Quick Question reg. C.O.L.

[snipes]

i have been reloading for yrs, i always go by the book-horn./speer or online, however i was talking w/ a buddy and he mentioned something that kinda threw me but it makes sense, i reload say 308 w/ 110g vmax, the book says col should be 2.74, he told me her was told to seat the bullet and load it-w/o powder, and chamber and close to get the max space, this way the bullet would seat to the correct length, that done, i came up w/ 2.77, is that .03 realy make that much difference? wouldn't there be not enough pressure or no biggie, as stated b4 i am getting really good results but there is always room for better, thanks again

 

[SBruce]

Doesn't hurt to try. Some bullets like to be seated out right up to the rifleing, every gun/bullet has it's own personality IMO.

.030 isn't much, you're right. If it's worth messing with is up to you I guess. Some rifles I've developed pet loads for actually liked the particular bullet about .030-.040 back better than jammed.

 

[boomtube]

"...reload say 308 w/ 110g vmax, the book says col should be 2.74, "

There is no "should be" about it, that OAL is simply what the book makers used when they developed their data. It's no more a law than the listed powder charges.

IF you want to try seated close to the lands do your intial load development at that OAL. Simply seating closer to the lands with a load established seated deeper will surely raise pressures and we have no way of knowing how much. Seems most facory sporters do best from 20 to 35 thou off anyway.

 

[Buccaneerfan]

I have a question about this too. Which is better to do first? Should I find the best oal first or should I find the best load first? There has to be a correct order to do those two things.

 

[boomtube]

"There has to be a correct order to do those two things. "

There is no "correct order"; both approaches work, both have adherants.

 

[rscott5028]

Boomtube is correct.

Nonetheless, the more common approach seems to be that you pick a seating depth (or jump to the lands) that seems reasonable and hold that constant while you run a ladder test to firstly look for pressure signs in your rifle throughout the published min/max load range. And, secondly to look for one or more nodes that give better results. i.e. tighter groups

Then, begin fine tuning with the seating depth or jump/jam.

Keep in mind that seating depth can change pressure substantially. I don't worry too much about giving more jump. That seemes to reduce pressure. But, as you get closer to the lands and jam the bullet into the lands, the pressure can go up substantially.

Similarly, rifles with a lot of freebore will typically exhibit lower pressures and consequently lower velocity. But, they usually tolerate/require more powder in order to get the velocity back up. But, pressure increases accordingly.

-- richard