At our local CBA matches I’ve been experimenting with the adjustment feature on my breech seating tool. How far into the throat area does it push the bullet into place?

The Randolph book, Schuetzen shooting for the new shooter, suggests adjusting the tool so the start of the barrel land marks are about halfway onto the bullet’s (lowest) base band. I messed around with doing that and even farther down on the base band. I eventually settled on having the barrel marks just short of the base band. I recorded the distance the “seating plug” extends beyond the case mouth in all of the trials. 

The judgement criteria was 100-yard 10-round group size. You know the old adage…almost anyone can shoot a nice 5-round group but adding five more shots can cause some of us “severe angst”, even ruining the group.

However, variables such as barrel characteristics and load variables like bullet size, design and alloy, powder type and weight, primer details, etc. will impact results. And the bench set-up, ambient conditions and of course the SHOOTER, are also influential.

FWIW

Tom

Being a dyed in the wool neurotic jibbering idget, I have 5 32-40 breech seaters for my 4 high walls.  All are set to different seating depths.  I manage to have that many since I keep the ones that have manufacturing defects. I think my average is one mistake for every 6 I make for sale.  I typically adjust so there is about 1/4 of the base band engraved.   

Jack.

I used to be a jibbering idiot, but one day I forgot the hex key needed to adjust my seater. I shot better than usual since I didn't need to concern myself about maybe improving with a different setting.

Hmm.  Now I understand a little bit more about myself 

One of the more interesting things I've read on breech seating depth is this little bit from the CPA web site on the 32-40 cartridge.   

"Our rifles are taper throated from .322 to .314 in about 7/8” length, and a matching bullet can be easily seated perfectly and without distortion.  Seated this way in the taper throated chamber, the bullet will have rifling marks its full length except for the base band."

interestingly, I had been shooting a .32-40 for a long while and had, in that time, located the point that worked best overall with the 'favorite' bullet. After arriving here at this site years later, I learned of the method Frank spoke of using the bullet backward in the seater. Guess what? It turned out that Mr. Webber's method as Frank explained would have been right where a thousand bullets finally said the same setting would be good. Smart cookie, that Webber feller

Thanks everyone for the input and experiences that you have had. You’ve given me some homework!
(Is it breach or breech?)

I have two range tests to re-do. The first with the tool adjusted to insert the bullet with the marks on the bullet just short of the bottom base band as noted in Gunlaker’s CPA suggestion above. The second with the barrel marks 1/2 way onto the base band. Little things count!

Tom

That testing might not happen until next spring. We just had our last CBA match this past Saturday and my Fall is starting to fill up with lots of family events. Winter up here in MN is a deterent!

A quote from Justice Clarence Thomas…
“Everybody has a will to win. What’s far more important is having the will to prepare to win.”

But I will report back whenever the testing is completed. 

Tom