OAL Test for 175 SMKs in a 308

[minnesotamulisha]

Good Morning Everyone. I will begin testing different OALs this week and I have a question. When seating at different lengths with the SMKs, should I start with some jammed .010"? It seems the consensus is a .020" jump.

Also, what different lengths should I try? Are 5 rounds at jump lengths of 0.010", 0.020", 0.030" and 0.040" sufficient or should I try jumping even farther, say 0.080"?

Thanks.

Adam

 

[masterblaster1]

find charge weight first then load that charge for different lengths, I like 5 thou increments off the lands and so on.

 

[minnesotamulisha]

Thanks Master blaster. I've got my charge weight already, now I'm ready for the OAL test. How far off the lands do you go? At 5 thou increments it would take a lot of rounds to get to 80 thou.

 

[Taildrag15X]

Since I wasn't going to load from a mag I started on the long side first......settled out at .015" off and best was .025" off.

 

[masterblaster1]

If you are 80 thou off I would just load book oal because you have a very loong throat. SMK's jump well.

 

[minnesotamulisha]

I am 20 thou off now. That's what I started with using Dan Newberry's load info. I didn't mean I was 80 off. Sorry. I am just throwing 80 out there to see how far off the lands I should go with my testing. Charge weight is 41.8 of IMR 4064 in Lapua brass so on the lighter side of the spectrum. I realize that pressures will increase when jammed and even when you start to seat bullets on the short side.

Thanks again.

 

[jlow]

Really depends on what you want to do. If you are interested in surveying the full breath of seating depth, then yes, you have a lot of work to do especially if you are seating 3 thousands each test (10 thousands is generally thought to be a bit too big of a difference).

If you are only interested in getting a load that is seated long i.e. close to the lands that is accurate, then I would suggest starting 10 thousands off and going deeper by 3 thousands using 3 round groups. Once you find a load with the degree of precision you think is good enough for you, then confirm it with 5 and 10 round groups. These would likely not fit in a mag unless you are using something like an AI mag.

If you are only interested in getting a load that produced mag length ammo, load them starting at mag length and go deeper by 3 thousands. Again if you find a load with the degree of precision you think is good enough, confirm with 5/10 round groups.

 

[minnesotamulisha]

I should have also mentioned that I am loading for a single shot so length is not important, other than OAL.