-Class target. Take all the advantage you can.

 

[Ned Ludd]

In a 308,i would keep it around 26",the extra 4 is not going to give a significant MV advantage and the rifle will be better balanced specially with a HV contour barrel.

This is absolutely untrue. The extra 4" of barrel DOES have an impact on velocity, especially if you start using the longer, heavier 185-200 gr bullets currently available to F-TR shooters. I ran 24" and 26" barrels for a couple years at both 600 and 1000 yd until I finally realized what a disadvantage they actually were.

To the OP - you can certainly use a 26" barrel to compete, but it will not allow you to get everything out of your bullets that you could be getting. Again, that doesn't mean a 26" barrel won't work, but a longer barrel would be to your advantage, even if you went 28" or 29", instead of 30" to 32".

In terms of contours, you should be looking at the heaviest contour you can use and still make weight with the rifle. In a 30" barrel, that typically means MTU or HV contour at the heavy end of the scale. Much will depend on the weight of the other components in your rig (scope, bipod, stock, action, etc.). M24 contour falls just slightly lower in weight than a comparable MTU or HV barrel of the same length. Finally, the Heavy/Med Palma barrels would be the next lower weight class commonly found in F-TR. For a given length, Bartlein can give you a very good expectation of what a finished barrel is going to weigh in any of these contours. I'd start by determining exactly how much weight you have to play with in your rig, then give Bartlein a call and see what they can do for you.

 

[Wildcats]

Article from Rifleshooter

308 Winchester Barrel length in inches versus Muzzle velocity in feet-per-second (ft/sec)
Rifleshooter.com
Barrel length Winchester 147 FMJ IMI Samson 7.62 150 FMJ Federal 168 Gold Medal Winchester 180 PP
Winchester 147 FMJ.. IMI Samson 7.62 150 FMJ... Federal 168 Gold Medal.. Winchester 180 PP

147fmj 150fmj 168GM 180PP
28 2965 2823 2706 2632
27 2962 2800 2697 2607
26 2955 2801 2673 2597

25 2917 2769 2659 2585
24 2909 2766 2635 2553
23 2877 2744 2618 2553
22 2837 2718 2597 2527
21 2807 2683 2580 2507
20 2804 2679 2565 2478
19 2757 2634 2532 2441
18 2739 2595 2523 2411
17 2707 2577 2481 2401
16.5 2682 2561 2466 2373
AVG velocity loss fps/inch 24.6 22.8 20.9 2

 

[Dgd6mm]

In my 30" I am running my 185 Berger at 2790 fps and could go faster with a different powder, but this works for me. Try to run this bullet this fast in a 26" and see what happens. All the top FTR shooters either frequent here or stop in once in a while, they will tell you the same as gstaylorg did. You can take his word to be factual and true.

Don Dunlap

 

[Ned Ludd]

Article from Rifleshooter

308 Winchester Barrel length in inches versus Muzzle velocity in feet-per-second (ft/sec)
Rifleshooter.com
Barrel length Winchester 147 FMJ IMI Samson 7.62 150 FMJ Federal 168 Gold Medal Winchester 180 PP
Winchester 147 FMJ.. IMI Samson 7.62 150 FMJ... Federal 168 Gold Medal.. Winchester 180 PP

147fmj 150fmj 168GM 180PP
28 2965 2823 2706 2632
27 2962 2800 2697 2607
26 2955 2801 2673 2597

25 2917 2769 2659 2585
24 2909 2766 2635 2553
23 2877 2744 2618 2553
22 2837 2718 2597 2527
21 2807 2683 2580 2507
20 2804 2679 2565 2478
19 2757 2634 2532 2441
18 2739 2595 2523 2411
17 2707 2577 2481 2401
16.5 2682 2561 2466 2373
AVG velocity loss fps/inch 24.6 22.8 20.9 2

Aren't these all values for commercial ammunition? If so, they have little bearing on handloads for F-TR competition rifles. Commercial loads are designed to shoot reasonably well out of a wide range of different rifles, typically having barrels up to about 26" in length. So the powder and charge weights used are not optimized in terms of their combustion properties for longer barrels. In addition, they are also designed to be loaded into magazines, meaning restricted COAL. For commercial ammunition, I agree that the velocity gains realized per inch of added barrel length for barrels longer than 26" are minimal compared to the gains you will see for barrels in the 16" to 26" range. Edited to highlight the "For commercial ammunition" clause.

