Interesting group

[ksubuck]

My 7-300 Win Mag produced this the other day. I was clocking the 5 shot group in front of a LabRadar. Only gave about 60 seconds between shots. Watched the rounds walk from low left to high right, one step at a time.

The stock is pilar bedded, the action screws are torqued to 50 inch pounds. The bedding supports the chamber while the barrel is free floated. No foreign material was found between the barrel and stock. Should I float the chamber too? Or what other ideas does anyone have?

 

[ksubuck]

Here it is cold clean bore with two followup shots about 5 minutes apart earlier in the day

 

[KinleyWater]

It could be heat, but, have you checked the scope/ rings, etc.? I am thinking that a walking like that might be the scope walking under recoil.

Alternatively, you could re-post the picture and just claim you're such an awesome shot that you can line them up along the diamond

 

[Firebird]

Whenever I get anomalies like that I go back the next day and see if it is a consistent problem or just me on a Monday problem-

 

[3 Meter Para Bellum]

Could be that the gun isn't quite happy with the ammo? Are you shooting factory rounds or do you hand load?

 

[RL338]

Whenever I get anomalies like that I go back the next day and see if it is a consistent problem or just me on a Monday problem-

This

 

[JD338]

+1

JD338

 

[ksubuck]

Thanks for the replies. I will attempt to repeat the situation this weekend to see. Just figured through slow and steady load development I had no issues. I never would have thought speeding the shot intervals up would change POI and string like that. Maybe a fluke, but I am a suspicious person

 

[PJGunner]

At one time when a barrel was considered more otr less finished, it was checked for straightness. If it checked out fine. If not it was sent to be straightened out on a tool designed to "fix it". Sometimes the job worked out and sometimes as the barrel heated , it would go crooked again but back to straight when cooled off. I've only seen this one time and it was back when I still lived in California, so sometime before 1968. I haven't heard of it happening in a long time. FWIW, I think most barrel might warp a bit if shot fast enough. Rare as this may be, it could be possible although the scope may be part of the blame, If I knew the pattern of the shots as each one was fired It might prove a clue. If the lowest shot was the first, then each successive shot being the next one up in the line, I'd be more inclined to suspect the barrel/bedding. I've gotten lazy in my old age but years back I always glass bedded my rifle myself. I did the action, recoil lug area and the chamber going two to three inches past the chamber area. Results were always 1.0" groups or better using 19093 and A3 rilfes and Mauser actions. Have done a Winchester M70 early Pre- 64 in .338 Win. Mag the same way with equal results.

That group looks as if the barrel might be touching somewhare. It might be a good idea to run the dollar bill trick to check for clearance with that barrel still hot from shooting that "rapid" fire group. You never know what you might find.
Paul B.

 

[lhsako]

Here it is cold clean bore with two followup shots about 5 minutes apart earlier in the day

Church!

 

[phil]

Are the groups at 100yds?

 

[ksubuck]

I shot it again this weekend. I didn't see the diagonal, but did see 1.5 inch vertical climb over 5 shots fired in less than 5 minutes. A 3 shot group fired over 15 minutes was a cloverleaf. I pulled the stock off when I got home to inspect again. I decided to float the chamber to see if that fixes it.

More on the rifle. Trued Rem 700 action, 26 inch Bartlein 3B, HS Precision stock, bedded with Devcon steel putty, barrel floated 40 mil, chamber was originally not floated, Nightforce 20MOA rail, Nightforce rings, Vortex Razor LHT. Groups all shot at 100 yards.

I wonder if the "issue" has always been there. That was the first time I fired it "fast" during load workup. I also wonder if I am making a mountain out of a mole hill. If the first cold barrel shot is dead on, not much is gonna need a second shot

 

[phil]

I’m thinking you have the possibility of shooting animals lot farther than 100yds with that cartridge.
stretch it out to 300 or more on paper and see what happens.
It’s not exactly terrible there, if it gets no worse at distance I’d be leary of making much of a change!
Good luck with it.
I can’t see a 3b getting whippy after just one shot though..?

 

[ksubuck]

Floating the chamber seems to have fixed the problem.

160g AccuBond over Retumbo, 3150 fps. That'll hunt elk out to 600 yards.

 

[NYDAN]

Congratulations on finding and correcting the issue. That should work very well for you. I hope a post a photo of some hunting results.

 

[walkinhorseman]

Bedding the action and barrel in two steps was probably the cause. Should have been done together.

 

[ksubuck]

Fifteen minutes into the first morning, we caught about 20 elk cresting a ridge top. By the time we got up top, they had crossed over to a second ridgeline and were casually walking up it. 423 yard walking broadside shot. she made it about 30 yards into the trees and expired. I didn't get pictures for some reason.

Second cow was that afternoon. About 150 yards running and quartering away. Dropped in a pile. Not much for pictures.

Pretty happy with how hard the 7-300 hits with the 160g AccuBond.

 

[salmonchaser]

Yep I think you got it fixed!

 

[gerry]

Congratulations! Glad it came altogether for you and you brought home a couple of fine cow elk. Pretty tough to beat a 160 gr AB at 3150 fps for open country.

 

[xphunter]

Fifteen minutes into the first morning, we caught about 20 elk cresting a ridge top. By the time we got up top, they had crossed over to a second ridgeline and were casually walking up it. 423 yard walking broadside shot. she made it about 30 yards into the trees and expired. I didn't get pictures for some reason.

Second cow was that afternoon. About 150 yards running and quartering away. Dropped in a pile. Not much for pictures.

Pretty happy with how hard the 7-300 hits with the 160g AccuBond.

Congrats on the fix and filled tags!