Can't get a 300 win mag zeroed, won't hold a group, suggestions?

[Mike Ryan]

Okay, the obvious answer is operator error and normally I'd agree, but in this case I think it's the scope. What do you think?

My buddy has a Remington 700 in 300 WM. He had a POS scope on it and we were able to zero it and get a decent group. Shot that way for about a year. He had a gunsmith mount a new scope while he installed a pretty beefy muzzle brake (not sure which brand). The scope is a Viper PST G2 5-25. We both shoot RPRs, his in 6.5 CM with a Razor 4.5-27 and mine in 308 with Viper PST G2 5-25 and can get sub MOA groups at 100 yds. Neither one of us can get the win mag to hold a group. We can barely keep it on a sheet of paper. We're shooting prone, on the ground, with a bipod and a rear bag at 100 yds. With the brake on it, there's not much more recoil than on my 308, and I can maintain sight picture through recoil to see impacts. I suggested to him that he put the POS scope back on it and we try again this afternoon. If we can hold a group, it would definitely point to the scope in some way, if it can't , it could be the muzzle brake. I've checked everything I can think of except the torque on the rings. Figured the gunsmith should get that right... I don't know what else to try. Any thoughts would be appreciated.

Mike.

 

[Vodoun daVinci]

I recently went thru a similar issue and long story short, the scope base was shifting. Removed, bedded it, new screws set with loctite and torqued to spec and now back to a bug hole gun.

I figured it out while dry firing. Gun would go snap at high magnification and the sight picture moved. A real wtf moment.....I was convinced it was me that was spoiling accuracy.

VooDoo

 

[BikePilot]

Sounds like the scope is defective or moving relative to the action. I suppose other things are possible, but would be odd if they cropped up just when the scope was swapped. The brake should not dramatically impact accuracy unless it’s making contact with the billet on the way out.

 

[Baron23]

Okay, the obvious answer is operator error and normally I'd agree, but in this case I think it's the scope. What do you think?

My buddy has a Remington 700 in 300 WM. He had a POS scope on it and we were able to zero it and get a decent group. Shot that way for about a year. He had a gunsmith mount a new scope while he installed a pretty beefy muzzle brake (not sure which brand). The scope is a Viper PST G2 5-25. We both shoot RPRs, his in 6.5 CM with a Razor 4.5-27 and mine in 308 with Viper PST G2 5-25 and can get sub MOA groups at 100 yds. Neither one of us can get the win mag to hold a group. We can barely keep it on a sheet of paper. We're shooting prone, on the ground, with a bipod and a rear bag at 100 yds. With the brake on it, there's not much more recoil than on my 308, and I can maintain sight picture through recoil to see impacts. I suggested to him that he put the POS scope back on it and we try again this afternoon. If we can hold a group, it would definitely point to the scope in some way, if it can't , it could be the muzzle brake. I've checked everything I can think of except the torque on the rings. Figured the gunsmith should get that right... I don't know what else to try. Any thoughts would be appreciated.

Mike.

Though the change came w swapping the scope, suggest you check action screws while you are at it.

 

[Mike Ryan]

I recently went thru a similar issue and long story short, the scope base was shifting. Removed, bedded it, new screws set with loctite and torqued to spec and now back to a bug hole gun.

I figured it out while dry firing. Gun would go snap at high magnification and the sight picture moved. A real wtf moment.....I was convinced it was me that was spoiling accuracy.

VooDoo

interesting... I hadn't thought about the scope base itself. It didn't feel like the scope was moving, but under recoil, who knows. Thanks for the tip, I will check it out.

 

[Newbie2020]

A friend taught me before every comp to take the scope out of rings, rings off rail, and rail off the rifle. Then put everything back in to torque specs. Then you always know for sure.

 

[Dbspaded7]

I would put money that it's the muzzle brake! Take the muzzle brake off and shoot, see if it tightens up your groups without. I had a similar situation. My brother just had the same thing happen to him too. Not all muzzle brakes are good and some seem to make things worst. It also could be both! Good luck

 

[OREGUN]

A friend taught me before every comp to take the scope out of rings, rings off rail, and rail off the rifle. Then put everything back in to torque specs. Then you always know for sure.

