Lee 309-230–BTF

" Extrapolation, interpolation, and a chronograph are still the principal tools I use to sanity-check starting loads and verify Quickload predictions. "

to vague for me I will have to wait for some published loads

Thanks
Francis
 

fiver

Well-Known Member
laughing out loud.
you'll be writing that book if you expect to see it published somewhere.

here is a little secret.
LEE also extrapolates data from one cartridge to another, close-nuff plus/minus 10% to compensate for case capacity

think about it more like this.
take any 357 magnum load you can think of,, any one.
how many of them are also 38 special or 38 special plus-P loads?
now take any one of those loads and put them in a bigger case like the 357 Maximum, you automatically drop the pressure by 25% [the H-110 load probably won't even light off]
since we all know unique let's look at what happens and how we derive a sane safe useful load.
drop that 357 in a lever rifle and shoot it over a chronograph and you'll see about 1150-1200 fps.

now move that load over to your 30-30.
150grs--158grs.
6grs of unique
6grs of unique
1cc of case capacity
6 cc's of case capacity
Boyle's law automatically says you decreased the pressure by half for every unit forward/away from the gas source.
so before you even pull the trigger you have a 30% decrease in pressure.
now factor in the gas volume outside the going away straight line part and you drop another 10%.
your velocity will also drop so you have to add more gas volume to fill in the gaps.
add .6grs to fill in the edges.
add in another 25% to fill in the straight line that gets you to 8.1grs and your back inline with the 1200 fps you started at.
you will of course have less room in the barrel for a slightly different bore expansion ratio but your trading it off by having the bullet further away from the gas source.
working up instead of down is preferable and even safer when load swapping.

take your average 7mm-08 load, it probably uses a powder a bit on the too slow side for your average 308 load.
taking it and directly dumping it into a 308 case and seating a longer bullet [like from 140grs to 165grs] isn't going to peg the meter on the pressure gauge.
in fact it's gonna need more powder to shoot anywhere near efficient.

substituting in a cast bullet will lower the speed and pressure into something that will work just fine for ''higher-ish velocity'' cast bullet shooting.
no data whatsoever never will be never was but is more than safe,, the book said so sorta, just not for your exact combination.

to take it even further off the rails.
do you shoot any LEE bullets?
how about Accurate? NOE? NEI? MP? Ideal? CBE?
none of them have any generated data in a book anywhere, I'd go so far as to say Magma Engineering molds have double the data as all them put together have. [you never heard of them?]

they are all ''off the book'',,,, yeah but [shrug] yeah it makes a difference,, they don't have the same friction value, same lube grooves, same engraving pressure, seat to the same depth... all of that adds up and matters.
 

Spindrift

Well-Known Member

Ian

Notorious member
There are some men whose names are "household" on these forums who have done a lot of work and written at length about it in the past 70 years. You know, the ones who developed "10 grains of Unique", "16 grains of 2400" and "13 grains of Red Dot" sorts of loads.
 

Bret4207

Perma-member, Northern NY
Guesstimating is a pretty common practice amongst the clan. But many times you can get into the older books and manuals and find loads that will help you get a start. Phil Sharpes tome, Mattern, old Ideal manuals, there's a lot of stuff out there is you look. Of course, you probably don't have an HiVel #2, Pyro, Lightning or Kings Semi Smokeless powder on hand, but there are enough oldies still around to get you going.
 

fiver

Well-Known Member
unique used to known as infallible back in the old day's when it was lafflin and rand making it.
lightning-2 is pretty much trail boss.
the others are gone but I bet there is an overlap powder that's so close that less than a half grain reduction or increase would be right in the ball park.
 

Bret4207

Perma-member, Northern NY
Didn't know that! Well, the point I was trying to get to is that things like 250's in a 30-06 used to be played with and there is data out there. Old data, but if you know your powders it can help find a starting point.
 
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fiver

Well-Known Member
correct.
and if you happen to find data for the 30-40 Krag, 7.65 argie, 303 Brit, etc, all of it can be directly safely swapped over to the 30-06.
or slightly modified to suit the powder you do have on hand.

scared of the higher 45-K pressures of the red-dot ''the load''? use green-dot, international clay's, or Unique.
instant pressure drop of 4-5K
 

Bret4207

Perma-member, Northern NY
I used the 13.0 RD for years w/o any pressure signs and had excellent accuracy in many guns. Then someone found out it was a 45K load. I think I have an old, unopened can of GD in the stash, thanks!
 

Ian

Notorious member
45K is no big deal on a 50K+ cartridge, but 45K before the gas check is past the case mouth is what spooks me.
 
Spindrift, this what I'm up to. I "want" a Ruger #1 and ideally it would be in 300 AAC but unless I had it re-barreled I don't think that that exists.
Why 300 AAC? Just because It would be fun to convert 223 brass. Ruger #1s do come in 308 and I would much rather have a #1 in 308 than some kind of AR in 300 AAC (nothing wrong with ARs, I'm old school in a big way).

I have seen loads for cast 200 grain bullets for 308 but they are all for jacketed bullets. Can Hodgdon's reduced rifle loads using H4895 be used for cast bullets?
 

fiver

Well-Known Member
yes.
it can also be used for other powders.

LEE has a pressure reduction factor [something like .96 per grain airc] for several powders, I worked it down for 4895 once all the way down to like 19grs. in the 308 and then predicted the velocity drops for it.
my actual velocity drops ended up being a little bit off, but I wasn't overly experienced back then and started out a bit optimistically on the top velocity.[I missed it by like 100 fps.]
shifting over to my actual velocities to correct from the top, things come back in line, so I am assuming the pressure reduction values were also correct, or close enough they overlapped at each step or two.