.338 barrel length

A

ArtoR

Private
Minuteman
Sep 22, 2024
9
2
Finland
#1
Hello.

Question about .338 LM barrel length (maybe applicable to other .338's too):
I'm interested to know your experiences of long barrels.
Idea is to shoot 300gr VLD bullets way over 1000m. Is there any benefit to have longer barrel than 30 inches?
I know the twist rate needs to be faster or equal than 1:9.3". I understand that velocity should be around 3000fps (900m/s).
 
#2
Who says 9.3 or faster for twist?

A 10 twist will fly the 300’s. I feel that’s on the ragged edge. I’ve run 9.5 twist with no issues and 300gr bullets.

3000fps… even in a 30” barrel is going to be a stretch. Pretty much guarantee you will be past max normal working pressure. Be safe with what you’re doing. You will be probably in the mid 2800fps range with max working pressure. Maybe 2900fps.

All of the AI barrels we make are 9.35 twist. That’s what they want. Most others we make are 9.5.

Unless you get into custom solid bullets… I don’t know why you would need faster on the twist.

Later, Frank
Bartlein Barrels
 
Last edited:
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#7
You also made several statement as to velocity and barrel twist and Frank was suggesting some changes. You got some really good advice from someone who has seen most of it in the past.
 
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#10
ArtoR said:
I am willing to learn about other shooters' experiences and having purely technical approach. Nothing silly in that :)
How much benefit there would be with that 34" barrell?
Click to expand...
Google search the below test done by rifle shooter site. Only goes to 30 inches but will give you a good idea of attainable velocity.

338 Lapua Magnum: Barrel Length Versus Muzzle Velocity (30-17 inches)​

 
#14
ArtoR said:
Hello.

Question about .338 LM barrel length (maybe applicable to other .338's too):
I'm interested to know your experiences of long barrels.
Idea is to shoot 300gr VLD bullets way over 1000m. Is there any benefit to have longer barrel than 30 inches?
I know the twist rate needs to be faster or equal than 1:9.3". I understand that velocity should be around 3000fps (900m/s).
Click to expand...
Get a 33XC if you’re looking for more horsepower
 
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#15
The practical tradeoffs of going over 30" are not worth it in my opinion. E.g. transporting the rifle, finding cases that fit, etc. 30" is already LONG, add a brake/can and things start getting ridiculous. A 30" Lapua will get you all the velocity you would ever need to well past 1000m. So would a 26" Lapua for that matter. If you want more velocity, I would move to a Lapua improved or XC as was mentioned.

Here is a 30" Lapua improved with a can. I would not want to go any longer. I had to buy a new safe just to fit this beast.

IMG_20191221_150241.jpg


IMG_20191221_150121.jpg
 
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#16
surgeon260 said:
The practical tradeoffs of going over 30" are not worth it in my opinion. E.g. transporting the rifle, finding cases that fit, etc. 30" is already LONG, add a brake/can and things start getting ridiculous. A 30" Lapua will get you all the velocity you would ever need to well past 1000m. So would a 26" Lapua for that matter. If you want more velocity, I would move to a Lapua improved or XC as was mentioned.

Here is a 30" Lapua improved with a can. I would not want to go any longer. I had to buy a new safe just to fit this beast.

View attachment 8507929

View attachment 8507930
Click to expand...
A new safe? What's wrong with under the pillow?
 
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#18
surgeon260 said:
The practical tradeoffs of going over 30" are not worth it in my opinion. E.g. transporting the rifle, finding cases that fit, etc. 30" is already LONG, add a brake/can and things start getting ridiculous. A 30" Lapua will get you all the velocity you would ever need to well past 1000m. So would a 26" Lapua for that matter. If you want more velocity, I would move to a Lapua improved or XC as was mentioned.

Here is a 30" Lapua improved with a can. I would not want to go any longer. I had to buy a new safe just to fit this beast.

View attachment 8507929

View attachment 8507930
Click to expand...
surgeon260 said:
The practical tradeoffs of going over 30" are not worth it in my opinion. E.g. transporting the rifle, finding cases that fit, etc. 30" is already LONG, add a brake/can and things start getting ridiculous. A 30" Lapua will get you all the velocity you would ever need to well past 1000m. So would a 26" Lapua for that matter. If you want more velocity, I would move to a Lapua improved or XC as was mentioned.

Here is a 30" Lapua improved with a can. I would not want to go any longer. I had to buy a new safe just to fit this beast.

View attachment 8507929

View attachment 8507930
Click to expand...
Thank you! Now we're getting to the point.
Yes I understand that carrying that long rifle is clumsy and not practical.
Still I wanted to consider that, plus a specially tall safe.

Br, Arto
 
#19
Edsel said:
How long should he go?

I know this would be getting silly, but 34”, perhaps?
Click to expand...
Really depends on what your doing with the gun. I wouldn't go any shorter than 27" and not any longer than 32". You can do 34" but I don't see it getting you anything extra unless your running like a 338 Lapua Improved or something with more case capacity.

Also the longer the barrel... you do tend to see more fouling can occur. Not always but something to keep in mind.
 
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#20
joetuono said:
Google search the below test done by rifle shooter site. Only goes to 30 inches but will give you a good idea of attainable velocity.

338 Lapua Magnum: Barrel Length Versus Muzzle Velocity (30-17 inches)​

Click to expand...
For most cartridges a good rule of thumb for a loss or gain per inch is about 25fps.

There are a lot of variables..... type of powder, bullet type and actual bullet diameter vs bore and groove size, case capacity etc...
 
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#21
I vote for as long as you are willing to carry. 28" or something very close to that would be my minimum. A 300g bullet is going to need a slow powder get max velocity out of them. Slow powder needs lots of barrel volume to expand the gas.

I built a few 338 Edges which are fairly close to the same case volume. 28" was the shortest barrel I used, also the slowest. My favorite was a fluted #7 contour that was 32" long. Great velocity and a sweetheart to shoot.
 
#22
Frank Green said:
Really depends on what your doing with the gun. I wouldn't go any shorter than 27" and not any longer than 32". You can do 34" but I don't see it getting you anything extra unless your running like a 338 Lapua Improved or something with more case capacity.

Also the longer the barrel... you do tend to see more fouling can occur. Not always but something to keep in mind.
Click to expand...
Thank you for comment!
 
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#24
As far as velocity goes, 3k fps in a standard Lapua is not realistic (at least not safely). My Lapua improved is a max capacity, min taper design with about 12 grains more capacity than a standard Lapua, and I am right at 3k out of a 30" barrel with N570. RL33 will get you another 50 fps, but that powder is non-existent.
 
#27
You can get the velocity ya want with the XC33. Reamers, brass, dies, loaded rds, available. It uses the same 338 Lapua bolt head size.
They use 300 gr Bergers to achieve up to 3250 fps.
Some are running a bit slower to save barrel life.
They are using the 32" & 34" lengths some reported using 9 twists of those who stated twist rates.
Look at the 2k winners, they have build lists for their rifles, load data, powder preferences and why, how to prolong the barrel life.
Going long... this is one of the best setups.
I could build this , but I'm not good enough to complete with it, so it won't do me much good, unless I could buy some eyes to go with it.
But I'd check out the XC33, before building the Lapua.
 
#28
N570 will yield the fastest velocity, but you'll need 36" at least to get 3k. It'll be close? I too want to get 300's going 3k (~6k if muzzle energy). Having a 4" mag box or single feed if throated long enough can help also. Since only shooting to 1k you're fine at 2,800 +/-. I like the more the better also, but sometimes velocity just gets chased.
 
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