Concentricity Question

[wildcat westerner]

I have read this and it seems to me there are a variety of things that could be culprits here. I am also writing to be informative. The depth of testing done in this category leads me to believe there is more than one thing causing problems and I have been down this road before. If the rifle is really well built, and by its description it appears to be, then the chamber could well be concentric and parallel with the bore and after you chamber the rounds and check them carefully after extraction, then the problem could be the dies. Seriously consider a straightline Wilson type of die. If your dies are at fault they will be at fault forever! Next: Long vid type of Bullets are so damnably finicky as to concentricity. When the 6.5 x 284 became popular in 600-1,000 yard shooting it was found that those long 142 grain Bullets, pushed at the near ultimate of velocities in this case only worked well when your loads were so concentric that a 1/10,000 gauge dial was used. So if you have a concentricity gauge, by all means get a 1/10,000,s dial! You will probably not like what you will be reading and it will take some time to get used to doing this operation correctly. Lastly, with no other changes in rifle loads ,weather etc. ,the difference is in the holder of that weapon. This is a brutal lesson I had to learn before I attained consistency and set two worlds records.

 

[Deputy819]

Deputy, Last time I saw a rifle shoot like that it was a bad scope. I think the rifle is broken. It has a bedding problem and the action is shifting in the stock, the rings are allowing the scope to move, the scope internals are bad, or all three of the above in any combination. I would have the smith look at this rifle and shoot it.

What distance were these groups shot at? If at 1000 yards forget everything I just said.

Isn't that awful? Distance was my typical 200 yards. That's what this rifle has done ever since I received it from my Smith back in June (except for a few 1/2" groups that have NEVER repeated). I adjusted seating depth on this last shoot by .010....it made NO DIFFERENCE AT ALL when compared to the last target I posted. Something is most definitely wrong and I just don't believe it's my handloads.

 

[Deputy819]

@Barrelnut
Also..I checked the headspace on all fired brass from this shoot. They all went in THE SAME, but they came out as much as .002 in difference (according to my Willis Headspace Guage). Is this a problem?

 

[Deputy819]

I have read this and it seems to me there are a variety of things that could be culprits here. I am also writing to be informative. The depth of testing done in this category leads me to believe there is more than one thing causing problems and I have been down this road before. If the rifle is really well built, and by its description it appears to be, then the chamber could well be concentric and parallel with the bore and after you chamber the rounds and check them carefully after extraction, then the problem could be the dies. Seriously consider a straightline Wilson type of die. If your dies are at fault they will be at fault forever! Next: Long vid type of Bullets are so damnably finicky as to concentricity. When the 6.5 x 284 became popular in 600-1,000 yard shooting it was found that those long 142 grain Bullets, pushed at the near ultimate of velocities in this case only worked well when your loads were so concentric that a 1/10,000 gauge dial was used. So if you have a concentricity gauge, by all means get a 1/10,000,s dial! You will probably not like what you will be reading and it will take some time to get used to doing this operation correctly. Lastly, with no other changes in rifle loads ,weather etc. ,the difference is in the holder of that weapon. This is a brutal lesson I had to learn before I attained consistency and set two worlds records.

Nice post! VLD's actually shot the worst in this rifle from the get-go....moved away from them. I've checked runout on my brass before and after on my Forster Concentricity Gauge. The chamber is concentric (measuring the neck of fired brass) and I NEVER find more than .002 runout after checking concentricity of a loaded round. Something else is amiss here I believe. Scope is coming off and being sent back to Leupold for the next "test"......

 

[Deputy819]

1. Have you cleaned the rifle? If not you definitely need to clean it new rifles can develop copper fouling bad some worse than others. I like boretech copper or eliminator personally. Kg12 is good too and safe on stainless barrels.

2. shoot flyers?
3. Is your rifle bedded, does it have pillars or bedding block?
4. What inch lb is it torqued to?
5. Put two pieces of masking tape behind bolt head of unshot loaded cartridge see if it closes if so you have too much headspace.
6. Reattach scope base and rings and make sure they are torqued at appropriate inch lbs.

Yep...rifle gets STRIPPED religiously after 20-25 rounds. Rifle has an aluminum bedding block and (according to the Smith) was skim bedded. Not sure of the action screw torque, but the Smith assured me that it was torqued properly. Gonna do that masking tape test after work today and see what happens and then yank the scope off and send it back for assessment....Thanks for your input!

 

[Barrelnut]

@Barrelnut
Also..I checked the headspace on all fired brass from this shoot. They all went in THE SAME, but they came out as much as .002 in difference (according to my Willis Headspace Guage). Is this a problem?

