Rifle problem with groups

[luke5678]

Hello, I am about 1 year into long range shooting. I have a remington sendero in 7mm Mag with a nightforce scope. The first year of owning my sendero it shot .5 inch groups on a clean bore (first dozen shots all together) then as barrel fouled they spread to about a inch at 100 yards.

Now (a year later) all of a sudden my groups are drifting about 1.5 inches left to right. The first shot on clean bore is 1 inch right. Then second is about 1 inch left of target. Then following shots drift about .5 inch right and stay there for about 10 shots. My elevation of shot is always perfect but now my groups drift on the windage.

I could really use some intelligent advice on what has happened. Did the barrel just change? I am not shooting on a hot barrel. Wait for it to cool each time and have exact reloads that have not changed.

I have duplicated this three times now at different settings/shootings so I know it's not me. I just don't know what the problem is or what could have changed.

 

[Shooter98]

Hello, I am about 1 year into long range shooting. I have a remington sendero in 7mm Mag with a nightforce scope. The first year of owning my sendero it shot .5 inch groups on a clean bore (first dozen shots all together) then as barrel fouled they spread to about a inch at 100 yards.

Now (a year later) all of a sudden my groups are drifting about 1.5 inches left to right. The first shot on clean bore is 1 inch right. Then second is about 1 inch left of target. Then following shots drift about .5 inch right and stay there for about 10 shots. My elevation of shot is always perfect but now my groups drift on the windage.

I could really use some intelligent advice on what has happened. Did the barrel just change? I am not shooting on a hot barrel. Wait for it to cool each time and have exact reloads that have not changed.

I have duplicated this three times now at different settings/shootings so I know it's not me. I just don't know what the problem is or what could have changed.

What works for me in those situations is the KISS method (keep. it. simple. silly.)

I usually start at the optics. Is the rings still tight on the mount, is the mount still tight on the rifle? Then I move to loads. Am I using the same exact load that the scope is zero'd on. Next is the stock and barrel. Is the stock touching the barrel now in any way it wasn't before. Is the barrel still tight and not shifted in anyway. Usually by now I've found my culprit. Only once has it been a scope failure as usually it's something alot more simple like loose base mounts.

 

[rscott5028]

I agree with Shooter98. Don't overlook the obvious.

- loose bases or anything about the scope that may be loose
- properly torqued stock/action screws
- anything touching the barrel
(my sendero had the fore sling swivel stud rubbing the barrel)
- clean bolt and trigger mechanisms
- changes in ammunition or shooting conditions (have a buddy shoot the rifle)
- does it have a muzzle brake and does the problem persist with/without the brake
- are your bolt lugs gauling

What's your cleaning procedure?
Do you...
- use a bore guide and run your rod only from the breach end
- use a carbon fiber or non-abrasive/plastic coated rod
- bronze brushes (never stainless... especially on stainless barrels)
- powder solvent
- copper solvent
- lubrication

Hope this helps!
Richard

 

[rscott5028]

The first shot on clean bore is 1 inch right. Then second is about 1 inch left of target. Then following shots drift about .5 inch right and stay there for about 10 shots.

If you disregard the 1st 2 shots from a clean bore, how tight is the group for the next 5?

 

[roninflag]

what they said. plus horizontal is usually the wind. of course with a the high bc of the 7mm you should have very little.

 

[bandit10-4]

I agree, Id start with the action screws, remove barreled action, see if anything is touching, and put it back in the stock and tighten screws to specs. Best thing to do would be send it to Shawn Carlock (Defensive Edge) and have him work his magic on it, I bet that would do it... Good luck and Good shootin to ya partner!

 

[Long Trang]

I agree with what was already stated. Check the action screws and anything touching the action/bedding. Rscott brought up something very interesting and I hope it does not apply. Check your bolt lugs to make sure they haven't gauled.

Another possibility is if you've had any work done on the rifle lately. After having my target rifle for a year, I noticed accuracy diminishing, like yours. After investigating the problem, I discovered I needed a pillar bed job done. Once I had it done, I keep the action screws torqued to a specific value each time I go shoot and I now sport 1/4 moa accuracy.

Good luck.

