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

[Baron23]

 

[Mike Ryan]

To let everyone know, we are using Remington factory loads. And have been using the same ammo since we started shooting the rifle. Saturday is looking good for range time...

 

[BeringNorth]

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.

I bought a brand new 700 in 22-250 w/heavy fluted barrel about 6 years ago, shot better groups with my model 12. So I had re-crowned, then bought a B&C stock, the had trigger reworked, the had another smith re-crown then figured out lands were and inch from bullet when try to figure out seating depth and the barrel was garbage- getting new barrel and started buying old winchesters. So sad, I bought a 700 in 300 win mag 22 years ago and before barrel seasoned was getting 1/4” groups at 100 yards

 

[Mike Casselton]

To let everyone know, we are using Remington factory loads. And have been using the same ammo since we started shooting the rifle. Saturday is looking good for range time...

Are the factory loads all the same lot number?

Just like 22 ammunition, lot number can make all the difference.

 

[Mike Ryan]

Saturday Update: Unfortunately there will be no resolution to the issue today. My buddy who owns the gun is at a Wounded Warrior Project fishing event this weekend and he didn't drop the rifle off before he left. I'll try to get out one day after work during the week.

 

[iceng]

Keep us posted anyway.

 

[Mac 1]

While the thread has seemingly run astray from the accuracy problem... To get back to the original issue. The short answer is spread through several posts. The rifle has been removed from stock, scope and bases have been removed and a brake installed.
You start with this by eliminating the variables.
Strip to bare barrel , check bedding reinstall and tighten action screws to spec. Check barrel channel ( the old dollar bill between barrel and stock.) Reinstall bases substitute a known scope. Remove brake.
Shoot . install brake . shoot. Put original scope back on . shoot.
It's not a major ordeal.

 

[Jscb1b]

While the thread has seemingly run astray from the accuracy problem... To get back to the original issue. The short answer is spread through several posts. The rifle has been removed from stock, scope and bases have been removed and a brake installed.
You start with this by eliminating the variables.
Strip to bare barrel , check bedding reinstall and tighten action screws to spec. Check barrel channel ( the old dollar bill between barrel and stock.) Reinstall bases substitute a known scope. Remove brake.
Shoot . install brake . shoot. Put original scope back on . shoot.
It's not a major ordeal.

What about the rail?

 

[OREGUN]

While the thread has seemingly run astray from the accuracy problem... To get back to the original issue. The short answer is spread through several posts. The rifle has been removed from stock, scope and bases have been removed and a brake installed.
You start with this by eliminating the variables.
Strip to bare barrel , check bedding reinstall and tighten action screws to spec. Check barrel channel ( the old dollar bill between barrel and stock.) Reinstall bases substitute a known scope. Remove brake.
Shoot . install brake . shoot. Put original scope back on . shoot.
It's not a major ordeal.

That definately sounds like a major ordeal to me.

 

[Awag1000]

I had this same issue with my 300 Winchester Magnum. I ended up shooting off a soft Bag/Backpack with a rear sandbag and it shrunk my groups way down compared to shooting off a bipod with a rear bag. Just my experience.

 

[iceng]

That definately sounds like a major ordeal to me.

Nah, just measure things in beers.

"That's about a one and a half beer job". Simple.

 

[OREGUN]

By that measure, he should just start by having enough beer that he doesn’t care about the group size.

 

[iceng]

Is that how you reload ??

"This is tomorrow OREGUN's problem. Today OREGUN wants beer.".

 

[Mike Ryan]

Sorry for the delay in following up, but we just shot the rifle for the first time since the original post yesterday. This rifle was a tack driver before my buddy sent it to a gunsmith to thread the barrel and install a brake. After a bunch of rounds down range with nothing hitting a target from 100, then 50 yds, we somehow got one on paper. Cleary, the bullet was tumbling when it hit the paper because the hole it made was about 1.5 inches long and in the shape of the bullet. It has to be the brake. I can't see any obvious signs of the bullet hitting the brake, but can't think of anything else. I need to get a barrel vise and then we're going to remove the brake and try again. Thoughts??

 

[Steel head]

Factory barrel?
I wonder if it had a ton of stress and when cut for the brake it relieved itself and went wonky?

 

[Mike Ryan]

Factory barrel?
I wonder if it had a ton of stress and when cut for the brake it relieved itself and went wonky?

yes, factory barrel with less than 200 rounds through it.

 

[Steel head]

yes, factory barrel with less than 200 rounds through it.

Gauge pin the muzzle to see if it opened up after cutting it.

 

[Huskydriver]

Gauge pin the muzzle to see if it opened up after cutting it.

Or maybe they cut the threads non concentric to the bore?

 

[Steel head]

Or maybe they cut the threads non concentric to the bore?

Another possibility for sure.
A gauge pin can also reveal that possibly.