Would not be concerned about 002. That is just the difference in hardness/springback of individual pieces of brass. IMO you are making some mighty fine straight ammo at this point and the rifle should shoot that ammo into much smaller groups than it is. The rifle should actually shoot plain factory ammo better than this.

IMO you are on the right track by starting to look at the scope. I would also have a good look at the rings and their bases with the scope off. Were the rings lapped? Did you mount the scope yourself?

You could ask the smith what torque he used on the action screws. Then get yourself a Wheeler torque wrench and check them yourself. Maybe they have loosed up. Is your smith local? If so maybe he could check the torque while the scope is off to leupold?

It would also be a good idea to have this wrench when you put the scope back on.

https://www.amazon.com/dp/B0012AXR4S/?tag=lrhmag19-20

 

[Deputy819]

@Barrelnut
Yep...rings were lapped/ Smith did the entire assembly. I figure since I'm sending the scope back to Leupold I may as well do away with the ring/base combo currently atop the rifle (Leupold mounts). Gonna look at Warne, Talley and Near. And it looks like I get to add yet ANOTHER tool to the reloading bench. Can't put a price tag on "peace of mind" in our hobby, right? -Thanks agin!

 

[Deputy819]

Oh, and yes....the Smith lives about 10 minutes down the road from me.

 

[Larry 4831]

I just loaded some 308 Winchester's with a 168 grain Amax. The run out on those with the Hornady gauge was measuring 1/1000 out of round.​

 

[wildcat westerner]

Hello, I do believe this consistency, particularly with a thirty caliber, in this bullet weight and that particular bullet should give you a reliable indicator as to the accuracy of your particular rifle. 308's tend to be quite consistent and not as specific as to loadings as a fair amount of certain cartridges can be.

 

[Deputy819]

Would not be concerned about 002. That is just the difference in hardness/springback of individual pieces of brass. IMO you are making some mighty fine straight ammo at this point and the rifle should shoot that ammo into much smaller groups than it is. The rifle should actually shoot plain factory ammo better than this.

IMO you are on the right track by starting to look at the scope. I would also have a good look at the rings and their bases with the scope off. Were the rings lapped? Did you mount the scope yourself?

You could ask the smith what torque he used on the action screws. Then get yourself a Wheeler torque wrench and check them yourself. Maybe they have loosed up. Is your smith local? If so maybe he could check the torque while the scope is off to leupold?

It would also be a good idea to have this wrench when you put the scope back on.

https://www.amazon.com/dp/B0012AXR4S/?tag=lrhmag19-20

Got the Wheeler Digital Wrench. Put the scope rings at 20" lbs per a thread by J E Custom some time ago. Was actually able to move 2 of the ring screws by about 5" pounds, but they're all the same now. Unable to use the wrench on the action screws right now as they are too deep into the stock to reach, but I absolutely cannot move them with a long Allen wrench. Gonna run one more OCW test with RL22 and then break it all down pending those results.

 

[brentc]

Hey All! Was reading an article by a guy who was comparing a shooting session between 6mm Creedmoor and 6.5 Creedmoor the other day and one of the things he said he did during the comparison was to check the Concentricity of his handloads on a Hornady Concentricity Gauge, mark the "High Side" of a loaded cartridge and then shoot that marked cartridge after loading it into the chamber in the "Twelve O' Clock" position. Anybody here doing that? I'm currently working on loads for a custom 6mm Remington that just doesn't seem to want to repeat really great groups and I was wondering if doing the above procedure might help. Thanks.

I do it the opposite way. I mark the low side then insert the low side in the chamber at the 6 o'clock position. It works much better this way.

Seriously, though. I doubt you'd ever be able to tell a difference in actual performance. There are reports of guys accidentally taking their runout cull ammo and winning matches with it. The best thing to do is figure out where your runout is coming from and eliminating it at the source.

 

[Deputy819]

I do it the opposite way. I mark the low side then insert the low side in the chamber at the 6 o'clock position. It works much better this way.

Seriously, though. I doubt you'd ever be able to tell a difference in actual performance. There are reports of guys accidentally taking there runout cull ammo and winning matches with it. The best thing to do is figure out where your runout is coming from and eliminating it at the source.

The worst I'm seeing with my current set-up is .002 runout at the finished product. The LCD I'm using is inducing very minimal runout as indicated by checking neck concentricity before sizing, after sizing and then again with a finished round. I'm pretty much convinced at this point that the issues I'm having are NOT concentricity related.

 

[brentc]

The worst I'm seeing with my current set-up is .002 runout at the finished product. The LCD I'm using is inducing very minimal runout as indicated by checking neck concentricity before sizing, after sizing and then again with a finished round. I'm pretty much convinced at this point that the issues I'm having are NOT concentricity related.

You're right. Concentricity is not your issue.