Reloading manuals getting more conservative?

[Bang]

I know someone posted similar a while back. Sorry for stealing the title, if I did...but it fits:

I've been reloading 357 SIG, which Sig Sauer and Federal Cartridge developed for police who were lamenting (note to admin...no negative politically incorrect statement intended) that semi-autos had nothing comparable to the 125 grain .357 Magnum JHP revolver cartridge fired from a 4-inch barrel.

Despite warnings that reloading 357 Sig is fraught with problems such as shoulder crunching, crimping problems calling for a tapered crimp die, set-back projectiles due to sparse neck retention, and headspace problems due to head spacing on the mouth rim (when in fact, despite designer and SAAMI claims, it just does so on the shoulder)...I have so far had none of these.

From researching 357 Sig loads simulating factory, which is around 1425 fps, I had settled on trying Power Pistol. I thought I had found a reliable source...M.D. Smith's table, which contains a prelude described above. It lists 124gr at maximum 9.5 grains/1435 fps/Speer/TMJ with warning to reduce 10% and work up...which would be 9.5 minus 10 percent= 8.55.

The latest 10th Edition Hornady reloading manual lists 8.7 gr as max, while yielding only 1300 fps. Bullet types and choice of primers account for variations, but notice that Hornady's max load is 1300 fps, nowhere near factory loads of 1425/1435. Gotta wonder about that.

I did load 9.0 to 9.1 Power Pistol. Very loud, nasty muzzle flash. Primers were not flattened and the case webs were not swollen from new unfired dimensions. The barrel is a Wolf in a G23. Wish I had a chrony.

[Pizza Bob]

Yes manuals are getting more conservative. This is more a result of better testing methods than any lawyer involvement (although I'm sure that played a part in it also). I was surprised to learn that it wasn't until Speer #9 that real testing equipment was used (pressure transducer / copper crusher). Prior to that they were going by visual pressure signs like flattened/cratered primers, sticky extraction etc. Apparently they found that those symptoms don't always manifest even if an overpressure condition exists - thus the dialing back of load data.

Adios,

Pizza Bob

[dkf]

There are differences from gun to gun and even universal receiver to universal receiver. Look at Hornady's .357sig ammuntion it makes, it is watered down velocity wise and that is advertised velocities. Run their .357sig ammo over the chrono and it is even less. But yeah I have noticed over the years that velocity has been dropped some. Federal even did it with the HST. Honestly I think these companies are trying to save money on powder, even .1gr less powder per cartridge over how many million cartridges a year can save money. Not to mention some companies don't produce .357sig specific bullets to take in account the extra velocity the sig can achieve over 9x19. Its something I'm used to, I'm always working off book with cast pistol and rifle rounds due to lack of data. Pick the closest jacketed data, reduce to start and work it up.

[Bang]

In all the information I posted I inadvertently buried my intended question. If factories can offer 1425 fps, why can't I get that by reloading. I used to be able to.
Corbon states their 124s are 1425. They use Starline cases, as do I. I should be able to reach close to 1425 but 1300 is a max load in the Hornady 10th edition. Does the factory have access to a propellant unavailable to the general consumer? Are they mixing powders to achieve the goal and keeping it proprietary?

[bamboomaster]

In all the information I posted I inadvertently buried my intended question. If factories can offer 1425 fps, why can't I get that by reloading. I used to be able to.
Corbon states their 124s are 1425. They use Starline cases, as do I. I should be able to reach close to 1425 but 1300 is a max load in the Hornady 10th edition. Does the factory have access to a propellant unavailable to the general consumer? Are they mixing powders to achieve the goal and keeping it proprietary?

Well you sure have a fun project ahead of you…

Correct me if I’m wrong, but you’re looking for additional velocity. To get “there” from “here”, you’re going to have to change either your selection of powder – or bullets.
Here’s why.

From a listing of powder burn rates I consulted (and indeed there are many lists so I’m using the one I printed out in 2014), here are the burn rankings on several powders you could use:

#10: Bullseye (Aliant)
#37: HP38 (Hodgdon)
#49: No.5 (Accurate)
#57: Unique (Alliant)
#62: Power Pistol (Alliant) - You're here
#88: No.7 (Accurate)
#101:N105 (Vihtavuori)
#102: No.9 (Accurate) - You should be here

I believe your selection of powder (Power Pistol) is too fast-burning for your 124 grain bullet weight which is why the velocity tops out at 1300fps even with 8.7 grains (max load in Hornady Handbook of Cartridge Reloading, page 775). Yes, I realize you’re only using 8.5 grains for that initial “FLASH/BANG!” load of yours.

