View Full Version : Barrel length and twist rate for .308
hotrodder636
07-07-12, 09:24
I am looking to build my first "precision" bolt gun that I would like to shoot anywhere from 100 to 1000 yards (after much learning from a fellow ex-Marine sniper). What I was wondering is how does one determine the correct barrel length and twist rate? Or does twist rate depend on barrel length? What determines the combo here? Thanks in advance for any replies!
And yes, I did try the orange search button for those who will inevitably ask.....
Bullet weight (and length) and bbl length guide twist selection. Heavier/longer bullets and/or shorter bbl's, if you're really wanting to extend range to 1,000 yds, require faster twists.
you generally want a faster twist rate the heavier the bullet. For long range 308 I would just say 1/12 twist rate just guessing that you would probably shoot 175 matchkings at the heaviest.
For length, thats a hot argument. Longer barrels will give a velocity boost. Shorter barrels of the same dia are stiffer.
Wolf Spyder
07-07-12, 14:18
hotrodder636,
How much do you have to spend?
It is important to figure out what your budget limit is before you start this project. There are budget rifles, in .308, that start in the $300 to $600 range and everything goes up from there to as much as $6,000 or more. Some of us, myself included, are building "budget" rifles where the finished product; factory Remington 700, medium grade scope, and an after market stock will put us in the $2000 range. So figure out what your willing to spend, first. Then second would be to figure out what caliber.
What I was wondering is how does one determine the correct barrel length and twist rate?
Barrel length can be any length from 16" to as long as 32" and greatly depends on the rifle's main purpose. Urban Tactical Rifles are very popular right now and tend to have barrel lengths around 20". While Intermediate & Long Range Varmint Rifles have barrel lengths around 26", and Long Range Competition rifles have barrel lengths around 30". Obviously, the shorter the barrel the lighter and easier the rifle will be to carry around. The opposite side of that coin is that the longer the barrel the greater the velocity of any given cartridge.
As for twist rate, like jmart said above; it greatly depends on the length of the bullet that you intend to fire. The heavier, and therefor longer, bullets require a faster twist to stabilize them during flight. Factory Remington 700's come in one of three, that I know of, twist rates; 1:10, 1:11.25, & 1:12.
To give you an idea here is what I am trying to do;
Remington 700 SPS-Tactical in 308 with 20 inch heavy barrel .......$500
Weaver Tactical 4-20x50mm mil/mil FFP 30mm Scope .................$750
Manners MCS T4 stock for Remington 700 Short Action (Tan) .......$500
Badger Ordnance 20MOA base & Medium Height Rings ................$300
Badger Ordnance M5 Stealth DBM kit ........................................$300
Timney Trigger ......................................................................$100
This puts me in the $2,500 range
Now trade out the $700 Weaver Tactical Series scope for a top of the line Schmidt & Bender Police Marksman 5-25x56mm PM with Illuminated P4F Reticle at about $3,600 and the price of the rifle goes up to $5,500. Add a Krieger barrel with 5-R rifling and have the action "trued" and polished and you've tacked on another $500 or $700 to the price of the rifle.
So figure out what your budget is first, and go from there.
ETA; Of course you can go the other direction...
Remington 700 SPS-T ($500)
Wal-mart Special Scope ($100)
Wal-mart base and rings ($50)
Add some Krylon camo paint ($4 @ Wal-mart) in Khaki and Army Green and your good to go. :haha:
hotrodder636
07-07-12, 14:40
hotrodder636,
How much do you have to spend?
It is important to figure out what your budget limit is before you start this project. There are budget rifles, in .308, that start in the $300 to $600 range and everything goes up from there to as much as $6,000 or more. Some of us, myself included, are building "budget" rifles where the finished product; factory Remington 700, medium grade scope, and an after market stock will put us in the $2000 range. So figure out what your willing to spend, first. Then second would be to figure out what caliber.
