The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Got a handful of Sierra 69gn TMKs off a mate to try in my AR. With three different Lee seating dies I cannot get the OAL below 2.260. 2.264 is the closest. The seating stem is wound all the way down and winding the die body further into the press will begin to crush the case.

I’m surprised at this having loaded 10s of thousands of rounds of .223 over the last few decades, with bullets ranging from 45 to 90 grains in Lee dies. Given that the Lee seating stem is cone shaped internally to protect the bullet tip, the ogive of the TMK must be such that it is “too slim”....

Thankfully P Mags will take the slightly longer cartridge, but DPMS marked mags won’t.

Easiest thing to do would be to put a washer behind the seating stem to gain more downwards adjustment.

Or reverse the seating stem.

Alpha1 wrote:Or reverse the seating stem.

Flat part pushing on the TMK isn’t pretty.

Long term solution is make a new seating stem or pack it out.

Do you have a hammer ?

Seat with a Lee loader.