Fussy 300 WinMag - can't find a group.

[WildRose]

I didn't need to hear that. But, you know, my 270 is somewhat similar, 27" Krieger tube and an older 3.5-10 Leupold Vari-X III. It's been shooting very unfussy single hole 100 yard groups for over a decade with ordinary Hornady hunting bullets. Am hoping it's not the optics since I love the Vipers. I've got 1" rings though so it'd be an easy test to mount it up.

Ugggh!

Thanks much!!

I occasionally whiz in folks post toasties but it's always (well usually) well meant.

After the Vortex failures I went back to all Leupold with the exception of 4 trijicon scopes I have that are on AR's and my DG rifle, a Ruger Alaskan in .375Ruger.

I'm mostly running VX-6's and older VX3's witih a couple of oddball VX-7's thrown in for good measure.

 

[AD5GB]

+1 on Beeman's Berger 215 comments. I'm shooting a 300 WM 26" Brux as well. Berger 215s in front of a very stiff dose of H1000. Grouping well under .341 @ 100 yrd and running 3,045 MV with 21 ES and 9.1 SD. Norma Brass
I have Two twin 300 WM only difference is one runs a Brux barrel, other runs a Krieger, Nosler brass for the Krieger just to keep the two separate. The Brux is a strong 100 fps faster than the Krieger same load. That said the Krieger likes the heavy Berger 230 OTM better than the Brux. I'm running the 230 OTM out of the Krieger at near 300 RUM velocities (2,865 MV) Brux digests the Berger 215s like no rifle I've ever owned.

Nice! Maybe the 215s will be the magic mine needs as well. I've wondered too if I wasn't loading heavy enough. I've gotten up to where the primers just started to appear to crater and stopped. Velocities were much higher than published, and with H-1000 and Retumbo, much higher than QuickLoad predicted - though I'm still learning to use that software. The barrel is longer than the 24" or 26" listed in the loading manuals so there's that too. This is my first go with a belted magnum anything so I'm open to possibilities I've not encountered with other rounds. Can't anticipate anything unusual there though since I neck size only - headspace should be off the shoulder.

LabRadar if you are wondering. This might be the best tool I've ever owned next to my rifles.
Elevation 5,140'

I was looking at these just last week and contemplating buying one. I'm holding off though until I determine whether it's a scope problem I'm fighting with - which would really suck!

Thanks!!

 

[Alaska2006]

Another thing I've found is the Brux like a short jump, .025 to .035 where the Krieger likes a bit larger jump .045 .055 jump. both rifles are long throat.
max to ogive on the Brux is 2.833 and the Krieger is 2.903. I'm running DBM on both and can go out to 3.725 COAL

Seating depth makes major changes in accuracy as well as pressure. In have to be careful especially with the 215 berger loads because I'm running boarder line. If I seat the Brux loads at >.050 jump I get hard bolt left, .060 I cannot eject. Yet the Krieger likes .050. That said the accuracy on the Krieger falls off if I seat to a short jump.
My go to load is backed down half gr from what I found as max with correct seating depth to allow a little safety factor, yet still pushing the fine line and getting above 3,000 FPS.

I too only neck size, thus the reason for Norma brass for the Brux and Nosler for the Krieger. The chambers are just enough different once fired brass in the Brux will not chamber in the Krieger.
Both are full customs and really I should sell one of them as they are so close in performance yet a real pain to have two of the same but have to keep different brass and load data and load practices.
gun)keep working on it, you will find the perfect loadgun)

 

[AD5GB]

Another thing I've found is the Brux like a short jump, .025 to .035 where the Krieger likes a bit larger jump .045 .055 jump. both rifles are long throat.
max to ogive on the Brux is 2.833 and the Krieger is 2.903. I'm running DBM on both and can go out to 3.725 COAL

Mine's still a factory chamber. I did put the 375 H&H mag box and bolt stop in so I can seat bullets out to at least 3.6" COAL. Longer than the heavy bullets need to get into the rifling with a stock throat. Haven't fooled with anything lighter than 165 - and wonder why I even did that, though they shoot OK for < 300 or 400 yd hunting. I've played with seating right in the rifling back as far as .050. Seems that closer than .020 is when I see 2 trying to share the same hole and one 'flyer'. (or that 3 and 2 group I posted) I've not loaded to bolt lift stiffness (yet) though I did get a surprise with the 212 ELD-Xs and Retumbo and got to 3100fps with no overt pressure signs. My chrony might be lying too. I'm actually going to revisit this combo again, carefully. Clearly, the WM likes heavy bullets!

keep working on it, you will find the perfect loadgun)

Thanks for your thoughts and encouragement!

 

[BEEMAN]

The 215's have worked great on whitetails for me. I have not shot one under 500 yds with them though. Not a lot of other game possibilities here in Manitoba. I will be going to Alberta for elk and hope to try a 215 out on something bigger than a deer. Alaska2006 your rifle sounds very similar to mine. I used a PT&G TAC reamer with a extra 50 thou of free bore. Mine is also a full custom. Borden Action, 26" Brux, Holland brake, Jewel trigger, Mcmillan Game scout, NF SHV 5-20X56. Other than my RBROS 6.5X47 my 300 WM is my most accurate rifle I own.

 

[AD5GB]

Update: Took the suggestion of ditching the Lead Sled to the range today and shot off a bipod and rear sand bag. I also went over the bedding before hand to make sure there was adequate relief where it should be and trimmed the magazine box a bit more - just in case.

Started with an experiment with some rounds loaded with Rem 9 1/2M primers, 75gr of H-1000 and 212gr ELD-X and 200gr SMKs. Both 'sets' had groups loaded to depths seating bullets .010", .050", .090" and .130" off the lands. I brought another scope with me to swap out just in case but doesn't seem I have to. I'm encouraged anyway. The results rather surprised me since the Hornady's shot the best groups with .130" @ 2902 fps av and the Sierras were best at .090" @ 2930. Both were 1/2" 100yd groups. Didn't feel near as steady as I did with the Lead Sled either. Didn't think my bench setup was all that stable but this is the best thus far with this thing. I should probably call it good but can't resist the urge to try to refine it further - and no doubt will. Looking forward to playing with the Bergers next....

I'm just surprised that such a jump made such an improvement. Thanks again everyone for all the suggestions!

 

[fiftybmg]

Can someone please explain how changing seating depth changes accuracy.

I get the part where it affects pressure / velocity, but I don't get the accuracy part.

 

[WildRose]

Can someone please explain how changing seating depth changes accuracy.

I get the part where it affects pressure / velocity, but I don't get the accuracy part.

It changes the harmonics of the barrel. A VLD type design slams into the riflings when jumped and won't necessarily center itself well rather than easing into them like traditional designs.

Substantial increases and decreases in pressure can also affect the harmonics as well.

 

[fiftybmg]

Did a bit of reading, and the deviation on the target is calculated, not measured.

Varmint Al's Fluted Barrel Stiffness Analysis

Exit angle variation is projected.

Rifle Accuracy: Barrel Harmonics Effects on Rifle Accuracy Explained

These small calculated / projected variations should still produce sub-moa groups.

A variation of 0.6 inches [ which is the max in the first link ] for a .308 means the holes overlap on the paper at 100.

This doesn't explain actual group size variations by virtue of harmonics, and actually suggests that the effect of harmonics by itself is small enough to be ignored.