Barrel length can be any length from 16" to as long as 32" and greatly depends on the rifle's main purpose. Urban Tactical Rifles are very popular right now and tend to have barrel lengths around 20". While Intermediate & Long Range Varmint Rifles have barrel lengths around 26", and Long Range Competition rifles have barrel lengths around 30". Obviously, the shorter the barrel the lighter and easier the rifle will be to carry around. The opposite side of that coin is that the longer the barrel the greater the velocity of any given cartridge.
As for twist rate, like jmart said above; it greatly depends on the length of the bullet that you intend to fire. The heavier, and therefor longer, bullets require a faster twist to stabilize them during flight. Factory Remington 700's come in one of three, that I know of, twist rates; 1:10, 1:11.25, & 1:12.
To give you an idea here is what I am trying to do;
Remington 700 SPS-Tactical in 308 with 20 inch heavy barrel .......$500
Weaver Tactical 4-20x50mm mil/mil FFP 30mm Scope .................$750
Manners MCS T4 stock for Remington 700 Short Action (Tan) .......$500
Badger Ordnance 20MOA base & Medium Height Rings ................$300
Badger Ordnance M5 Stealth DBM kit ........................................$300
Timney Trigger ......................................................................$100
This puts me in the $2,500 range
Now trade out the $700 Weaver Tactical Series scope for a top of the line Schmidt & Bender Police Marksman 5-25x56mm PM with Illuminated P4F Reticle at about $3,600 and the price of the rifle goes up to $5,500. Add a Krieger barrel with 5-R rifling and have the action "trued" and polished and you've tacked on another $500 or $700 to the price of the rifle.
So figure out what your budget is first, and go from there.
ETA; Of course you can go the other direction...
Remington 700 SPS-T ($500)
Wal-mart Special Scope ($100)
Wal-mart base and rings ($50)
Add some Krylon camo paint ($4 @ Wal-mart) in Khaki and Army Green and your good to go. :haha:
Thank you for the time and info you provided. I am going into this knowing that all said and done that this would be significantly more expensive than my AR project. I already have decided on a Nightforce scope, Bartlein or Krieger SS barrel, McMillan or Manners stock. Still deciding on an action and the length of barrel I want. I have been thinking either 22 or 24 inch.
i always do this the same way. first, i pick a bullet i want to shoot. second, i call the sierra ballistics hotline or berger etc and ask them the range of twists that will stabilize it, and what twist shoots my chosen bullet best. they usually ask what cartridge and what i'm going to do with it, but that's usually a 30-60 min conversation where i wind up getting educated on a wide range of tangents. next, i call the gunsmith that i plan to use to chamber the barrel, and ask him what everybody else is using and what he recommends. if he says same thing, i go with it. if he says something different, i usually get another 30-60 min of education.
yeah, i know what you're thinking... it's no wonder the good gunsmiths have a 6-12 month waiting list when they spend all day on the phone talking about bullet and barrel selection!
Wolf Spyder
07-07-12, 15:37
hotrodder636,
Sounds like your all set. I am limited in the amount of money I can spend, but it sounds like you don't have quite the same limitations. When you get done building your "Race Horse" you'll have to post a range report and lot of photos. :dance3:
hotrodder636
07-07-12, 17:46
hotrodder636,
Sounds like your all set. I am limited in the amount of money I can spend, but it sounds like you don't have quite the same limitations. When you get done building your "Race Horse" you'll have to post a range report and lot of photos. :dance3:
I most definitely will do, but am going to have to buy part by part as it will be as I want to save up the coin for it! I have done enough research and know enough shooters who have helped me with my combo. Like I said really just need to decide on an action and barrel length.
ICANHITHIMMAN
07-07-12, 17:55
I would expand your list of barrel makers and order that part first. Give A LOT of consideration to barrel profile it is the most important and under considered decsion.
hotrodder636
07-07-12, 18:10
I would expand your list of barrel makers and order that part first. Give A LOT of consideration to barrel profile it is the most important and under considered decsion.
I have looked through several barrels and the two I listed keep coming up in discussions with shooters at my local club who shoot long range (1000 yard) competition, several of which I personally know and were snipers for the Marines and Army. If you have others to recommend, please do as I have not built the rifle and still have time for research. Thank you.
