Barnes TTSX 223 seating depth

Working up a load for Barnes TTSX 62g in 223 for a DPMS AR15

Barnes load data states a COAL of 2.25 and recommends 0.05 off the lands so in theory I'd start with 2.25 - 0.05 = 2.2" COAL

Using a gauge I measure 2.392 base to end of plastic tip which is a mile longer. Just for fun I measured base to junction of copper and plastic tip and found it to be 2.255 ... almost the same as the Barnes load data.

I'm thinking I need to start at 2.392 - 0.05 = 2.342 COAL for starters or maybe even 0.08 off the lands which would be 2.392 - 0.08 = 2.312 COAL

Insights? Are guaged COAL's on various guns going to differ that much or am I missing something?

Since it's magazine fed don't you stick to COAL and not worry about distance off the lands?

I believe that 2.240" is as long as you can go with the ar15 mags, anything longer won't feed into it.

You theory is wrong. You may be limited by magazine length, but you have to measure the col required for the bullet you are using to touch the lands. There are several different methods you can use to do this. Freebore and bullet shape varies and is not a constant.

Did I not do that with the Hornady OAL guage?

Here is the method i use to determine distance to the lands: Link

That site has a lot of good information for developing accurate handloads, and it is worth taking the time to look around.

I'll read it, thanks

You did, somehow I skipped right over that. I am home in bed fighting a virus and evidently I am on some good meds

The number you got is probably right. I would load them as long as I could get them to feed, work up my powder charge and then play with reducing col to,see if it makes a difference, which it probably will, even being that far off the lands.

Well take care and get well soon!

Just set them to 2,25 and load them. You're never going to touch the lands in your AR15 and still be magazine fed.

You can reliably load to 2.258" in most standard AR15 magazine as max length for them is 2.26"

And as stated before your theory is wrong.

Also when measuring to the lands you don't measure to the tip of the bullet...you measure to the ogive using a bullet comparator

Measured mine this morning, 2.237"

Good info, thanks. It doesn't make a lot of sense to chase the lands if it can't fit in a magazine

I already been through everything your doing, so if I can help let me know. I measured the ogives on every bullet I have and some were closer than others, but all were limited to magazine length so I just loaded them all to 2.240" and let it eat.

What mags are y'all using to not get anywhere close to 2.26"? Only being able to squeeze in 2.23" is low...

Some off brand, not even labeled. I'm switching to a Toolman Tactical, getting 2.275" with it. I'm gonna just seat 5-6 rounds with different charges at 2.25" and see where my pressure breakpoint is. After I find it and back off a bit I'll tinker with the seating depth

Thanks All, especially horsey300