Seating Depth

[Rumpus]

Anyone offer advice as to the best way to work out seating depth in a .223 and a .22-250..

[Dr G]

most people I have spoken to recommend 0.020" off the lands. What I try and do is work out the powder charge that gives me the least amount of vertical spread at 200m the adjust my seating depth in and out from this point to tune it for accuracy.

Up till now I have been struggling with consistency due to not having a good rest or a trully tackdriving rifle but that has changed (is changing) so I will see even more effort here tweaking seating depth.

for the actual methods I use a sinclair seating depth tool to measure the distance to the lands and a Redding competition seater to make precise and repeatable changes to seating depth.

cheers mate

Dr G

[andy303]

i heard of this way of finding the start of the lands in a rifle from an american forum, start with a reload that has been neck sized only no primer or powder seat a bullet the same as a factory round coat the projectile with either texta or spray it black ,let dry load bullet into action then remove, on inspection you will see the marks from where the projectile has engaged the lands ok so now you seat the projectile a fraction lower and recoat the projectile with the texta or paint(what i did because i didnt want paint residue inside the die was i took off the texta or paint after it had been thru the rifles action)and repeat the process until you can just see the land marks on the projectile,and from there i seat the projectile a fraction more so there is no contact with the lands .It is alot of rooting around but it does the job and as a matter of reference i keep the bullet to one side marked with pattern on the side so in future i have a reference on bullet seating for this particular pill .I do this with every different weight projectile i use,one other thing i do is i scratch a line on the projectile where it meets the case mouth just in case you drop the bullet on the ground and it lands on the tip i hope this has helped regards andy

[Yowie]

Hi Guys,

Seating depth is one the post important measurements for accuracy, look at the
articles in Guns & Game magazine compring factory to reloads, factory is one size
fits all.

This is my way, not original, not the most accurate but very close.

You need, 1) cleaning rod(jag removed), 2) 2 x cleaning rod stops, 3) digial calipers.

Step 1) slide a cleaning rod stop up the cleaning rod.
2) with the cocked bolt in the rifle, from the muzzle drop rod down barrel
3) tighten stop snug against barrel
4) remove rod
5) remove bolt
6) drop selected projectile into chamber
7) tap the projectile with rod so it is snug in throat and wont fall out
slip a another cleaning rod stop onto the cleaning rod
9) cleaning rod into the barrel via the muzzle
10) tighten the cleaning rod stop

Measure with clipers 1) the distance between the two rod stops 2) measure the thickness
of the stop closed to the end of the rod. Add 1 & 2. This the OAL (over all length)

Say OAL is 85mm, to seat 0.05"/1.27mm = 83.73mm

To get the best OAL repeat steps 1-10 x 3 and ave.

Adjusting the seater die.

In the press, set the die so the shell holder kisses the die on the up stock, with a collect
type seater the bottom of the die is pushed up 3/4mm.

By trial and error seat the projectile to OAL 85mm.
11) measure the distance from the bottom to the top of the seater die, this is
DOL (die over all length)

With a competition seater die you can set the seating to required depth very accurately.
If you dont have the above die, adust the top spindle down 1/2 a turn, seat the projectile,
measure OAL, keep adjusting until say 83.73mm, tighten locking nut.

To check everthing is OK,a) check the loaded cartridge will fit in the magazine, b) chamber
without the projectile engaging rifling.

Variables can be, projectile lengths vary slightly, you don't measure accurately, caliper accuracy(cheap Chinese) etc.

Using this method I can reload to 0.8moa accurracy.

Benifits are cheap, easliy done, repeatable, once the measurements are done setting up
the dies for next reloading session is easy.

Cheers,