Are you honestly saying you dismantle your rail and rings and dismount your scope before any “critical” shooting event? That’s nuts. After you do that, do you shoot any rounds to rezero/verify reticle alignment? Then do you take it all apart again to make sure nothing loosened up? This is an interesting follow-on to a comment @lowlight made on a podcast about people damaging threaded fasteners by constantly “re-torquing” them…essentially saying that hitting a fastener with a torque wrench repeatedly eventually leads to an over torque situation. Appropriate thread locking compounds, appropriate torque values, high quality parts. Done. Forever.

To the OP: definitely check any threaded fastener on the gun…action screws, rail, rings, cross bolts….are the rings mounted forward in the ring slots? Is the base bedded…not that it necessarily needs to be, just curious. Action screws…loosen them up and go back through whatever process of re-tightening you like which ensures that the recoil lug is seated against the stock and the screws are tightened evenly so as to reduce any tension on the action. Are there any marks on the brakes that might indicate bullet contact? Brass colored streaks, “smudges” of metal moving at the exit hole? If it’s easy to take off, try it. If it’s been rocksett attached, I’d try all the other stuff before I went beating, soaking, heating anything to get it off. If it’s easy enough to switch the scopes between your 308, you could try that too.

 

[308pirate]

A friend taught me before every comp to take the scope out of rings, rings off rail, and rail off the rifle. Then put everything back in to torque specs. Then you always know for sure.

Just when I thought I had heard the most ridiculous shooting-related thing, something new proves me wrong.

That's completely unnecessary. It's like removing and re-installing all four wheels of your car before driving it to make sure the lugnuts are on tight.

 

[308pirate]

This is an interesting follow-on to a comment @lowlight made on a podcast about people damaging threaded fasteners by constantly “re-torquing” them…essentially saying that hitting a fastener with a torque wrench repeatedly eventually leads to an over torque situation.

I doubt that's what he said. But if he did, then he is grossly mistaken.

Threaded joint behavior and tightening techniques are part of my professional skillset.

 

[Vodoun daVinci]

In my case the base was shifting literally thousandths - not enough to feel when rocking/stressing the scope but enough to open up groups at 100. One shot would be dead on, the next one 1 inch or more away and never consistently. A sub .5 MOA rifle turned (slowly) into a 2 MOA gun and it was driving me crazy. I was told over and over that my skill was the weak link so decided to spend an hour dry firing and then noticed that when the gun went snap and the firing pin fell the center of the crosshair moved on the target significantly...like the exact amount of MOA I was having.

So I pulled it all off and discovered that some of the holes for the rail were not drilled all the way thru and the screws were actually bottoming out in the hole - so even with proper torque the rail was still floating a couple thousandths and I could see the wear in the finish on the bottom of the rail when I pulled it off. Bought new screws (shorter) and bedded the rail and retorqued to spec and *whammo* I got my bug hole shooter back. Now when I dry fire the damn sight pix never drifts.

That's my WTF moment.

VooDoo

 

[Near miss]

I will join the spicy offtopic..
I guess LL meant those people who torque all screws to specs, but then annually torque them again, just to be sure.

This brings nothing to the table, as with multiple screw systems you can easily over-torque it by switching between screws.

Truly, the best is to torque all screws properly in manufacturer's given order with loctite applied.
This solution will last for a long time. My spuhr is on with VC3 if I remember correctly and I move and carry my rifle by the optic often. I have also slammed it really hard to knock snow and water off and it has fallen too..

I understand you can always try if a screw is loose, but apart from that I do not see a reason to touch or redo them.

I hope the OP's issue will solve by remounting everything.

 

[308pirate]

I will join the spicy offtopic..
I guess LL meant those people who torque all screws to specs, but then annually torque them again, just to be sure.

This brings nothing to the table, as with multiple screw systems you can easily over-torque it by switching between screws.

That's now how it works. But I've learned that trying to educate people here about a technical subject is a complete waste of time.

Believe what you want or who you want. IDGAF

If someone actually wants to learn about torque, PM works.

 

[Carlos Danger]

I recently sold a 300 Win Mag. Buyer had to do some pretty involved load development before he could get it to group. The few rounds I put through it didn't impress me.

