My son has a model 7, 308 that can't seem to group anything better than a 3 inch group at a hundred. The main problem is with a nosler balistic tip and winchester 540 powder. Anyone come across this problem?
I think I identified your problem. Win 540 is a SHOTSHELL powder and also suggested for use in 10 mm Auto carts (according to the Seirra manual). I would switch to these other powders:
IMR 3031, 4064
WIN 748 or 760
Hodgdon H-380, Varget, or BLC 2
Hurcules Re15
The burn rate on the Win 540 you are using is not proper for your round rifle combo. Ihave used all of these powders except for Varget and BLC2. They all gave less than 1" in my rifle. I get best results in my rifle from IMR 3031, H-380, and Re15. I shoot a .308 too.
I am very curious as to where you got reloading data on the WIN 540 powder for the .308 application. Where did you get it? I can't find it in any of my reloading manuals.
Can you give us the specifics on your Win 748 load?
Off the top of my head, a 44.5gr load of 748 with 150gr Nosler BTs ought to give very acceptable accuracy results.
Personal experience leads me to believe that either 4064, 4895, Varget, or Reloader 15 will give you better results than 748..............especially if you're shooting the 165gr Noslers.
Oh..................one other question/suggestion.........................
How many rounds have been put thru the rifle and have you used a solvent that removed the copper build-up from the bore after previous shootings? If you have a significant build up of copper in the bore, it will definitely throw off the accuracy of the rifle.
Also, if you're using a scope, check the mounts for tightness and the scope for error....................that would be the simple solution.
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We tried numerous loads in the 40+ grain load range and weren't too successful. I do know that this gun has a little head space problem, with the bullet seated almost all the way out it will not touch the lans and I'm thinking this gun might be able to get down to a specific accuracy and that will be it.
Polack
Its not a headspace problem if the bullet dosn't touch the lands- its that the leade or "freebore" is cut deep into the barrel. I wouldn't worry too much about trying to get near the rifling- if you seat the bullet too far out, you might not have enough bearing surface held in the neck of the cases causing inconsistant bullet pull. Seat the bullets at least .308" deep and forget about the rifling.
With a 165-168gr. bullet, I find that 4064 will give a very accurate load at the maximum load and approximately 2 gr. less than the maximum load.
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loosen the fore end screw and slip a spacer like a piece of macth book cover. Tighten the screw good and tight and try it again. Remington relies on a pressure point near the end of the forearm. Sort of the oppisite of free floating. I have seen this cure a lot of Remington problems. If it works just coat the cardboard with a sealer and leave it in there. Or glass bed it. I had a 788 Remington 308 that just would not shoot. An old gunsmith told me to try that and it instantly started shootin one inch groups.
Model 7, 308 problem?
