reloading 9mm & 357 sig

[Challenger44]

I reload for both 9mm and 357 sig. When I try using the 124gr 9mm bullet in my 357 sig round I have a problem with powder compression and the powder pushes the bullet back up. If I use the 125gr speer bullet everything works fine. Should I not be using the 124gr bullet for the 357 sig?

 

[venomballistics]

first, there is no "The" 124G 9MM bullet, there are many.
odds are you are just using one that differs from the one in your data.

 

[Challenger44]

I'm using Speer 124gr HP and Speer 125gr HP. Following my reloading data to the T. The 125gr has a more concave base which I believe allows for proper insertion to maintain COL. The flatter 124gr base is compressing the powder and pushes the bullet back up.

 

[venomballistics]

where the 125 HP is a 357 rather than a 9MM ... right?
look at the cavities.
in order to expand at the lower velocities of the 9MM the cavity is going to be a little wider and a little deeper than what is needed in a 357 HP at magnum velocities. that material taken out of the nose had to be put somewhere. That makes a longer bullet.
I take it you are trying to sub in this 124 over a load you have developed for the 125 ... I strongly suggest you drop back to the minimum charge and start over.

 

[Coastie762]

The Sig has a rather short case neck. Round nose, long ogive bullets meant for the 9x19 or the .38 Super have a relatively short bearing surface. Depending on the bullet you are using, there may not be much of the bullet actually contacting the case neck. These are not considered safe for loading the Sig as they may be pushed back into the case during the loading cycle, causing excessive pressures.

The 125 grain Speer Gold Dot designed for the Sig has a proper length full diameter bearing surface. Other bullets that work well for the Sig are the Hornady 124 gr XTP and 125 gr HAP. Both work well in my .357 Sig loads as well as the Speer GD you mentioned above.

 

[firecracker6]

I think you're getting good advice. I think you're stuck w/ conical bullets w/ this round. By any chance is the 124gr bullet longer than the 125gr one?

 

[Challenger44]

I used a micromiter to check the length of both and they were the same. I'm just curious if anybody else has had this problem using bullets designed for the 9mm and not specifically for the 357 sig.

 

[Coastie762]

Attached is a photo showing a Speer .357 Sig 125 grain Gold Dot and a generic 9mm 124 grain round nose alongside a Sig case. Also included is a 9mm 124 grain Hornady XTP-HP and 125 grain HAP alongside a loaded round with the XTP. The truncated cone shapes of the Hornady and Speer bullets incorporate a long full length bearing surface that provides proper neck tension.

None of the major reloading manuals recommend using standard 9mm round nose bullets with the Sig case due to their shape and possible lack of proper neck tension.

 

[firecracker6]

I think the Coastie's got it right.

 

[blujax01]

To echo, my Speer manual has a separate section on 357 sig and cautions against using "just any" 9mm bullet because of the symptoms you mentioned. They recommend their Gold Dot 125 grain JHP #4360.

 

[Coastie762]

A couple more photos to flog the horse some more.

I got bored last night and took the 124 grain 9mm RN, blackened it with a sharpie and loaded it into a resized WW .357 Sig case to my normal "load to" length. I then used a knife to mark the location of the case mouth on the bullet. Next, the bullet was extracted using a kinetic puller (one whack) and measured to get the bullet diameter at the mark, as well as where the contact marks started and where the bullet reached its full .355" diameter.

The expander ball diameter is .353". From my readings, the full .355 bullet diameter was at or below the shoulder of the case. The diameter at the case mouth was .345". The diameter of the bullet at contact with the case neck was .353". Essentially no neck tension. If this had been a loaded round and chambered, the bullet would have likely set back and a potentially dangerous high chamber pressure would have been the result.

 

[Challenger44]

Coastie762,

This is great information and exactly what I was looking for. Thank you for putting this together, It is a huge help. I will stick with using the Speer 125gr. Gold Dot as recommended.

Thank you!

 

[Coastie762]

You are very welcome. Good shooting!

 

[perrazi]

you can also use remington 124hp and nosler 9mm hp. they will also work. have been using them since the 357 sig first came out. none of the round nose bullets will work.

 

[twall68]

X-Treme bullets

If your looking for good bullets for reloading .357 sig ammo try X-treme's 124gr FP bullets. I've been using them without problems. Their prices include shipping!

X-Treme Bullets the finest hard-cast bullets and plated bullets money can buy

 

[fredj338]

Not all 9mm bullets will work for the sig but all 357sig bullets will work for the 9mm. The 357sig needs a bullet with long bearing surface & short nose. Most truncated cone shaped bullets will work, regardless fo weight. I have load 88gr to 147gr in my 357sigs. lead, plated & jacketed..

 

[SMSgt]

The case neck of the .357 SIG is short, having a longer "bearing surface" on the bullet is irrelevant if it isn't contacting the case neck. A longer bearing surface will allow for a longer COL, provided your mag, chamber, and feeding will allow.

 

[scooter123]

IMO a simple and likely much LESS costly solution may be to just load the 9mm bullet to a longer overall length. That will solve the powder compression issue AND get the Driving Diameter of the bullet up into the case neck where it needs to be for proper neck tension. The only question is whether that longer required length will chamber correctly in your barrel.

That is a test that you'll have to do yourself but that's dead simple, field strip your pistol and drop an assembled dummy at the new length into your chamber and see if it seats fully in the chamber. BTW, it should come out freely by just tipping the barrel, if it hangs up that's an indication that you are too long. If your bullet is just barely snagging on the rifling shorten your dummy up by 0.005 inch and see how that fits. It's also a good idea to mark the point where the bullet just starts to taper down and check to confirm that mark is in FRONT of the edge of the case, by doing that you can confirm that your full diameter bearing surface is engaged in the case neck.

 

[HCH]

Change your powder.

 

[colt_saa]

Many 9MM and 380 projectiles work fine with the 357SIG, but not all.

The Lee FCD is a fantastic tool for use with projectiles that have a short bearing surface. It makes it possible to load the 88 grain JHPs to 1700 FPS from my P229 Sport.