What bullet do you want to shoot? Thats the main thing for twist. Then deside how long you are willing to go with it.
AR15barrels
07-08-12, 00:18
Let's assume 175smk's and 178 hornady BTHP bullets as the standard 1000yd 308 fodder.
Then let's pick 26" as a good compromise between weight and length.
Go 1:11 twist and you are good to go.
ICANHITHIMMAN
07-08-12, 08:51
I have looked through several barrels and the two I listed keep coming up in discussions with shooters at my local club who shoot long range (1000 yard) competition, several of which I personally know and were snipers for the Marines and Army. If you have others to recommend, please do as I have not built the rifle and still have time for research. Thank you.
Brux, Lilja, hart(of NY), Pac Nor, there are a lot more but these are the ones I have used. I made the barrel profile mistake once, The barrel litterly shot the best of any barrel I have ever had but it was useless for anything but prone shooting. I will never again pic any barrel larger than a sendero profile, thats about .850 at the muzzle.
I also like long barrels its just me, I like to get every bit of speed I can and I think they look good. Of the 3 rifles in 308win I have, I always go with a 1-10 twist. I like to play with a lot of bullet weights and prefer heavy bullets.
The barrels take the longest to come for some reason, unless you buy one that the builder has just lying around.
Do you have a gunsmith? Thats another factor, the better the smith the longer the wait.
Jon
5 of my last 6 barrels were bartlein and the other was brux.
If you order from the maker it will take a while and it depends on where you catch them in the their production schedule since most make a run of 6 then 6.5 then 7 then 7.62 etc before going back. (not necessarily in that order of course)
However you can almost always find them in stock at retail places. I bought my Bartleins from Accuracyone because they always have had them in stock. Grizzly also keeps them in stock.
hotrodder636
07-08-12, 12:01
Brux, Lilja, hart(of NY), Pac Nor, there are a lot more but these are the ones I have used. I made the barrel profile mistake once, The barrel litterly shot the best of any barrel I have ever had but it was useless for anything but prone shooting. I will never again pic any barrel larger than a sendero profile, thats about .850 at the muzzle.
I also like long barrels its just me, I like to get every bit of speed I can and I think they look good. Of the 3 rifles in 308win I have, I always go with a 1-10 twist. I like to play with a lot of bullet weights and prefer heavy bullets.
The barrels take the longest to come for some reason, unless you buy one that the builder has just lying around.
Do you have a gunsmith? Thats another factor, the better the smith the longer the wait.
Jon
Thank you for the info. You have now brought in something I hadn't been thinking about and that is the profile. I do have a smith, I have shot some of the rifles he has built and they are quite nice. I was thinking of 175 grain SMKs. Once I get the setup and throw a few hundred factory loads down range, I want to reload my own. I have reloaded thousands of pistol cartridges but no rifle. Again thank you all for the advice so far.
My 308s have all been 1-10 with one 1-12, l cant tell much of a difference they both shoot 175smks without any problems.
l have always used 26 inch varmint barrels, l dont have any reason to switch. If your not gonna be hunting or lugging the thing around all day l'd get a 24-26 inch barrel in a standard varmint profile which is usually around .890. l also dont care for the huge bull barrel profile.
nineteenkilo
07-26-12, 16:47
ETA; Of course you can go the other direction...
Remington 700 SPS-T ($500)
Wal-mart Special Scope ($100)
Wal-mart base and rings ($50)
Add some Krylon camo paint ($4 @ Wal-mart) in Khaki and Army Green and your good to go.
Singularly one of the most useful pieces of information I've ever seen given to a long range rookie. It may have been intended as tongue-in-cheek, but it is what more people need to do. Spend enough money on ammo and range time to get the 'Wal-Mart' rig where you want it - then start looking at Nightforce, etc.
Some people don't want you to believe you can score thousand meter hits with 'junk'.
