no need to buy an oal gauge, here is a home made oal guage.

Theres a lot of people that dont trust the oal gauge, and im one of em, so what do i use? An actual cartridge that i can chamber so I am getting an actual reading from the bolt face... You dont think it works, well i shoot groups at 300yds that look like clovers, consistantly. So how do I do it? I take a case NO PRIMER..DO NOT PUT A PRIMER OR POWDER IN IT.. I seat a bullet til the base of the bullet is past the neck inside the case, then I wiggle the bullet with pliers loosening the case neck tension and pull the bullet free, then if needed i will re insert the bullet by pushing it in with pliers or wood and keep going till desired neck tension. Desired neck tension is when if i push hard with thumb the bullet will slide into case, not loose enough that the bullet will slide under its own weight or light pressure. Well by now that bullet you used is mangled so DO NOT use it for the next step.... Ok, push a nice new un mangled bullet into the case "not very deep" we want the coal to be ridiculously long. coat the bullet with black marker "to see where lands are contacting it" put cartridge into chamber and close the bolt, SLOWLY open the bolt push on cartridge with your finger to minimize bullet chamber contact upon extraction which could skew results, "dont let the cartridge fly out, keep a hold of it" now measure cartridge, write that number down. Ok, wrap a piece of cloth around bullet grab with pliers extract bullet "if you damage, gouge the bullet get a new one". Repeat procedure starting with pushing bullet in and having ridiculously long coal. Do this 3-5 times, add the numbers and divide by number of measurements.. Example, 1) 2.811, 2.810, 2.809, 2.810 add those numbers= 11.24 divide that by 4 "because you took 4 measurements" = 2.810 so thats your number you use. Now if in that series of numbers we had a measurement of 2.815 or 2.804, we know something went wrong, the numbers should all be within .002-.003 if not somethings wrong and most likely you loosened the neck tension to much.. Well, now I know my coal what do I do.. Jump, jam, or touch? Well that depends on the bullet and something called ogive "o-jive" and I will be covering that later and what the pro's prefer for their particular bullet... Stay tuned..