Confused . . . and Frustrated

[lckytylr]

Rifle:
Remington 700 Factory 26" Barrel
7mm RUM

Load:
Handload
Hornady 175 SST
Retumbo 88.5 gr

Shooting History: Last time at the range, 4-shot groups (not 5 because barrel gets hot and wanders). Shooting off a bench and a lead sled, very solid rest, high level of comfort and confidence in my shooting. Have done some load development, 3 different bullets, 1/2 grain powder increments until I arrived with what works best.
200 yards - 2-1/4" out to out group
300 yards - 2-3/4" out to out group

Obviously somewhat odd that my 300 was so much better than my 200, but that's just shooter error.

Confusion, New Years day, I shot again. NOTHING has changed with my load or rifle. Temperature, Elevation and Wind (2-3 mph) were all nearly identical to last time at the range. Shot 3-shot groups as I was suspecting that as my barrel was getting warm, bullets were starting to wander more than I like.

First Group
1st 300 yard shot, 2-1/2" from center bull at 10:00 position on the target.
2nd shot, 8" from center at 9:00 position
3rd shot, 12" from center at 9:00 position

Went to check target, barrel completely cold upon return to bench.

Second Group
1st 300 yard shot, 2-1/4" from center bull at 10:30 position on target
2nd shot, 8-1/2" from center at 9:00
3rd shot, 11-1/4" from center at 9:00

Take a quick minute and plot those 6 shots on the same target.

Anybody else as confused as I am? VERY Consistent wandering. I assumed that the issue was that my barrel wasn't free floated as it once had been . . . dollar bill ran unobstructed all the way to the action with plenty of clearance. Everything on my rifle is tight and secure including lug, scope bases and rings . . . can't figure out what's going on.

I have only shot at 300 twice now. The first time was great as the rifle was doing much better than I'd expected. This last time, is frustrating as could be.

Any suggestions on where to start?

 

[sendero72]

I didn't see a 7 mm 175 SST listed on Hornady's site. So I'm confused too.

 

[Bullet bumper]

The thickness of a buck may not be enough free float clearance on a high recoil gun. Depending on how rigid the stock is.
Try shooting without the lead sled as it could be bad recoil tracking .
If using a bi-pod and you are a right hander , bullets going to the left 9 oclock could indicate a weak hold on the gun and poor recoil control.
Maybe you are letting the lead sled do too much ?
Change one thing at a time and see what makes it better.
Don't ignore the possibility that the scope could be faulty .
Stock rigidity and good bedding is essential with big cartridges .

 

[AZShooter]

I agree that the barrel might need more relief. I had two rifles that had issues shooting at 500M with a bi-pod. Both rifles were bedded in McMillan stocks. More space between barrel and the stocks cured the issue for both rifles.

 

[Greyfox]

I agree with Bullet Bumper about the Lead Sled. A few years at the range a shooter using a Lead Sled was working on loads with a 300 Weatherby with shots going all over the place. His buddy shot the rifle on his sand bag set up and the group size/accuracy was significantly improved. Not sure of what had caused the difference, or if this is your issue, but it might be worth checking out.

 

[82ndreddevil]

I have had issues with grouping on a lead sled too. The recoil always felt unnatural or akward. My 300 WM Sendero also required bedding work for good results.

 

[lckytylr]

Awesome, thanks guys, appreciate the suggestions. Time to break out the sand bags again. Kind of a bummer, since I assumed that purchasing the lead sled was supposed to be such a magnificent aid for load development and longer range sessions with a magnum. Oh well, it doesn't kick too bad, I can take it and keep my form and breathing under control regardless.

 

[Greyfox]

Not sure if you have a muzzle brake on your rifle but it sure makes a big difference when shooting high volume with a magnum, with no effect on precision.

 

[Salar600]

Don't forget to look all bolts, base, ring, action, etc.

When something goes wrong, I always go back to basics.

I had two 7RUM in kind of cheap rifle (700 BDL) nothing custom I mean and both rifle were shooting accurately and consistently so to me there is obviously something going wrong with your kit. Mines were 3/4 moa guns.

 

[squirrelduster]

+1 on Salar600's comment.
Back to the basics.
I would pull the scope and rings off and remount everything using locktight.
It shot good for a while so it would appear that something loosened up. Check bedding screws also.

 

[Kiwi Greg]

Have you cleaned the barrel ?

Was it coppered up ?

Does it need a few shots to "settle down" after cleaning ?

Were you just having an "average shooting day" ?

I have those from time to time, couple that with changing wind conditions & there you have it...

Just a few ideas

 

[WapitiBob]

I had to put forearm pressure back into the barrel on my Rem 700. 2-3 business cards between barrel and stock about an inch from the end. Long term fix was a Brux barrel.

 

[Dosh]

Icky, 1+ on all the checks suggested. A coworker has the same rifle with a B&C bedded stock shooting 168 Bergers with Retumbo. Accuracy past 300 yd was not there. Our armorer who competes at 1000 yd suggested trying a heavier bullet due to the powder capacity of the RUM. Went with 180 gr Berger and it is shooting lights out after some minor tweaking. Good luck

 

[HuntFarther]

If it was me I would ditch the lead sled. I feel if you need them you have to much gun, and either need to go to a brake or smaller. When we used them once breaking in barrels and did some load workup on the big 338's in light guns. We had everything just perfect, and move to over the bipods. Had huge groups. Even had from day to day the point of impact would change. I think this was from not being able to shoulder the gun right. So in a sense it was getting canted. One gun never did shoot good until we restocked it because that stock was broke from the sudden impact. Those lead sleds in my eyes have no use unless you were just breaking in barrels and don't like shooting. They change the harmonics of the gun to which we cannot duplicate in normal hunting shooting conditions.