Do I have this right?

[Ol` Joe]

He said he loaded to 3.175", Sierras #5 lists 3.185" as the COL the data was developed with. What is the problem? 0.010" is not going to mean squat in a 30-06 case as far as case volume or pressures. Powder lot variation will likely make more change in the load then 0.10" increase in seating depth. The Sierra manual shows 56gr as max for IMR4350, Speers #13 goes with 58.0 gr, and IMR data on Hodgons site lists 60 gr as max for IMR4350 with a 165 gr Sierra SPBT.
I agree one should start at least 5% below max minimum and work up, and with this much variation in max powder charge between different sources I`d suspect there is some variation in powder lots that are showing up. I don`t think he is in trouble where he is at but, it would be prudent to reduce the load with a couple of 1 gr increments up to his present load and shoot them first watching for problems. I wouldn`t tear down what he has but, load a few more cases with the reduced loads.

 

[Bartkowski]

I understand that he said to back off by at least 5%. But why would I back off from the maximum instead of just shoot the starting load?

 

[Mal H]

Your confusion about the statements is understandable. Personally, I think it is better to begin at an established starting load and work up from there, at least until you get the feel for what constitutes a minimum load for your own firearm. Starting at 5% below max is somewhat arbitrary since the max load can vary, sometimes widely, from one manual to the other.

 

[GP100man]

it`s all about pressure!!
controlling factors that make it are :
case capacity
bore dia.
bullet weight & depth of bullet will vary case capacity, also bullet jump if any.
for instance i have a rem. 700 in 30-06 that loves 4064 at 47 grs. under a rem flat based corlok bullet that`s 1whole gr under any published starting load , but i chronoed this load & it`s still makin 2645 fps .
is it because i seat it to the lands enuff to make the bolt drag a little ???? case capacity ??? lot# of powder ????? primers ???? who knows but i know 48grs start to flatten primers a little more & the gain in fps is`nt worth the wear & tear on rifle or me!!!!& 47grs 4046 groups just fine for me at 200yds.
so in the end startin loads are a pressure point to start the process of load work , too many variables from rifles , powders ,cases & powders to say deadnutts this WILL work is impossible !!!
i think that factory ammo does what its supposed to do & some people are satisfied with its performance & i know some BR shooters that carry consistensy to the extreme also!!!
please stay safe !!

GP100man

 

[Bartkowski]

Alright, thanks for the help. I will load up some new ammo with some safe starting loads and recommended COL.

 

[kount_zer0]

Good idea.

There are other benefits to working up loads in .5gr increments. If my experience with 30-06 is any indication, you'll find your most accurate load before you get near max. Then you can use finer increments around that load, then you can try primers, slight changes to OAL etc.

My advice is to get a chronograph as soon as you can. You can get a Chrony brand for about $75, and they will work fine. You can have your own measurement data: group size and velocity. Once you know the velocity that gives good groups with a particular bullet weight, this gives you a good starting point if you change bullets, powder etc.

Get advice from this board whenever you need to. There is a LOT of reloading experience here...


Have fun, be safe.