Freebore for .308?

[03machstock]

I have a free barrel cert I need to use and I’m thinking of doing a .308 as a trainer for the recoil and wind. I already have a .223 for cheap reps but it lacks recoil. What freebore would work good for 168 smk, 175 tmk, 185 juggernaut, and other popular bullets around those ranges? 1:10 twist, 24”, bolt action, aics bottom metal to mag feed, but I can get a sled to single feed if I had to. Might shoot an f t/r match with it for fun but I am by no means trying to have a competitive f class rig. Just want something that isn’t fussy.

 

[Precisionhunter417]

Rather than picking three bullets I would settle on one in particular. The 175 SMK is by far the best middle ground. The mill spec M118 LR round with the 175 smk had a chamber reamer specially made for the 168 and 175 smk and it had .117” freebore.

308 Winchester - M118 Tactical Long Range USMC Finish Chambe

www.pacifictoolandgauge.com

 

[Straightshooter1]

I have a free barrel cert I need to use and I’m thinking of doing a .308 as a trainer for the recoil and wind. I already have a .223 for cheap reps but it lacks recoil. What freebore would work good for 168 smk, 175 tmk, 185 juggernaut, and other popular bullets around those ranges? 1:10 twist, 24”, bolt action, aics bottom metal to mag feed, but I can get a sled to single feed if I had to. Might shoot an f t/r match with it for fun but I am by no means trying to have a competitive f class rig. Just want something that isn’t fussy.

You might take a good look at 169 and 177 SMK's, which you can use the same freebore you're looking for. I've been using them a lot in my .308 and found they're performing better than the 168 and 175 SMK's that I've used. . . even better than the 175 TMK's (IMHO). They're cost only a hair more and well worth it???

 

[Alantra]

I really liked the Obermeyer in my 1-11. Shot 155s-185s beautifully at 100-1000. I just went to the FTR 2013 in a 1-10. Just measured touch with the jugs at 2.366 CBTO. My buddies sits at 2.196. The previous fire formed brass sat real snug against the the chamber. May just swap to new brass with the new chamber.

 

[Sgt. Brumbaugh]

I have shot a ton of the 175's / 169's and various 185 Bergers. The 169 SMK is a great bullet for the cost.

 

[tonyben]

Edited post

Here are some chambers, in order of freebore from shortest to longest (this list isn't even close to all the possible 308 chambers that are out there!)
-The Obermeyer has a freebore of 0.085" and a leade angle 2.5˚
-The standard 308 Win uses a freebore of 0.090" and a leade angle of 1.75˚
-The 308 Palma Match uses a freebore of 0.096" and a leade angle of 1.5˚
-I use a custom match reamer that has a freebore of 0.105" which uses a 1.5˚ leade angle
-The M118LR was designed with the 175 grain SMK and uses a freebore of 0.116" and a leade angle of 1.5˚
-The M852 was designed around the 168 SMK and uses a freebore of 0.122" and a leade angle of 1.5˚
-The original M118 (not the LR version) was intended for use with a 173 grain HPBT and used a freebore of 0.131" with a leade angle of 1.5˚
-The 7.62 NATO chamber uses a freebore of 0.150" with a leade angle of 5.7˚

Most match reamers use a 1.5˚ leade angle except the Obermeyer.

I use 169 SMK's with my match reamer with the 0.105" freebore and a 1.5˚ leade, and they shoot great out of my M14's and out of my bolt gun (as well as my customer's too). I use it with great success with projectiles from 125 grain TNT's to 178 grain Hornady ELDM's.

I find with the 169's, I have to seat the bullet's to about 2.875" and they're still not touching the lands. The 169's have a higher BC but the ogive sits much farther back than a traditional SMK so you have to seat it longer than mag length. For long range, it's not a problem since the matches I shoot at 600 yards are single-feed only.

On all other bullets, like the 168's, and 175's, I seat to 2.815" and call it good. I seat my 125 grain TNT's to 2.750".

For all-around use, the M852 and the M118LR are good candidates. All my customers get a 0.105" freebore, unless they request something different. I know two custom M14 rifle builders that use M852 in their standard builds. But I know guys that run Obermeyer chambers exclusively and get great results.

Tony.

 

[Hondo64d]

I have a free barrel cert I need to use and I’m thinking of doing a .308 as a trainer for the recoil and wind. I already have a .223 for cheap reps but it lacks recoil. What freebore would work good for 168 smk, 175 tmk, 185 juggernaut, and other popular bullets around those ranges? 1:10 twist, 24”, bolt action, aics bottom metal to mag feed, but I can get a sled to single feed if I had to. Might shoot an f t/r match with it for fun but I am by no means trying to have a competitive f class rig. Just want something that isn’t fussy.

Pay attention to freebore diameter too. I have found that a tighter freebore diameter keeps the bullets well aligned with the bore before land engagement, making distance to lands much less critical. With the Bisley Palma reamer my ‘smith uses, I have run seating depth test and found seating depth makes little to no difference. Those chambers seem to shoot everything pretty darn good.

John

 

[WSnyder]

Post in thread '.308 Win Reamer Suggestions'

Apr 8, 2023

Palma 95 works great with 168-175 SMK’s and Rem mag boxes. The only thing I’d do is add .002-.003” to the .200” line. The original .470" is too tight for most size dies. .472-.473" seems to work well with commonly available sizing dies.

For reference: A 95 Palma chamber w/Sierra 175 SMK touching lands is ~2.814” OAL. 168’s pretty much the same. Just about perfect for a std box. If you have or install an extended box you can then use a reamer with another .100-.125” of freebore added over the Palma freebore to touch lands and still have a bit (~.050” give or take) of room in the box.

• WSnyder

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