Seating Depth ???

For my birthday I got a hornady Oal gauge and bullet comparator.

Im loading 100 grain Hornady btsp for a 243 win. I measured where the bullet contacts the lands, I used 5 different bullets and took a measurement and these were my results..

3.255"
3.253"
3.254"
3.255"
3.254"

with an average of 3.2542"

So what is a typical jump/distance from the lands that works well for this style/type of bullet? I have always don't it by feel in the past, start at magazine length and shorten till it will close. The comparator and OAL gauge are new for me and not really sure what jump should be.

Thanks.

For hunting I would start at .010 or .015 off the lands and see how it shoots and go from there if that fits the magazine.

I have a different hunting load worked up so these will be primarily for paper punching, got them for free so just playing at this point. I already have a good hunting load, but it may get tinkered with as well.

Would your recommendation be any different being a target load? or still .010-.015

Thanks.

I'd start at about a tenth of a caliber, or 0.024" in this case, but I wouldn't be surprised to end up at 0.015 or even 0.050---or anywhere at all, really.

Start at .010 jammed and work back in .003 increments...something will tighten up you will like or you need to switch bullets. I used to do .005 but I changed to .003 when I missed a good window.

Good luck and be careful...shooting small is an addiction!

0.010 jammed would be setting the bullet at 3.264 for my measurements, correct?

I loaded the Hornady Interlock and they liked to be touching the lands which was 2.71 for me. Now I am shooting Bergers and they shoot best for me at .05 off the lands. Just one of those things you have to see where the bullet likes to be seated.

I like to load some dummy rounds and check what length the bullet is jammed into the lands, you can tell because it sticks when you try to extract. I then seat the bullet a little deeper and try again. When the bullet has slight rifling scratches and extracts easily. Usually that is about .005-.015 off being jammed into the lands. I use that length for powder weight testing. Once I find powder weight I play with seating depth if I need to but sometimes I don't have to.

What rifle are you shooting? To me, 3.25 sounds kind of long for OAL but what do I know, some guns have longer throats.

That's not the OAL of the round, its the length using the bullet comparator. I would have to subtract out the length of the comparator to figure the exact length to the Ogive(not oal) I figured it was a needless step because im going to be using the same comparator to check the measurements on my loads as I set up the seating die. Or is there something wrong with that?

If it makes any difference its a savage.

Yes.

Here is what I would do...I'd load 30-40 shells up at that length...take them to the range with your press and seater. Shoot 2, if they aren't touching (or real close) move on...don't waste the 3rd shell just for the sake of shooting the 3rd one. When you find a seating depth that touches, shoot the 3rd for validation...keep going until you are out of shells or you've hit the jump to over .030. If the gun will shoot that bullet you don't need to go past that in my experience.

My tuning experience tells me most of the time you will hit something between .010 jammed and .025 off. I really prefer not to shoot jammed but will if they will shoot best there. Right now I've got 2 guns tuned really good...one is just touching and the other is .012 off.

The Hornady BTSP bullet is a tangent ogive bullet. So, it's not seating depth sensitive. So, if you tune the load using the powder charge only, you will find a good load. I would seat it about .010"-.030" off the lands, and tune it with your powder charge. If you were shooting a VLD type or secant ogive bullet, I'd say seat it touching the lands for best results. But this 100 grain BTSP 243" bullet out of a hunting rifle won't care on the seating depth, once you tune it with the powder. The issue you have with playing with the seating depth is you can change up the load that it likes with a certain powder charge.

Havent loaded any of these yet so I don't have a charge it likes. I will probably be using IMR 4350, its what I have a good amount off. Found a nice cheap 1-300 yard range close to home. My plan so far is to set .010 off the lands load in .3 grain icrements and shoot at 200/300 yards.

Thanks for the help fellas.

I like that idea of taking the press to the range, Judd. I've often considered taking the equipment to load prepped brass but never done it because of the hassle factor. Tweaking seating depth only seems like it would be minimal extra effort. I may well do this one of these days.

Everything I load for I start even with the lands as long as it will still fit in the mag. Test various powder charge, then play with the jump to rifling. Only one rifle (not mine) showed an improvement playing with jump to the lands. That was a friend's 6.5 Creedmoor with a 140 Berger VLD. All of my rifles have shot tiny even with the lands with THE right powder charge, so I never had the need to play with the jump.

But as Judd mentioned, the 7 Rem Mag with 180 Bergers is jammed .001", and that is a hunting rifle as well as a target rifle.

do you use recommended powders to try or do you have your favorites?

RC - I didn't realize you didn't have a powder charge yet...I'd shoot a ladder to get your powder charge node then work on seating depth. If you know where that node is powder charge wise you can start with seating and then tune powder charge but without knowing I'd do it the opposite way and a ladder will tell you where your nodes are. Shoot one at 300...you'll be able to see the nodes at that distance (that is the closest I'd ever shoot a ladder test though).



I do it often...I've even switched to Wilson chamber seating dies and rarely do I go to the range or match and not have my arbor press and seating die. The arbor press and Wilson seating dies are the ultimate in seating at the range and consistant OAL's. You can't FL size with an arbor but you can seat. I've learned a lot with my arbor press regarding the importance of neck tension.

First priority for me with powder is it must be a temperature stable powder because I shoot all year long, and want stupid consistency no matter what. For any cartridge I research what most everyone uses as far as powder goes. .308 Varget, 22-250 Varget, 7mm-08 Varget, 243 H-4350, 6.5 Creedmoor H-4350.

When it came time to get powder for the 7 Rem Mag I was stuck between H-Retumbo, and H-1000 so I called Chad. Told him I was torn between the two, he asked what bullet I was going to run, I told him, he told me H-Retumbo. I took his word for it dove into 16 pounds of it for that rifle.

Same thing with a friend's 300 Win Mag I am going to help with. I was pretty sure I needed H-1000. I called Chad and he confirmed it. He sure is handy!