K&M Small and Large Rifle Primer Pocket Reamer Question

[sawacs]

I decided to ream the primer pockets using Hornady 6.8 SPC brass. The issue, if there is one, is the small reamer is labeled as 0.122" in depth.

The reamer sticks out quiet a bit on all of the Hornady brass and requires a substantial amount of reaming to get the disk of the tool to contact the rear of the case. My concern is the tool is reaming the pockets out too much: this isnt confirmed yet.

The KM rifle reamer is labeled as 0.131 and it also sticks out substantially on once fired Hornady brass and brand new Lapua brass.

I have not touched any of the new Lapua brass for fear of reaming too deep. It appears that either both KM tools are not correct on the depth or every piece of brass I own, new and once fired, have screwed up primer pocket depths.

How should I proceed?

I have thought about placing the reamer into all of the case primer pockets and picking the case that has the deepest pocket. From there I can adjust the tool to match that case.

Until this is figured out, I think I will load the cases and not worry about primer pockets.

Almost forgot, it would be nice to have a reamer guage that you could slip the reamer into and confirm the tool is in spec for the primer pockets kinda like a case gauge. Maybe drill a hole into a piece of aluminum that is 0.122" thick etc..



Thanks,

Shawn

 

[tdogg]

I'd take your calipers and verify that the cutter depth is to spec and also measure how deep the primer pockets are on your brass currently. I usually cut to the minimum depth for the size/type of primer:

Primer pocket dimensions and tolerances
Pocket Type Depth Min Depth Max Diameter Min Diameter Max
Small Rifle/Pistol 0.1170 0.1230 0.1730 0.1745
Large Rifle 0.1250 0.1320 0.2085 0.2100
Large Pistol 0.1170 0.1230 0.2085 0.2100

I'd target the minimum depth for the primer size, as measured by how deep it cuts the primer pocket. It's a bit off trial and error to get the tool set but once there it should be good for a long time. Once you get the K&M tool set there shouldn't be any need to readjust the depth or for a "primer pocket cutter depth gauge".

Cheers,
Toby

 

[dmoran]

The K&M tools are adjustable (set screw - see image below) and can be adjust to any depth desired.
With that said, they normally come preset to standard (.122").
Donovan

 

[swampthang]

i use the exact same tools and mine are spot on.
my groups shrank when i started uniforming primer pockets. maybe you got a "monday morning batch"
good thing is- they are adjustable. easy fix/

 

[Shynloco]

The K&M tools are adjustable (set screw - see image below) and can be adjust to any depth desired.
With that said, they normally come preset to standard (.122").
Donovan

Not trying to hijack this thread, but Donovan, what advantage or disadvantage is there to making primer pockets any deeper than the standard (.122)? I've always used the Sinclair primer pocket reamers to even all my brass so I can't go any deeper. I tend to think that going any deeper would shorten the thickness of the wall of the primer pocket in relationship with the chamber of the casing and would also shorten the life of a casing. Just curious as I never gave it much thought. Thx guys.

Alex

 

[Patch700]

What you are most likely experiencing is a case where your pockets have a large radius down at the bottom...

I would not adjust the cutter , I would uniform the pockets with the tool as is.