6.5 Grendel PTG Reamer

[Lead Chucker]

You're welcome!

Also, a question from BjornF16 got me to thinking about the effect of allowing the throat to be just .001" tighter than spec.

From the SAAMI Drawing:

• Dia at start of throat = .2644"
  
• Dia at front of throat = .2617"
  
• Position of start of throat = 1.5478
  
• Position at front of throat = 1.7025
  

This makes change of diameter = (.2644 - .2617) = 0.0027"
and the change in length = (1.7025 - 1.5478) = 0.1547"

Now, suppose we are .001" tight, that makes the change in diameter to the front of throat = (0.0027 - .001) = 0.0017"

We get the new distance to front of the throat through geometry:
[INDENT]L = .0017 x (.1547/0.0027) =0.057" [/INDENT]
That means that folks who have throats that are on the minimum side of the presumed reamer spec will need to seat their ammunition about 0.060" shorter than they would with a throat with the minimum SAAMI spec diameter.

This difference could explain a lot of what we are seeing in the way of symptoms.

The corrective action I would ask for is to get my throat cut to the SAAMI spec.

Folks are welcome to wildcat and offer for sale any configuration their liability insurance is willing to cover. I would submit, however, that blaming the symptoms of an out of spec throat on an already excellent performing chamber is not necessarily a good marketing strategy.

This explains one of the stoner barrels I have perfectly. It is .035" short in the throat! With a dummy round, a 123gn amax touches the lands at 2.212"