Rem 700 counterbore with M16 extractor

[Dave in WI]

I have my first Defiance action here to barrel. It has the M16 extractor. I have been using pre-formed piloted counterbore cutters in .705". How much more would I have to open diameter of counterbore for this type extractor?

 

[Adam in WI]

Does the extractor extend out past the o.d of the bolt nose when snapping over a cartridge rim? If not, your regular diameter should be fine er no? If it does you could just measure how far it sticks out when there is a cartridge rim under it and add that (plus a little) to your radius of the counterbore.

 

[Roeder]

I looked at one on my workbench in .308 Boltface. The extractor does not clear the OD at the widest opening, so you may not need to open the counterbore at all. It it's a magnum boltface it might need to be larger. When you finish the tenon and chamber you can check to make sure the extractor snaps over a new case rim without resistance and increase the clearance if necessary. This is a case where I would prefer not to go larger than required. Other makes of extractor such as Badger definitely need a larger counterbore. I really like the Mini M16 extractor that Defiance uses.
It's worth mentioning that Lapua brass may have a slightly larger rim than other brands. I've had factory Remingtons with extractors that would not clear Lapua cases, particularly in .284 variants.

 

[Stan Taylor]

Yep you will about another .005 or a touch over.
Stick a cartridge in chamber an try pushing the bolt nose over it to see if snaps over case I would be surprised if it did.