 

[DocRDS]

When I had supressor troubles, the guy who threaded my barrel did a runout test on both the brake and the suppressor. It was eye opening. The brake had very little runout, but the supressor was pretty bad (we could see it visually). The whole think behaved very similarly to what you are saying--throwing bullets all over the place--but there was no obvious baffle strike. Even a glancing blow is enough to throw things way off target.

I may be calling it the wrong thing, but it was a gauge with a needle--we mounted barrel in a lather and slowly rotated the barrel. any imperfections in the concentrically were measured in the thousandths of an inch. If there is a bad mount--I bet that would show it (assuming the brake has a cylindrical portion.

 

[BuildingConceptsllc]

R

When I had supressor troubles, the guy who threaded my barrel did a runout test on both the brake and the suppressor. It was eye opening. The brake had very little runout, but the supressor was pretty bad (we could see it visually). The whole think behaved very similarly to what you are saying--throwing bullets all over the place--but there was no obvious baffle strike. Even a glancing blow is enough to throw things way off target.

I may be calling it the wrong thing, but it was a gauge with a needle--we mounted barrel in a lather and slowly rotated the barrel. any imperfections in the concentrically were measured in the thousandths of an inch. If there is a bad mount--I bet that would show it (assuming the brake has a cylindrical portion.

Yeah that's an indicator.

I would think it would just about have to be either the muzzle threads or the break threads being off, given the other info the op provided. Assuming he doesn't have some scope or mount issue, it would have to be threads on one or the other .

 

[Dbspaded7]

It's the brake, I had a similar situation on a Tikka t3 lite. I ended up sending my scope in(wasn't the problem). Than I had my stock opened up, because it was no longer free floating. Ended up putting a new stock on. Still didn't fix the problem. Had my muzzle brake opened up(still didn't fix the problem. Finally I had it recrowned and put a different muzzle brake on, new stock bedded in new bottom metal. It's shooting great finally. It really changed the harmonics of the barrel. Those sporter barrels sometimes are finicky things.

 

[iceng]

Brake. Has to be. Remove brake, shoot, install brake, shoot. Bet it's rubbing somewhere.

The quickest way to do it, with brake on. Take the bolt out, look down the barrel from the chamber end. You should NOT see the brake at the end. Move the barrel around slightly in a circular motion from the chamber end, keeping the muzzle as still as you can. Keep looking down.

Bet you can see the issue "come in and out" as you move the barrel in a circular motion.

 

[clcustom1911]

How do you guys do your witness marks???

Silver sharpie on my black rifles, or some other high-contrast color. Orange, bright blue paint pens too.

 

[clcustom1911]

Stop being a pussy and tig the screws to the mount.
That's what real men do.

900⁰ silver solder paste and MAP torch while optic is mounted.

 

[Mike Ryan]

The more I've read, the more I believe it will be the threads on the barrel. The brake is an APA Fat Bastard 3, brand new, not likely that we got a bad one. The barrel was threaded by a local gunsmith. I don't know him at all, he was recommended to my friend by someone else. I will remove the brake and shoot it this weekend and I expect it to be good. If the barrel threading was bad, what are the options? Cut and rethread (with a competent smith)? New barrel? That would really suck. He'd have to go back to the original gunsmith and try to get him to make it right. Thanks for all the input!

 

[DocRDS]

The more I've read, the more I believe it will be the threads on the barrel. The brake is an APA Fat Bastard 3, brand new, not likely that we got a bad one. The barrel was threaded by a local gunsmith. I don't know him at all, he was recommended to my friend by someone else. I will remove the brake and shoot it this weekend and I expect it to be good. If the barrel threading was bad, what are the options? Cut and rethread (with a competent smith)? New barrel? That would really suck. He'd have to go back to the original gunsmith and try to get him to make it right. Thanks for all the input!

While that is likely the case--don't assume--check everything. Obviously its easy to pull the brake off and see if shooting performance returns to normal--but if it doesn't check the brake. The reason I'm a little cautions is everyone told me it was my threads, and it turned out the threads were fine--lemons do happen. I was lucky that the machinist helped me out measuring and finding the problem and I had a good company that RMA's the can.

 

[Mike Ryan]

okay, thanks everyone for hanging with me through this. It has taken a while, but.... it is the brake.

Removed the brake, installed a new viper pst gen 2 5-25 and got this at 100 yds. First shot was my finger. Couldn't get a good cheek weld and without a brake it packs a bit of a punch, so I was a bit all over.

Adjusted the scope, installed a precision armament M11A2 that I had lying around without crush washer or anything, and shot this while adjusting the scope.

Final 3+1 shot group (mosquito got me just as I pulled the trigger on the high one)

Ended up using a spare rear bag to get a decent cheek weld and it worked ok. Next step is to contact APA and ask them what they can do about the brake.

Thanks again,

Mike.

 

[iceng]

Super happy you got it sorted. Nothing better than finding an issue that you can fix, so you can enjoy what you do.