I was loading a Rem 125 sjhp for my first 357 mag test in my 686 and noticed how full the case was in the loading block.
I then noticed how much of the Rem bullet went into the case to be seated to get to the cannelure for a medium crimp.

This 16.5 grs of 2400 looks almost like a compressed loading but I know that there is data of 17.5 to 19.5grs out there !!

Hope to get 1450 +/- for a fac dup load but will be happy with 1300 plus if it shoots well. Does any one out there shoot the 17.5gr or more loadings ? Do I need to use that much powder?

Thanks for any help.

The Speer #10 manual states 2400 125 JHP/JSP 17.5 to 19.5grs with speeds @ 1399 and 1555. But the #10 manual runs HOT IMO. Lyman 49th loads 2400 @ 13 for 1159 and 17.7 for 1478. The speer #10 loading recommends mag primers with warnings of max loads should be used with caution. I years ago used 19gr 2400 and many case head separations happened in older brass so I don't recommend that high a charge. But had good results at 17.5.

Speer #10 is a tad out of date, up to #14 now.

Current data shows 17.5 as max. Mag primers no longer required.

I've used 16.3-16.9 with good results. 16.9 is a hot load but I never chronoed it.

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USAF, 69-92
Vietnam, 72-73

Loads like that are why I think so many K frame magnums are so loose as a goose. I've loaded some hot 158gr loads with those maxed out 2400 listings for my GP100 though and they did look like the bullet was comressing the powder. But it was data right out of the Speer book. I would not do that in a J magnum for the gun or my wrist's sake!

^^^ I would not argue at all, that is why I gave the Lyman 49th data. I shoot a GP100 and M27 N frame with the hot (17.5) load. I was trying to show where the high loading data mentioned came from.

Why not just move on up to a Max Load of H110/Win 296 when it has to, positively get there overnight.

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Still Running Against the Wind

I will offer no recommendations on heavy loads of 2400. I will offer no recommendations on heavy loads of anything else in the .357 Magnum. I will simply observe that in my youthful ignorance... when I thought reloading data was probably "conservative," I loaded a lot of ammo for my 6" 28-2... I loaded it hotter than the proverbial hinges of the theological place of eternal torment. And... I found out... load hot enough and shoot such stuff often enough and you can give a nice revolver a bad case of the shakes.

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My "sweet" 2400 load is 15.0g under a 125g XTP with a mag primer, but I safely loaded up to 17.0g when develoing the load. Actually, the 17.0g load was just as accurate as the 15g load, however the recoil was fairly abusive, and it produced an impressive fireball out of a 4" Ruger. Certainly not a load I would shoot on a regular basis.

From what I read, H110/W296 are extremely sensitive to load and over-pressure is easy to come by; hence the min/max range published is very tight. I have done some but kept at or slightly below min. Seating depth, etc. can have big effect on pressure. Winchester data cautions even testing every can or lot of 296 you open, like developing new load every time you open a new can.

I think that you have misunderstood the "sensitivity" of 110/296. IT is a well behaved powder at full pressure loadings. the concerns are erratic and possibly dangerous behavior with reduced loadings....and that gets disputed a bit but the makers say don't reduce.

Yes it is. H110 is more of a problem with reduced loads, not max loads. It was said kind of tongue in check. The OP wants to "play" with max loads. I see no need to too. 2400 is more forgiving. Any of the Magnum powders will fill the case up. I see no reason to load Max levels even for hunting. A powder such as HS 6 will give great results with less powder

The current Max for 2400 is in the 17 gr range which IMHO will not do much more than a safer 16 grain load

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Still Running Against the Wind

Rule3;

I have tried W/H powders in my rifles, shotguns and 38 specials and they come in at 2nd or 3rd place with either accuracy or velocity .
I have posted pictures of some of my snub nose test and
you can see that w231 was not liked in my revolvers but
I have to also say that Bullseye was a poor performer also
with the velocity department, except for the lighter lead bullets.
I might try 110/296 if the 2400 does not pay out but from what I have seen with my first test with two groups with 4 of 5 bullets under .45" and one group of 5 of 5 shots under .54" , it might be a while................

I'm not surprised W231 and especially Bullseye didn't perform well in the .357 Magnum, those powders are just too fast for top performance.

If velocity is your need or you are loading heavy bullets in the .357 Magnum W296/H110 is the powder to turn to.

I tested 2400 and W296 under a 125gr XTP bullet in a 18.5" Carbine.
Here are the results:
125gr XTP - 17.7gr 2400 - WSP primer - AV 2055 fps
125gr XTP - 22.0gr W296 - CCI-550 primer - AV 2239 fps

Sorry I didn't run any of those rounds over the chrono from a revolver but I didn't make a lot at the time and I was more concerned with Carbine velocities at the time. I tested 125gr, 140gr, 150gr, 158gr, 170gr and 180gr bullets that day. (the 140gr bullets were very impressive)

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Freedom is never free!!
SWCA #3437

Older data, Speer #11, went to 19.5 grs 2400 with a mag primer. The
17.5 grs max is within current 35,000 psi pressure maximums per my
Speer #13. Some 125 gr factory ammo is said to run 1400 fps in an
actual 4" revolver barrel, not some vented test barrel. I decided a while
back to load a few to compare W296 and 2400 with my 125 gr Sierra
JHCs in a 4" revolver, my 28-2. 21.0 grs 296, Win mag primer = 1335
fps in my 28. 17.5 grs 2400, CCI 400 SR primer = 1370 fps in the 28.

There is a link here somehere for Skeeter Skeltons pet 38/357 loads, if it was good enough for him.... has worked well for me for years.