Tikka 1:8 243 - 108 eldm seating depth

[satchamo]

This is a ridiculously specific question so not sure anyone will have the answers I seek but here goes…

I’ve been trying to find the lands using a Hornady OAL tool and a modified case and it seems like I’m getting all sorts of varying measurements. I’m struggling to get a feel where to stop.

I’ve gotten anywhere from 2.17 to 2.26. I covered the bullet in sharpie and I’m not seeing land marks but yet I managed to jam a bullet in there and had to use a cleaning rod to get it out.

Does anyone with the same rifle/bullet have their cartridge base to ogive measurement with the same setup? I know there will be variance from gun to gun but just trying to get a sense of whether I’m close on one end or the other…

Any other tips or tricks are appreciated!

 

[swavescatter]

Try to use the same light pressure each time to get the bullet to *just* contact. Let go of the plastic push rod before tightening. I've seen where people get measurements all over the place by tightening the screw with pressure on the rod.

If all that fails, you can try the loctite trick.

 

[dirtytough]

I pull my bolt apart and remove the ejector and firing pin. After they are gone the bolt will close on it's own when the bullet isn't touching the lands.

With Mitutoyo calipers and Hornady comparator.

108 ELD 2.276"
103 ELD 2.278"
105 HPBT 2.262"
112 MB 2.270"
109 LRHT 2.272"

 

[Harvey_NW]

I didn't really care for the Hornady gauge and buying all the extra modified cases. For just finding the lands and tracking throat erosion I've found this to be pretty handy and mostly repeatable, +/- a few thou. I just hand seat a bullet in the neck of a sized case as straight as possible, and push it in the chamber with my finger, then push it back back and forth with the cleaning rod a couple times to make sure it feels like it's straight in the throat and the "touch" is consistent before setting the second stop.

 

[Chris in TN]

Take a fired case and dent the mouth just enough to hold a projectile.

The problem with this method, is that if you dent it a lot, it'll hold a bullet, so tightly that when you hit the lands, it'll jam slightly as it pushes into the case. You want to dent it only enough that the bullet will stay under its own weight, so that the slightest touch of the lands pushes it. Doing this without overdoing it can be tricky.

 

[NWBLKTAIL]

I use the Hornady setup, I don’t push the bullet into the lands this is where everything got really inconsistent for me.

I push the bullet out to where it’s barely in the modified case and then push the case in until I feel the shoulder contact. Tighten the screw down and measure. Even with my basic bitch tools I’m within +\- a few thousands through all my measurements, usual for me 5 or more.

Edit: My 243 is a M70 with an aftermarket barrel but from what I’ve read my chamber seems pretty close to what everyone else has for their tikkas max COAL 2.850-52 are my longest measurements with a 108eldm.

 

[Harvey_NW]

Take a fired case and dent the mouth just enough to hold a projectile.

The problem with this method, is that if you dent it a lot, it'll hold a bullet, so tightly that when you hit the lands, it'll jam slightly as it pushes into the case. You want to dent it only enough that the bullet will stay under its own weight, so that the slightest touch of the lands pushes it. Doing this without overdoing it can be tricky.

The lands can grab and pull the bullet back out on extraction too, but if you color the bearing surface under the dented portion with sharpie you can usually see where it stopped from scratches on the jacket, and get it back to real close.

 

[Castle Rock]

Run a cleaning rod down the barrel til it hits t face of the closed bolt and mark it with a blade against the muzzle.
Drop a bullet into the chamber and lightly hold it there with a pencil or dowel ( helps to have someone else to do this)

Repeat the measure with the rod ( it must have a flat face and if it’s a shiny rod run a stripe of black marker on it).

Difference in the measurements is the oal of a round loaded to touch

 

[Shortschaf]

I pull my bolt apart and remove the ejector and firing pin. After they are gone the bolt will close on it's own when the bullet isn't touching the lands.

With Mitutoyo calipers and Hornady comparator.

108 ELD 2.276"
103 ELD 2.278"
105 HPBT 2.262"
112 MB 2.270"
109 LRHT 2.272"

+1 to this method.
I don't think there is a more repeatable method

 

[Ryan-9_111]

Take a fired case and dent the mouth just enough to hold a projectile.

The problem with this method, is that if you dent it a lot, it'll hold a bullet, so tightly that when you hit the lands, it'll jam slightly as it pushes into the case. You want to dent it only enough that the bullet will stay under its own weight, so that the slightest touch of the lands pushes it. Doing this without overdoing it can be tricky.

I do something similiar but I take a fired piece of brass and lightly coat the inside of the neck with red loctite, put the bullet in the case loaded long and lightly close the bolt. Leave it there till the next day and extract it and you have a dummy round where it's just touching to measure from.

Sent from my Pixel 10 Pro using Tapatalk

 

[mtnbound]

I don't do any of that. I set the COAL to just under the max allowed length of my mag and call it good. I have chased seating depth, but I am not a good enough shooter to say it helped.