twist rate for .308 custom

Bear_Blade

Bear_Blade

Regular
EE Expired
Rating - 100%
5   0   0
Location
Alberta
I have decided to jump in after a whole pile of reading here, and comission a custom build on a savage action, McGowan barrel, trued action etc. I thought that a 1 in 10 twist would be best, but recently I have found a lot of info stateing that a 1:12 or 1:11.25,11:5 might be better options,

The type of thooting I do doesn't often excede 400m, but I want to get back into ranges of 800 to 1000m. It been quite a while since I have been at these distances, and never paid a lot of attention to rate of twist, just shot what was issued.

Could you gents recomend an "ideal" rate of twist, I know the variables make ideal tough, but will likely stay between 150gr, and 180gr. Mostly (80%) will be 165-168gr. The barrel will be 26", in a bedded stock for now, and upgrade later to a better stock, I got my eye on a XLR Industries set up.

Thanks in advance, and appologies if this starts arguments.

Pierre
 
the 11.27" was designed around the 173/175 grain M118 LR load

It is probably the best all around twist rate for a 308, I've shot 155's to 190's to 600m with success.

Just avoid extremes and you will be fine, the 9" twist was designed for the Sierra 240 BTHP, the 10" for the 30 Krag and 30-06 with a RN 220, the 13" for the 155 Palma, and the 14" for the 147 ball.

While I have zero experience with McGowen barrels, for the relatively small price difference, I would buy a Krieger, Lilja, (or insert name of barrelmaker who regularly shows up in the winners circles).

Let someone else who goes through several barrels a year prove how good they are, then buy one.
 
You are not going to want to shoot 168s past 600m.They become unstable and do funky stuff.
You'd be smart to go with 11.25 and shoot 175s which are very stable out to 1000m and beyond.
 
A 12 twist will do anything you want to do. It will stabilize anything up to and including the Sierra 200MK and will work great for the 175's. McGowan barrels are one of the better inexpensive barrels but they are not a select match barrel. While the price difference between a McGowan and a select match Shilen is substantial, it isn't much when figured into the overall cost of your project.
I have a 12 twist 308 McGowan on a Savage (CIL)single shot which I have not shot enough to really judge yet. This week, I'll be testing it some more and we'll see how it stacks up. Regards, Bill
 
Yes 12" twist in 308W will do everything you are asking for. I have 12" twist 308W LH Sportco 44, shooting 190gr Horn match bullets and 185gr D46 Lapuas to 500m with no complaints what so ever.
 
An approximate 1 in 11" twist is a great compromise with the bullet weights in that calibre.
Originally 1 in 12 was popular due to military use, but 1 in 10 came about when heavier bullets became more popular.

When a maker gives me a chioce/option, the 1 x 11 (ish) is the twist I've chosen in my rig(s).
 
Thanks for the input guys, as this is a budget build, I would like to go to a better barrel for sure, but am not sure if I can squeze much more out of the wallet. So I'm reading that the 1:10 may not be my best option. How well do they stabilize say a 165/67 grain bullet at greater renge?
 
Leeper said:
A 12 twist will do anything you want to do. It will stabilize anything up to and including the Sierra 200MK and will work great for the 175's. McGowan barrels are one of the better inexpensive barrels but they are not a select match barrel. While the price difference between a McGowan and a select match Shilen is substantial, it isn't much when figured into the overall cost of your project.
I have a 12 twist 308 McGowan on a Savage (CIL)single shot which I have not shot enough to really judge yet. This week, I'll be testing it some more and we'll see how it stacks up. Regards, Bill
Click to expand...


Bill is one of the true experts with credentials on here. His advice for a 12" twist is bang on.
 
I said I would shoot that Mcgowan some more and did so this evening. As I mentioned before this is a twelve inch twist. It is a chromoly barrel which I got as a 28 inch blank. I turned it to a heavy varmint contour; about .930 at the muzzle. The barrel is 28 inches long. I chambered it with an Obermeyer spec palma reamer. My original intent was to shoot it with 155 Lapua bullets and this chamber was well suited to these. I fitted the barrel to a CIL 950T (Savage single shot) action. The barrel was fitted conventionally with no nut (nuts are for squirrels!).
I treated the action just as I would a Remington. It was set up with the bore running true in a jig I use for this purpose. The threads were re-cut with a single point tool, the receiver was faced, and the locking lug seats re-cut. The bolt head was set up and the face was re-cut as were the locking lugs. The recoil lug was replaced with an RPA piece. A third screw hole was drilled and tapped in the bottom of the receiver because I thought it should have one. The trigger (not an accu-trigger)was set at 1 1/4 pounds. The barreled action was bedded into the factory stock which I had re-shaped and re-finished. I mounted a Weaver KT 15 on top in Warne rings. The whole outfit weighs right at 13.5 pounds.
I had previously tested this rifle with 155 Lapuas and it did shoot them quite well. About 5/8 MOA with the only load I tried (42 grains of 4895). Tonight, I loaded up some 190 Sierra Matchkings ahead of 41 grains of 4320 in Lapua brass. I don't mess around with this ladder test stuff. It either shoots or it doesn't. I was told many years ago that if a rifle is fed a reasonable load with a good bullet, it should produce reasonably good groups. If not, there is something wrong with the rifle (I was told this by Bob Forslund so the language was somewhat more colourful than I have related). My experience has supported this contention.
I loaded ten of these rounds for this rifle and ten more for another 308 I have with a ten twist barrel of obscure origin but a proven performer. This one is throated longer to use the 190 to 200 grain bullets and is mounted on a Winchester Model 70 short action which has received the same truing treatment.
Anyway, the Savage was up first and I fired three shots at 100 yards to see where it was sighted. These three shots made a nice little equilateral triangle of about .4" on centers. the group was four inches above center so I dialed in two moa more elevation and switched over to the 300 meter target. The remaining seven shots went into a group which measured right at 1 3/8 inches. The group was about an inch tall.
The Winchester is slightly hampered by being saddled with a scope of only six power but it printed a tiny three shots at 100 (.2") but I got caught in the wind at 300M and shot a three inch group. this group was less than 3/4 inch tall, however, and five of the shots were under an inch.
The bottom line is, the McGowan seems like it will shoot right along with the other barrel which is a proven performer. The barrel is smooth and uniform in size. It shows no tendency to foul. There is room to bump the powder charge up a bit which should get rid of some of the vertical. I have not chronographed anything out of this barrel yet but I felt this load was a bit slow. I'll check this out in days to come.
I have fitted a dozen or more of these McGowan barrels and all have been satisfactory. All feedback I have gotten has been positive. I think they represent good value. This particular barrel is certainly meeting or exceeding expectations.
So Bear Blade, I don't think you would be wasting your time trying one of these. Like I said, good value. I don't think you have to have everything done to your action that I did to mine (I don't charge myself much) but do replace that lug! Regards, Bill
 
You must log in or register to reply here.
Back
Top Bottom