Barnes TTSX 223 Seating depth

[pleopard]

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

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?


Thanks,
Paul

 

[horsey300]

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

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?


Thanks,
Paul

I think you don't quite understand being off the lands, if your rifle's chamber allows a coal of 2.367 then the Barnes should be seated no longer than 2.317. You do not just subtract .05" off of your final coal.

 

[pleopard]

I think you don't quite understand being off the lands, if your rifle's chamber allows a coal of 2.367 then the Barnes should be seated no longer than 2.317. You do not just subtract .05" off of your final coal.

Perhaps I don't understand. I'll describe my understanding and you can educate me if I am wrong. That's why I come to this forum anyway, to get educated. I certainly respect experience and aim to absorb as much wisdom from those that have it as I can ...

In the following pic is my OAL guage with 223 adapter. I seated the bullet as far down the chamber as I could, assuming that it was stopped by the rifling (or Lands). I sinched up the thumb screw, pulled it out, and measured 2.392". Now, if I seat the bullet at 2.342" does that not pull the bullet off the lands by 0.05"?

Also, to the original question, if I am measuring a COAL of 2.392" why does Barnes state 2.200"? Is that just a 'ballpark' number thrown out by Barnes?

 

[horsey300]

Perhaps I don't understand. I'll describe my understanding and you can educate me if I am wrong. That's why I come to this forum anyway, to get educated. I certainly respect experience and aim to absorb as much wisdom from those that have it as I can ...

In the following pic is my OAL guage with 223 adapter. I seated the bullet as far down the chamber as I could, assuming that it was stopped by the rifling (or Lands). I sinched up the thumb screw, pulled it out, and measured 2.392". Now, if I seat the bullet at 2.342" does that not pull the bullet off the lands by 0.05"?

Also, to the original question, if I am measuring a COAL of 2.392" why does Barnes state 2.200"? Is that just a 'ballpark' number thrown out by Barnes?

See that is the confusion I think my friend, Barnes is not stating 2.2" they state 2.25" OR .05 off the lands to stop people who like to "kiss the lands" from causing any pressure problems and/or accuracy issues, all monometals I've ever heard of/dealt with like a bit of a "jump". So, you can seat at 2.25" (which I do with no troubles) or you can seat .05" off the lands. If you choose the latter, you may need a bit more powder to fill the case to get proper accuracy as seating depth affects pressures. Seating at 2.34" would be .05 off the lands of YOUR rifle based the information given. Barnes gives us 2.25" as a starting point for those who do not chase the lands ETA this should be at LEAST .05 off the lands of every production rifle and should remind us the lawyers impact everyone differently, nosler gives a longer coal on their coppers but admonish never starting above the middle range load during a work up do to the difference between coppers and more conventionally constructed bullets. But we do not shorten it to 2.2. One other recommendation, check the length to the lands about 10x do not formulate your coal off of just one measurement. After checking it and rererererererererechecking it, you'll have a good data sample to be sure and safe.

 

[pleopard]

Now that makes a while lotta sense, thanks for taking the time to write it all up. Yes I checked that measurement at least 10x over the period of several days so I am confident of it. I'll start it at 2.392 - 0.08 = 2.312 COAL and see what kind of groups I'm getting. If they are good then I'll work my powder load up from there. Thanks again bud

 

[horsey300]

Now that makes a while lotta sense, thanks for taking the time to write it all up. Yes I checked that measurement at least 10x over the period of several days so I am confident of it. I'll start it at 2.392 - 0.08 = 2.312 COAL and see what kind of groups I'm getting. If they are good then I'll work my powder load up from there. Thanks again bud

I don't know exactly what you define as a good group, but don't change your seating depth till AFTER you've worked up a load UNLESS you are having feeding problems/other malfunctions etc..... depending on your powder, you may not get what I consider a good group until you're within .5 gr of Max (ish) my current .223 load uses a mid range charge of h322 both of my favorite .243 loads are maxed, and honestly, until I got to the last two steps of the ladder, my .243 target with h1000 looked like I was patterning my open choke 18.5"barrel at 35 yds! Work on one variable at a time pardner, if you swap between changing depth and charges without a full work up, you'll chase your tail with luck keeping you from blowing up your gun and luck showing you a good group eventually. And you're very welcome, I reckon we all have questions, when I have em and am lucky enough to get good answers I too appreciate it but that's what we're all here for I think.

 

[pleopard]

I'm not a competition shooter, just a deer hunter that likes to tinker. So, a good group to me would be 0.5" to 1.0" at 100 yards

All good info, I'll start with tweaking my powder charge and find my max load and go from there

Thanks again!