Need help diagnosing rifle inaccuracy

[yakimanoob]

Hey folks!

I need some advice on my 7mm-08 Savage 16 Lightweight Hunter. I've had the gun for 5 years now, and it's very reliably outperformed me that whole time. It has typically loved the Nosler non-lead 140gr factory loads, and I can typically shoot 1-1.5 MOA at 100yds (and I figure I'm mostly to blame for it being north of 1 MOA).

Anyway, after a crazy high country mule deer hunt involving a lot of sliding around on sketchy terrain and a flat miss from 350y on a beautiful buck, I went to the range and my POI was 4-5 MOA high and 2-3 MOA right -- I assume I hit my scope on a rock or something harder than I realized.

The scope (Nikon Prostaff 4 2.5-10x40) doesn't seem to have moved in the rings, doesn't have any noticable damage on the outside, and seems to be holding the new zero just fine through about 20rds doing a 10 MOA square tracking drill.

However, all through the tracking drill I was shooting ~4 MOA with my cheap russian ammo that usually shoots closer to 2 MOA, and when I checked final zero after the tracking drill with my Nosler hunting rounds, the three rounds were along a 3" vertical line roughly averaged to the correct zero.

Normally, I would just check my stock screws, scope mounts, clean the bore, etc and shoot between each idea to figure out the problem, but I am now extremely low on ammo and (unsurprisingly) unable to buy factory ammo at the moment. I have just enough hunting ammo (7 rds, to be exact) to keep me chasing bear and elk, but not enough to diagnose rifle accuracy problems.

So I'm hoping to get some expert intuition on this -- what would you suspect is causing this problem?

I posted the same issue on Rokslide and only 3 people responded, but they all said the scope was the likely culprit.  Is there a way to tell if the scope is bad besides replacing it? 

FYI - I have a buddy who's going to help me hand load some ammo so within a couple weeks I should have the ability to shoot again 

Thanks!

[92xj]

Just slap any other scope you have on it and shoot a group.  If it groups to your standards with the “new” scope, you’ll know it’s a scope issue.  If it performs the same with the replacement scope you can rule it out and start farting around with new loads.


Edit, I just read you only have 7 rounds left. That being said, either find more ammo to do testing or give it up for the year.  No sense in hunting and wounding all sorts of game by no knowing how the gun is shooting now. 

[Karl Blanchard]

Just slap any other scope you have on it and shoot a group.  If it groups to your standards with the “new” scope, you’ll know it’s a scope issue.  If it performs the same with the replacement scope you can rule it out and start farting around with new loads.


Edit, I just read you only have 7 rounds left. That being said, either find more ammo to do testing or give it up for the year.  No sense in hunting and wounding all sorts of game by no knowing how the gun is shooting now. 

 

[JimmyHoffa]

Could also be the rifle (rare though).  Are all the stock screws tight?

[ASHQUACK]

Have you done a good copper fouling cleaning? And my second question is, is the barrel touching the stock anywhere?

[OltHunter]

A $200 scope that got knocked out of zero is most likely a gonner in my opinion. If it has a warranty, send it back in, if it doesn't, time to upgrade. Look for one that you have the budget for with a lifetime warranty on things likes this.

Like others have said, start there first, eliminate that as either the problem or not a problem.

After that, I'd look at your action screws. And retorque to spec.
https://www.accurateshooter.com/technical-articles/savage-action-screw-torque-tuning/

[JimmyHoffa]

Have you done a good copper fouling cleaning? And my second question is, is the barrel touching the stock anywhere?

These would be my next questions too.

[boneaddict]

Leupold

[yakimanoob]

Thanks all.  As soon as my reloading supplies arrive and I determine that I can, in fact, load more rounds, I will throw a different scope on there and see if it fixes the problem. 

I did a good cleaning after last hunting season and have only put ~40-50 rds through it since (all in the last two months).  I will check the action screws as well. 

[buckfvr]

Need to be using an inch lb torque driver for action screws on that rifle ( 40 in lb ) and also should be torqueing rings and bases to mfgr specs.  Over-tightening can cause problems even though you dont appear to be sliding in the rings..  Bases could have loosened if they had any oil on the screws or threads.

[yakimanoob]

Hey folks!

After securing the components I needed to load some more ammo, I followed your recommendation and did a full disassembly, cleaning, and re-torquing / loctite-ing of the action and scope/mounting screws. The aforementioned action screws were the only ones out of spec.

I just got back from the range testing my first set of reloads (and some Superformance GMX factory ammo I scrounged up), and I'm very happy to report that my scope performed flawlessly. I sent 72 rounds downrange and saw no walking POI, I didn't shoot a single group today over 2 MOA, and a couple of my groups were right around 3/4 MOA.

I'm getting about 100 fps slower velocities than the Nosler manual indicates and I didn't see any pressure signs, so I'm going to load a little hotter and see if I can get over 2600fps (with my 150gr e-tips) and stay in the 3/4 MOA range. If I get there, I'll call myself happy for this season and next year try and find a combo that runs a little hotter with similar bullets.

Thanks for all the help!