.357 Magnum, residue in case after firing

[Loudcherokee]

Hey guys,

Loaded up some test rounds for .357 Magnum and finally got to shoot some today. I'm using Hornady 158gr XTP-FP over W296 powder. Per Hornadys 10th, I loaded starting at 13.1g up to 15.9 in .4gr increments. Brass is brand new Starline with Federal small pistol magnum primers.

Was able to shoot all loads up to 15.9 with no pressure signs, and 15.5gr appears to be a good accuracy load for my 4" Ruger GP100. After examining the fired cases, there appears to be some residue that looks kind of like sand mixed with black pepper.

I've attached some pictures, one of the case and one of a pan where I scraped some into it. Its sporadic where it shows up in the rounds. I'll have a few rounds that are clean as can be, just a little black, then one of these.

Any ideas?

LC

 

[M-61]

Not a clue, but my compliments on fabulously clear pics!

 

[Uncle Ed]

Not all the powder is being burnt, you might need a tighter roll crimp or switch to a faster powder for your 4 inch barrel. I had the same problem with a 6 inch .357 and you need to be at the highest pressures to get a clean burn with 296.

My Friend, The .357
by Skeeter Skelton
Shooting Times Magazine
June 1988
http://www.darkcanyon.net/MyFriend_The357.htm

 

[Conaso]

I believe Uncle Ed is correct. Experienced same issue using 15.0gr IMR4227 (most accurate) with Dan Wesson 8" barrel. I increased crimp. Didn't get rid of all residue in barrel but definite improvement.

 

[243winxb]

Use a magnum primer & eject fired shell with the muzzle pointing up.
Then forget about it.

For my 158 gr cast bullet , i use 2400. But the shortage had me using IMR 4227 & W296 a few years ago. They all leave some soot.

 

[243winxb]

This is what Winchester had in there 1996 reloading manual, back in the dark ages.

 

[Oso]

As others have indicated you are not getting complete powder burn. There is just no way to achieve Magnum velocities out of 4" barrel using W296. If you are happy with the velocity you are getting then start reducing the powder charge until the velocity begins to decrease (find the equilibrium of powder load vs powder burnt in barrel). If you want to achieve a greater velocity then you will need to change powders. There are some hotter powders ... you will just have to balance velocity desired and case fill.

W296 / H110 is a popular powder for 300Blackout, which has about the same size cartridge as 357 Magnum. My loads for 300BO using 125gr bullet is approximately 18gr-19gr of H110. Even out of 8" barrel I am not getting 100% powder burn.

 

[GotRDid]

The residue is indeed incompletely or unburned propellant; the yellowish spheres are the actual granules of propellant with the graphite surfactant burned away.
I'm not sure if the CCI-550 small pistol magnum primer is "hotter" than the Federal SPMs you are using, but I get a cleaner burn with both H110, and W296 using the 550s.
You might also chuck up your expander and polish it down about .0005-.001" to increase the neck tension on the bullet in conjunction with a good crimp to aid in ignition.
I really like 296 and 110 in my 10" .357 Mag Contender, and 12.5" .44 Mag Contender. The barrels are long enough to minimize such residue. On the other hand, my 7.5" .44 Mag revolvers prefer Ramshot Enforcer; it appears to be easier to ignite. Enforcer leaves far less residue even with barrel/cylinder gaps and less than optimal bullet "pull".
GotRDid

 

[Loudcherokee]

So is there a "problem" per say of continuing to use these loads? Its sporadic, not every case. 1 in 4 or 5 I would say. Which kind of makes me think it's a crimp issue. I use the Lee factory Crimp Die set to touch the shell holder then tightened 1/2 turn beyond that.

LC

 

[243winxb]

The crimp should just roll into the bullets cannelure. There is only so much a crimp can do. Avoid post sizing with a Lee die.

Measure the outside diameter of a case before seating a bullet. After seating, the case diameter needs to get larger by .002" or more. This should provide good neck tension.

The closer to the maximum powder charge, the cleaner W296 will burn.

