I have a Voere in .300 Win Mag that I load for, and a friend who also loads for the same caliber uses this method to determine the overall length. He takes a sized case, places a bullet very lightly in the mouth and gently chambers it, allowing the lands to push it into the case until the bolt closes. He then removes the case, measures OAL, and seats the bullet another .005. This gives him the OAL he then uses for that particular rifle.
I have been using 3.34 oal from the book, but tried his method. I came up with 3.54 and shells were so long they wouldn't feed out of magizine! My question: Is my throat eroded? Or might this be freebore that was intentionally done? This rifle is a Voere 98K conversion built in 1969, and it shoots very well with the 3.34 seating.

Opinions? Please.

Bubba
You could have some erosion but manufactures seat bullets to certain parameters.My 300 hasn't been a repeater for quite sometime.I had just recently purchased a 260 Rem. brand new in box and started loading and did what you do and i can't ge them into the mag either.This doesn't bother me because i prefer to get the most accuracy out of my rifle.To tell if you are having erosion problems (Which in time you will) shoot some more rounds(quite a few) at whatever seating depth and then after a while recheck the seating depth.You will probably find it is eroding

Matt

If it shoots very well with 3.34 OAL they use that length. If you test the 3.54 and the extra length version is very, very much more accurate, keep that data at hand and save a box loaded with Match Kings for sand bagging your friends at the range--

The other option is to find a bullet with a shape that will that will fit to the lands at 3.34. My guess is that you can make this happen by choosing a more bluntly shaped bullet. I had a .30/06 that had enough throat erosion that only a long seated Hornady 180 Grain Round Nose would shoot inside two inches. This was not a problem as our shots were allways inside of 300 yards and the bullet performed well.

Pulling out one of my .300 Win. Mag. handloads I find an overall length of 3.587" with a 220 gr. HPBT. Normally I don't measure them that way because I use a comparator. The rifle probably has just about 100 slow fired rounds through it, so I wouldn't expect much in the way of throat erosion. The C.O.A.L. was originally set with a Stoney Point OAL gauge and their modified case to be just off the rifling.

If I haven't got a modified case, I use the old-fashioned method: color tbe bullet with felt tip marker, and chamber and inspect and seat deeper and recolor until there are no scratches through the felt tip color. Change bullets during this process if the one you are using gets too scratched up.

I don't like measuring to the end of a bullet if I can avoid it because that measurement varies more on bullets than the distance from the base of the cartridge to the full-diameter portion of the bullet. You can imagine that if you set your COAL with your shortest bullet, that then all of your loads could be into the lands and produce high pressure. Perhaps I am paranoid, but I would prefer the felt-tip marker method described above over stuff-and-seat-deeper-and measure. I just gotta know I'm off the lands and that I have a consistent measurement.

For similar reasons I don't like seating bullets very lightly and getting COAL off chambered and extracted dummmy rounds. What if the bullet sticks in the rifling a smidgen, and drags out a little bit? Again, all of your cartridges will be overlength and probably overpressure.

Good dies set bullet seat depth where the bullet will contact the rifling. You want your dies and your rifle and your measuring method (comparator) to all consistently measure the cartridge the same way.

I believe that these are the flimsiest of criticisms, but I take what is at stake very seriously: you don't get to shoot any more without your eyes. Dial calipers you must already have, and you have to measure at least to the nearest thousandth. An OAL gauge and a comparator are luxuries, but a felt tip pen is insurance that is so cheap that there can be no excuse. You should understand that seating close to the rifling is a slightly risky activity that the manufacturer originally made the chamber overlength (compared with the magazine) to prevent, and that if you do this, you must take the appropriate measures to stay safe.

Bubba,

I have a Win. Mdl 70 in .300 Win. Mag. . Right out of the box I used the same process you described to determine seating depth. When I seated the bullet to that length they were a long ways from fitting into the magazine.

I found that the Nosler Partition Protected Point works very well in my rifle. This bullet was designed for the 300. The point is somewhat blunt with that extra material in the profile of the bullet. This in effect puts the bullet closer to the lands while letting it clear the magazine. Even with this bullet I still can�t seat .005� of the lands.

Is your barrel eroded?? My feeling is no, most who own .300�s don�t shoot them enough to do that. I think you are seeing a typical factory chamber.

Kind regards, shoot safe.
cjw3

Thanks to all for the very good info. I am a hunter and average shooter, not into super accurate shooting where freebore, ect. enters in.And I hadn't even considered the pressure factor in seating the bullet just off the lands. The factory AOL is working for me, and as the old saying goes"If it ain't broke, don't fix it".