 

[Megahoser]

I would put money that it's the muzzle brake! Take the muzzle brake off and shoot, see if it tightens up your groups without. I had a similar situation. My brother just had the same thing happen to him too. Not all muzzle brakes are good and some seem to make things worst. It also could be both! Good luck

^^^This!
If the muzzle brake is poorly machined or has slightly misaligned threads...it would let rounds pass, but send them all over the place. Best to check your zero without it. Heck of a lot easier to check and eliminate this issue than swapping out scopes.

 

[Mike Ryan]

Are you honestly saying you dismantle your rail and rings and dismount your scope before any “critical” shooting event? That’s nuts. After you do that, do you shoot any rounds to rezero/verify reticle alignment? Then do you take it all apart again to make sure nothing loosened up? This is an interesting follow-on to a comment @lowlight made on a podcast about people damaging threaded fasteners by constantly “re-torquing” them…essentially saying that hitting a fastener with a torque wrench repeatedly eventually leads to an over torque situation. Appropriate thread locking compounds, appropriate torque values, high quality parts. Done. Forever.

To the OP: definitely check any threaded fastener on the gun…action screws, rail, rings, cross bolts….are the rings mounted forward in the ring slots? Is the base bedded…not that it necessarily needs to be, just curious. Action screws…loosen them up and go back through whatever process of re-tightening you like which ensures that the recoil lug is seated against the stock and the screws are tightened evenly so as to reduce any tension on the action. Are there any marks on the brakes that might indicate bullet contact? Brass colored streaks, “smudges” of metal moving at the exit hole? If it’s easy to take off, try it. If it’s been rocksett attached, I’d try all the other stuff before I went beating, soaking, heating anything to get it off. If it’s easy enough to switch the scopes between your 308, you could try that too.

If it dries up a bit, we're going to test the scope swap this afternoon. While on the range, I'll check for any sign of impact on the brake. Everything else on the gun is the same as it was before the scope and brake were installed. I'm sure it is possible that things come loose especially if not properly torqued/loctite'd, so we'll check that next. This rifle was pretty impressive before, despite the POS scope. One thing I did notice when I shot it the other day, the ejector is not kicking the spent casing out with any authority. Half the time it barely clears the breech and the other half it doesn't eject at all. It always pulls out of the chamber though. This is a gunsmith issue beyond my skillset, but I wouldn't think it could contribute to the accuracy issue.

 

[OREGUN]

I doubt that's what he said. But if he did, then he is grossly mistaken.

Threaded joint behavior and tightening techniques are part of my professional skillset.

I’m not gonna go back through all the old podcasts to find the segment, but he was talking about mounting scopes and talking about how people have a tendency to constantly check fastener tightness by repeatedly torquing the fasteners and I don’t remember whether it was specifically stated or just implied that there was damage being done to some components by that sort of obsessive-compulsive behavior that he sees among shooters. Threaded joint behavior is absolutely not a part of my professional skill set and it’s entirely possible that I completely misunderstood what @lowlight was saying but I do enjoy completely derailing a thread every once in a while. Sorry OP.

 

[Near miss]

That's now how it works. But I've learned that trying to educate people here about a technical subject is a complete waste of time.

Believe what you want or who you want. IDGAF

If someone actually wants to learn about torque, PM works.

Torquing with or without torque wrench?

With, should be ok. Without, a disaster.

If not, please elaborate, I only know some basics, you know, from the internet and the scopes I have destroyed.

 

[Powder_Burns]

Boogered up crown or funky brake?

 

[BuildingConceptsllc]

That's now how it works. But I've learned that trying to educate people here about a technical subject is a complete waste of time.

Believe what you want or who you want. IDGAF

If someone actually wants to learn about torque, PM works.

Since you are a professional at this particular aspect, why don't you elaborate a little bit about this subject as well as thread locker and it's effects in torqued value? I realize someone will argue or whatever but some others would like to hear (read) it too.

 

[Lowlight]

Guys are hitting scope rings every time they take the rifle out, and it’s having an effect

the broken Spur mounts are not from doing it once at 15 inch pounds, it’s from doing it 25 times

I was filming a video yesterday on the subject and one screw absolutely turned after it was previously torqued with the same limiter - best part camera was running so you can see it, wasn’t all but it was enough

use witness marks not the wrench

 

[308pirate]

Guys are hitting scope rings every time they take the rifle out, and it’s having an effect

the broken Spur mounts are not from doing it once at 15 inch pounds, it’s from doing it 25 times

I was filming a video yesterday on the subject and one screw absolutely turned after it was previously torqued with the same limiter - best part camera was running so you can see it, wasn’t all but it was enough

use witness marks not the wrench

See this is why I don't bother

 

[GrumpyOleFart]

Alignment marks are a great idea.
Torque to specs, then leave it alone.
If it isn't broken, don't fix it.