Test - Fill the cylinder & shoot all but the last round. Measure the COL see if there is any bullet movement. If bullet has moved more then .005" its not good. More neck tension is needed.

The W296 will produce top velocity. The barrel length has nothing to do with a clean burn.

Sporadic is dangerous. It may produce a squib, leaving a bullet in the barrel. Firing a 2nd bullet into a plugged barrel , very bad.

 

[K22]

I've tried both H110 and 296 which require magnum primers and a solid roll crimp in the cannelure of the bullet to burn properly. While these powders yielded excellent velocity especially with 158 grain bullets, accuracy wasn't all that great, at least for me.

For full power loads in the 357 magnum, 2400 is difficult to beat especially with 158 grain bullets. I had my best results, velocity & accuracy, with this powder for full power loads. According to the Speer Reloading Manual, 13th edition, 2400 was reformulated by Alliant, which was formerly made by Hercules. Speer advises not to use magnum primers with the Alliant 2400.

 

[243winxb]

Crimp- To much may reduce neck tension & bulge the case, so that the round will not chamber.

Brass trim length for crimping is best within +/- .0025" col.

 

[edwardware]

That's unburnt powder. W296 is a magnum powder that will benefit from a heavy charge, a healthy roll crimp, and maybe a SPM primer.

OTOH, if it's consistent, it's ok.

 

[Uncle Ed]

So is there a "problem" per say of continuing to use these loads? Its sporadic, not every case. 1 in 4 or 5 I would say. Which kind of makes me think it's a crimp issue. I use the Lee factory Crimp Die set to touch the shell holder then tightened 1/2 turn beyond that.

LC

It's not a problem if you wet tumble with SS media or use an ultrasonic cleaner to clean out the unburnt powder residue.

And it would be simpler if you use the Skeeter loads I posted with powders not so hard to ignite.

On top of this using 296/H110 with max loads will make you blind if fired in the dark. You will have fire coming out the sides of the cylinder gap and have a huge muzzel flash. If you want to keep using 296 then buy a .357 rifle and burn more of the powder in its longer barrel.

296 is a double base powder that contains nitroglycerin and has more deterrent coatings to slow down the burn rate. This in turn makes the powder harder to ignite, this means a hot magnum primer and a tight roll crimp to get the fire burning in the boiler room.

Your loads are not getting to peak flame temperature and peak pressure to consume all the powder. And the cylinder gap and barrel length have a big effect on the combustion.

 

[Loudcherokee]

I'm going to keep experimenting with it I suppose. I dont have any other calibers to burn the 296 in and when I bought the small magnum pistol primers I bought 1000 of them. There was nowhere local to buy just a 100 pack for testing.

I'm going to try and tighten up the crimp a little and see what happens, this weekend. Here's a couple of pictures of my current crimps. The first being how these rounds were crimped, the second, with the blue background, being another full turn on my crimp die.

LC

 

[243winxb]

Seat the bullets deeper. Just so a tiny bit of the bullets cannelure is visible.

To hard of a crimp will cause the case mouth to split after many loading.

Remember, neck tension keeps the bullets from moving to early when the primer fires, more then a crimp.

 

[GotRDid]

As I mentioned in my post, perhaps polish your expander down to reduce diameter to increase case neck tension.
Yes, 243WinXB is correct, you are on a path to premature case mouth failure at that crimp setting. Likewise, seat a smidge deeper as 243WinXB directs to fully engage that cannelure.
UncleEd also shares his experiences which mirror mine in regards to the slight venting effects on pressures from barrel/cylinder gaps.
GotRDid.

 

[Loudcherokee]

As I mentioned in my post, perhaps polish your expander down to reduce diameter to increase case neck tension.
Yes, 243WinXB is correct, you are on a path to premature case mouth failure at that crimp setting. Likewise, seat a smidge deeper as 243WinXB directs to fully engage that cannelure.
UncleEd also shares his experiences which mirror mine in regards to the slight venting effects on pressures from barrel/cylinder gaps.
GotRDid.

