misterc01
Well-Known Member
Rule of thumb - minimum is one bullet diameter.
30 cal Minimum bearing surface in case neck?
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NEMTHunter
Well-Known Member
yea. I still can not figure out who came up with that one. Theres a lot of 30 cals that the neck are less then .308. some are even down to about .27 so that tells me the ones designing the cartridge did not feel that way about it.
Going that deep is just wasted powder space.
I found a nick in the dummy round that I gave my Smith and now that I think about that, I realize it was nicked when I gave it to him. Measuring off of that Nick way out on the leading end of the bearing surface it measures .309. I am thinking this could be the reason for confusion. If this is the case, it makes it partially if not mostly my screw up.
misterc01
Well-Known Member
It is like the rule of thumb for nuts and bolts - minimum is one full turn of threads to retain bolt.
ar10ar15man
Well-Known Member
great for thumbs , not so much for shooting.
starting spot maybe, but not a RULE
starting spot maybe, but not a RULE
ar10ar15man
Well-Known Member
misterc01
Well-Known Member
Here is another one.
"Set your seating die to seat at a depth between .015 and .03 inches less than your rifle seating depth. B. Lightweight bullets may need to be seated further from the rifling. A depth of one bullet diameter inside the case neck gives good alignment and neck tension for ignition" The subject goes all over the place, but the bottom line I took from it to seat it enough seat it so the bullet is and stays concentric and does not "tip" before reaching the lands. I try not to seat so deep that I end up compressing the powder and inadvertently get an over pressure situation.
"Set your seating die to seat at a depth between .015 and .03 inches less than your rifle seating depth. B. Lightweight bullets may need to be seated further from the rifling. A depth of one bullet diameter inside the case neck gives good alignment and neck tension for ignition" The subject goes all over the place, but the bottom line I took from it to seat it enough seat it so the bullet is and stays concentric and does not "tip" before reaching the lands. I try not to seat so deep that I end up compressing the powder and inadvertently get an over pressure situation.
misterc01
Well-Known Member
Industrial Fasteners Institute, Joe Greenslade, Director of Engineering Technology.
- "How Many Threads Should Be Beyond The Nut?. The answer is: A minimum of two thread pitches should extend beyond the top surface of the nut."
ANOTHER rule of thumb all over the place
I think that is for the threads above the nut, not the threads in the nut. One thread internal to the nut or hole would be ridiculous. And besides that, it's a pretty rough rule because nuts can have different thicknesses. Another reason I don't like rules of thumb.
That said, the case insertion depth is really mostly about keeping the case and bullet intact if dropped. It's also important to make sure the bullet stays in the case if the cartridge is withdrawn before shooting.
However lots of other things affect acceptable insertion depth. Case condition, sizing condition, neck friction, bullet base shape, and throat length. Even the size of the bullet matters because the alignment / holding force is not linearly proportional to caliber / bore diameter.
A million years ago, an article in Handloader magazine recommended trying to push the bullet in against a bench edge and trying to bend it against the bench top. Stone age I know, but it worked back then and probably still does.
I use whatever works for me.
I still think I have too much freebore but after looking closer at the case, 225 eld & 230 Berger, I don't see how .235 freebore would be enough to get the bearing surface/ boat tail junction of the bullet above the neck/ shoulder junction of the case.
NEMTHunter
Well-Known Member
How long is your Neck? My .30 cal I got built I had the freebore set @ .280"..
The berger 230 Hybrid has a bearing surface of .529 That put about .250 in the neck on my gun if I am just off the lands. I wish I would have gone with a .300 freebore.
Neck on my reamer measures about .300. I actually think that .300 freebore is about right for a 230 Berger & 225 eld. I just think that he let his throater get away from him and he went to far. My cousin has the rifle right now fitting a muzzle brake for it. But Dave Kiff insisted a .235 freebore reamer for 230s. I think .235 is more appropriate for 215s.
First off, I wouldn't take any information from PTG too seriously, that outfit has been on a down hill slide for a couple years now. The smith probably just got a little carried away with the throating reamer. Those things cut fast!
