Its been awhile since I have worked up a new load in my .17. I've been shooting 20gr Hornady V-Max for a while and have decided to try 25gr Bergers. When I checked the OAL with the berger its .046 longer than the modified case and bullet combined. The rod on the OAL gauge sticks out .046 past the end of the Mod. case when the bullet reaches the lands.
I have recently fired lapped the barrel, did this bore out the throat?

Any help is greatly appriciated!

Welcome to the forum bigK. Rules are simple, be nice and join in. I would recommend that you check out our FAQ section and read some of the stickies at the top of the general forum to get an idea about what were about.

Most times if your working with a magazine fed rifle the magazine length will dictate the OAL. Many times you just can't get enough length to still have the bullet stable in the case if you load out to the lands on factory cut chambers.

I guess I'd just shoot it and see what kind of accuracy you get. I know that I'm pretty far from the lands on my Ruger 204 and am getting excellent accuracy. I couldn't tell you about the fire lapping, so far I've only done that to revolvers.

Thanks, faucettb!

When I originally loaded the 20gr V-max,I loaded them .020 from the lands,soI am almost positive that something drastic has changed inside the chamber.

Welcome again. Assuming you kept good records of where the lands were using that tool, measure again with the original bullet to see if anything changed. If the lands were worn or displaced by firelapping, a new measurement should tell you. But using a different bullet, it won't.

I have since learned to keep better records.

Ahh. Too bad. Well, when knowing the "offlands" distance becomes difficult or impossible, just do what I do: ignore it.

Instead, simply find a seating depth that gives you best accuracy with a given bullet, and then be sure to seat that bullet to that depth every time. I measure from cartridge base to a point on the bullet that is bore (not groove) diameter, and seat to that length. Using such a datum line instead of full overall length takes out any errors due to variation in nose shape.

As long as I know what seating depth gives me best accuracy, I don't need to know where the lands are. My most accurate load will be the most accurate whether the lands are a hair or a cubit away.

As Bill Cosby says "What's a Cubit?" :p