6mm Reloading and Accuracy. HELP!

[Layne Zuelke]

So I first need to admit that I’m relatively new to loading accurate rifle ammunition. I’ve loaded plinking ammo for 20 years but this is my first year really paying attention to my practices. That being said I believe I’m producing good stuff short of neck turning.
Here’s my situation. Factory Bergara 6mm Creed HMR Pro. Gun was printing a true consistent .25.-.33 MOA groups with decent ES/SD with 40.4 grains IMR4350 under Hornady 108 ELDMs in Peterson brass using Hornady bushing dies. This was the case up until 400 rounds when accuracy fell off and I figured out I’d developed a major carbon ring due to listening to too many Snipers Hide members telling me to baby my barrel and not clean. So I didn’t. I cleaned carbon lightly every 150 rounds or so and for my efforts I got a carbon ring which caused a pressure jump, (ejector swipes, blown primers, speed jump of 150fps) along with a loss of accuracy.
So the Accurate shooter forum folks schooled me and got me straight. I got a bore scope which confirmed carbon ring and far more fouling than I though I had. I thoroughly scrubbed the barrel. Squeaky clean. Using proven techniques. And I should mention I’m a jeweler and gun engraver so I know how to mess about with precision objects and not screw them up so I doubt my full scale cleaning attack is a factor in my accuracy issue. And so in a sense I’m starting from scratch. Accuracy came back, but not consistency, using my old loads or near my old loads. Obviously my lands have moved (40-50thou) so seating is something to address. I also added a A&D FX120 with auto trickle to the bench so I can now trust my charge weights.
So that’s where I’m at. Fast forward to yesterday and I shot a ladder from 39.4-40.6gr. (My previous nodes were 39.6 and 40.4) This is where I’m into new territory. I saw accuracy down at 39.4 but ES/SD wasn’t great. Around 24/11. At 41.1 I got an ES of 7 and SD of 4. Luckily I had 10 rounds of this charge weight on hand to confirm and that’s what I got over that 10 rounds. So I’m thinking I nailed it, However with two different seating depths, (15thou off and 45thou off) I didn’t get decent accuracy. .75MOA at best.
So all this leads me a couple questions. First, with a tight ES/SD like I see at 40.1, should I run a seating depth ladder and see what comes of it? And two, is it possible my earlier treatment of this barrel has put me in a place where I may never get back the accuracy I was seeing in the first 400 rounds. Or is it possible I just got really lucky with my load the first time around and now I’m really gonna have to work hard at it to get that accuracy back.
I ask all this because I have a Brux barrel waiting in the safe but I’d planned on using the factory barrel to learn with till it was shot out. Obviously I should have another 800-1000 rounds left to figure this stuff out but I hate chasing my tail and wasting components that are hard to find if I’m not going to get anywhere with it. It may just be better to hand the gun to my smith and spin the Brux on.
Sorry for the verbose post. I’m way down the rabbit hole now where the minutia gets weird.
thanks for the help in advance.

 

[ShootDots]

A seating depth test, as you mentioned, is exactly what you need to do. One thing to remember>>>your first barrel on a "NEW TO YOU" cartridge should be viewed as a barrel to learn the cartridge. I had 2 6mmCreeds and several 6 x 47 Lapuas. They are great cartridges, however, under the stresses of competition, they smoke barrels pretty quickly. You are on the right pathway, so stay the course. ONE QUESTION: "Are you annealing your brass?" .... This, in MY opinion, is an absolute necessity in MAINTAINING accuracy..

 

[Layne Zuelke]

Yes. I’m annealing every firing for consistencies sake. Thanks for the confirmation.

 

[Ccrider]

your first barrel on a "NEW TO YOU" cartridge should be viewed as a barrel to learn the cartridge. I

Interesting. I have taken this approach to new to me barrels. Thought I was the only one.
I would suggest accuracy over es/sd. Listen to he target first.

 

[urbanrifleman]

You moved the lands 40 thou in 400 rounds?

 

[Layne Zuelke]

You moved the lands 40 thou in 400 rounds?

That was a misprint. I moved 20 thou though. So about .005 per hundred rounds which is a lot but not crazy for a 6mm creed.

 

[urbanrifleman]

That was a misprint. I moved 20 thou though. So about .005 per hundred rounds which is a lot but not crazy for a 6mm creed.

Whoa, that is a LOT I think.

 

[Lucky6547]

One thing to think about is if you’ve change scales, take the old scale, measure out the good load, then weigh it on your new scale. This caused me a headache a while ago.

 

[RegionRat]

Since this is a risky guess anyway, I will throw in my two cents...

“So all this leads me a couple questions. First, with a tight ES/SD like I see at 40.1, should I run a seating depth ladder and see what comes of it?”

Yes, the only way to know anything now is to try and test. No one else can answer this for you.

“And two, is it possible my earlier treatment of this barrel has put me in a place where I may never get back the accuracy I was seeing in the first 400 rounds. “

Yes that is certainly possible, but lets not abandon the ship without a fight unless you are so short on ammo that punting to the next bbl makes sense in your situation. Again, only you can answer that.

“Or is it possible I just got really lucky with my load the first time around and now I’m really gonna have to work hard at it to get that accuracy back.”

Yes, if you had <.33 MOA drop right into your lap up front, take it and run... Now you are about to learn how difficult staying well below 1/2 MOA really is...

Check to make sure your scale change didn’t cause a bias offset in powder weight up front. Then, run your seating depth node test and go from there. I would not complain if the rig shot an honest <0.75 MOA with a good ES/SD unless you are shooting F-Class where it really should stay <0.5 MOA.

 

[Layne Zuelke]

Well seating test is over and I wish I had started closer to the lands. Looking back the gun always seemed to like being between 15-20thou off. I started this at 20thou off and that was also the best group of the bunch. I seated these .002 apart. Seems to do well up to .026 off the lands with 3 consecutive groups between .3-.4 and goes south from there. A few brief flashes of tightening up further off but not enough to dig into. I think I’ll rerun a few rounds between .012-.020 off and if it confirms then I’ll pick the middle and run with it at the next match.
No this isn’t an F Class gun but I am shooting local 600yd Field Precision matches and staying in the 10ring is important and the only way I can be competitive. If it was a steel plinker or hunting gun I wouldn’t bother.
This whole deal has been a learning experience and tells me alot about the Facebook warriors who claim to print .25moa all day long with factory guns. By that standard my gun is a .10 gun. I’ve learned that Stacking 3 bullets through one hole a few times does not make for a .10 gun. If I can keep this gun printing .4 MOA I’ll be darned happy with it. It’s a lot harder than I ever dreamed to keep a 6mm shooting tight.
I may consider switching to 6br on the next run. I like tinkering too much to run a cartridge with a 1500 round barrel lifespan. I’m at 725rounds and just now feel like I’m getting a handle on this. I suppose I’ll be a bit more prepared when I spin up the Brux though and this won’t have been wasted ammo.