300WSM, string shooting and carbon build up?

[Aussie Denis]

Hi All,

I've been playing with a 300WSM in F-class. Its a brilliantly accurate 32", 10 twist, 1.125 straight profile McGowan Savage pre-fit barrel. I'm running 185 Juggernauts, Federal GM210M primers, Winchester brass with AR2213sc which is equivalent to H4831.

I'm running a low node at 2915fps to comply with local muzzle energy restrictions.

I had developed this load within 80 rounds and at that stage was loading 67.1gn of powder. The barrel now has 880 rounds through it. Through the course of the barrels life the MV has kept increasing and I had to keep dropping the powder charge to keep it in its accuracy node at 2915fps. At 800 rounds the powder charge was down to 62.7gn for the same speed.

I have been cleaning this barrel regularly using the same system that I do with my .284W and my 6BR. I don't clean any of them during the course of a prize shoot.
Contrary to my other guns, using a bore scope, I've found that this barrel is heavily carbon fouled which has been causing the speed increase.

I believe the heavier than usual carbon fouling is probably typical of string shooting a larger powder capacity Magnum case and not using abrasives in the cleaning regime. Also I believe that AR2213sc (H4831) may be a dirtier powder than that which I use in the .284W and 6BR.

There are plenty of 7SAUM shooters here though they run different powders and less capacity. I don't know any 300WSM F-class shooters here in Australia to share info with.

I'm wondering if any 300WSM F-class shooters abroad have had the same or similar experience?

Thank you,
Denis.

 

[dkhunt14]

I have not ran into that problem. Usually if a barrel carbons up it is not running enough pressure to burn the powder. I use H4350 with 210 Bergers. Matt

 

[Aussie Denis]

Thanks for the reply Matt. I haven't heard that before and I'll start looking in to it. H4350 is a faster burning powder. What powder charge and speed are you getting with the 210's?

 

[dkhunt14]

I shoot them around 2850. I have a .210 freebore. Most guys shoot around 60.5 to 62.5. Start LOW ,and work up. Freebore and barrel can change the amount of powder. MATT

 

[dragman]

Great advice from Matt.
I usually push them a little more usually end up between 63 and 64 grains and 2900 -2930, but I think the 2850 like he said is the real sweet spot.

 

[Fulvio]

Hi All,

I've been playing with a 300WSM in F-class. Its a brilliantly accurate 32", 10 twist, 1.125 straight profile McGowan Savage pre-fit barrel. I'm running 185 Juggernauts, Federal GM210M primers, Winchester brass with AR2213sc which is equivalent to H4831.

I'm running a low node at 2915fps to comply with local muzzle energy restrictions.

I had developed this load within 80 rounds and at that stage was loading 67.1gn of powder. The barrel now has 880 rounds through it. Through the course of the barrels life the MV has kept increasing and I had to keep dropping the powder charge to keep it in its accuracy node at 2915fps. At 800 rounds the powder charge was down to 62.7gn for the same speed.

I have been cleaning this barrel regularly using the same system that I do with my .284W and my 6BR. I don't clean any of them during the course of a prize shoot.
Contrary to my other guns, using a bore scope, I've found that this barrel is heavily carbon fouled which has been causing the speed increase.

I believe the heavier than usual carbon fouling is probably typical of string shooting a larger powder capacity Magnum case and not using abrasives in the cleaning regime. Also I believe that AR2213sc (H4831) may be a dirtier powder than that which I use in the .284W and 6BR.

There are plenty of 7SAUM shooters here though they run different powders and less capacity. I don't know any 300WSM F-class shooters here in Australia to share info with.

I'm wondering if any 300WSM F-class shooters abroad have had the same or similar experience?

Thank you,
Denis.

 

[Fulvio]

Hi Denis,
I have 600 rounds in my 32" 300 WSM barrel and I see no carbon build up. If anything, I see a bit of copper on my cleaning patches.
I shoot the Berger 215 with 67 gn of H 4831sc. The speed is 2850 fps. Very accurate and consistent. The Berger 215 has low drag and it seems ideal for the 300 WSM at 1000 yards.
Fulvio

 

[Aussie Denis]

Thanks for the advice you guys have given. I've got this problem sorted by pasting the barrel back to metal and moly coating the 185J's. I had to bring the powder charge back up to 66gn ar2213sc for 2915fps and the barrel speed is very stable now after 300 rounds. 1200 rounds on this barrel now in total and it still superbly accurate, The barrels much easier to clean carbon out of when using moly.
I think Matt must be right about not enough pressure. The trouble we have here is that the way our range muzzle energy restrictions work, we can't run 185gn bullets past 2920fps or 210gn bullets past 2740fps, so slower powders have to be used in a 300wsm to get a better case fill. I love shooting the 300wsm but its not the wisest competitive choice in Australia.

I'm starting another barrel now in another action. I'm looking forward to seeing how moly coated 210 VLD's go.

Thanks again.