Hornady manual confusion

[saskboy]

So im a little confused by my hornady reloading manual. I bought a bunch of 150 gr bt fmj's for loading in my 300wsm and 308. The book says c.o.l. for the 300wsm is 2.800'' for the fmj's, but all other 150 gr bullets are listed at 2.840'' (what i normally put them at). Now when I look up the c.o.l. for the 308 its 2.780'' for the fmj's. All other 150 gr bullets are 2.735''. Now why in the hell would they make the c.o.l. different lenghts when comparing the same bullets? The fmj's c.o.l. are longer in the 308 and shorter in the 300 when comparing the same bullet! I dont get it, should I just measure from the ogive and do what I know works and forget about the manual numbers. Sorry for boaring everybody here

 

[ilike223s]

thats only a guied,its not in stone,and most of FMJ seem to always be longer on the OAL.I always,measure free bore on every bullet im loading anyhow
I have a tikka in 223,all the book say my OAL for all bullets should be this or that,well I loaded to the books OAL.I couldnt get a good group , so i moved the OAL longer,so as not to have a lot of free bore,I shoot 1/4 goups now.
Some oh horndys,bullets loaded to some longer,col.run up in to the lands,so they shorten them too...
what Book are you using,what Number.? i have a few hornady books.

 

[steve4102]

The COL listed in manuals is nothing more than a guide. It is only there to tell you what COL they used. It is not mandatory that you use their listed COl, hell, Nosler doesn't even list a COL in their loading manual.

Here is what Accurate Powders says about COL.

SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must
be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of
the barrel, 3) ogive or profile of the projectile and 4) position of cannelure or crimp groove.

 

[saskboy]

Im using the 7th edition, ya you guys are right I guess its only a guide. Just if you were to crimp these bullets they would really be far in and suffer in accuracy. How do most people measure ogive diffences in bullets, is there a gauge you can buy or just disasseble your seating die and measure differences with that