HELP!! 300 Win Mag Ammo

[bbru]

Ok guys, I recently rebarreled my Winchester M70SS 300 win mag. I've kept the caliber the same, but replaced with barrel with a 1-10 twist Hart#5 contour fluted barrel cut to 24". The action was also blueprinted and squared, sitting in a HS precision stock. I went with the 1-10 twist on the recommendation of Hart, as they said it would be the best all-around twist for my style of hunting. Is my twist to fast for lighter bullets????The gun will be used for mostly whitetail, but will be used on bigger game in the future.


So far I have tried:
1. Remington Corelokt 150gr psp 1.5" group (advertised @ 3250fps, chrono'd 2909fps
2. Winchester Powerpoint 150gr and 180gr 2" group on 150's and 1.5" group on 180's
3. Hornady Custom 165gr btsp 2.5"group
4. Hornady Superperformance 165gr GMX 1.5" groups
5. I just received today my HSM 168 Berger VLD Hunting. I will try those in the morning.


I"m starting to get a little frustrated with the accuracy of this gun after spending almost a grand in custom work. I know my gunsmith does excellent work and I don't believe that is the issue. I shot all these off a solid rest and I'm not sensitive to recoil, so I don't think its me either. I really don't want to have to get into reloading to get this gun to shoot sub moa. Could ya'll please provide some insight on some other ammo I could try that you may have had or not had good luck with.

 

[elkaholic]

First of all, your rifles twist is not the problem with your accuracy. I would probably try some Federal premium ammo, but with everything you have already tried, I'm not too sure that will work either? You may have to handload to squeeze out the accuracy? There could also be something else wrong, including bedding, scope, etc. Good luck........Rich

 

[TXshooter]

Before I started reloading I use to shoot hornady 180 gr spt. I tried the 160 s and the rifle hated them. But it loves 180gr. Give those a try

 

[reeldawg]

With a 1-10 twist, I think a 180 or heavier would work

 

[Lefty7mmstw]

I've got a 1 in 10 twist browning 300 win and it'll shoot from 125 grain to 220 grain match well. I'd try fed ammo or let a custom loader or buddy that loads get their hands on your rifle. Custom loading may be the only way to shrink the groups without spending a fortune.

 

[Dalebow]

i have same barrel on a 300wsm, do me a favor, buy a box of the vortex 150 grain 300win mag TTSX and watch what happens, you can screw around with all those others, buy one $40 box of ammo and watch what happens

 

[clambdin]

I would think that gun should shoot far better than it is even with factory ammo....I have done alot of reloading for the 300WM and they are usually not that hard to please...if you can find somone that reloads and see if they can help you out..I would probably start with some 200gr accubonds or the 208 amax using H1000 or ramshot magnum...or some 180gr accubonds with RL22 or 7828..somwhere in there that setup should shoot under .75...

 

[bbru]

Thanks for the input guys. Im praying the 168 bergers shoot. At 50 bucks a box, its getting expensive, but thats all part of it i guess

 

[Bart B]

A new rifle's poor accuracy can be caused by several things. I'm gonna get a little bold now.....

Have you ever shot a rifle with a .300 Win. Mag.'s recoil into sub MOA groups at 100 yards before? If so, then your rifle or ammo probably has a problem. If not, try shooting slung up in prone with a bag under the stock toe and fore end. Most folks shoot rifles designed for firing off ones shoulder more accurate from a good prone position than holding it against their shoulder as it rests on somthing atop a bench. Or get brave like I did years ago when I couldn't shoot worth a darn from a bench and asked a friend to shoot my rifle and he did; very accurate and impressive proving to me I had a lot to learn.

Was that Hart button-rifled barrel fluted before it was gundrilled, reamed, rifled and lapped? If not, then the fluting probably changed the bore and groove diameters enough at the flute ends to cause accuracy problem. Seen that happen with several button rifle barrels.

 

[rscott5028]

Take the rifle and ammo to your smith and get him to try it.

He may also be able to try some handloads.

I don't think the ammo or twist is the problem.

That basically leaves the rifle and shooter.

-- richard

 

[Bart B]

I went with the 1-10 twist on the recommendation of Hart, as they said it would be the best all-around twist for my style of hunting. Is my twist to fast for lighter bullets????.

After seeing a lot of folks shooting .300 Win Mag's in 1:12 twist barrels for 190's and 200's in long range matches and doing very well accuracy wise, a 1:10 may well be too fast. Note that virtually all modern 30 caliber magnums are steroided children of the .30-06 wildcats and original magnums based on 1:10 twists and most folks think that's what they need. The first 30 caliber magnums shot a given bullet weight out only about 100 fps faster than a .30-06. And they were mostly used with heavier bullets so their 1:10 twist worked well. I had a .300 Win. Mag. made from a shot out 30 inch .308 Win. barrel with a 1:13 inch twist that shot Sierra 180 HPMK's and SBT's well inside 2 inches at 300 yards.

If the bullet weights you listed are what you asked Hart about, I'm surprised they suggested a 1:10 twist When it's well known among other high-end barrel makers that 200's do great from a 1:12 twist in 30 caliber magnums and those around 170 grains you listed would be much better off with a 1:12. Spinning bullets too fast tends to make the more unbalanced ones jump too far off the muzzle axis when they leave. And the centrifugal force on their jackets sometimes causes those with very deep rifling grooves to break apart.[/QUOTE]

 

[Lefty7mmstw]

I've never seen nor had an issue with a 10" twist 30 cal., mag's or otherwise. I've owned three 300 win's, a 30 ultra, and four '06 rifles and all were 10" twists that shot any bullet they liked at all into 1/2 moa. My brother and father own or have owned more than me and the only real problem child is a hawkeye 300 win that only likes hornady 150 grain fb bullets and won't shoot heavier bullets worth a darn. Not to say they aren't cranked up just a bit from minimum rpm. The worst trouble is always spinning to slow so I'll take a bit fast any day.

 

[rscott5028]

Regarding twist, too fast is better than too slow.

A 1:10 will certainly do a better job than 1:12 with the heavier bullets.

But, it will also do very nicely with the 150's.

Without question, you should have had sub-MOA at 100 yds from a good custom rifle using at least one of those boxes of premium factory ammo.

-- richard

 

[elkaholic]

I agree that if all you were ever shooting was 150-180 grain, a 12 twist is better but as others have stated, I have had several 10 twist 30's that would shoot well under an inch consistently even down to 130 grain so I don't think twist is your problem.....Rich