Factory 357 Mag 158 XTP coal 1.549 Lee Manual min coal 1.575 ??

[glaizinman]

I started loading 357 magnum. I got some Hornady 158 gr XTP. Lee 2nd edition manual says for 158 gr XTP min coal 1.575. When a factory round with the same bullet is 1.549. I don't understand.I think I must be missing something. In the the Lee manual for all powders listed for the 158 gr XTP. The min varies from 1.575 to 1.590 which are all longer than a factory round. So please help me understand. Thanks guys

 

[ray15]

The load data isn't reflecting the factory cartridge you are measuring. It is stating that at the specified OAL with the powder, charge and primer listed they achieved the published velocity and pressure with their test gun (or barrel). The OALs given are not the minimum, only the ones used.

The factory round you have is most likely loaded with a different powder and thus its length may be anything that isn't so long as to bind the cylinder up. Its maker doesn't have to build to a published recipe, they can measure pressure directly and optimize the powder and charge for whatever OAL they decide to use.

 

[cp1969]

Isn't the OAL of .357 determined by where the cannelure is on jacketed bullets or the crimp groove on lead bullets? There are a few exceptions to this, like full wadcutters, but most .357 rounds are roll crimped, which uses the cannelure or crimp groove.

 

[glaizinman]

Isn't the OAL of .357 determined by where the cannelure is on jacketed bullets or the crimp groove on lead bullets? There are a few exceptions to this, like full wadcutters, but most .357 rounds are roll crimped, which uses the cannelure or crimp groove.

That is what I always thought. To crimp in the middle of the cannelure grove. I was just wondering if I could use the same OAL as the factory round using the same bullet? But on the box it states 1250 fps. I know some of the listings with the same bullet had a range of fps lower than factory and higher. But all with a longer OAL

 

[ray15]

As reloaders we can't choose where the cannelure is placed on the bullet so we are a bit along for the ride. But it still matters - if we end up using an OAL that is say .050 or .100" shorter than the load data we are basing our efforts on the pressure is probably somewhat elevated even in a spacious cartridge like .357 magnum. I'd still crimp in the groove, but would reduce the max charge a bit if that puts me significantly shorter than the load data, at least until I can chronograph the round to gain more insight into the pressures being developed.

But again, the load data you are reading has nothing to do with the factory round you are measuring. They use the same bullet, and are both for .357 magnum, but there's no other connection between the two.

 

[glaizinman]

As reloaders we can't choose where the cannelure is placed on the bullet so we are a bit along for the ride. But it still matters - if we end up using an OAL that is say .050 or .100" shorter than the load data we are basing our efforts on the pressure is probably somewhat elevated even in a spacious cartridge like .357 magnum. I'd still crimp in the groove, but would reduce the max charge a bit if that puts me significantly shorter than the load data, at least until I can chronograph the round to gain more insight into the pressures being developed.

But again, the load data you are reading has nothing to do with the factory round you are measuring. They use the same bullet, and are both for .357 magnum, but there's no other connection between the two.

Ok thank you Ray I will crimp at the grove. And load powder at the min

 

[ray15]

Ok thank you Ray I will crimp at the grove. And load powder at the min

It's always a good idea to start at the minimum. But most times, especially with full magnum loads, it works best to work up to or near the max load. It's when doing that that the actual OAL you end up with matters a bit. If you're shorter than the load data you may need to stop a bit below their max charge as a result.

Are you using W296/H110?

 

[rg1]

To add: Hornady 10th and previous editions lists the overall length of 158 XTP's in .357 Mag at 1.590". That's the length I've loaded 158 XTP's for many years for my pistol and lever action rifle. At 1.590" it has always put the cannelure in position to crimp. If you have short cases you may seat a little deeper. You do need to roll crimp for the .357 Magnum. I too would recommend medium towards maximum loads for .357 Mag and 158 gr. XTP's. Always a good safe plan to start lower and work up but I wouldn't load a lot of rounds at minimum charges without testing. Like mentioned, if you're loading a slow powder like H110 or Win 296 then it's not a good plan to load minimum charges.

 

[ray15]

Definitely. I've been using 1.580" with the 158XTP-HP as stated in the latest Hodgdon data for W296/H110. It hits the groove fine too. Obviously there's a little bit of lattitude but I also don't see any reason to deviate from the 1.580-1.590" range, especially when that's what the load data is using.

 

[glaizinman]

It's always a good idea to start at the minimum. But most times, especially with full magnum loads, it works best to work up to or near the max load. It's when doing that that the actual OAL you end up with matters a bit. If you're shorter than the load data you may need to stop a bit below their max charge as a result.

Are you using W296/H110?

W296

 

[glaizinman]

To add: Hornady 10th and previous additions lists the overall length of 158 XTP's in .357 Mag at 1.590". That's the length I've loaded 158 XTP's for many years for my pistol and lever action rifle. At 1.590" it has always put the cannelure in position to crimp. If you have short cases you may seat a little deeper. You do need to roll crimp for the .357 Magnum. I too would recommend medium towards maximum loads for .357 Mag and 158 gr. XTP's. Always a good safe plan to start lower and work up but I wouldn't load a lot of rounds at minimum charges without testing. Like mentioned, if you're loading a slow powder like H110 or Win 296 then it's not a good plan to load minimum charges.

Hey guys thank you for your replies I will load medium towards max at 1.585 to 1.590

 

[ray15]

Yes, use the Hodgdon data. Their max charge of 16.7 grains is generally good for the 158XTP. Just start a little bit lower and work up to it Good luck.

 

[Walkalong]

As posted, roll crimp into the canellure and that is the proper OAL. When doing full magnum loads in .357, and especially with powders that need pressure to burn well like W-296/H-110, I would start in the middle of the data instead of the minimum. Of course,, as posted, it is always safer to start at the minimum for anything we are not totally familiar with. We might make a mistake, it happens.

 

[ArchAngelCD]

I just want to add my voice to the already supplied good information. Like said crimp into the manufacturers supplied canellure. W296/H110 reacts better at the top end if the pressure curve like said above.

One thing, it's not always true seating the bullet deeper will raise pressures. If you are using a different bullet than in the data and the OAL is shorter than the data it doesn't mean the bullet is taking up more case volume. Bullets are made different than others and the resulting depth may not reduce the volume in the case and in turn will not raise pressures.