Rifling selection in a new barrel

BigBraz15

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I am contemplating rebarreling a rifle I had a decent amount of work done to a few years back. It was setup to be a good all around gun, but it has always struggled with the factory barrel in the accuracy department.

As I look at new barrel options there is different twist rates, which I have narrowed down, but with the different rifling options between 4 groove, 5R and 6 groove I’m not sure which is the best route to go.

Chambering is and will stay 300 SAUM and I want to be able to shoot a good selection so twist will be 1-10 or 1-9.

Any input is welcome.

Thanks!
 
Maybe is a minor issue and maybe it is not important to you. To measure groove-to-groove size - some feel that is important to know - is much easier with even number rifling, like 4 or 6 grooves - the grooves are directly across from each other - push a slug through the barrel and easy enough to measure groove-to-groove diameter. Not so with odd numbered rifling - like 3 or 5 - end up with rifling top face opposite a groove - gets harder to measure what is the groove-to-groove size - can be done with an anvil tool shaped like a "V" that is ground to a specific angle.
 
I am contemplating rebarreling a rifle I had a decent amount of work done to a few years back. It was setup to be a good all around gun, but it has always struggled with the factory barrel in the accuracy department.

As I look at new barrel options there is different twist rates, which I have narrowed down, but with the different rifling options between 4 groove, 5R and 6 groove I’m not sure which is the best route to go.

Chambering is and will stay 300 SAUM and I want to be able to shoot a good selection so twist will be 1-10 or 1-9.

Any input is welcome.

Thanks!
What is this rifle? Are you loading for it? What is a decent amount of work done?
 
Rifle is a Remington model 7.

Has a wildcat stock, bolt fluted and skeletonized handle, trigger upgrades, lightened mag well and bottom metal, recoil pad weight reduced.

I have tried multiple loads and bullets with it before I found 1 acceptable load. I’m looking to find a barrel that isn’t so fussy (factory ammo when I could find it was in about 4” groups at 100 yards.)
 
Did this rifle shoot terrible before the work was done? Thats a fairly stout round for a light rifle, you sure it may not be flinch induced? Do you have lots of experience rifle shooting? Im not trying to be a smart axx. Is the barrel free floated? Has it been bedded properly? Check the crown also. Keep us informed as too whst the culprit is. Best of luck.
 
I appreciate the question as when I started to work with light/ultralight rifles there is definitely a learning curve to be able to shoot them well, especially in a heavier caliber.

Yes it’s been from day 1. The load I have now was sub 4” at 400 yards, but as I look to change bullets or grain of bullets it adds significant complexity of burning up components during a shortage to see if I can find “the one.” Yes rifle is bedded and I am able to shoot it well once I find the load it likes.

Back to the original question, any difference in 4 groove vs 5R vs 6 groove rifling?

Thanks!
 
I appreciate the question as when I started to work with light/ultralight rifles there is definitely a learning curve to be able to shoot them well, especially in a heavier caliber.

Yes it’s been from day 1. The load I have now was sub 4” at 400 yards, but as I look to change bullets or grain of bullets it adds significant complexity of burning up components during a shortage to see if I can find “the one.” Yes rifle is bedded and I am able to shoot it well once I find the load it likes.

Back to the original question, any difference in 4 groove vs 5R vs 6 groove rifling?

Thanks!


Can't say I've seen any definitive evidence of one performing consistently better than the others. I own samples of all of them, and a couple two grooves, as well as a few gain twist rifles barrels. Maybe one of the BR guys can way in, they likely have more in depth opinions on this. - dan
 
Grooves have little to no effect on accuracy, they have found 5R rifling is slightly easier to clean and has slightly less affect on B.C.s out at 1000 yards and beyond, it’s easier on the jacket of cup and core bullets as tested by Bartlein Barrels.

Any good aftermarket barrel ie- Benchmark, IBI, Bartlein 4 or 5 groove cut rifled barrel in a 1-9,1-9.5 or 1-10 will serve you well for your desired cartridge 300 WSM, I wouldn’t go lighter than a #2 contour or heavier than a #3 contour if you want to stay inline with weight for a model 7 actions.
 
