Jam Length and LOA

[CharlieNC]

I'm in final stages of putting togeter a 338-06, and am working on loading specs. For best accuracy I have measured the jam length, where bullet contacts the lands, and it is 3.51". Recommended LOA for reloading the 225gr Hornady is in the 3.25-3.30" range. By moving just off the lands and working back, there appears to be a major difference between what I will end up with vs the manual recommendations. These are long bullets so there will still be plenty of length in the case, and the jam length feeds fine from the magazine. Any experience or advise regarding this difference?

[GaCop]

The manuals are giving you an overall length to the bullet tip. Ignore that data if your measuring on the ogive with a Hornady OAL gauge.

[groupshooter22]

If it feeds where it shoots the best then you are one of the lucky ones. The manuals are as stated above.

[CharlieNC]

I measured the jam length by running an over-length dummy round, with the bullet I will use, into the chamber a number of times to obtain a consistent loa measurement. This is the length I will back off from.

Just took the rifle apart from bedding with JB Weld, and the good news is it did come apart easily!

[Slowpoke Slim]

Charlie,

The OAL in the manuals is basically just what they seated their bullet to, in their test rifle (or pressure barrel-depending) and used that listed recipe to develop that given pressure and accuracy in their gun. With the differences in chamber reamers, throat reamers, and individual rifle and barrel manufacturers, there are almost no 2 barrels that are the same (unless the same smith cuts duplicate barrels with the same reamer on the same tooling setup).

As an example, I have loaded for 2 different Win mod 70 30-06's that were made in different decades, they do not have the same OAL's, nor do they shoot the same load as each other. My brother's Savage 30-06 won't shoot either of those Win loads at all (it won't chamber them without crush seating the bullets), and has a MUCH shorter throat than either of the Win's (it's a full TENTH of an inch shorter throat-and no that's not a typo, it's a tenth of an inch shorter). With it's own handloads, that Savage will run with the best of them though.

Each rifle is an individual, and should be treated as such. Treat the "book" OAL as a guideline only and proceed with what works in your rifle. That's one of the biggest reasons to "work up" from starting or "mid-scale" loads from any manual when working with a new rifle and load. If your OAL's are shorter than the "book", then expect your pressures to come on a little sooner, but knowing that in advance, it shouldn't come as a surprise (surprises are BAD when handloading).

;D