Hornady SST 125gr - Where Do I Start

[rlandry6]

First off, my measurements were taken using the Comparator to find the length with the ogive touching the lands. That measurement is 1.631". With the understanding that projectile length is going to vary, that gives me an overall length of 2.270" which is obviously too long for a magazine. At that length, there is approx .125" of the tail of the bullet in the case neck and the bullet is already to long for the magazine.
Where would you guys start with seating depth with this bullet?
When I loaded for bolt guns, my procedure was to start .025" off the lands and go longer by .005" at a time until I found the depth that particular gun liked. This is a whole new game for me.

I'm also going to ask he same question on the Barnes 110gr TAC-TX but I'll do that in another thread and give the numbers so that this one doesn't get bogged down. I'm going to be using these two bullets primarily, at least until I get this under my belt and get comfortable and H110 since I have quite a bit of it on hand..
The elephant always goes down easier in small pieces.

Edit: If I shorten the seating by .025" that gives me an overall length of approx 2.250" and the bullet ia about 2/3 down inside the case neck.
I guess the source of my anxiety is that I don't know how much of the bullet has to be seated to get good neck tension.

[dellet]

For the Barnes bullet it is easy, just start with Barnes own data for the #30321 Blacktip. It is one of the few bullets designed ground up for the cartridge. The only way to get it in the same zip code as the lands is in a single shot. It will be 2.400" +. Seating at the cannalure it will be around 2.250" depending on where you trim your brass. It will probably shoot well somewhere 18-18.5 grains H110/296.

For the SST it depends on your sense of adventure. They are a pretty forgiving bullet for jump, and you can get close to the lands, You may need to increase neck tension to make up for the less amount of bearing surface in the case. That you will have to play with if you want to run them long. If you polish about .002" off your expander it will be plenty.

I generally seat at 2.255" and trim brass to 1.368" +/-. Again I want as much as I can get holding the bullet.

The battle with loading long in this cartridge is neck tension. The neck is short at about .250" so you will never have more than that. .200" will hold a 150 grain bullet in place when cycling.

One thing you want to check is pull a few after chambering, and that have been in the magazine. Write the OAL on the case, compare them and make sure they have not grown from inertia, or shrunk getting beat around in the mag.

[rlandry6]

I'm trimming my brass to 1.360 +/-. Am I trimming it too short when I may need that little bit extra for neck tension?
I don't mind jumping the lands if it won't have an adverse effect on accuracy. I never thought about it because I never had to do it with bolt guns. I could get as close to the lands as I needed to and never worried about neck tension, but it wasn't with this short a case.

[smustian]

Book says to load the 125 SST at 2.060. I have mine at 2.168.

[dellet]

I'm trimming my brass to 1.360 +/-. Am I trimming it too short when I may need that little bit extra for neck tension?
I don't mind jumping the lands if it won't have an adverse effect on accuracy. I never thought about it because I never had to do it with bolt guns. I could get as close to the lands as I needed to and never worried about neck tension, but it wasn't with this short a case.

Doesn't matter too much, it's one of those things I do different looking for an edge. In the long run it's easier to use bullets that are jump friendly.

My load development for light bullets and 296 makes gds cringe every time I post it figuring someone will blow something up. Just keep the bullet close to the powder and make sure that length doesn't change when it chambers and your golden.

[rlandry6]

Thanks,

All of this makes me feel a lot easier. One more question before I dive in. Am I correct in assuming that your seating depths are going to remain constant for these bullets and when you start tweaking for accuracy you are going to do it by changing the charge?

[smustian]

Thanks,

All of this makes me feel a lot easier. One more question before I dive in. Am I correct in assuming that your seating depths are going to remain constant for these bullets and when you start tweaking for accuracy you are going to do it by changing the charge?

That's how I do mine. Pick a COAL and then ladder test (ex: 17.2, 17.4, 17.6, 17.8, etc) the powder charge looking for the sweet spot. Some use .5 grain increments then fine tune off the best. With limited range time I had rather get it all done in one session.

[rlandry6]

Book says to load the 125 SST at 2.060. I have mine at 2.168.

Is that COL or to the ogive using the comparator? The Hornady manual says 2.100 COL for the SST 125.

[smustian]

Book says to load the 125 SST at 2.060. I have mine at 2.168.

Is that COL or to the ogive using the comparator? The Hornady manual says 2.100 COL for the SST 125.

COAL. My comparator measurement is 1.547.

http://www.hodgdonreloading.com/

[rlandry6]

My comparator measurement is 1.639". There must be a pretty good spread on chamber dimensions from different barrel makers.