shot pattern problem

I just bought a swfa ss 10X42 riflescope and I am having trouble with my shot pattern a 3 shot group at 100 yards is about 6 inches from one shot to another.  I have talley rings and base on a winchester model 70 300 win mag any suggestions on how to tighten my grouping and how can you tell if the scope is malfunctioning eventhough I just put it on yesterday 

I had a similar problem with a Leupold 4x, but was totally remedied after reading John Barsness' article on scope mounting in the Dec 2008 American Rifleman. My problem was proper screw tightening torque on the rings. Too tight or too loose can each cause odd behavioral problems with the scope.

This will be a process of elimination so a few questions will have to be answered.

If they are alloy mounts the very first shot with a 300Win can bend them. The next shot again and so on, hence the shift in impact. They only need to bent 2 thou of an inch.

I have Talleys on my 45-70 and only shoot very hot loads out of it.  Mine have never given me a problem by bending, they are very well built.  I am certain they have been used on lots harder kickers than a 45-70 or .300.

Did you torque them properly or just tighten them?  They only need 15 to 18 inlbs of torque,  that is not very much.  You can typically do that with a nutdriver and your thumb and forefinger.  That is on both mounting it to your action and the ring caps.

If you have them to tight it can really screw things up and even ruin the scope.  If it is to loose you should see movement in the scope sliding.

Edited by 8shots - October/16/2009 at 10:31

A quote from John Barnsness.  http://www.opticstalk.com/forum_posts.asp?TID=15632&KW=Talley&PID=177600#177600

What Roy said--plus the Talley Lightweighst are also very strong. Some people don't accept this, because they are aluminum, but they were originally designed by Melvin Forbes for his New Ultra Light Arms rifles, which can generate quite a bit of recoil.   The LW's do not use bases. Instead the bottom half of the mount includes the bottom half of the ring, and screws directly onto the action. This bottom half is a solid block of high-grade aluminum, so ain't going anywhere.   When my wife got a .270 NULA in 1991, I mounted a 2-7x Bausch & Lomb in the mounts and it never changed point of impact over the next decade, until the scope itself went belly-up. This was on a .270 that weighed 6 pounds with scope. I have also used the NULA/Talley mounts extensively on various magnums from .300 Winchester up (and one of those was a NULA weighing 6-3/4 pounds with scope) and the only problems have been with scopes, not the mounts that held them.   Many people who shoot big-bore magnums (mostly for African hunting) like the Talley steel rings, because these come in a detachable model that allows the use of iron sights if desired. It is a probably the most popular detachable mount for the purpose, partly because unlike some other detachable mounts, the Talleys are machined rather than cast.

Based on Johns input and my personal experience with the Talleys I would say your talleys are just fine.

If it is not the rings, then either the screws are loose, or the scope is faulty.

jeez, thought this post was going to be on shotguns.

The Talley mounts are plenty strong.  If the receiver of the rifle isn't true, holes aren't drilled straight, etc, this could cause a misalignment between them that may pinch the scope or prevent the rings from tightening properly.  That (along with other simple mounting errors) is what I'd look for first.

Its shooting true now Im holding a sub-one inch group again.  I looosened the rings and changed ammo and it is shooting fine now.  Thanks for all of your help I appreciate it.