 

[hafejd30]

I always prefer to mount my own optics. Torque to spec base, rings etc with blue loctite. Have always had great results. I always torque the action screws as well so if I need to remove the chassis/stock in future I can return to same torque as previously tested at

If everything checks out here the easiest thing to check is the brake. Remove it and shoot without the brake


If the problem still exists then try another optic. I had terrible luck with the Viper PST (Gen 1) so I wouldn’t rule out the scope being an issue

Also don’t assume just because a “gunsmith” looked it over that everything is correct

 

[Baron23]

See this is why I don't bother

Actually, I don’t really see and am a bit confused.

are you agreeing w Frank or have an opposing view.

As posted above, I too would wish that you would expound a bit more on this subject.

or not. Haha

 

[308pirate]

Actually, I don’t really see and am a bit confused.

are you agreeing w Frank or have an opposing view.

As posted above, I too would wish that you would expound a bit more on this subject.

or not. Haha

I haven't seen any evidence that anyone who's posted here has a correct understanding of how to check fasteners for proper torque. That's because most people don't actually understand what's going on inside the joint.

They all think they do. I actually do, since it's been part of my jobs for over 15 years but I just don't have the desire to get into it any more in places like this.

 

[hafejd30]

I haven't seen any evidence that anyone who's posted here has a correct understanding of how to check fasteners for proper torque. That's because most people don't actually understand what's going on inside the joint.

They all think they do. I actually do, since it's been part of my jobs for over 15 years but I just don't have the desire to get into it any more in places like this.

Isn’t it just 3 drops of blue loctite and 2 ugga duggas?????

 

[BuildingConceptsllc]

I haven't seen any evidence that anyone who's posted here has a correct understanding of how to check fasteners for proper torque. That's because most people don't actually understand what's going on inside the joint.

They all think they do. I actually do, since it's been part of my jobs for over 15 years but I just don't have the desire to get into it any more in places like this.

I mean, I'm not going to beg you to explain, but you are aware that you don't have to "get into it" with anyone right? If you are going to say how much you know since its your profession ect...then you should go ahead and explain it. If someone else thinks otherwise, so what???

I do understand, as I avoid all of the building topics here for the same reason. I don't want to argue with someone about things which I am an expert at, knowing that they aren't. Of course, I also don't go into those threads and say how much I know about the subject either..... So.....

 

[White Death]

You've probably checked but the first thing that comes to mind is parallax.

 

[ma smith]

I'll take a cut at explaining what might be going on...

Torque needs to be checked/confirmed/established from a value WELL BELOW 100%, typically around 70-80% (measured). So you would loosen at a minimum to say 80% and then recomplete each bolt to 100% without stopping. If you have a bolt stopped at 90% and you crank it to "100" (set on the torque tool) the stiction needed to get the bolt moving again can cause you to overshoot 100% in the actual fastern itself (regardless of the tool setting).

 

[GrumpyOleFart]

There couldn't possibly be more than one person on this site with a trade qualification.

 

[beetroot]

Why are people checking their torques constantly anyway?
Unless you're subjecting the rifle to a ridiculous amount of vibrations screws won't work themselves loose, if they are coming loose then just use thread locker and use some torque stripe or some sort of witness mark if you want to check them.

You don't get your car mechanic to go around and check every bolt on your car on an ongoing basis, if your scope is installed correctly then just leave it alone.

I know that Frank isn't recommending folk do this was just saying thats what he found people were doing.
I don't see how constantly hitting the screws with a torque wrench can cause a mount to break but it's unnecessary to do it in the first place.

 

[iceng]

Isn’t it just 3 drops of blue loctite and 2 ugga duggas?????

Tighten it until it strips, back off 1/4 turn. Usually works good.

