What works for me is if you have a throat that allows the first or second grease groove to sit just in front of the case mouth then upon firing the pressure fills the "void" with grease/lube and minimizes lead shaved.

RJ-35-40 wrote yesterday at 12:15pm:

In Dr. Franklin Mann's book "" The Bullets Flight From Muzzle To Target ""  he wrote that he discovered that if a defect was oriented in the chamber at the same position for each shot they would still group well but outside the group made with non defect bullets.  That is why orientation of bullet to case and case to chamber is importent.
With your runout issue dispersion at the target can be minimized by orientation of bullet to case and case to chamber. It was common practice to put an orientation mark in the mold cavity for that purpose. I believe it is still common practice to mark case rims for the same purpose.

I can see how indexing cases and making sure all your cases are the same brand helps accuracy. But not sure how much you can do with the bullets? You could put a punch mark in your mold to have some point of reference on all bullets cast from the mold, but does that really tell you about any differences or defects inside each bullet? I think you'd have to sort and weigh all your bullets and toss any that are outside very tight tolerances to ensure accuracy, and if you did that there's no reason to worry about indexing bullets.

Just for kicks years back built a 30-30 bench gun with 375 Brass. I turned the necks to get them concentric, even lathe turned off the web a thou or two so all brass exact. Shot very good. How much time you want to put in for your returns......A fixed chamber has the straight shoulder cut on lands to engrave bullet. By using a 1.5 degree throater you just barely cut that straight shoulder to A slight taper...for breech seating OR for fixed also.  For fixed you'll be pushing in the bullet A tad more to engrave , and for breech the bullet will slide in easier. My one 32-40 breech five shots 100 yds 1/2"...fixed it opened up to 3/4" WITH A tapered bullet, the same bullet I breech seated with.  You put the time in and experiment,you get results....

"I used to", just out of curiosity take the 'light bullets'
and from a sampling of same, take a torch to the bullet nose to expose any void if there was one.

It was a surprise the first time I did this that the void showed up as a bubble as the nose melted. 

Some of the other 'light ones' had no voids but I am guessing that the weight changed as I got deeper in the cast iron pot. 

A fun experiment might be to 'create a off center void' to see if that creates fliers ..

Where is Harry when you need him.

Dan Theodore was proponent of TIGHT Tolerance chambers, SAMMI being too loose for accuracy was his mantra. While this practice called for brass trimming, it did keep things aligned. 

Side note It's pretty obvious why the Breech Seating practice produces better accuracy. 

Anyone out there ever designed a bullet where 90% of the bullet, nose and groove section, was bore diameter with the exception of the base band, so when breech seated 90% is already in the rifling...??

Maybe Steve Brooks or another mould maker could tell us is anyone ever commissioned such a design 


marlinguy wrote Today at 11:55am:


I agree, but for match shooting I still weigh all my bullets and toss out anything that's outside my weight parameters. It's easy to spot bad ones, but even bullets that look perfect can weigh slightly different, and for long range shooting with 500 gr. bullets my parameters are plus or minus .5 grains difference. So 499.5 to 500.5 is what's acceptable to me. For lighter bullets I cut that in half as that range is too wide for a 300 grain