I recently picked up a CDL SF in 257 Roy from a fellow campfire member. He provided some 100 gr tsx rounds that he had made up for it that shot real well. So I needed to make up some more rounds and started at 70.5 and worked my way up to 71.5. The faster I pushed the 100 TTSX's the tighter the groups got (as I expected) But what blew me away was the velocities. Factory 100 gr Spires shot 3570 ish, the previous owners loads of 70 gr RL 22 shot 3600 ish, my 71.5 gr load clocked an average of 3800 (3780,3808,3797,3802) and showed no signs of excessive pressure. I've had a few of these and I've never clocked one that had this fast of a barrel. I have some 80 gr TTSX's I was gonna load up and was expecting to see this kind of speed with the 80's not the 100's. Pretty cool!

How many rounds of that nature can one reasonably expect to put through that barrel before its accuracy starts to go south? Not trying to be a smartass, I just never fooled with something that sizzles like that.

That ought to do it! I have not loaded for mine yet, but will load the 100 TSX with Rel 22. What COL were you loading??

And that is a 26" barrel....correct? Mine's cut to 24".

3800 fps is a sign of excessive pressure.

I know that velocity is hot but man there's no extractor marks on the brass, primers looked good and no stiff bolt lift. I know the Chrono was right because I shot several loads to include factory for confirmation. But those velocities definitely had me wondering? It is a 26" and I'm actually loading em of Ogive measurements and I was .05 off the lands on these loads. The TSX loads that came with the rifle were .09 off the lands.

Those signs often don't show up until well over 70k psi.

You may find that the same load shot in 100 degree summer temps causes issues.

Velocity = Pressure

The #1 load recommendation for the 257 Roy here on the campfire is 72 gr of RL -22 with a 100TSX, of course I was working my way up. I figured I'd see some pressure signs before backing off and seeing as I havent reached the coveted 72 gr I didn't expect these speeds without signs of excessive pressure. Now you've got me wondering. It was mid 80's today so it's not like it was cool out. I have clocked factory loaded 100 TSX's in the 3700+ velocities so I wasn't sweating it too much, just thought I was reaping the rewards of hand loading!

one my next reloading projects was to try TTSX's in my .257wby...also a CDL-SF, which i stuck in a KS stock. what sort of accuracy were those smokin fast loads producing?

I didn't take a caliper type measurement but around 1/2" -3/4", three were touching and one just off. This is a tough rifle to shoot for groups when your shooting multiple loads, the barrel gets hot enough to fry an egg after 3 shots also seems to take a while to cool down.

This rifle is in a McMillan Edge, and I swapped the trigger for a Timney after attempting to adjust the Rem trigger to my satisfaction. Bolt is on the way to Karl for a knob and some dazzle.

Mine shoots 120 partitions at around 3450, which seems high, but its with factory loads and no other signs of pressure. 100 TTSXs at 3700'ish with 72 RL22.

Mine is 3670 with a 26 in. barrel, I tried some of my handloads in my nephew's new .275 Vanguard, shot two groups that averaged .470, didn't chrono it however. That is with the 72 RL22 100 TTSX load.

How far off the lands are you loading the TTSX's?

Mine must be slow, only pushing them to 3500 with r25.

Weatherby factory ammo is famous for running on the ragged edge. Not much if any room to push it. But it�s your face, do as you wish.

Cub,

First off, congrats on the Roy. Very fine cartridge!

3800 is a little high. 3600-3700 is maxed out with the 100's.
You're already very close to book max with 71.5, but if perhaps your freebore length is out of spec(too short),71.5 with a reduced freebore will probably put you over max. Even though Remington is supposed to have the same freebore as the Weatherby(.378), your's may be a tad short. Just a thought.

I agree with the others and would back it off a bit. 3600 range is still flat out smokin and will kill the chit out of any game you would encounter around TX.

I appreciate the insight guys, I loaded up some rounds with lower powder charges to try out, just waiting to get my bolt back from Kampfeld to shoot em.

Cub,

If you have any RL-25 laying around, try it out with either the 115 Ballistic Tip or 115 Berger VLD. I'm on my 3rd 257 Roy and every one of them has given the best accuracy and speed, by far, with with RL-25. You should find your sweet spot between 70.5 and 72.0 grains. Expect 3300-3450. The 115 BST is an incredible killer of Whitetail and Hogs at those speeds.

Weatherby rifles are always "interesting" to load for. I have a buddy w/2 custom built 300 wby....by the same maker. The first one is a hunter w/normal wby type freebore. We worked up a load just short of normal Max data. The other one was built for "accuracy" w/virtually no freebore. We backed off the first guns load 3 grains......fed it to the 2nd gun.....and promptly began to blow primers out of the cases. I think we were only a grain or two over start loads. THAT was an eye opener.

I was getting 3,640 from my Vanguard with 73gr of RL22 and the 100gr TTSX. I've loaded the same 20 pieces brass for five loading's and all is still good.