Walking POI

[Kenster-Boy]

I was recently shooting at 970 yards with my 7 RM and after a couple of cold barrel sighter rounds I preceeded to shoot a 5 shot group on paper. The first two rounds were maybe 3 inches side by side (same height). Then the thrd one was centered but about 4 inches low. Then the fourth was about 7 inches low and the fifth about 12 inches low?

So do I have a walking gun or what. Do different guns walk in different directions? It seems to me that once things heat up it would cause a higher velocity and such causing the gun to walk up. But this wasn't the case.

The five shots were done in about 2 min. Then I let it cool down and it did the same thing. It shot the first couple about right then started sinking down.

Any thoughs or insight would be much appreciated!

 

[1doug]

Did you check you es with a chrony? It could be you loads.

 

[Michael Eichele]

Its possible if you have a sporter weight barrel that the barrel is warping due to the high heat this case tends to generate. Cold bore shots at that range are rarley right in the group. Sounds like a total of 7 shots were fired in a very short amount of time??

Tell us a little about the rifle. Factory or custom? If custom, who's bbl is it? What contour? Also as d-a pointed out have you checked the ES?

 

[Kenster-Boy]

Yes I did chrony my loads and came up with a maximum variation of 30 fps. The part that bothers me though is the order in which the shots hit.

 

[Kenster-Boy]

I have a Savage 112BVSS with the heavy 26" barrel. It is factory for the most part and is free floated with a glass bedded action.

Yes the 7 shots were fired in a fairly short period of time (less than 5 min).

Thanks for the replies, Ken

 

[zingdingo]

7mmag man,

How hot would you say that heavy Savage barrel is getting firing 7 shots in 5 minutes? (I'm thinking like warm to the touch, hot to the touch, or too hot to hold.) Also, what kind of ambient temps were you shooting in?

Thanks,
Carl

 

[royinidaho]

Hmmmm,,,,,Heavy barrel, supposing heavy bullet guessing 140 or 160 pushed pretty near top velocities. Generates lots of heat.

Barrel is thick (lots of metal between bore and exterior).

I'm betting that the bore temperature is much much maybe much much much higher than the barrel surface temperature.

The greater distance the heat has to travel the longer it takes to dissapate. Also heat dissipates slower on a hot sunny day than when it is cool and in the shade.

I'd recommend good cleaning (wipe out or copper melt) to see how much copper fouling is there.

From then on I'd consider slowing down the firing rate. If you have to shoot that rapidly, then I'd search for the bullet with the shortest bearing surface that shot well and switch to ball powder. All of this is a pain and probably not desirable but.......worth at least considering.

Also, was a proper barrel break in process used?

 

[HoytemanPA]

My 1KBR gun started doing that to me later this year. Or should I say I started doing that to my groups this year, 1000yd. shots one and two 2 inches apart drop low and left 6 inches shots 3,4,5,6,7 in 4 inch clump drop low and left another 6 inches shots 8,9,10 three inch clump.

First couple of times it was mixed in with some switching winds so I couldn't determine the pattern. Match before last it did as above, last match same pattern but worse.

Couple of things I started doing earlier this year. Freefloated entire 30" barrel and started shooting one hand. These two things did shrink my groups some. Also started cranking them down there even a little faster.

I asked for some advice from one of the long time regulars of the club. I asked about the bedding, load, gun, heat, barrel, etc just as everbody here is picking apart. The rifle does less than 2 inches at my practice 500 on my homemade portable bench. I get some horizontal (I practice across a flat riverbottom) but very seldom ever get vertical. Countless times, after a match, my lesser rifles have shot better groups than my regular gun.

After listening to my prejudged theories and "Is it this?", "Is it thats?" he simply said...What are you doing different after the first two shots?

So I thought a second and said.
Well after the second shot I generally have to squeeze the back bag to get back on target (quickly in my self imposed hurry)......

He asked: You ever squeeze the rear bag any other time? I said no. He said: Always do things "THE SAME" no matter what that is.

My advice is a retransmitted....Always do things "THE SAME" no matter what that is.

Good Luck!