Neck thickness

[mjcmichigan]

So my Marlin 336 XLR ( remlin micro groove)
Has shot no better than 1.25” at 100 yards.
I find that satisfactory, but it was difficult to get there. I think I might have found the issue/irregularity… I got the Hornady kit to measure neck thickness and I found a lot of my brass has an abrupt bump. The brass I necksized with a Lee neck sizer (undersized by 0.0005”) is pretty consistent at 120-135/10,000th (so 0.012-0.135”). The other brass will range 0.012-0.015, and on the ridge jump to 0.020…. So 6-8/1000ths thicker. To me, this seems like a potential source of inconsistencies.
To try to remediate this brass, I think I will 1) anneal it, 2) neck size with the undersize rod.
3) trim it, 4) turn the necks…
I didn’t mention it is starline brass.
I inherited a bunch of R&P brass… I had horrible concentricity…. RCBS seater.
Got some Redding dies, that helped concentricities. Still was having issues and made a good batch with some FC nickel brass. Upon examination, neck wall was running 0.011-0.015. That is the brass that was giving a decent group. I don’t recall SD, but it was single digits.

All this to say, asking if anyone thinks I should try something else…(ie throw the brass out and start over with a new batch)

 

[RL338]

What cartridge are you working with? With 0.006-0.008” variance I would run a clean up skim pass on the necks.

 

[mjcmichigan]

That’s my 3030 Winchester.

 

[RL338]

All my 30-30 brass is Starline , no issues with it.
I checked mine 2 different lots and they average between 0.008” - 0.009” thickness.

 

[mjcmichigan]

All my 30-30 brass is Starline , no issues with it.
I checked mine 2 different lots and they average between 0.008” - 0.009” thickness.

Thank you! I’m wondering if one of my expanders is Janky. I think I have 100 pieces of starline in 3030. 50 pieces are pretty good. Neck thickness is within 0.002x”.
The other 50 are in various stage of being fired 1x or loaded still ( had a bake off with Nosler CTBT RN(for 3030) and some thing else… can’t tell by looking, will have to check my notes.
We’ve got some cold weather coming in (sub zero) and my wife has to work 12’s on sat and Sunday.
The ones that measured nicely were run though my Redding FL and Lee Neck Sizer (undersized by 0.0005”)

Appreciate the extra data points.

Brad barber posted an article from outdoor life about how to get more accuracy out of a lever… couple little tricks similar ti free floating. I haven’t tried them.