skelso said:

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Sounds like you are headed down the right path. When folks bring me guns that all of the sudden have precision issues, I first check for loose screws, check the crown, then go straight to cleaning. Especially if the gun has sat for an extended time.

Gun powder residue is corrosive. If you dont get it all out and let a gun sit a while, it will cause micro pitting that is guaranteed to give you precision issues. I clean with a quality copper solvent, then follow with a bore polish, then cleaning solvent. It's a slow boring process, but it generally tightens them up.

As Dr. Boogs said, be careful with copper solvent. Dont let it sit in a barrel too long because it can start eating molecules in the metal. Always follow copper solvent with a regular solvent or oil to flush the barrel.

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Some gunpowder is corrosive, but almost no commercial manufacturers or readily available major brand reloading powder is corrosive, even after burning.

What does happen though is that the residue gives moisture a place to adhere to, and that can induce pitting.

I handload for all my rifles but the one factor I have found that makes a world of improvement in all my cartridges was bullet concentricity.
I was amazed as how inconsistent factory and my hand loaded rounds were off.
I started checking all with a Hornady Concentricity Gauge/Tool and it made a world of difference. Sometimes as much as .75 MOA.
What schmellba says is correct but I don't think you have that many rounds shot yet to cause throat issues as Cooper uses quality barrels.
A lot of times by handloading you can adjust your bullet seating depth specific to your rifle (distance from bullet and the lands) that will increase accuracy as well.
I'll bet that your issue ends up being an inconsistency in your factory rounds or copper fouling.
Good luck and hope you can figure it out.

Two thoughts: sounds like it's an moa gun. Tough to shoot a group at the guns capability on demand/under pressure. Also i find its easier to shoot an moa group a 200 or 300 than 100. Seeing those first two holes close together gets me all excited

2: did you adjust your parralax back to 100?

Good point. Cooper claims 1/2 MOA accuracy "guaranteed". But I get what your saying. I'll make no "guarantee" as to my own accuracy, but I'll check a few more things mentioned here before I take full responsibility

I squinted through the scope for a few seconds before the first shot, but I did make the parallax adjustment before firing.

If you need a new rifle, I have a 700 in 300 WSM. Bought it as a wild hair and has sat in the safe and has never been fired.

agingcowboy said:

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Maybe my re-torquing did some good, although i didn't notice anything that seemed loose when I did it. I'll try it out at the range again next week.

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To eliminate the scope itself (and not the mounts), you need to take off the scope and try a different optic. Scope internals go bad too, and the symptoms of a bad scope match your issues. It could be a lot of things, but that'd be an easy thing to rule out before you spend money.

Edit to add this reference, which describes some of the indicators that could mean a bad scope:

https://www.accurateshooter.com/optics/diagnose-scope-problems/

I also have experienced poor factory ammo. Then I found, I think, was Winchester Power Point. In a red box. And I don't think they make it anymore. It was a hot and accurate round, and my 300 loved them. But I agree, ammo is very important. Either reload or find a high end rounds that work in YOUR rifle.

Welcome to Copperhead, OP!

Ha! Thanks. I'm glad I found that place. Very impressed with what I've seen so far.

Purple is fine.

Well I read some articles about copper fouling and watched some videos about how to clean your barrel. Ordered up some tools and supplies I didn't have and gave it a whirl this evening. The video I watched started with Hoppes 9 until there was no carbon. Then ran a wire brush through. Then used the copper solvent on a patch and let it sit for 5 mins. Then he kept running copper solvent patches through until there wasn't anymore green. In the video he said 4-5 patches and you should be clean. Then Hoppes 9 again, then dry patches and you're done.

I followed his method. Thirty-five soupy green patches later, and the last one finally came out clean. Sheesh...makes me suspect the quality of my barrel that it was holding so much copper. Hopefully this is the problem and not just one of my problems. Got the lead sled in the car and gonna try to test it out again tomorrow. Fingers crossed.

What copper solvent did you use? Hoppes or another brand? Post a range report tomorrow!

