6.5-284 OAL & freebore

[memilanuk]

Hello all,

I'm curious as to what those of you who have been thru a barrel or two on a custom 6.5-284 normally see for an OAL with a bullet seated to the lands, give or take,realizing some folks seat long, some jump theirs, etc. but they all start from some reference point, typically the lands). I realize there is a standardized SAAMI/CIP spec drawing from QL on the 6.5-284 page; I'm interested in what people are seeing for numbers 'in the wild'.

My first 6.5-284 is a Savage 12 F-Class, and a Berger 140gr VLD seated to touch the lands is sitting out there around 3.215' or so... only about 90 thou of bearing surface still in the neck. I'm trying to get a feel for whether thats 'too long' and the freebore,approx. .250') could be shortened up some without leading to other problems - such as getting down into the donut region on the case neck, or encroaching on case capacity, etc.

FWIW, the throat on this barrel didn't seem to move too much,~0.010') for the first 875-900rds or so... but its scooted out a touch over 0.090' in the last 100rds or so,~1000rds total) by my measurements. The conditions lately haven't been good for testing,windy and lots of mirage) so I can't say just how much the accuracy may have slid in the process. Figure I'll wear it out fire-forming new brass.

 

[dennisinaz]

There are so many custom reamers floating around in the caliber, that this would be a difficult question to answer and still provide you with a meaningful answer.

There are 6.5-284 Winchester specs and 6..5-284 Norma as well as myriad variations on both. I have a reamer that is closer to the Norma but with shorter throat as I use more Norma bullets than Bergers.

 

[memilanuk]

Okay... so for the reamers you have ground to your specs, what are you seeing for OAL for a loaded round? Something shorter than 0.090' of bearing surface left in the neck on a new barrel, I hope?

 

[bugsplat]

I load my 6.5-284 with 140gr Berger VLDs to a OAL of 3.240 which is 0.040 back from the lands. My groups are Sub 1/4 MOA. When I test a load I start from touching the lands and work my way back in 0.010 increments. Because everyone said that Bergers like to jump I testing in 0.020 increments. found the sweet spot at 0.040 off.

As said above, different reamers will allow different OAL with different bullets. Best to test this with the bullet you are using.

 

[1shot]

milanuk,
I purchased a reamer that had .190 freebore. After 7 different powders, 6 different primers and two different barrels,1-8 twist, 1-8.5 twist) that were chambered at the same time with the same reamer, I couldn’t get ANYTHING to shoot 140 class bullets at much over 2800 fps. I sent the reamer to Dave Kiff, and he reduced the freebore to .148 and also tweaked the diameter of the freebore as well. Re-chamber the bbls. and presto, 2,900-3,000 fps. with .2 to .3 moa accuracy right from the start. This season, the coveted “clean' has so far eluded me, but I’ve shot multiple 197-199 strings with good x counts, so it is definitely working.
I hope this helps,
Lloyd