Thank you. I'm definitely taking all this into consideration, and will be adjusting my crimp before loading any further rounds.

I need to uniform my OAL on the cases, I think. On one bullet, it will be seated correctly at the cannelure, the next may be a shorter case, like pictured, then one correct, then one that may be too long and completely covers the cannelure. Its brand new Starline brass, and I wanted to fire it all before trimming to see if there would be any growth on the cases or not.

With regards to polishing the rod in my sizing die, would the flare that the powder die gives the case mouth not negate any smaller tension placed on the case by a smaller sizing rod?

LC

 

[243winxb]

With regards to polishing the rod in my sizing die, would the flare that the powder die gives the case mouth not negate any smaller tension placed on the case by a smaller sizing rod?

If using a Lee powder thru expanding die? This Lee die is said to permit charging the case while expanding and flaring the case mouth.

The case only needs expanded 1 time. I don't use Lee. But any 38/357 expander diameter should be about .002" smaller then bullet diameter.

There are times when a full length sizing die, does not size the case down small enough. This may happen if the case walls are thinner then normal.

Measure the OD of a sized case. Measure again after expanding. Dont be supprised if its almost the same. Brass will spring back at different rates.
Measure again after bullet seating.

Most all dies will provide good bullet hold. But never hurts to check.

 

[Oso]

Thank you. I'm definitely taking all this into consideration, and will be adjusting my crimp before loading any further rounds.

I need to uniform my OAL on the cases, I think. On one bullet, it will be seated correctly at the cannelure, the next may be a shorter case, like pictured, then one correct, then one that may be too long and completely covers the cannelure. Its brand new Starline brass, and I wanted to fire it all before trimming to see if there would be any growth on the cases or not.

With regards to polishing the rod in my sizing die, would the flare that the powder die gives the case mouth not negate any smaller tension placed on the case by a smaller sizing rod?

LC

Keep in mind that pistol brass shortens as it is shot, which is the opposite of rifle brass which tends to elongate. Unless you are shooting Bullseye and are very good, you aren't going to notice any difference by trimming cases. Go low tech - Just stand them upright and if there is a noticeable height difference then separate out the obvious oddballs.

Your biggest handicap is the 4" barrel. The 357Mag was designed for +6" barrels. Unfortunately, you can't get a complete powder burn with W296 loading to max. charges per reloading manuals and can't reach the velocities. Your best answer is to change your mindset and load to your specific gun. Reduce amount of W296 powder to only amount that you can effectively burn inside your gun. There are two easy ways to determine this threshold:

1) Shoot at a white sheet to determine amount of excess/unused powder being thrown out end of barrel; or
2) Measure velocity to determine at what powder charge the velocity starts to decrease (easiest technique)

Improve you neck tension/crimp will improve some burn rate, but you will never burn a full load of powder. After you have dialed in your neck tension/crimp, begin reducing the amount of powder in the cartridge until the point where the velocity begins to decrease. Start at your 15.0gr charge and load 6 rounds, and then decrease the powder charge by 0.5gr and load another 6 rounds...continue until you reach 10.0gr of powder. Use some form of marking on bottom of each case to distinguish the different powder weights (I use different colored Sharpies and place an "X" across bottom). Use a chronographer or similar radar device to track this velocities. You will quickly find an optimal charge weight for this specific powder, bullet, primer combo in your pistol.

After you burn through your W296, you may consider changing to a faster pistol powder to increase the velocity. The downside of the faster powders , such as Bulleye or TiteGroup, is the very small amount of case fill... there is a risk of double charge and flash-over.

I shoot a 4" S&W 686 that I download to 38SPL and shoot 160gr Round Nose coated bullets. I load for IDPA power factor, which is a bit of a powder puff load, but very accurate and fantastic to shoot. Everybody likes this setup ... I tested a number of different powders and settled on Trail Boss because it shot the cleanest, had best recoil impulse, AND it had 2x-3X amount of case fill as any other popular powders (no risk of a double charge). I can shoot 300 rounds in a session without being punished.