What bore size 308 barrel to buy

[Hossman84]

Im wanting to build a 300 win mag to shoot mainly 208 to 225 Hornaday eld bullets as accurately as possible . As I was looking at different barrel sites I noticed that there are different bore sizes ( hope I'm saying this right). For example I have found .298 .299 and .300 308 barrels. How do I figure out what the best/optimal diameter is. I tried Googleing this but did not find much useful information. I am hoping someone can shed some light on this or put a link to a past post on this subject. Thanks!

 

[Martin52]

..... I am hoping someone can shed some light on this or put a link to a past post on this subject. Thanks!

Here's a few relevant posts:

http://forum.accurateshooter.com/threads/30-cal-299-vs-300-bore-diameter.3760689/

 

[butchlambert]

A good barrel is a good barrel. You are not shooting competition bullets either. My competition 30 cal and my 300 Win Mag have .300 barrels, but if you have Deltronic pins in 10th increments you will not find any brand of barrel that is exactly as marked.

 

[Ggmac]

If a best /optimal barrel existed , it would be easy !
Too many variables , are you experienced BR style reloader ?
Want shooting experience ?
How much do you plan on spending , action , barrel , stock , trigger , scope , rest , equipment ?
Barrel , rifle weight ? Etc....

 

[Hossman84]

Thanks everyone for the replies. I greatly appreciate the vast knowledge you guys share. I will probably just go with what is available first.

 

[msinc]

It is always nice if you can match the bore with the pilot or pilots you have for the reamer you intend to use.....just sayin'....
I have scoped several barrels that were chambered with a reamer that had a pilot too tight and the rifling just ahead of the throat area was gunched up pretty bad. many moons ago i even did it once myself...it is not hard, it is also not desirable!!!!

 

[butchlambert]

Better yet, a precise taper bore before reaming makes the bushing superfluous.

 

[Rustystud]

.298 and .299 barrels for 155 grain bullets are fine. Anything with a longer bearing surface I would recommend a .3004" - .3008" bore. Another factor will be your land to groove ratio.
Nat Lambeth

 

[butchlambert]

.298 and .299 barrels for 155 grain bullets are fine. Anything with a longer bearing surface I would recommend a .3004" - .3008" bore. Another factor will be your land to groove ratio.
Nat Lambeth

Nat, if you get a certain lot of 308 barrels, check them with your pin gauges. They ain't necessarily as marked. A .3004-.3008, well only if you are lucky.

 

[Rustystud]

Nat, if you get a certain lot of 308 barrels, check them with your pin gauges. They ain't necessarily as marked. A .3004-.3008, well only if you are lucky.

Butch I use to buy barrels from a manufacture that stamped bore and groove diameters. After I started checking I found they were not as marked. I was later told by a couple of former employees the barrel maker did not even have any pin gauges or any other bore measuring tooling and just stamped what the customer ordered. I am almost exclusively using Dan Muller's barrels now. They are hand lapped. He gives me all of the specs. bore diameter, groove diameter, land/groove ratio, twist rate. I find his barrels have a .0001"-.0003" choke in the muzzle end. Have never found his markings to be incorrect.

 

[butchlambert]

Butch I use to buy barrels from a manufacture that stamped bore and groove diameters. After I started checking I found they were not as marked. I was later told by a couple of former employees the barrel maker did not even have any pin gauges or any other bore measuring tooling and just stamped what the customer ordered. I am almost exclusively using Dan Muller's barrels now. They are hand lapped. He gives me all of the specs. bore diameter, groove diameter, land/groove ratio, twist rate. I find his barrels have a .0001"-.0003" choke in the muzzle end. Have never found his markings to be incorrect.

That is great Nat.

 

[fguffey]

I want a barrel with a small diameter of .300", I want a barrel with a large diameter that is .308". if the diameter is larger or smaller it will be a fast and or slow barrel. I had a friend that claimed he had a rifle that shot heavy loads without showing signs of high pressure. I told him he had a loose/large diameter barrel. He was so exited because he could add 3 grains over the maximum load. I told him I would be happier if I would be required to reduce the load to eliminate signs of pressure.

And then one day I purchased an 03 Rock Island that had a barrel diameter of .297 without rifling. I never worried about that receiver.

F. Guffey

 

[fguffey]

And then we move to the chamber, in the perfect world the chamber is go-gage length from the shoulder to the bolt face and the case is considered minimum length/full length meaning the case is .005" shorter than the length of the chamber from the shoulder to the case head.

If we want to increase the pressure we can cut the chamber .005" shorter from the shoulder to the bolt face, that makes the chamber and case the same length, pressure increases because we have eliminated clearance. As I have said before I am the fan of off setting the length of the chamber with the length of the case from the shoulder to the case head.

F. Guffey

 

[Eddie Harren]

And then we move to the chamber, in the perfect world the chamber is go-gage length from the shoulder to the bolt face and the case is considered minimum length/full length meaning the case is .005" shorter than the length of the chamber from the shoulder to the case head.

If we want to increase the pressure we can cut the chamber .005" shorter from the shoulder to the bolt face, that makes the chamber and case the same length, pressure increases because we have eliminated clearance. As I have said before I am the fan of off setting the length of the chamber with the length of the case from the shoulder to the case head.

F. Guffey

Hee, Hee, Hee! I see that the record is still broken and repeating the same drivel over and over.

 

[gunsandgunsmithing]

Butch I use to buy barrels from a manufacture that stamped bore and groove diameters. After I started checking I found they were not as marked. I was later told by a couple of former employees the barrel maker did not even have any pin gauges or any other bore measuring tooling and just stamped what the customer ordered. I am almost exclusively using Dan Muller's barrels now. They are hand lapped. He gives me all of the specs. bore diameter, groove diameter, land/groove ratio, twist rate. I find his barrels have a .0001"-.0003" choke in the muzzle end. Have never found his markings to be incorrect.

I can and do buy the land/groove ratio part and to some extent, bore diameter. But with a cf cartridge, the pressure expands the bore and the bullet expands to fit it. As the pressure drops, so does the bore expansion. There's your choke.