Boretech Cu2+ was the name of the brand the guy in the video suggested. It was available on Amazon so that's what I went with.

Sounds about right for an old barrel.

I wouldn't suspect it is poor quality. Maybe just older and possibly not shot in correctly. The Bergera I recently got did a better job of explaining the WHY of proper barrel break in. It said you can leave micro deposits of copper or carbon that fuse with a new barrel. If not cleaned (between every shot for 20 shots, then every 5 for 50), those deposits become traps and pitting that catch copper and carbon every time you fire. With proper break in, you have a smooth hard barrel that resists small deposits that become big build up.

I would be highly surprised if you don't see your groups tighten up. Keep in mind, your first 2-3 rounds out of a newly cleaned barrel are fouling shots. It will begin to settle in after that. Don't be surprised if you need a small scope adjustment.

#Truth

I guess my thought is- manufacturers have done WAY more R&D on this than I every will, so I'll trust their opinions over my own.

cupofjoe04 said:

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#Truth

I guess my thought is- manufacturers have done WAY more R&D on this than I every will, so I'll trust their opinions over my own.

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Very true

Well, I was able to hit the range again for a short little session this morning and check the status of my .300 win mag. With all of the copper I got cleaned out of the barrel yesterday, I had high hopes that the problem would be solved. I took one of my 6.5 CMs to prove/make sure I could even shoot a 1" group with any rifle. The first groups was a hair over 1" at 100 yds. The second group pictured below was less than 1". Felt good about that and moved on to the 300 WM.



The first 3 shots I was holding the crosshairs on the bottom of the black diamond, lining up the thicker horizontal lower line with my reticle lines. The first 3 shots were the lower 3 of the 6 in the pic below. I didn't stress it too much thinking fouling shots, etc. The second group of 3, I held the center of the red diamond. Those came out pretty decent at just over 1".



Pretty pleased with the results, but thinking the gun should be able to do better (especially since I had my sled). I thought I'd give it another try and see if I could tighten it up. This time I shot a 5 shot group, again holding the center of the red diamond. The result pictured below (looks to be about a 5" group at 100 yards). At this point I pretty much rage quit, packed up and left (forgetting my sled that I had to go back for which made me even angrier).



I don't think its the rifle. Especially after giving it a good cleaning with significant results. I guess my next step is going to be to swap the scope out and see if that changes anything. I'm not looking forward to this as it seems like a pain. After that I guess I'll have to take it to a gunsmith. Not even sure where to take it really for accuracy issues. Can a gunsmith diagnose and fix problems like this to include the optic?

AgEng06 said:

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cupofjoe04 said:

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#Truth

I guess my thought is- manufacturers have done WAY more R&D on this than I every will, so I'll trust their opinions over my own.

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I thought I had read somewhere that one of the guys at Bergara suggested a break-in routine. When asked if his rifles required that he responded something like "No, but people don't believe me when I say no break-in is required, so I just tell them that routine."

I wish I could find it again to verify, however.

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Very well may be... would be fascinating if so. I'll guess it was something regarding the traditional reasons for break in- the belief that new barrels can twist and move as the heat up and settle in. This is something modern barrels don't seem to suffer from, and my modern break in suggestions are minor.

They still print it in the owners manual, but stated preparing the internal surface as the reason. I figure, if its printed in the manual, and I have to have warranty work some day, question #1 might be "Did you follow the procedures for proper break in?". Who knows.

Before you do that - tell us about the gun. Wood stock? Synthetic?

I would look at the potential of something inducing stress on the barrel that was not there before - take a $1 bill and you should be able to slide it between the stock and the barrel up to the action (assuming it's not glass or pillar bedded). If you can't and are reasonably certain you used to be able to do so, check under the barrel in the stock channel for anything abnormal - something got in there during one of your trips, wood got wet and swelled an area that needs to be sanded down, etc.

