284 WIN Reamer

Brathany

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Joined
Oct 6, 2024
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540
Location
TX
Long action/CIP length mags.

I'm thinking a .318 Neck
Loaded brass neck is .315. (Norma)

I'm thinking a .190 FB for 180gr Hybrid. If that's a length that allows seating with only the boat tail below shoulder/neck junction?
 
Last edited:
Here is my reamer print for reference
That's a dandy! Helps my brain narrow down closer to what the 180 Berger will need. Probably that .220 that Magnum said. Then there is the thinking I get the reamer made for the thousands of 162ELDMs I have, and if I need the 180 Berger throat, just throat it out longer. Better to be short than long with machining stuff!
 
More information:

From Accurate Shooter:
Jerry Tierney, a past NBRSA 1000-yard champion and .284 Win "guru", has observed that overly tight chamber neck tolerances can cause accuracy problems. Jerry says "some guys who were running minimal neck clearance .284 chambers weren't getting the accuracy they expected. If you open up the neck to allow more clearance, say .0015-.002″ per side, that seems to solve the problems.

I have two 284 reamers one for a SA the other for a LA:

Short throated for 168 VLD to engage the lands and to fit and feed from a SA mag box of 3.050", .317 neck, .311" loaded neck OD. throat angle is 1 degree 30 min
(I have a huge supply of Winchester brass. This brass is known for neck wall variances, so it was setup to neck turn)

Long throated for long action and 180s .3165" neck .172" FB, throat is also a 1 degree 30 min. Got this reamer from a friend who no longer shoots.
 
More information:

From Accurate Shooter:
Jerry Tierney, a past NBRSA 1000-yard champion and .284 Win "guru", has observed that overly tight chamber neck tolerances can cause accuracy problems. Jerry says "some guys who were running minimal neck clearance .284 chambers weren't getting the accuracy they expected. If you open up the neck to allow more clearance, say .0015-.002″ per side, that seems to solve the problems.

I have two 284 reamers one for a SA the other for a LA:

Short throated for 168 VLD to engage the lands and to fit and feed from a SA mag box of 3.050", .317 neck, .311" loaded neck OD. throat angle is 1 degree 30 min
(I have a huge supply of Winchester brass. This brass is known for neck wall variances, so it was setup to neck turn)

Long throated for long action and 180s .3165" neck .172" FB, throat is also a 1 degree 30 min. Got this reamer from a friend who no longer shoots.
That .003 total neck clearance is what I'm gunning for!
 
When i was going thru ordering my prefit from Preferred Barrel the back n forth about which reamer suit my needs and freebore for my goals with long action, we decided to send in a couple dummies.

So i seated a 175EldX at 3.2" and a 150BD-2 @ 3.190", with request to ensure there was just 0.005 jump to lands on the longest. Both bullets being seated with boattail junction being a touch below the neck junction so Id have room to chase lands in the future.

It was. SAAMI reamer with freebore added. Neck clearance worked great for Lapua brass.

It worked great.

Edited for reamer info
 
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