Question about OAL?

[BigK75]

Hey guys:

I should have asked all of my questions in one thread, but as I keep getting further I run into new issues

The tikka T3 tactical 223 is being loaded with Varget Powder/ 55grain Hornady SP. I made some dummy rounds larger then I knew the action could handle. Then I closed bolt and forced the bullet to go in so that I could the maximum size of the bullet. I was going to subtract .010 from that and that would be my over length. To my suprise one came out as 2.260 and the other one came as 2.280. That a pretty big difference is it not? How do I about making the proper sized bullet the Lyman manual states the OAL length should be 2.260. Should I just go with that and then make adjustments as needed?

Thanks for all the help for a newbie, its much appreciated.

Claude

 

[sunray]

Trial and error by adjusting the seating plug. You can try taking out the plug and running a factory round into the die then putting the plug back in until it stops though.

 

[iceman2]

Your longer one might have stuck a bit in the chamber and pulled the bullet out a bit before releasing.

 

[maynard]

I don't think a loaded 55 grain bullet is long enough to touch the rifling in a Tikka T3.

 

[1shot]

I have an older Tikka M55 in .223 and use Hornady 50gr flat base bullets with outstanding results seating very close to the rifling. Quite simply, I blacken the bullet of a dummy round with magic marker, and chamber the round again and again while seating further and further outwards until I see rifling marks- then back off a touch! I'm sure there is a preferred/expensive/fancy method to doing this, but try the magic marker trick...

 

[cosmic]

There's an easier way to establish OAL. Buy a wooden dowel that fits in the bore. Drop a bullet into the chamber, tamp it with the dowel lightly to ensure its seated in the lands. Push the dowel into the muzzle until it touches the tip of the bullet. Scribe a line on the dowel with a pencil at the barrel crown. Repeat with bullet removed, bolt closed and cocked. Measure the difference with vernier calipers. That is your OAL to the lands...
If your a newbie, I'd be careful in going down to 10 thou clearance. There exists geometry variations from bullet to bullet, and box to box, from the same manufacturer! Suggest you go out to 30 - 40 thou to start.