I have Speers' number 12 manual and as I was browsing through it the other night I came across something I thought was rather interesting. Of all the load manuals I have come across I have seen several that list 73.0 grains of IMR 4831 as a max charge for a 180 grain bullet, including Speer #12. I don't have all the load books, let alone the older ones but I have never seen a load listed that is higher than that.

As I was flipping through the pages I noticed that the max charge for a 190 grain bullet was 74 grains, with a max velocity higher than that for the 180's .

Anybody have a rationale explanation?

In the case of the 180gr bullets, Speer has " 5 " of them and the Loads shown reflect the most Powder that stayed under 54k c.u.p.s for which ever one reflected the highest Pressure.

In the case of the 190gr bullet, it "probably" has a very slightly smaller Contact Patch(Bearing Surface) with the Bore.

Or it could be a different Powder Lot or a different barrel on the same rifle.

Actually, it doesn't make a difference because your specific rifle may be able to use that amount of Powder and then again it might not. Just think of the Load Manuals as Guidelines and not as exact formulas.

You always have to determine what is the SAFE MAX in your firearm rather than blindly dumping in some randomly picked Load.

180:
IMR-4831 From 59.4 grains to 75.5 grains
Winchester WLR Primer

190:
IMR-4831 From 57.1 grains to 74.0 grains
Winchester WLR Primer

Does that make you feel better?

Steve,

I was hoping you would reply. Could you tell me where you got the 75.5 figure for the 180 grain bullet? I have worked with several .300's and most can go above the 73 grain mark, but I would like to aquire the book(s) that show the higher values.

Thanks.

From the firing range....

300w -

Just FYI:

Barnes #3 lists: (24" barrel) 180gr XLC and 75.0gr I4831 at 2989fps;
A-Square #1 lists: (26") 180gr Nos BT, 77.0gr I4831 at 3202fps and 55260 CUP;
Hodgdon #27 (24") 180gr SPCL Rem, 75.5gr at 3105 and 53700 CUP...

But otherwise, have to agree, most list a max load around 73 or 74gr.

do shoot straight,
greg
www.gmdr.com

My old Lyman manual #44 lists
180 gr. jacketed 4831 (no brand so guessing it is surplus)
A WHOPPING 77 GR. Asterisk denoting compressed load.
Velocity listed with this load was 2958.
This in a Model 70 with 24 in. barrel. 1 in 10 twist.

This is a scary load for sure.
Frank