 

[luke5678]

Thank you for the feedback. What does lug's gaulded mean? I have never heard of that. The lugs on the bolt do show some wear after 1 year and about 400 shots. I did recently take the action/barrel off the stock and just tightened the bolts very tight and put some muscle into it. I didn't realize there was an appropriate torque. What is it?

After the first two shots my groups are about 3/4 of an inch spread left to right at 100 yards. Not too terrible but should be better.

Thanks,

Brian

 

[luke5678]

I just looked at my bolt and a lot of blueing is off the bolt. One spot in between the lugs is worn off a lot and even shows on the end of the bolt like it's been flattened a bit. It's only a year old and a $1,200 rifle from Remington. So do I have galling? The lugs don't look bad but the spot in between shows a lot of wear. The bolt works smoothly and I don't have any trouble opening or closing the bolt during any time.

But I have never put grease on my bolt lugs. I didn't see that on owners manual and never heard that before. I do keep it very clean just not greased up.

Hope that helps diagnose my problem.

Thanks

 

[Shooter98]

I did recently take the action/barrel off the stock and just tightened the bolts very tight and put some muscle into it. I didn't realize there was an appropriate torque. What is it?

After the first two shots my groups are about 3/4 of an inch spread left to right at 100 yards. Not too terrible but should be better.

Thanks,

Brian

Well, in my opinion this describes your possible problem area. The torque on those bolts is very critical. I'd loosen them fully and torque them to spec.

 

[SBruce]

I just looked at my bolt and a lot of blueing is off the bolt. One spot in between the lugs is worn off a lot and even shows on the end of the bolt like it's been flattened a bit. It's only a year old and a $1,200 rifle from Remington. So do I have galling? The lugs don't look bad but the spot in between shows a lot of wear. The bolt works smoothly and I don't have any trouble opening or closing the bolt during any time.

But I have never put grease on my bolt lugs. I didn't see that on owners manual and never heard that before. I do keep it very clean just not greased up.

Hope that helps diagnose my problem.

Thanks

Galling is when you see grooves and (especially) built up metal that's been "scraped and then piled up" so to speak by the lack of lubrication. Yes, you should lube the back of the lugs every time you clean the gun. Wipe off excess grease after you've cocked and dry fired the gun a few times (what I have to do in cold climates) if you're shooting somewhere really warm, then it doesn't really hurt to leave some excess on the bolt, provided your action is staying clean and not getting sand and dirt blown into it.

Now, the blueing worn off and flattened in between the lugs.......?? Huh...when the action is cocked and locked (fireing position) the lugs are 12:00 and 6:00 usually............So, if your groups are spreading horizontal and the wear spot is at 3:00 or 9:00 (when being fired)..........there may be something to this.

Maybe a question for the gunsmithing section....??

 

[rscott5028]

We can only infer what may be going on and give suggestions due to the fact that we're not holding/shooting the rifle.

If you've done all the simple things that were mentioned earlier, it may be time for you to bed the action. Even with the alluminum bedding block in a Sendero stock, you can have slack/slippage and/or vibration. This may have grown over time along with removing/replacing the action and under/overtightening the bolts on top of 400 magnum rounds.

...plus a little throat erosion ...plus possible changes in mfg components in the ammo ...perhaps your crown has been slightly marred from cleaning ... all of these tolerances may stack up such that you're now shooting .75" groups after 2 fouling shots. ...not bad for a factory hunting rifle by a lot of standards.

Nonetheless, you might see some improvement from a do-it-yourself or a gunsmith tuneup. ...bedding, trigger ...then workup a new load as the harmonics and throat might've shifted slightly

That's just my $.02 and it's stuff that many guys do on their own with lots of info on the web. If it's absolutely critical, take it to a reputable gunsmith.

Good luck,
Richard

 

[luke5678]

Thanks guys. I appreciate the valuable feedback.

I am probably going to shoot it some more and see what happens. If I am still not happy I will have the action bedded.

Only concern is on that bolt where the flat spot is on the end. It even raises higher than the rim around the end of the bolt. Like a bump in the rim and on the inside wall by the firing pin there is a little washer. Weird deal. I'll post a question on the gunsmith section and call remington too.