However, handloads are a completely different story. Optimized loads for an F-TR rifle with a 26" versus a 30" barrel can easily show velocity differences of 50 fps or more. It's not just loading to equal pressure, it's finding the optimal charge weight window and seating depth where precision is at its best for that specific setup. When you do that for a long time as I have, you develop a pretty good feel for how large the differences can actually be. They're not as small as you think they are. Further, other issues such as pressure and bras life come into play. If the performance for optimized handloads with a given bullet was comparable between rifles with 26" and 30" barrels, everyone in F-TR would be using a 26" straight contour barrel. I can assure you that they are not doing that.

 

[Wildcats]

Aren't these all values for commercial ammunition? If so, they have little bearing on handloads for F-TR competition rifles. Commercial loads are designed to shoot reasonably well out of a wide range of different rifles, typically having barrels up to about 26" in length. So the powder and charge weights used are not optimized in terms of their combustion properties for longer barrels. In addition, they are also designed to be loaded into magazines, meaning restricted COAL. For commercial ammunition, I agree that the velocity gains realized per inch of added barrel length for barrels longer than 26" are minimal compared to the gains you will see for barrels in the 16" to 26" range.

However, handloads are a completely different story. Optimized loads for an F-TR rifle with a 26" versus a 30" barrel can easily show velocity differences of 50 fps or more. It's not just loading to equal pressure, it's finding the optimal charge weight window and seating depth where precision is at its best for that specific setup. When you do that for a long time as I have, you develop a pretty good feel for how large the differences can actually be. They're not as small as you think they are. Further, other issues such as pressure and bras life come into play. If the performance for optimized handloads with a given bullet was comparable between rifles with 26" and 30" barrels, everyone in F-TR would be using a 26" straight contour barrel. I can assure you that they are not doing that.

I'm not disagreeing with what you are saying
But you are splitting hairs....

It's all good brother,i was simply stating my opinion.

 

[Ned Ludd]

It's not splitting hairs; your original statement was flat out wrong, and you keep coming back trying to save face, divert attention, or prove your point, I'm not really sure which. However, if you're going to highlight my statements, don't pull the "fake news" trick and highlight only the part that supports what you're trying to argue; highlight the whole statement.

I specifically stated that for commercial ammunition, the velocity gains with barrel lengths longer than 26" are less than those for barrels between 16" and 26" in length. The reason for that was because you used velocity values obtained from commercial ammunition as an example to try and support the notion that barrel lengths over 26" don't make much of a difference. I was trying to point out why there is little similarity between commercial ammunition, which isn't really optimized for rifles with long barrels, and handloads, which can be optimized for rifles with long barrels. Trying to compare the two is comparing apples to oranges. In fact, in many cases with a 26" barrel, you can't even hit the same node as with a 30" barrel without going to ridiculously unsafe pressure. In those cases, the difference in velocity isn't merely significant, it's huge. If you reloaded and competed in F-Class regularly, you would already know the answer and wouldn't continue trying to prove a point that is incorrect.

 

[Ray Gross]

I have an older Remington 700 Mil Spec that is in an AICS chassis and wanted to get a new barrel for it so I can shoot F-TR. Leaning towards a Bartlein barrel but not sure what length and contour. Is it really a disadvantage if it were 26" in length as far as MV as opposed to a 30"? With weight being a concern was thinking about heavy varmint contour and wanted to see if I was on the right track?

Follow the link for barrel lengths and contours as listed on the US Rifle Team (FTR) equpment list.

 

[Dgd6mm]

Al

Follow the link for barrel lengths and contours as listed on the US Rifle Team (FTR) equpment list.

Also, take note in the bullet being used.

Don Dunlap

 

[ballisticdaddy]

Follow the link for barrel lengths and contours as listed on the US Rifle Team (FTR) equipment list.

Thank you this is exactly the kind of information that I was looking for!

 

[ballisticdaddy]

Al



Also, take note in the bullet being used.

Don Dunlap

One of the few things that looks like they are being used across the board, not a coincidence I am certain!

 

[ballisticdaddy]

It's not splitting hairs; your original statement was flat out wrong, and you keep coming back trying to save face, divert attention, or prove your point, I'm not really sure which. However, if you're going to highlight my statements, don't pull the "fake news" trick and highlight only the part that supports what you're trying to argue; highlight the whole statement.