 

[GrumpyOleFart]

 

[Mike Ryan]

With the crappy weather, I didn't get out to check the rifle yesterday. It was a really heavy mist all day long. This will have to wait until next weekend. Thanks for all the suggestions. I am sure we will get it sorted out. I will post an update after the next round of tests.

Mike.

 

[Jscb1b]

Isn’t it just 3 drops of blue loctite and 2 ugga duggas?????

Tighten until you feel it slip then back off a blonde cunt hair. Be sure to use RED loctite.

 

[supercorndogs]

I haven't seen any evidence that anyone who's posted here has a correct understanding of how to check fasteners for proper torque. That's because most people don't actually understand what's going on inside the joint.

They all think they do. I actually do, since it's been part of my jobs for over 15 years but I just don't have the desire to get into it any more in places like this.

So, instead you make 20 posts in thread telling us how smart you are and how you don't want to get into it. How about put up, or shut up?

BTW, From a person who used to calibrate torque wrenches daily. And build extremely torque sensitive automotive parts. If you aren't extremely consistent in the way you click the torque wrench, you will get fairly different torque values in the end. Going through and clicking on each bolt over and over does overtourque threaded fasteners and I have seen people ruin transmission valve bodies by doing so. There is a very good reason using one click on low torque items is the recommended method.

 

[308pirate]

So, instead you make 20 posts in thread telling us how smart you are and how you don't want to get into it. How about put up, or shut up?

I have nothing to prove. I offered to explain and one person took me up on it.

You are right about click wrenches being the wrong tool to check for torque loss. So are fixit sticks/borka tools/similar stuff.

As it so happens most of my experience with this comes also from transmission assembly and we didn't rely on click wrenches for anything critical. For those we used DC nutrunners.

 

[supercorndogs]

O.P Check the rings, never assume some else's work is correct when diagnosing a problem.

 

[Steel head]

View attachment 7637955

I learn something everyday!

O.P Check the rings, never assume some else's work is correct when diagnosing a problem.

This!

 

[iceng]

Gunsmiths make mistakes. We are not perfect.

 

[2aBaC̶a̶]

I doubt that's what he said. But if he did, then he is grossly mistaken.

Threaded joint behavior and tightening techniques are part of my professional skillset.

Nah, he was talking about people breaking Spur mounts and stripping screws by incessent re-torquing. NoT taking everything on and off all the time. Thats just ludicrous.

 

[Jscb1b]

Damn it! Now I got to get my head bolts retorqued.

 

[BuildingConceptsllc]

I learn something everyday!



This!

I've had 3 different rifles where the scope mount/rings came loose that were all done by a gunsmith.

I always do my own now and haven't had any issues since I started doing it myself.

 

[Powder_Burns]

Nah, he was talking about people breaking Spur mounts and stripping screws by incessent re-torquing. NoT taking everything on and off all the time. Thats just ludicrous.

How else am I supposed to find out I stripped out my threads and rounded out my cap screw sockets if I don’t loosen and retighten them every week?
Also, you guys wouldn’t need torque wrenches and fix it sticks if you just use red loctite and a 3/8” drive impact the first time around.

 

[BuildingConceptsllc]

How else am I supposed to find out I stripped out my threads and rounded out my cap screw sockets if I don’t loosen and retighten them every week?
Also, you guys wouldn’t need torque wrenches and fix it sticks if you just use red loctite and a 3/8” drive impact the first time around.

Some idiot is going to see this and think you are serious.... Which is fine, just a sad observation

 

[Huskydriver]

A friend taught me before every comp to take the scope out of rings, rings off rail, and rail off the rifle. Then put everything back in to torque specs. Then you always know for sure.

Lol uhhh no.....

Torque once witness mark everything and rock n roll

 

[BuildingConceptsllc]

How do you guys do your witness marks???

 

[Highbrass]

While I don't claim to be a expert. I do troubleshoot for a living.
So did the rifle shoot groups prior to all the work being done? If it did, just start un- doing each item and test for groups. Start with the brake( by the way it is spelt brake ! Not break) just remove and shoot for groups...
If that taint it swap the scope and logic would dictate if you still have an issue your mount is wonky . Be sure to use consistent ammo and maybe a lead sled ? It's rocket science ya know!

 

[OREGUN]

How do you guys do your witness marks??

I use a fine tip sharpie on parts where it shows and a tiny touch of wife’s nail polish for dark parts.