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Bushing Size Help

CandianHunter

New Member
Joined
Jan 6, 2024
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Location
Edmonton,Ab
Hello I have a question regarding bushing size for a redding FL bushing die I purchased for my 300wsm. I measured the neck of my adg brass with a loaded Berger 180 Elite hunter. .340" I'm also starting to use an expander mandrel for neck tension at .306". So am I right in thinking I want my neck size before using the expander Mandel to be around .304-.305 so that I'm working the nrass as little as possible ? What do you guys recommend for a bushing size ? I'm thinking 3.36 would give me 4 thou neck reduction and leave room to expand 2 thou with my expander mandrel ??
 
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My own best practice, after neck turning new brass for uniformity, is to use the largest bushing that exerts just enough pressure to resist bullet movement when I press a dummy round against a hard surface. I've found that as bushing size decreases past that minimum, group size increases.
 
My chamber is not custom so I don't turn necks and use .002 neck tension.300 win mag Lapua brass loaded round measures .337 and I use .335 bushing which gives me .002 neck tension.If your chamber is tight you will need to do as Jesse09 does.
 
I measured the neck of my adg brass with a loaded Berger 180 Elite hunter. 3.40"
I don't know what your neck clearance is but I would start with a bushing 2thou under loaded OD, as die makers recommend.
0.338"
If you have high neck clearance, the downsizing with this could end up a bit more than stamped on the bushing. Not a lot.
IMO, your mandrel should be around 1thou under cal.

This works necks minimally.
 
Old Rooster, I think we pretty much agree, overall; but, uniformity and consistency are the names of the reloading game. To that end, regardless of chamber tolerances, turning case necks gives that little bit more all-around even seating pressure. BTW, I think my bushing selection method yields the same .002" neck tension you report.
 
I use a 30 cal decapper that's been turned down to .288 to straighten any necks that may have gotten dinged. That gives me the same neck od as fired rounds. Then I step down with two bushings, last is 5 under for .004 tension.
 
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like you all, I use bushing dies and Mandrels in every gun of my own.
Took a few hours today to work on a friend's custom 280 Rem.
Nosler brass, H4831 and BR2, 160 AB&BT. Nothing complicated or sophistcated.
Around 2850mv.

Both bullets averaged less than .5 moa groups after I found a good load, at 300yds.
Reading this after I got home and thawed out I have to ask myself, why I go through all that extra trouble 😆🤣😁???
And his ES was no more than 15 on a 500yd max gun.
Regular ol sizing die, no mic adjustment and no bushing.
Answer for me is, I enjoy consistency.
And the dividends it pays at distancs
 

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