Not enough freebore ?

[Dave in WI]

Customer brought in a rifle that was built somewhere else. Chambered in 6.5 PRC. When chambering factory Hornady 147ELD it grabs the bullet out of unfired round and pull it out when tried to extract it. I split the neck of a case and put the factory bullet in there to check for bullet seating depth in this chamber. Using that method, my bullet comes out .060 inches shorter than the factory loaded rounds. Here are some pictures of the freebore. Looks like the lands come almost all the way to the neck.

 

[Jud96]

I’ve seen this exact thing happen in a 6.5 PRC with factory ammo.

The SAAMI reamer dimensions in the freebore are .2645 and the Hornady bullets I measured were .2643-.2644 in the particular box the customer was using. If the reamer is worn in the freebore area just a little bit it will cause it to be tight.

The fix was running a sharp reamer in the chamber to just clean up the throat. You could also use a throating reamer to do the same thing.

 

[Dave in WI]

Thank you. Pic of bullet that was chambered

 

[SKWERLZ]

It’s throating reamer time.

 

[Dave in WI]

It's about time I learn to use a uni-throater. I'll order one out.
Thanks, guys.

 

[Jud96]

Thank you. Pic of bullet that was chambered
View attachment 1761916

Yep you can see where it’s rubbing the freebore. If it was in the lands it would just have the marks from each individual land.

You can mic the bullet and see what it actually measures.

 

[LVLAaron]

This is why when I was spec'ing my first custom reamer, everyone told me go a full thou over bullet diameter.

 

[Dave in WI]

Bullets are measuring .2644"

 

[Jud96]

Tight freebore spec, probably a worn reamer, and fat bullets is a recipe for problems

As @LVLAaron mentioned, I also have been advised and spec my reamers .0007-.001 over nominal bullet diameter. The reamer manufacturers have a plus tolerance so you know you’ll at least be right on size which will give you clearance even on a fat lot of bullets.

 

[SKWERLZ]

This is why when I was spec'ing my first custom reamer, everyone told me go a full thou over bullet diameter.

^^^^

 

[LVLAaron]

Tight freebore spec, probably a worn reamer, and fat bullets is a recipe for problems

As @LVLAaron mentioned, I also have been advised and spec my reamers .0007-.001 over nominal bullet diameter. The reamer manufacturers have a plus tolerance so you know you’ll at least be right on size which will give you clearance even on a fat lot of bullets.

Plus a little bit of carbon ring during a 60 shot match... things go south real easily.

 

[SKWERLZ]

It's about time I learn to use a uni-throater. I'll order one out.
Thanks, guys.

The fancy one PTG makes is a no brainer, super easy to get good results and control depth.

The simpler ones aren’t bad.

 

[Dave in WI]

The fancy one PTG makes is a no brainer, super easy to get good results and control depth.

The simpler ones aren’t bad.

I ordered the PTG one.

 

[LVLAaron]

I ordered the PTG one.

They're like a hot knife through butter. Proceed carefully.