As far as barrel length to me it would depend on what you want to do with it. A 20 inch barrel will get you to 1000yds with no problem. I'm sure an 18 inch would do the same. Having a short barrel is nice for maneuverability. If you are just going to be shooting prone at a range it doesn't really matter.
A 20 inch barrel will get you to 1000yds with no problem. I'm sure an 18 inch would do the same. What exactly are you basing this information off of? A 24" barrel 308 isn't an authority at 1000yds. It's anything but, actually.
So if that's the case (and it is) then how can a shorter barrel pull it off?
Answer: It can't.
A 28" 308 shooting 155 lapua's can basically match a 300WM shooting 190SMK's. Not on energy, mind you, but on trajectory and pretty close on wind.
If getting to a thousand yards is the only qualifier, then just about any cartridge would do it. Being proficient at that distance is entirely another matter. I have thousands of rounds through an 18" and 20" 308. To 600yds on full size IPSC plates, they do their job regardless of the conditions. Past that however, once the wind gets up over 10mph, shit gets quite difficult. My 22" barrel eats it for breakfast at 800-1000yds using the exact same bullet/load.
Put the best shooters in the world behind an 18" 308 at 1000yds on a gusting 15-20mph full value wind... and I bet they wouldn't go 50% on first round hits. Probably much less, actually.
My point was it depends on what you want to do with the rifle. If you are going to use it to shoot prone on a range then by all means go for a longer barrel, but if you are going to be running around with the rifle you might consider something shorter. He said anywhere from 100 - 1000yds so it will not just be a 1000yd rifle.
DTA SRS - Short overall length, long barrel. Problem solved.
Did I mention I'm a dealer? lol
What is going to be the primary use for this rifle (e.g. hunting, tactical competitions, etc). If you want to soon matches/competitions, I'd consider going with something other than 308. I've talked to some tactical competition shooters and none of them shoot 308 unless that is the required caliber for a match. If you don't reload, then 6.5 Creedmoor is the way to go. It has a very high BC, compared to 308, and as a result won't get pushed around by the wind nearly as much. I'm not trying to change this to a caliber discussion, but I thought it was worth a mention.
If you are considering a custom build, you might look at Surgeon actions. They are expensive, but you'd be hard pressed to find something better.
I agree with what rudy said. For factor ammo, it's virtually impossible to beat the 6.5 Creedmoor. If reloading, the 7WSM rules the roost.
What exactly are you basing this information off of? A 24" barrel 308 isn't an authority at 1000yds. It's anything but, actually.
So if that's the case (and it is) then how can a shorter barrel pull it off?
Answer: It can't.
A 28" 308 shooting 155 lapua's can basically match a 300WM shooting 190SMK's. Not on energy, mind you, but on trajectory and pretty close on wind.
If getting to a thousand yards is the only qualifier, then just about any cartridge would do it. Being proficient at that distance is entirely another matter. I have thousands of rounds through an 18" and 20" 308. To 600yds on full size IPSC plates, they do their job regardless of the conditions. Past that however, once the wind gets up over 10mph, shit gets quite difficult. My 22" barrel eats it for breakfast at 800-1000yds using the exact same bullet/load.
Put the best shooters in the world behind an 18" 308 at 1000yds on a gusting 15-20mph full value wind... and I bet they wouldn't go 50% on first round hits. Probably much less, actually.
I'll say that my knowledge of the subject is more research than practical at this point (I'm working on that ;)), so I'm asking you about your statement here more to pick your brain than to give opposing view points.
So when you say the above about a sub-20" barrelled .308, is this because the round will go subsonic before it hits 1,000 yds? Or is that statement just meant to say that it's "less easy" to hit consistently at 1,000 with that setup? Due to wind, trajectory, or both?
What about when using the heavier projectiles? Would that be of any help?
First, don't ever make a statement like you did if you don't have first hand experience. There are enough windbags on the internet. Trust me. I'll forgive you and move on, since you were man enough to admit you don't know what you are talking about. ;)
In my AO under typical conditions, using an 18" krieger barrel firing 175SMK's at 2550fps... at 1000yds the bullet is going 1160fps. That could be subsonic (borderline) on some days.