So let’s start with keeping the bullet, but changing your powder selection because you need a slower burning powder for that bullet instead of a fire-breathing dragon!


From the Speer Reloading Manual #14, page 842(for 125 gr GDHP and TMJ-FN):

A No.7: Min 11.1 gr – 1264 fps Max: 12.3 gr – 1403fps

A No.9: Min 13.1 gr – 1287 fps Max: 14.6 gr – 1437fps

(Note: if I used a 125 gr bullet and looking for velocity, I would be inclined to test a series of loads wth A No. 9 and would be gratified if it shot well at something under the maximum 14.6 grain load – I always stay on “this side” of any maximum load by a few tenths of a grain)

Unique: Min 7.2 gr – 1231 fps Max: 8.0 gr – 1344 fps

VVN105: Min 10.1 gr – 1257 fps Max: 11.2C gr – 1400 fps

(Note: the 11.2 grain maximum load is a compressed load. I wouldn’t recommend using it. Besides, that powder is expensive!)

While this 14th edition of the Speer Reloading Manual provides data for Power Pistol, it’s only for 147 gr bullets…

So, now let’s think about changing out the bullet to 90 grains (I’m thinking the Hornady 9mm XTP sized at .355” – the right size for a 357 Sig):


From the Hornady Handbook of Cartridge Reloading, 9th edition, page 774. Remember, these are 90 grain bullets!:

Bullseye: Min 5.8 gr – 1250 fps Max: 7.3 gr – 1500 fps

HP 38 : Min 6.2 gr – 1250 fps Max: 7.7 gr – 1450 fps

Unique : Min 7.3 gr – 1250 fps Max: 8.8 gr – 1400 fps

From the Lyman Reloading Manual, 49th edition, page 348. Remember, these are 90 grain bullets!:

HP 38 : Min 7.3 gr – 1422 fps Max: 8.0 gr – 1537 fps

(note: the 7.3 gr HP 38 load was designated “most accurate”. FWIW, I ALWAYS start with the most accurate loads. Remarkably, this has a velocity in your designated neighborhood and the powder is probably on your reloading shelf.)

A No. 5: Min 10.0 gr – 1422 fps Max: 11.0 gr -1595 fps

Unique: Min 8.1 gr – 1420 fps Max: 9.0 gr – 1566 fps

Power P: Min 9.7 gr – 1488 fps Max: 10.8 gr – 1656 fps

A No 7: Min 12.0 gr – 1419 fps Max: 13.5 gr - 1605 fps

So, you’ve got a lot more data here to work with that comes from current reloading manuals that will get you to your velocity without breaking the bank. I know you’ll have more than your share of fun working up the load that is not only safe, but right for you and your pistol.

BTW, thanks for kicking my ass on this project which I have delayed for years! I've got the firearm, about 5K brass, about 3K 125 grain bullets, the dies, etc. Just gotta finish hunting season and the .45-70's on the bench. At least I know which powders I'm using for 125's and 90's.

[Bang]

bamboomaster, thanks for all the input and info. I am interested in driving 124-125 bullets only. I have been shooting 6.5 Unique for indoor target range to get the practice with the Glock 23 trigger. Other than that, I'm after duping the 124/125 bullets at 1425fps or higher 1300s in keeping with the reason the cartridge was invented. Yeah, I can relate to needing to be in the mood for some projects...or reviving it. :-)

[Gunsnwater]

In all the information I posted I inadvertently buried my intended question. If factories can offer 1425 fps, why can't I get that by reloading. I used to be able to.
Corbon states their 124s are 1425. They use Starline cases, as do I. I should be able to reach close to 1425 but 1300 is a max load in the Hornady 10th edition. Does the factory have access to a propellant unavailable to the general consumer? Are they mixing powders to achieve the goal and keeping it proprietary?

Bamboom touched on your answer. The companies have the equipment to produce the perfect powder to drive their chosen projectile. They can blend powders and know what they have. They can measure and quantify everything.

We have little to go on. Chronographs are now affordable and one maker puts out a transducer based pressure measuring tool. Then we have the "signs" to read like tea leaves. To top it off, we work up loads for lot numbers. Same powder with different lot numbers can give significantly different results. Sometimes it's enough to push you over the limit.