I specifically stated that for commercial ammunition, the velocity gains with barrel lengths longer than 26" are less than those for barrels between 16" and 26" in length. The reason for that was because you used velocity values obtained from commercial ammunition as an example to try and support the notion that barrel lengths over 26" don't make much of a difference. I was trying to point out why there is little similarity between commercial ammunition, which isn't really optimized for rifles with long barrels, and handloads, which can be optimized for rifles with long barrels. Trying to compare the two is comparing apples to oranges. In fact, in many cases with a 26" barrel, you can't even hit the same node as with a 30" barrel without going to ridiculously unsafe pressure. In those cases, the difference in velocity isn't merely significant, it's huge. If you reloaded and competed in F-Class regularly, you would already know the answer and wouldn't continue trying to prove a point that is incorrect.

I have been shooting FT-R for about a year now with my 700 Mil Spec with a 20" barrel 11.25 twist shooting the 175 SMK in Lapua brass over RE-17 and can push that 2,740 fps with no pressure signs or primer pocket issues. What are the velocities you are getting with which projectile at 30"? I understand there is a drop in MV with the shorter pipes but would 50 fps make a huge difference? In reading the equipment list for the US Rifle Team they seem to vary from 28 to 32" in length but all use the same projectile.

 

[Dgd6mm]

A lot of it has to do with with what mv is retained down range. We took note of this one day at a 600 yard shoot with electronic targets that measure the speed your bullet is going when it passes thru the target. My buddy running a 175 SMK at 2830 out of a 28". My other buddy running 200 20x around 2650 out of his barrel length, which is either 30 or 32. His barrel length and his starting mv I'm not 100% on but can later check if needed. The end results for mv thru the target was that the 200 20x was almost 300 fps faster. That definitely is a retention in BC. JBM will confirm these types of numbers.

Don Dunlap

 

[Down South]

There's a reason the majority of FTR shooters are running 28-32 inch barrels................As for contour, I personally go as heavy as i can and still make weight.

 

[ballisticdaddy]

A lot of it has to do with with what mv is retained down range. We took note of this one day at a 600 yard shoot with electronic targets that measure the speed your bullet is going when it passes thru the target. My buddy running a 175 SMK at 2830 out of a 28". My other buddy running 200 20x around 2650 out of his barrel length, which is either 30 or 32. His barrel length and his starting mv I'm not 100% on but can later check if needed. The end results for mv thru the target was that the 200 20x was almost 300 fps faster. That definitely is a retention in BC. JBM will confirm these types of numbers.

Don Dunlap

Appreciate the reply Don but that is not really apples to apples. My question is if you fired the same projectile, let's use the Berger 200x, with the same powder charge in a 26" and a 30" barrel what do you think the difference in MV would be? I intend to have the new barrel chambered for the 200x but trying to establish what the length should be.

 

[Wildcats]

It's not splitting hairs; your original statement was flat out wrong, and you keep coming back trying to save face, divert attention, or prove your point, I'm not really sure which. However, if you're going to highlight my statements, don't pull the "fake news" trick and highlight only the part that supports what you're trying to argue; highlight the whole statement.

I specifically stated that for commercial ammunition, the velocity gains with barrel lengths longer than 26" are less than those for barrels between 16" and 26" in length. The reason for that was because you used velocity values obtained from commercial ammunition as an example to try and support the notion that barrel lengths over 26" don't make much of a difference. I was trying to point out why there is little similarity between commercial ammunition, which isn't really optimized for rifles with long barrels, and handloads, which can be optimized for rifles with long barrels. Trying to compare the two is comparing apples to oranges. In fact, in many cases with a 26" barrel, you can't even hit the same node as with a 30" barrel without going to ridiculously unsafe pressure. In those cases, the difference in velocity isn't merely significant, it's huge. If you reloaded and competed in F-Class regularly, you would already know the answer and wouldn't continue trying to prove a point that is incorrect.

Well you have obviously turned an other simple Post/question the OP asked into your own personal attack on another member who was trying to help and post their opinion,wich is what this Forums are all about.
We all have our own opinions based on our own experiences.
So you feel that i need to Save face,not sure what that means in you part of the woods,normally that term is reserved for someone that has undoubtedly done something really wrong to someone else. whatever... Yet you still go ranting about how wrong i am ,without substantiating your claims, without real time data and testing.

But your the forum expert!

Saving face is now reserved for you..

Enough said.

My sincere apologies to the Op.

 

[Dgd6mm]

Appreciate the reply Don but that is not really apples to apples. My question is if you fired the same projectile, let's use the Berger 200x, with the same powder charge in a 26" and a 30" barrel what do you think the difference in MV would be? I intend to have the new barrel chambered for the 200x but trying to establish what the length should be.

This being an educated guess, 65-85 fps from 26" -30".