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That light barrel on a Model 7 and the caliber is part of the accuracy problem. If you re barrel put a heavier barrel on about 22 inches. Buy a custom chambering reamer made for your favorite reload. Keep bullet jump to a minimum. Make sure the action is bedded stress free and the barrel floated. Number of lands means nothing... Make the twist quicker rather than slower.
 
guntech and WF give you good information. Model 7 rifles often have thin pencil barrels, which are not conducive to good accuracy.

Some shooters get lucky, and find a load that works very well, some don't and at best the rifles shoot in a mediocre manner.

If you're going to this much expense and effort, do it right the first time, buy a reamer and if possible, get a set of dies made up for that reamer. I don't know if the reamer makers still offer that service or not, but you can send that reamer to Redding or whomever you choose and they will make up a set of dies to match your rifle's new chamber.

As for rifle barrel contours, especially with your cartridge of choice, I would go with a No3 contour for rigidity and have it fluted to remove weight and aid in cooling if you're going to shoot long strings.

Then, you want to make sure the barrel has been properly heat treated so it won't change points of impact as it warms up, over a ten shot string.

If you don't want to go to the expense of heat treating as a precaution, then you're relegated to shooting until your barrel is almost uncomfortable to grasp with your palm after shooting and allow it to cool back to ambient temperature or cool it down some other way.

guntech suggests a 22 in barrel, most likely to wring as much velocity out of the barrel as possible, while still maintaining rigidity, good call.

I would likely have such a barrel finished at 20 inches to reduce weight and maintain rigidity for best accuracy. The advantage of this is the ability to shoot heavier bullets a bit faster.

You don't say which bullet weights you want to shoot.

Many people like a 1-12 twist rate if they're going to shoot 165 grain bullets or less and that usually works very well. Some folks say their 180grain bullets shoot extremely well with this twist rate. It may be luck of the draw or the bullet design they're shooting. I don't know if long for weight monometal bullets will shoot well with this twist rate. Maybe someone else has tried them, such as trevj?

1-10 was deduced well over a decade back to successfully stabilize 220 grain bullets at velocities around 2300 fps. The bullets of that weight were all flat based, round nose design. Monometal bullets will be much longer for any given weight than conventional lead core offerings, even some of the ELD types. So, you may want to consider a faster twist rate as you suggested a 1-9 or even a 1-8 if you're going to try shooting the heaviest 30 cal. monometal types available and designed for long range shooting.
 
In your situation reamer matched dies will have an insignificant effect on accuracy. I would choose regular 5 grove not 5R because it is favoured by a group of 1000-2000 yard shooters who have some hot rod cartridges that blow up bullets in fast twist barrels. I have 1/9 WSM that blows up 110Vamx loaded down to 3600, 110 Hornady Spire points shoot good at 3940. Beyond that the 1/9 appears to be a do it all choice.
 
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Thanks for all the information. The barrel that my rifle came with is either a #3 or #4 contour, so it is not pencil light. I have worked with a number of ultralights at this point, and have been able to develop reasonable loads for them (with much lighter barrels).

I do have faith that there is a barrel concern on this one with what I am seeing. For replacement I will be sticking with the 22” barrel, as it is the best balance of length for the overall weight.
 
You may be over thinking it for a hunting rifle. For the 300 SAUM, a good barrel from a reputable maker with a 1:10 twist should work for any hunting bullets up to 220 gr. In your short action, a 1:9 twist for high BC bullets may be wasted as your magazine box is going to be limiting your COAL, and you will be seating bullets deeper...unless you are OK with single feeding ammo that is too long for the magazine, just so you can seat out closer to the rifling with longer/heavier bullets.

I only have one rifle with a Benchmark barrel; 6.5 Creedmoor with a 24" SS 5R barrel. (What Rocky Mountain Rifles had in stock when I rebarreled the rifle for me). It does shoot very well. The average group size of all factory ammo tried to date (5 different types) is 0.634" in this barrel (best 130 gr Terminal Ascent @ 0.291" to worst 129 gr Power Point @ 1.251"). Velocities vary from less than factory spec to more than factory spec by up to 50fps, except Hdy Precision Hunter 143 gr ED-X which was 190 fps slow, but produced 0.494" groups. (I'll take accuracy over velocity any day)

While this is just a sample of one, it does compare well to my other rifles sporting after market barrels from MacLennan, Wilson, Krieger, McGowan and King, in overall performance. I wouldn't hesitate to buy another Benchmark barrel.
 
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