COAL Question

Please let me apologize up front for my ignorance. I bought a Sinclair International bullet seating depth tool because I wanted to be as accurate as possible determining my COAL. I followed the instructions and got repeated results that were consistent. Now I'm not sure what to do with this information. Again, sorry for such ignorance, but I'm just not sure where to go from here. What's the next step in deterring seating depth?

I understand that these dimensions will change with each type and brand of bullet, etc. but I wasn't expecting the length to be so much greater than the SAAMI standard. Maybe that's what's throwing me off. Thanks for any help or advice.

Don't pay attention to the standard book length. Seat the bullet to your rifles' chamber and/or magazine. Depending on what type of bullet you are running, depends on where to seat it. For example, if you plan to run a Berger VLD, it is a secant ogive bullet (the type of the radius angle where the bullet goes to full diameter). A secant ogive bullet can be seating depth sensitive. It, generally, likes to be seated very close to the rifling to shoot well. So, it depends a lot on the caliber and bullet you are running on where to seat it.

^^What Chad said^^

Also, now you will know where your rifling is from the case head. You can decide to load jammed in the lands, even with the lands, or jumping to the lands. All measured in thousandths of an inch.

SAAMI specs are for mass produced ammo and do not have any bearing on what the handloader does to produce ammo tuned to HIS rifle.

There's no downside to being over the SAAMI OAL spec as long as 1. you're not jamming the bullet into the lands unintentionally when you chamber the round AND 2. your finished cartridges will fit the magazine of your rifle and feed properly.

If you can't get a particular bullet to seat so that it will be "close enough to the lands," don't sweat it. Many times there will be more than one sweet spot for OAL. Just choose a seating depth and adjust shorter and/or longer in experimentation, and keep good records.

Guys, I really appreciate the help. Thanks!

A cheapie way to determine seating depth for a given bullet: This assumes that you have a dial caliper.

With a decapped neck-sized case (for your gun) that is extra, or nearing the end of its service life, use a thin Dremel cutting disk to cut a slot down one side of the neck, from the case mouth down almost to the shoulder. De-burr the slot. Make sure the prepared case chambers OK. - Maybe neck-size it again.

Use a magic marker or sharpie to blacken the sides of the bullet to be tested. Seat it in the case by hand, very shallow. ( Maybe 1/4 inch)

Carefully single-load the resulting "cartridge" into the gun, and very slowly close and lock the bolt. Now, slowly open the bolt and pull out the "cartridge" being careful not to disturb the bullet, which will now be seated just the right depth to touch the lands.

If you examine the bullet in the case, the blackening on the sides will reassure you that it did not get stuck on the lands and get partially pulled back out. If it did, you will see where the black was rubbed off as the bullet moved outward again. - If all is well though, use a dial caliper to measure the COAL, which will be the length for having that bullet touch the lands.

Subtract how ever many thousandths of jump that you prefer (I like 15-20 thousandths) and this new number will be your ideal COAL with that bullet.

Keep the altered case around to do the same thing with other bullets for that gun. It's cheap, but it is also very effective if you don't have a specialized tool handy.

If the altered cartridge case starts to lose its grip, neck-size it again.

A good method indeed. I usually repeat the first step a number of times to make sure I'm getting a true length, so I do not use or need a marker.






I would strongly suggest using a comparator with your caliper for taking measurements. It really is a lot more consistent.

I tried the dremel slot method and found it too tedious. It just didn't hold the bullet still. I found myself taking several measurements and averaging. Threw it out and bought the Stoney Point tool. Solid as a rock. Repeatable. Accurate.

Get the tool. Hornady is now making the tool.

The split neck method is very repeatable. If done CORRECTLY.

If the tool was free you would have one. Grumpy.

Maybe, maybe not. Dopey.