Anybody have any good 243 Winchester loads using H4831(SC) and 100 grain bullets ? I know a lot of you fellows try to be helpful with loads, but I'm only interested in one powder and one weight bullet right now. Through the years the data for this powder has changed drastically. Hodgdon once listed a max load of 48 grains for a 100 grain bullet, but now they list their max load at 42 grains (which seems awful low to me)? I haven't tried this powder in a long time, so I'm trying to get a good handle on where to start without going to low ... reloading supplies are to hard to get and expensive right now. Thanks, Ben

The powder itself has changed significantly. Rather than the U.S., Canada, or England, all of which are where it once was manufactured, it is now made in Australia. Follow the latest Hodgdon loading guides if you are using their powders made in the last 3 or 4 years.

I think its a good powder choice for the 243. at or near max loads and do follow the present loading manuals.
I have loaded 100gr nosler and 100gr sierra bullets and had good results with both. loaded a batch of 100gr noslers and IMR4350 trying to match a hornady load 2950 to 3000f/s.
I use mostly 95gr bergers and H4831sc in my 243AI getting about 3150f/s. Very consistent loads. Noticed some variations in the loads with the powder weight at 38 to 39 grs .
Hope this helps.

Before I launch into my tirade, let me provide you the simple information that for many years I have used the formula of 46 grains of original surplus 4831 under a 100 grain Nosler Solid Base (now obsolete) which yields 3100 FPS and nominal pressure from the 23" barrel of my favorite Sako. Note: This rifle likely has a "fast" barrel, so velocities may be a tad lower from other/shorter barrels.

I have compared the currently available H4831 to my remaining supply of original surplus 4831 and was surprised to find that it is very slightly slower. This is the opposite to earlier commercial versions of 4831, and particularly to IMR-4831 which is significantly faster than any version of H-4831. If I were loading the current H4831 for my gun, I would expect, starting as always a tad lower, to end up using 46 to 47 grains of the current H4831 with a 100 grain bullet.

Now for the tirade: The .243 suffers from its own popularity. Literally hundreds of different models of rifles in almost every conceivable action type have been chambered for the .243. SAAMI standards are not always followed. Some mathematically challenged manufacturers have been unable to convert the English .243" accurately to millimeters, so the groove diameters of some foreign-made barrels are exceedingly tight -- as tight as perhaps .239".

To complicate matters, almost every ammunition manufacturer which has ever poured powder in a brass case has made ammunition for the .243. Again, SAAMI standards have not always been rigorously adhered to.

So, after six decades of rifles and ammunition often mismatched to one degree or another, the "major" ammunition companies are downloading .243 ammunition several hundred FPS below its potential in order to keep it reasonably safe in the plethora of guns of varying chamber and bore that are floating around out there.

Likewise, the reloading data published by the major companies has gone the Fox News route (become ultra-conservative.)

There is no fundamental difference in the strength of cartridge cases used in a .243 and those used in a 6mm Remington. At one time, both were loaded to similar pressures. But now you'll find that .243 data stops around 55,000 PSI (not CUP!), while 6mm Remington data goes to around 63,000 PSI.

As always, use common sense when loading the .243 as you would with any rifle. If you are shooting a modern turn-bolt with forward locking lugs and a barrel of 22" or longer, then you can typically use H4831 with 100 grain (conventional cup and core) bullet to achieve a velocity of around 3,000 FPS before you stray into the zone of marginally excessive pressures (read: pressures which will expand case heads within three or four firings.)

By the way, the .243 has also suffered from a prejudice toward faster than optimal powders. H4831 is near perfect for bullets of 80 grains and heavier. For 100 grainers, if I didn't have H4831 available, my first choice would be to go slower rather than faster and use either IMR-7828 (SSC version preferred) or RL-22.

I had a 243 win, Tikka M-55 with a tite bbl but fortunately they gave it some free bore. It tended to jkt foul a bit.
The mag length was very generous and l could easily seat bullets out to what looked like ridiculous col's.

It was a very accurate rifle no problem to get .5" groups.

I ran IMR-4350 behind a 95gr Nosler PT for my hunting loads.
My varmint load was IMR-4895 behind a Sierra 75 grain flat base HP.
Always ran Fed 215 primers in my hunting loads.

It was the most accurate hunting rifle l ever owned.

To back up Stonecreek's comments
Maybe 15 to 20 years ago SAAMI down graded the pressures that the .243 was loaded to.

The reason for the down grade was some .243s had developed rough throats after years of use and the rough throats caused elevated pressures.