How do you work out what the correct seating depth is for a projectile?

Is it relative to the rifling lands, projectile type/weight, brass, powder level, cannelures (if any), or what looks correct?

all of this will depend on your gun and the Caliber.

examples are as follows:

The TC 7TCU shoots the best when the base of the bullet is seated at the bottom of the neck.

While the 7BR actually shoots best when the bullet is within .005" of touching the rifling.

It is for our TC Contenders.

We have 2 x 300 Whisper barrels coming from MGM (BB Standing and Production).

I just seated my bullets according to the COL in the manual. I took 200 rounds of 300 whisper this weekend to TUSCO. This was my first excursion on steel with the caliber. Load is 8.5 grains of 2400 with 150 grain Hornady. There is a Ken Light taco rail with peep and I shot it standing. Chicken and pig was same sight setting and I was holding top of the rail. Turkeys were +28 clicks and rams were +20. Out of all of the rams hit or lack there of, only rang one and it was a low hit. Overall a good amount of rams were struck between sighting in and matches for my brother and me. I finished with 18/40. I am hoping to make it to Bellefontaine and a 180 grain load will be tested on rams.

With my Whisper (and some others) 125gr and 165gr. I use the base of bullet even with base of neck theory
Like most trial and error. But what do I know i've never even shot a 40 with the whisper STANDING. With cast more of cram and ram

That sounds like a good theory to start with! ;)

All guns are not the same,I have some in the same caliber,one likes touching the lands another likes 10 off even the powder & primers makes a difference, that's talking about shooting off a sand bag just to work up a good load,I know we aren't shooting paper I just try to take out all mechanical problems and leave only human error. ;)

Shoot2Thrill wrote:I just seated my bullets according to the COL in the manual. I took 200 rounds of 300 whisper this weekend to TUSCO. This was my first excursion on steel with the caliber. Load is 8.5 grains of 2400 with 150 grain Hornady. There is a Ken Light taco rail with peep and I shot it standing. Chicken and pig was same sight setting and I was holding top of the rail. Turkeys were +28 clicks and rams were +20. Out of all of the rams hit or lack there of, only rang one and it was a low hit. Overall a good amount of rams were struck between sighting in and matches for my brother and me. I finished with 18/40. I am hoping to make it to Bellefontaine and a 180 grain load will be tested on rams.

Newbie question: What manual?
So you found 150gr not heavy enough for Rams?
Well done on TUSCO and getting your 300 Whisper up and running.
We are really looking forward to ours getting here and getting them into comps.
Cheers.

Some use 150-155 with no problem but their good shots and can place the bullet were it needs to be
If I hit a ram it maybe anywere from it's eye brow to it's manhood
So I need a little more force
165 @ 1320 mv gives me about 1100 @ the ram line
1100 X 165 / 225200 = .80 "They" say over .70 will take down
" properly set Rams" I'm not sure if it doesn't if your suppose to tell the match director
His rams are not " properly set"

Most of my TC barrels have long throats and seating cast bullets out to the rifling will result in bullets just seated to the gas check. Not good. I read something years ago that said to seat bullets (for TCs) so the base of the bullet is at the bottom of the neck and that has worked well for TCs. For bolt guns, I seat .030 to .050 off rifling just to keep pressures down for my wimp loads. I'm not the experimenter that other handloaders are and when something gets me minute of ram, I'm happy. I not a good enough shot to tell if a seating change will get me another one inch of accuracy at 200 meters.

Richard, that is why the rams have horns and "manhood" so we can hit them there!!!! Sometimes I wished the horns didn't have holes in them since I can place some shots through the holes. Now that takes skill!!!!!