Take a factory live round and color the projectile with a sharpie. Chamber it fully, then work the bolt and remove the round - can you see rifling marks or any other marks on the projectile that indicates there may be a change in the chamber that you aren't aware of? If you know somebody close that reloads, see if they can measure your chamber for you. I"m still not convinced that you are starting to get into the territory of throat erosion and the rounds you have simply don't like any jump. 400-500 on a .300 win mag, especially if there are multiple shots with a hot barrel, is getting into that territory IMO even with a good barrel maker.

Changing the scope certainly won't hurt and will eliminate a variable - but I'd look at anything else I can first personally.

AgEng06 said:

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cupofjoe04 said:

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#Truth

I guess my thought is- manufacturers have done WAY more R&D on this than I every will, so I'll trust their opinions over my own.

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I thought I had read somewhere that one of the guys at Bergara suggested a break-in routine. When asked if his rifles required that he responded something like "No, but people don't believe me when I say no break-in is required, so I just tell them that routine."

I wish I could find it again to verify, however.

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This is Shilen's:

Quote:

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Break-in procedures are as diverse as cleaning techniques. Shilen, Inc. introduced a break-in procedure mostly because customers seemed to think that we should have one. By and large, we don't think breaking-in a new barrel is a big deal. All our stainless steel barrels have been hand lapped as part of their production, as well as any chrome moly barrel we install. Hand lapping a barrel polishes the interior of the barrel and eliminates sharp edges or burrs that could cause jacket deformity. This, in fact, is what you are doing when you break-in a new barrel through firing and cleaning.

Here is our standard recommendation: Clean after each shot for the first 5 shots. The remainder of the break-in is to clean every 5 shots for the next 50 shots. During this time, don't just shoot bullets down the barrel during this 50 shot procedure. This is a great time to begin load development. Zero the scope over the first 5 shots, and start shooting for accuracy with 5-shot groups for the next 50 shots. Same thing applies to fire forming cases for improved or wildcat cartridges. Just firing rounds down a barrel to form brass without any regard to their accuracy is a mistake. It is a waste of time and barrel life.

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Seeing those groups my money's on a loose scope base. Maybe a cracked ring or base screw? While you're still mad grab the scope and give it a shake and see what's wiggling

schmellba99 said:

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AgEng06 said:

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cupofjoe04 said:

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#Truth

I guess my thought is- manufacturers have done WAY more R&D on this than I every will, so I'll trust their opinions over my own.

---

I thought I had read somewhere that one of the guys at Bergara suggested a break-in routine. When asked if his rifles required that he responded something like "No, but people don't believe me when I say no break-in is required, so I just tell them that routine."

I wish I could find it again to verify, however.

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This is Shilen's:

Quote:

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Break-in procedures are as diverse as cleaning techniques. Shilen, Inc. introduced a break-in procedure mostly because customers seemed to think that we should have one. By and large, we don't think breaking-in a new barrel is a big deal. All our stainless steel barrels have been hand lapped as part of their production, as well as any chrome moly barrel we install. Hand lapping a barrel polishes the interior of the barrel and eliminates sharp edges or burrs that could cause jacket deformity. This, in fact, is what you are doing when you break-in a new barrel through firing and cleaning.

Here is our standard recommendation: Clean after each shot for the first 5 shots. The remainder of the break-in is to clean every 5 shots for the next 50 shots. During this time, don't just shoot bullets down the barrel during this 50 shot procedure. This is a great time to begin load development. Zero the scope over the first 5 shots, and start shooting for accuracy with 5-shot groups for the next 50 shots. Same thing applies to fire forming cases for improved or wildcat cartridges. Just firing rounds down a barrel to form brass without any regard to their accuracy is a mistake. It is a waste of time and barrel life.

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That is GOLD right there! Thanks for sharing. I love the blunt honesty. And, at the end of the day, they seem to say it really doesn't hurt anything either way- so you might as well practice good shooting technique during that time.

This is step-by-step the same procedure recommended by Bergara. I love how Shilen explained that they mechanically do in the factory what break-in procedure used to do on the range.

schmellba99 said:

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Before you do that - tell us about the gun. Wood stock? Synthetic?

