If I have to believe the books (and I do, just for my own sake ), The 300gr Sierra butllets seats to 3.602 inches COL (lapua data).

If I seat this bullet this deep, it is more than 50% IN the case!

The 250gr scenars (who have a different convex curve, I know), are seated at a COL of 3.682, and this for a smaller bullet.

I loaded 5 shots with the Sierras and plan to burn them next saturday at the 600m range, but I'm still worried about the HUGE difference in the Sierra data (Speer guide says 3.680 COL for the 300gr HPBT), and the official Lapua data (which is 3.602 COL).

Can a bullet this deep in the case be propelled out of the case correctly?

The seating depth won't be an issue, and that can be adjusted to longer COAL if your chamber throat and accuracy allow, infact it may well shoot better if you can seat it out longer.

Bigger issue would be is your barrel twist fast enough to handle that longer bullet?

A 10 twist will stabalize the 300 grain SMK..... I set mine up for a COL of 3.9" and a magazine to allow this length.... The 3.6 inch loaded lenght is inorder to work through any and all magazines.....

quote:

Originally posted by jwp475:
A 10 twist will stabalize the 300 grain SMK..... I set mine up for a COL of 3.9" and a magazine to allow this length.... The 3.6 inch loaded lenght is inorder to work through any and all magazines.....

That is good to know. I have stockpiled some of those 300-grain SMK's but have not had a chance to load and shoot them yet. My barrels are 10" twist.