Trouble shooting an issue with my 30.06.... Need advice

[Rob]

I spoke to John at Adventure Sports in Lynnwood and after describing the problem and the firearm, he provided input that leads me to a possible new cause.

See photo below.  The stock it attached in three places - the red circles.  One screw behind the trigger, one in front of the shell plate, and one in the foregrip where the shoulder strap attaches.

The front attachment point could be my issue.  There is a band around the barrel that a screw threads into.  The band may be causing issues when shooting due to heat expansion. I did take the gun off of the stock when I received it to do a deep cleaning and to "get to know the new gun". So it is also possible I did not put it back on correctly.

I am hoping to get it out to the range this weekend.  I have put a different scope on the gun to eliminate that as a cause.  I'll do a few sets with the band on to see if it continues to have shifting groups.  If it does, I'll remove the front band and see if it that solves it.  I'll only use one load too.

[Rob]

Oh yeah, forgot to answer the question...  I'm shootng off sandbags while sitting at a bench. 

[Skinnyman]

I have an old Springfield armory surplus 30-06. Mine does the same thing. One thing I have found, is it is VERY picky about bullets and powder. If you can get decent groups with a certain bullet like the Core lokt stick with it (decent grouping means its not the bullet). For me, mine only like certain Nosler bullets (it hates core lokt's and barnes, it sprays them!!).

The other thing I have found, is powders in that gun make a HUGE difference. I can use one powder and I get about a MOA at 100yds. Same bullet with a different powder that it doesn't like, I am lucky to get a 6 inch group at 100yds. Extremely picky!!!!

I have had to find a bullet and powder that suits the best of my contraints and shoots well (might not be my 1st choice though) and stick with that combo only. Not too surprised that different powders and loads, even though speed is similar, shoot vastly different. As long as each powder/bullet combo is grouping well in and of itself, thats great!! You have more options.

Part of my gun's pickyness is the barrel is original and pretty well worn (probably should be replaced). So that could be part of your problem as well.

[lokidog]

I had a similar gun.  Shot 165 grain boat tails at 2800 fps to less than 1" groups with the stock peep sight.  Yours might like a heavier bullet.  67.5 grains IMR 4250, maybe.......It's been a while since I loaded, could be wrong!  2800 is pretty close though for velocity.

[Rob]

I looked over my data and I seemed to have the tightest groups with the 58 grains of H4350.  There were no primer issues or extraction issues so I am going to bump that load to 59 grains (max in the Hornady book is sixty point something).

Gotta VIP about 15 scuba tanks on Saturday so I can get them filled for the Neah Bay dive trip next weekend, so if I can get that done on Saturday, I'll be able to hit the range on Sunday.

[whacker1]

I had this problem with my .270 years ago.  It turned out that my ring bases weren't tight to the Action.  You shoot a few rounds and get a decent pattern.  Then you lay  the gun down and let it cool.  When you pick it back up and shoot the next volley - the pattern was still tight, but moved slightly.  I think the rear base had just enough play in it that it would move ever so slightly when the gun was laid down.

my second guess is that you are changing too many variables with loads.   Shoot 20 - 30 rounds with the same load and see if it repeats the same problem in 4 shot volleys.  That would at least eliminate some variables.

[Rob]

Ugh.

Got all packed up and went to Kenmore to play with this and the range was shut down for a 3D archery shoot all weekend.

I'm out the next weekend so It looks like I am two weeks out before I can play with this again.

[JackOfAllTrades]

After reading all of this.. There are some good points made, but I still think that you have way too many variables involved to be able to troubleshoot this.

You need to shoot one load and see what that does for you, adjust the scope to the grouping and see if you can get it dialed in.

This is spot on, but I will suggest, (as someone else did also), factory ammo. Winchester Silver tips in the heaviest weight you can find. They have a thicker jacket than Remington CoreLokts, although I love that bullet. Heavier bullets tend to be longer. That provides more land contact in a barrel that most likely has thousands of shots under it's belt.

The comments on powder variations that can change POI are also correct. So, if you're going to shoot hand loads, then shoot a longer heavy bullet from a military barrel. Also, If you've got some IMR4064 on hand, try it. It is about the best powder I have used for ANY 30-06, with only a few exceptions, no matter what bullet you're shooting.

Initially I was thinking scope, but your data indicates that there are good groups within shot set. A loose stock/action would probably promote more erratic groups also.

The only one other thing that comes to mind is metalergy and barrel heat. 

So, here's my suggestion. Factory ammo, Cold barrel shots. Don't adjust the scope between shots. See what your results are. I think you'll agree, what throwing all of us is the tight groups within shot sets. If everything was erratic, then I think we'd all lean toward scope, stock/action, loose bolt lockup, loads, headspace or barrel damage.

-Steve

[Rob]

FINALLY got the rifle to the range yesterday.  

Whatever the problem was, it seems to be gone now.

I made the following changes:
-Swapped scopes with another gun.
-Used single load (Hornady Interlock, 150 Gr, with 59gr of H4350)
-re-tightened some screws on the scope mount.

After using 5-6 shots to get the re-mounted scope to place bullets in roughly the correct spot, I did four 5 round sets at 100 yds.  I pulled one of the 20 shots so I removed that from the grouping calculations.  The data is in the table below.

My first set had pretty poor groupings (3.25 inches), but the other three sets were between 1 5/8 and 1 3/4 inch groups.  So the changes I made did not impact the group sizes.  These are typical for me:  I usually shoot around 2 inch groups at 100 yds.

What was good to see was the Horizontal drift from the Point of Aim (POA) all but stopped.  The Center of the groups were all within an inch of the POA.  My vertical drop from the POA moved around a little but overall they held within 1 3/4 inch of each other.

I'll need to take her out one more time before I declare victory, but this is much better.

I am thinking my root cause was the screws holding the scope mounting base in.  There are three sets of screws to keep track of:  One set that attaches a mounting base to the rifle, a second that attaches the rings to the mounting base, and a third that keeps the rings clamped around the scope.  That first set was looser than I would have liked to have seen.  I moved the scope that was on this gun to another rifle and sighted it in on Sunday too.  It shot well off the other gun so I don't think it was my scope.

Thanks for all the input, it was very helpful

[JackOfAllTrades]

I think you'll agree, what throwing all of us is the tight groups within shot sets.

I'm glad you're on the road to success, but which of the three things you changed do you think had most affect on the groups you're shooting?

-Steve

[Rob]

Swapping out the scope I think indirectly fixed the issue.  This caused me to look at the screws used to mount the ring base to the rifle.  They were not as tight as I would have liked.  I always check the other two sets of screws, but I evidently missed this group of screws.

I was seeing the group drift within the same load in my earlier tests so I don't think that was the issue (besides, I would not expect to see different loads change the point of impact to the right or left which is what I was seeing.  Although I suppose that is possible)