I would look at the potential of something inducing stress on the barrel that was not there before - take a $1 bill and you should be able to slide it between the stock and the barrel up to the action (assuming it's not glass or pillar bedded). If you can't and are reasonably certain you used to be able to do so, check under the barrel in the stock channel for anything abnormal - something got in there during one of your trips, wood got wet and swelled an area that needs to be sanded down, etc.

Take a factory live round and color the projectile with a sharpie. Chamber it fully, then work the bolt and remove the round - can you see rifling marks or any other marks on the projectile that indicates there may be a change in the chamber that you aren't aware of? If you know somebody close that reloads, see if they can measure your chamber for you. I"m still not convinced that you are starting to get into the territory of throat erosion and the rounds you have simply don't like any jump. 400-500 on a .300 win mag, especially if there are multiple shots with a hot barrel, is getting into that territory IMO even with a good barrel maker.

Changing the scope certainly won't hurt and will eliminate a variable - but I'd look at anything else I can first personally.

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I agree with this. I once had a gun suddenly quit grouping after being in storage for awhile. The culprit ended up being a slightly warped stock. Used the dollar bill trick to diagnose. Once the pressure was relieved, it went back to shooting like it always had.

Its a "hand-laid synthetic stock reinforced with kevlar" according to the manufacturer.



I was able to slide the paper through and all the way up to where you can see there. It slides pretty easy, there's maybe some grit between the barrel and stock but nothing I could blow out of there. Otherwise, the spacing looks consistent all the way around.

I tried the sharpie to a live round and didn't get any marks on it after chambering it several times.



I've always thought this brake was odd and mickey mouse looking. It was "custom made" and installed by a gunsmith in Idaho. 95% of the round I've put through the rifle have been with that brake installed. Perhaps I should take it off and see if that changes anything?

I also tried shaking the crap out of it but the scope doesn't rattle. I grabbed the bell of the scope and tried to rotate it in the rings but it feels solid. I bought some new rings anyway because I was pissed and my current ones are a hair too low and interfere with casings getting ejected.

Man- sorry to hear that. I was really hoping that you would be center-punching dimes again. Well, you know you did nothing but help the gun.

Follow other's advice on here- good stuff has been said. Take a look over a few more things for tightness and fit, and then try changing scopes. Cant hurt to try without the brake as well. Just start eliminating things.

After following some more of your post I am still questioning your factory ammo. Are you shooting out of the same box of shells when it was grouping fine? If not you need to check the lot number on the box you have and see if it is the same. If the manufacturer changed the overall cartridge length, which is based upon bullet seating depth, Your distance from the ogive of the bullet and where it touches the lands (rifling) could have changed by the ammo manufacturer. This could change accuracy (groupings) as well as pressures.
I have seen many instances of manufacturers changing bullet seating depths with the same factory ammo and same bullet. When I find a factory round that shoots well I always measure the C.O.A.L. and record it for future reference.
Typically the shorter the distance from bullet to lands will give better accuracy as the bullet has less time to wobble before entering the lands.
Before you tear off your scope I would just suggest trying another quality factory round and see if the group improves at all or gets worse. If it improves it may put you on the right track.

Brake looks fine. Taking it off wont change anything other than how hard it thumps your shoulder when you send it.

Either try different ammo or change your scope at this point, you have eliminated all of the more common issues IMO.

How quickly did you shoot each group? When your last group really opened up, was the barrel so hot that you couldn't hold your fingers on it for more than a couple of seconds? Interesting that after your 3 fouling shots the rifle produced a pretty nice group, then it opened up on you with the next 5 shots. Same ammo I'm assuming? It's possible the barrel and action temperature is also affecting your accuracy. This time of year if it's 95-105 degrees your barrel never cools down after you take it out of your truck's AC. It gets hot and then hotter. You can wait 30 minutes between shots and it still won't cool off to allow you to really achieve the best accuracy. Perhaps your good group was produced once the barrel became excessively hot. I ran into this problem with one of my ARs I use for hunting.

