09-15-2024, 11:35 AM
+1 on Bob there. Couple of other things.
Seating depth of a particular bullet is heavily dependent on its ogive shape, the curve part for the end of the parallel shank out to the tip. In the case of the 105 Hdy bthp, it's ogive is rather "stubby", as a "tangent" ogive, so it hits the lands of your rifle quickly, meaning the OAL will be shorter than expected, usually around 2.200.
The only real way to see what any given bullet will do length-wise in your barrel is to use something like hornady's bullet OAL comparator, with the 6 Arc modified case, plus a caliper (preferably digital, they're not too expensive any more).
Bullets such as the 103 eldx, or 108, have a more sleek, "secant" ogive and so can be seated with a longer OAL without hitting any lands.
The final comment is that, for most AR type mags, as stated above, you won't in many cases be able to get close to lands since you are limited to 2.280-2.290 or so and some bullets may need to hit 2.340-2.400 before they touch the lands.
There's a lot more that you can go into on talking distance to lands, what OAL to choose, whether to "jam" or not (I don't jam) and so on... but this ought to get you started.
1000's of theories as to what is the "best" OAL or "best" M.O.... keep a log of what you're doing so you can track any good or bad loads and results, etc... I use a spreadsheet.
Seating depth of a particular bullet is heavily dependent on its ogive shape, the curve part for the end of the parallel shank out to the tip. In the case of the 105 Hdy bthp, it's ogive is rather "stubby", as a "tangent" ogive, so it hits the lands of your rifle quickly, meaning the OAL will be shorter than expected, usually around 2.200.
The only real way to see what any given bullet will do length-wise in your barrel is to use something like hornady's bullet OAL comparator, with the 6 Arc modified case, plus a caliper (preferably digital, they're not too expensive any more).
Bullets such as the 103 eldx, or 108, have a more sleek, "secant" ogive and so can be seated with a longer OAL without hitting any lands.
The final comment is that, for most AR type mags, as stated above, you won't in many cases be able to get close to lands since you are limited to 2.280-2.290 or so and some bullets may need to hit 2.340-2.400 before they touch the lands.
There's a lot more that you can go into on talking distance to lands, what OAL to choose, whether to "jam" or not (I don't jam) and so on... but this ought to get you started.
1000's of theories as to what is the "best" OAL or "best" M.O.... keep a log of what you're doing so you can track any good or bad loads and results, etc... I use a spreadsheet.