Weird results seating my first 223...any advice?

[Wise_A]

The loss of Sinclair's store and their unique products is a great loss to the entire shooting community!

I have their insert-style comparator tool, a .223 insert, and a 6.5mm on the way.

I also have their Gen 3 F-Class bipod, which is just damn sexy. It's not the most convenient bipod in the world, but it's great to shoot. Sort've like a front rest clamped to your rifle.

My only complaint is that they sell it with a swivel-stud mount--which is fine and works well--and you can get a picatinny adapter for it. I'd really like an Arca-Swiss type mounting option for it.

 

[Ivan the Butcher]

I stand corrected!! and I'm glad they are in production. I must have received bad information during the buy-out transition.

This is what you can use to determine that all the bullets have their datum point at the same distance (from the bullet's base) and that will put you in the .001 or .002 consistent OAL. The Stony Point/Hornady Comparator won't help with this!

 

[Wise_A]

You'd be forgiven for not realizing they were still in business. Brownells does a miserable job promoting the site or any of the excellent products on it. It certainly doesn't help that Sinclair isn't subject to any of the various 10%/free-ship/etc deals from Brownells main site.

 

[Twoboxer]

Variations in bullet length do not directly cause OAL variation. (FYI, neither does case length variation.)

To figure out what can cause OAL variation, you have to remember that bullets are seated by pushing them down using a contact point below the tip (so the meplat isn't crushed), somewhere along the curve of the bullet's front section (the ogive).

A deformed meplat (or just a piece of extra material on an edge of the hollow point) can force two otherwise absolutely identical bullets to have different OALs. Your caliper will measure one from base to tip, the other from base to deformed tip. Your seating die ignores the bad tip because it never touches it, but your caliper includes the damaged tip in its OAL measurement. For ALL practical purposes, these two otherwise identical bullets have actually been seated identically.

The second cause is a slight difference in the ogives of the two bullets. This will force your seating die to contact the bullet at slightly different points - think slightly different heights. So even though the die pushes down exactly the same amount, one OAL will be longer than the other. These bullets are NOT seated identically; however, for most folks small differences don't matter much if at all.

The reloader aiming for top precision will not use OAL measurements. Seating depth is controlled by measuring from the base to to a point on the ogive very close to where the bullet reaches full caliber size. This measurement is often called CBTO or cartridge base to ogive. The theory here is the fat part of the bullet will always be seated the same distance from your barrel's lands . . . which is considered by many to be the most important control measurement. IOW, the shape of the ogive, the condition of the meplat, and OAL are ignored.

TLDR Unless you control cartridge length by CBTO, you will always have OAL variations because bullets are not identical in shape. Controlling CBTO requires tools that allow your caliper to measure CBTO (duh). Those tools were mentioned in previous posts.

 

[Jellybean]

...I was aiming for Sierra's listed 2.260"...I cycled them through my AR and all are fine, none hang up, all seat just fine.

Am I splitting hairs here? This is my first time reloading where OAL is that tight...perhaps this is normal and I just don't know it.

Sierra lists 2,260" as the maximum OAL for an AR-15, but the real maximum is determined by what will feed through the magazine and what won't. As long as all of them fed okay you should be fine. If you want to you can measure a few bullets, or all of them if you wish, and use the longest to set up your seating die. Whether you care about the ogives or not they will still all be seated to the same length as this is what the seating die does. After you set the seating die to a happy place, make a dummy cartridge by loading a bullet into a case with no primer or powder, then if you ever change the die for a different bullet you can easily reset it for the 69 grain Match Kings.

 

[lrrifleman]

This may be off track a little, but even if the bullet lengths vary, why would COL vary? It should be the same length from the seater stem to the shell holder. It seems like the variance would be how much bullet is inside the casing.

I'd agree that for everyday shooting in an AR, +/- .003 shouldn't matter as long as they cycle.

Al,

Some view the COAL from the tip of the bullet to the case head, but the critical measurement works from the base of the bullet. You are correct with your statement about how much bullet is in the case, I worded it improperly. While the reloader wants a uniform COAL, the resultant internal volume established by a uniform seating depth is critical for repeatable accuracy.

 

[bigggbbruce]

Gun will load and cycle 2.262"OAL.. minimum measured.. 2.256".

Spent way too much time on this already...go shoot them..

 

[AlHunt]

Al,

Some view the COAL from the tip of the bullet to the case head, but the critical measurement works from the base of the bullet. You are correct with your statement about how much bullet is in the case, I worded it improperly. While the reloader wants a uniform COAL, the resultant internal volume established by a uniform seating depth is critical for repeatable accuracy.

Definitely a finer point of reloading, but an interesting discussion. I appreciate the information.

 

[bigggbbruce]

Al,

Some view the COAL from the tip of the bullet to the case head, but the critical measurement works from the base of the bullet. You are correct with your statement about how much bullet is in the case, I worded it improperly. While the reloader wants a uniform COAL, the resultant internal volume established by a uniform seating depth is critical for repeatable accuracy.

Definitely a finer point of reloading, but an interesting discussion. I appreciate the information.

When I loaded for my TC Contender, I set the Ogive .010" off the lands..

 

[RonPagan]

If you want an exercise in futility try loading up some CBC magtech .308 bullets. I quit worrying about the oal after I started weighing them and found they ranged from about 145-144 grains to over 150 regularly. Some had to be seated way too short to chamber in my national match. Basically, dont be surprised by varying oal of your cartridges. Obviously your bullets are of better quality than what I was using but it's still a mass produced item and irregularities do occur. For what it's worth regular old hornady 150 fmjs are always within a grain of 150 so
Who's making the bullets matters a lot. )