My 1st 100 rounds through this rifle were Winchester BSTs. I then shot probably 50 rounds of different stuff until i settled on the Hornady Precision Hunter (ELDX). I bought 30 boxes of it at the same time (ordered online through Midway USA) and have been shooting through it over the years. I'll have to check the lot numbers but I haven't bought any new since the initial purchase.

I wish I knew more about hand loading, but I've never gotten into it. I'm still trying to wrap my head around some of these details. I will at least get a new box of different ammo and give that a try and see if things tighten up.

Temps were already in the 90s while I was shooting yesterday morning. I shot the first 3, then only waited a couple of minutes before the next 3. I waited between 5-10 minutes before the 5 shot group as i walked down to check targets, etc. the rifle was in the sled and I never checked the barrel temp, i suspect it was pretty hot but I only fired 11 rounds total.

agingcowboy said:

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My 1st 100 rounds through this rifle were Winchester BSTs. I then shot probably 50 rounds of different stuff until i settled on the Hornady Precision Hunter (ELDX). I bought 30 boxes of it at the same time (ordered online through Midway USA) and have been shooting through it over the years. I'll have to check the lot numbers but I haven't bought any new since the initial purchase.

I wish I knew more about hand loading, but I've never gotten into it. I'm still trying to wrap my head around some of these details. I will at least get a new box of different ammo and give that a try and see if things tighten up.

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When you checked your scope mounts a while back, did you actually take the scope rings off the bases and check the bases?

I would take out the action from the stock. Make sure no little pieces of debris got in there. Grass seed, sand, whatever can get in there and cause issues. Blow out the inletting with compressed air. I would put it back in, being cognizant of how you tighten the action screws, and see if you hear anything odd as the action goes back into the stock.

Make SURE that the internal mag box, if it has one, is able to move slightly. If it binds it can cause stress in the action as you screw the action into the stock.

Make sure that your action screws are torqued properly.

Check the bases without the scope on the rifle. Take the rings off. Check every base screw.

Check the rings. Every screw.

Take off the brake and see if their is any damage to the crown of the barrel. I know that is a slight possibility, but just check while you're going through this other crap.

While you have the scope off put another, proven scope on it and try that. It very easily can be the scope. NF is great, but everyone makes a lemon.

Also, when you shoot, do you shoot with a rear bag? If so, make sure the sling swivel isn't sitting on the bag. The rear sling swivel can make your rifle act schizophrenic if it's sitting on the bag weird. I know that sounds crazy, but I've seen it.

For what it's worth, I've been having great luck with the KG cleaning products. There's a review from a guy named Corey (from MidwayUSA) on their KG-2 Bore Polish who details his cleaning procedure:

"KG two-step: Punch through their carbon cleaner as directed, then about 20 one way passes with this stuff on a patch wrapped around a nylon brush...blow some carb cleaner (ooh-rah) down and clean patch till dry. What this does is remove all carbon and the copper along the inside of the barrel. What it doesn't do is remove all the copper from the little imperfections that usually have to get laid down by your fowling shots."

I've started doing this when I clean and it's been effective for me. But I don't clean very often. My 308 has 80 rounds fired through it since last (first) cleaning @ 52 rounds. That's not a ton, but my last 2 5 shots groups have gone sub 0.500" @ 100 yards.

My 300 WM has 173 rounds since last cleaning in 2015 and the last three shot group @ 100 yards went 0.630".

Most guns like at least a little fouling to shoot their best. If a rifle only shoots accurately only when it's super clean, get the hell rid of it. You want to shoot, not clean.

Good stuff, lots of ideas here that I'll give a try. I did take the rings off the bases and checked the bases as well. I didn't remove the rings from the scope, just made sure they were each torqued properly.

It's been a couple of years, but I did add a monopod that attaches to a short rail that connects to the rear sling stud. Hadn't consider this, but could that somehow screw with precision?