However, its a question of wind, more than trajectory. The difference between a 10mph wind and a 11mph wind is 0.3 mils. That is a ton. That results in misses. A 10mph wind isn't even a stiff breeze in south dakota.
First, don't ever make a statement like you did if you don't have first hand experience. There are enough windbags on the internet. Trust me. I'll forgive you and move on, since you were man enough to admit you don't know what you are talking about. ;)
In my AO under typical conditions, using an 18" krieger barrel firing 175SMK's at 2550fps... at 1000yds the bullet is going 1160fps. That could be subsonic (borderline) on some days.
However, its a question of wind, more than trajectory. The difference between a 10mph wind and a 11mph wind is 0.3 mils. That is a ton. That results in misses. A 10mph wind isn't even a stiff breeze in south dakota.
Umm, not sure which statement you're making reference to (since I didn't make one, as it was a question)...unless I missed some sarcasm :confused:
But thanks for the response.
Yeah, I was just poking fun. Hence the ;)
Yeah, I was just poking fun. Hence the ;)
Gotcha...internet and all ya know... ;)
With a 24 inch 308 and 168 SMK I had a chance to shoot unknown distance out to a bit past 1000 yds. We had variable winds. Even with a 24 inch barrel the 168 SMK was not too predictable as targets got closer to 1000. Furthest hit I got (2 chances per target) was 940 yards. For serious use at that range I'd want to use 175 SMK's and keep every inch of that barrel if you are trying to make first round hits in variable wind. I've got an 18 inch 308 on order but it wouldn't be my first choice if I seriously wanted to increase my odds of a first round hit at serious distance, not that you can't hit, not that the bullet won't travel that far, but when it goes subsonic you can't count on any consistancy. I see all kinds of folks touting the virtues of 16 inch barrels at 1500 yards and I can only say they cannot be talking about reliable first round hits with unknown distance and variable wind etc.
I see all kinds of folks touting the virtues of 16 inch barrels at 1500 yards and I can only say they cannot be talking about reliable first round hits with unknown distance and variable wind etc. Run away from those people and their "advice." Don't walk... run.
AR15barrels
08-20-12, 18:23
Run away from those people and their "advice." Don't walk... run.
Yeah, I love how they always post up Frank's video as proof...
Yeah, I love how they always post up Frank's video as proof... That's my favorite too. Cracks me up. :D
hotrodder636
08-20-12, 19:06
What is going to be the primary use for this rifle (e.g. hunting, tactical competitions, etc). If you want to soon matches/competitions, I'd consider going with something other than 308. I've talked to some tactical competition shooters and none of them shoot 308 unless that is the required caliber for a match. If you don't reload, then 6.5 Creedmoor is the way to go. It has a very high BC, compared to 308, and as a result won't get pushed around by the wind nearly as much. I'm not trying to change this to a caliber discussion, but I thought it was worth a mention.
If you are considering a custom build, you might look at Surgeon actions. They are expensive, but you'd be hard pressed to find something better.
I am not dead set on .308, I just figured it was a good "all around" caliber and I have a good amount of 175grain SMKs. Since I will most likely eventually reload, I have been pondering the 6.5, 7 and .300wm. Any advice on caliber selection here?
My smith is recommending a Badger action. Any thought on a Badger vs a surgeon?
I am not dead set on .308, I just figured it was a good "all around" caliber and I have a good amount of 175grain SMKs. Since I will most likely eventually reload, I have been pondering the 6.5, 7 and .300wm. Any advice on caliber selection here?
My smith is recommending a Badger action. Any thought on a Badger vs a surgeon?
as for ammo...
http://demigodllc.com/articles/the-case-for-260-remington/
if u reload, i would say 260 due to cheeper and more brass... if you dont, creedmoor
http://demigodllc.com/articles/6.5-shootout-260-6.5x47-6.5-creedmoor/
surgeon is better....
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