seating depth ?

[rebs]

I am reloading for my Tikka T3x in 223 cal. I found a very good load seated at 1.868 and want to try seating on both side of this depth to see where the optimal seating depth is. How far on each side of the 1.868 would you seat at looking for the best seating depth?

 

[CNC-Dude]

Nodes can be wider than others, I would only change the seating depth in .003" increments, longer or shorter.

 

[Jeff Porter]

What type of shooting are you doing with the Tikka? What bullet? Have you tried any other BTO depths with this bullet or did you just get a real good group the first time out doing a powder charge work up?
How much experince do you have with that bullet?

 

[rebs]

What type of shooting are you doing with the Tikka? What bullet? Have you tried any other BTO depths with this bullet or did you just get a real good group the first time out doing a powder charge work up?
How much experince do you have with that bullet?

I am shooting 300 yd benchrest. I worked up this powder charge by loading 23.6, 23.8, 24.0 and 24.2 of reloader 15 as advised by another member here. Now I want to try to improve group size with seating depth. It might not get any better since I am getting 1 1/4" groups now at 300 yds. The bullet is 80 gr SMK. The seating depth to touch the lands is 1.955 and this load is seated at 1.856. this is about 90.000 off the lands and seems like a long jump

 

[JFrank]

You can tinker with the seating depths as well as testing different neck bushing’s, I also would sort those bullets.

 

[Metal God]

Rebs , how you doing ?

I usually don’t recommend ever seating closer to the lands because getting to close or jammed with a max load can really raise start pressures . However you are way off the lands so Id say you can seat closer but I’d start being careful when you get within .030 to .020 off the lands .

How much is always a tough question IMO . I don’t disagree with the .003 when fine tuning and is likely all you need to adjust at a time . However you have a lot of available adjustments to work with and only moving .003 increments would take a ridiculous amount of components and barrel life through 100 thousandths of adjustments.

Since you are already at sub half moa at 300yds . If you can get it better you like will not need to adjust the depth much at this time .

 

[BoydAllen]

A couple of things: Anytime I start out with a new powder or rifle I do my own pressure test, one shot per charge, in increments suitable to the case size. I do this with the bullet seated into the rifling but short of jam. (The definition of jam that I use is the length that a bullet will be pushed back to from a long seated dummy round being chambered.) The reason that I do not use jam is that I do not want to stick a bullet in the rifling if I need to unload. The reason that I seat into the rifling for this test is because my maximum load will be a worst case situation. Anything shorter should have less pressure, until you get to the point where you have reduced the case capacity significantly with the bullet. I stop shooting when I see pressure signs that are a little more than I want, I designate the previous load as my maximum with that bullet, primer, and case, at that ambient temperature and humidity.

On seating depth, if you look on the Berger site, up at the top of the page there is an article on finding a seating depth for a VLD. I asked one of their technicians and he assured me that the method works for other bullets as well. I suggest that you look it up and read it.

Third thing: All of this is greatly facilitated by loading at the range.

Last: Do you have anything between you and the target to tell you what the wind is doing?

 

[lawman29]

Might consider a macro test: 5 off, 20 off, 35 off, 50 off, 65 off, 80 off and 95 off. See if anything "speaks" you. Do it at a 100 yards.

 

[dgeesaman]

No wrong answers here. If the initial load had some promise, I’d go .003 increments at whatever quantity makes sense to you. Me, I usually load 25 and test 3x8 lengths or 4x6 lengths.

If the initial load is unimpressive, I don’t panic but I next try the extended seating range test with .020 increments or so.

 

[Jeff Porter]

I am shooting 300 yd benchrest. I worked up this powder charge by loading 23.6, 23.8, 24.0 and 24.2 of reloader 15 as advised by another member here. Now I want to try to improve group size with seating depth. It might not get any better since I am getting 1 1/4" groups now at 300 yds. The bullet is 80 gr SMK. The seating depth to touch the lands is 1.955 and this load is seated at 1.856. this is about 90.000 off the lands and seems like a long jump

I have had bullets shoot well with long jumps before so not a big concern for me. 24.0 is of RE-15 is a known 'golden load" for SMK 80's. If you just want to make sure you are in the right ballpark I would run the macro test Lawman suggests. There is a couple of plans for jump testing a bullet on the Berger website.

Once you confirm that the 0.090" is the best or find a tighter area, then tweak in each direction from that length by 0.003" increments to 0.005" that and see if it gets better or worse. I do this by loading all the rounds up with my chosen powder charge to the longest length and push them back at the range with my press clamped right at the shooting bench. usually n less than 30 rounds I know where I want to be and have proven it with a 5 shot group. Best of luck. sounds like you have a pretty good place to start from.

 

[TTE]

I usually load 25 and test 3x8 lengths or 4x6 lengths.

What does this mean ?

 

[dgeesaman]

What does this mean ?

8 groups of 3 or 6 groups of 4 in each length.

I usually come back after that and take the best two seating depths and do a very fine ladder around them (+.002, 0, -.002) using 4 or 5 shot groups to improve statistical certainty.

 

[Webster]

I am reloading for my Tikka T3x in 223 cal. I found a very good load seated at 1.868 and want to try seating on both side of this depth to see where the optimal seating depth is. How far on each side of the 1.868 would you seat at looking for the best seating depth?

Any changes in accuracy at 300 yards may be too small to detect. The wind and your bench techniques may be big enough to mask it. Good luck give it a try.

 

[Metal God]

I’ve been think a load that is likely in the 3’s at 100yds should not need .040 adjustments, .003 to .005 should be just fine to see if it can get better . That said , that isn’t to say Rebs will not find a better grouping seating depth way different then he’s at right now . He could do the Berger method and jump around in .040 adjustments and see if there’s another seating depth that gives similar or slightly better results then what he has now . At that point he could start the .003 to .005 increment fine tuning on the completely new seating depth ,

IDK , if rebs gun is shooting a consistent 1.25” groups at 300yds , I’d be pretty dang happy with that and wouldn’t go completely change the seating depth by .040+ . I could be wrong but I thought the Berger method was to find a node in a rifle that’s not already sub half moa ???

He could always try better brass ;-) lol

 

[rebs]

A couple of things: Anytime I start out with a new powder or rifle I do my own pressure test, one shot per charge, in increments suitable to the case size. I do this with the bullet seated into the rifling but short of jam. (The definition of jam that I use is the length that a bullet will be pushed back to from a long seated dummy round being chambered.) The reason that I do not use jam is that I do not want to stick a bullet in the rifling if I need to unload. The reason that I seat into the rifling for this test is because my maximum load will be a worst case situation. Anything shorter should have less pressure, until you get to the point where you have reduced the case capacity significantly with the bullet. I stop shooting when I see pressure signs that are a little more than I want, I designate the previous load as my maximum with that bullet, primer, and case, at that ambient temperature and humidity.

On seating depth, if you look on the Berger site, up at the top of the page there is an article on finding a seating depth for a VLD. I asked one of their technicians and he assured me that the method works for other bullets as well. I suggest that you look it up and read it.

Third thing: All of this is greatly facilitated by loading at the range.

Last: Do you have anything between you and the target to tell you what the wind is doing?

I use wind flags