Strange Rx25 Loading

[MtnCreek]

Working up a new load in a .300wm. 190gr SMK @ 3.50", Rem Brass, WLR-M Primers, Reloader 25.

Off memery; Lyman 49th lists starting @ 73gr, max @ 83gr using Standard Primers & Win Brass. Rem Brass is pretty close (weights ~10grs less than Win). Same bullet @ 3.34".

I skipped the starting charge (I know...) and started at 74grs. Loaded 5 cartridges at 74, 75, 76, 77, 78. 76grs was sticky and 78grs was damn near impossible to open the bolt. Lyman listed their max getting just shy of 3,000 fps in a 24" barrel; everything 76grs and up was giving me North of 3,000 in a 26" barrel. I went back and checked data, scale, length, weighed bullets to confirm 190grs... I've loaded a lot closer to max w/ this rifle & other powders and have never seen pressures like this.

Other than skipping the start charge and shooting the the 77 & 78 grs loads (hey ya'll, watch this...), does anybody see anything wrong with this load?

Thanks!

 

[GooseGestapo]

Not really that suprising.
With any powder, there is lot to lot variation. Then you add in variations in components, rifles, bullets, atmospheric conditions and what you're seeing is not that suprising.

I've seen slight variations in RL25, and RL22. Back in '04, there was a recall on an entire lot# of RL22. I had a pound of it and it was a bit "hotter" than the subsequent lot#s. But, since I had already shoot 2/3 of the pound, I shot up the rest. 61.0gr's is listed as max in a .30/06 with 180gr bullets. At 60.0gr, I was getting over 2,800fps and near 1-hole accuracy. I wasn't about to "give it back"!

The latest lot# of RL25 I've got is a "tad" slower that the previous lot# I had. The previous lot# gave me 3,650fps @ 73.0gr under a 100gr Hornady Spt from my .257wby. The current lot# gives a much closer to "book" performance of 3,600fps from 74.0gr. (from a 24" Vanguard).
I suspect another lot# may give you closer to "book" perfomance. Also, switching brass or primers can also do such. Check and see what primers Lyman is using. The Win-LRM are hot primers. Substituting CCI #250 will "cool" things down a little.

Likewise, IMR7828 with the Lyman data from the #48 manual is too Hot at max for my .257wby. The listed data is 2gr higher than Alliants. My rifle agrees with Alliant. I had to back down from 73.0 to 70.0 with the listed load for my rifle. The first shot over the screens at 3,800fps! was my first clue it was too hot!. That, that the sticky bolt operation and the cratered primer and burnished case head got my attention! But, it was accurate!
I've relegated the remainder of the IMR7828 to my .300RUM which delights with this powder. The 26"bbl gives 150fps higher velocities than listed data, matching fps/fps with the .30/378wby. (a 26"bbl with weatherby free-bore!).
Where at in GA? I bet we've met,rubbed shoulders at least....

 

[Blue68f100]

That pretty much the way I start to get me in the ball park. But once you start getting Over Pressure Signs STOP. Don't shoot any hotter loads, you should pull them down. Then I start with the best ones and do a 0.5gr change. Pick the best, then start playing with OAL. With a crony you can see if a charge is very consistent, with out one you have to go by group size. But not just one outing. You may be off your game or the weather conditions were not the best to judge things on, High Winds.

 

[MtnCreek]

Little update: The R25 seems to load like R22. I got it back out last night and worked it back up w/ Standard Win primers. The load info in my first post was not correct; off memory again, I think Lyman lists 72gr start w/ 80gr max. I loaded 5 rds at 73 -77gr. It was dark, so no chrony info. The bolt started to get a little sticky at 75 and 77 was just plain hot. Just a heads up, there is some hot R25 out there.