Pressure signs.

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Joseph Dawson

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I went to the range today to shoot my new reloads. I made 30 .357 cartridges. For 10 cartridges I used 13.5gr of 2400 and for the other 20 I used 12.7gr of 2400. I was using 158gr LSWC.
When I fired the recoil I experienced seemed much more than I was used to. I'm used to .38 special or a .357 4.3gr bullseye load using the same lead.

What pressure signs should I be looking out for? I think I know them but I just wanted to check with you guys to see if I missed anything. Was just a bit worried I could have damaged the gun but I think I'm overreacting? The recoil was a bit much and it's the first time using this powder so I just wanted to check and refresh myself on what to look out for.

I was using a Marlin 1894CSBL 16.5'' barrel.

Just want a bit of reassurance. Thanks.
 
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Those loads are actually on the mild side. I'm running 14.7gr of 2400 pushing a home cast/coated 158gr hp in a 2 1/2" bbl'd 357.
 
You won't damage anything with 13.5 gr of 2400. You just finally loaded a normal .357 magnum. I'll bet the 13.5gr load shot very accurately from your rifle.
As far as pressure signs, I doubt you'll see any with those loads.
13.5 gr of 2400 with a 158gr JHP is one of my practice loads.
With a lead SWC you will want something at around 16 Brinnel or harder or you will see leading.
Shoot flat based bullets if you can find them, they are much more accurate at rifle range than bevel based bullets are.
 
It just worried me because the recoil felt hard and it was really loud. Much louder than I was used to and I've shot store bought factory .357 rounds. What pressure signs should I be looking for? Like you said I shouldn't be getting any at that gr but just to settle my mind what should I be looking out for?

I also only got to shoot about 6 rounds because it was so loud and at the indoor range I go to there's a limit to what I can shoot and the range officer seemed to think it was too loud and over the 450ft/lbs limit which is fair enough. Think that just got my mind racing and overreacting. I'm gonna go try some at the outdoor range tomorrow.

Also the lead I use is hardcast so I should be ok with that right?
 
Yes, the hard cast is good for those loads but don't use it for light loads or you will lead your barrel in spite of it. The lead is to hard for a light charge to make the base expand to seal in the barrel and gases will blow past it and cause leading.
Store bought .357mags can be pretty watered down these days depending on who made them.
As far as pressure signs go if you have harder extraction than normal you probably have a pressure problem. I use Winchester primer so looking at them is worthless as far as pressure signs go. They are a harder than some other brands.
Federal has to be the softest primers and they may show some flattening even at lower pressures than an over pressure sign would show. So you can't really use primers in handgun loads to check for pressure issues.
Hard extraction is the best one most of us use.
 
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With a rifle you may also see the machine marks from the bolt imprinted in the head of the case. With rifles that is a danger sign.
With a 35000lb round like .357 Mag I doubt you will ever see it. Most high power rifles are in the 50-60k range in pressure.
 
We talking really light loads? I use the same lead for my .38 special loads, 158gr RNFP 3.3gr bullseye.
 
How hard is the lead? Hard cast is usually 20-22 Brinell, Cowboy Action Shooting grade bullets are around 12 Brinell. They are not hard cast.
What brand are you shooting. If your shooting 12 -16 you may be fine regardless.
 
Not sure how hard the lead is. I'm from the UK so I'm not exactly spoilt for choice and the ones I use are GM Hardcast. They're one of the only lead bullet brands over here.
 
Like said above, the most likely pressure with in the .357 Magnum will be hard or sticking extraction. You probably won't even see loose primer pockets with over pressure .357 Magnum ammo.

I guess you are finding out first hand how light factory .357 Magnum is being loaded. I have been saying for years we are being cheated of the full potential of great cartridges.

Many reloaders as a standard load charge between 14.0gr and 14.5gr 2400 under a 158gr LSWC without problems. If you loaded those rounds correctly a charge of 13.5gr 2400 is perfectly safe in any .357 Magnum in good condition. It's good to be cautious but relax now and enjoy real magnum ammo you made yourself.
 
You can use common pencils to test the hardness of your lead bullets/alloys. It's surprisingly accurate.
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Take standard pencils and expose the full diameter lead shank about 1/2". Take a piece of sandpaper and place it on a flat table. Hold the pencil 90* to the sandpaper and sand the full diameter pencil shank down until it's flat. Take the flat pencil and hold it at 45*/angled and try to scrap a groove in the bullet/ingot/alloy. If you not scrap/gouge the bullet/alloy go to the next hardest pencil and re-test.
 
There are many signals of overpressure.

1. hard extraction (unusual resistance at the lever when opening the bolt)
2. the extractor "letting go" and leaving a case in the breech
3. a severely flattened primer (but any stout safe load will flatten it somewhat)
4. damage to the case rim or to the spent primer, as in metal that's been blown through or torn away
5. unusually swollen fired cases (swollen where not supported by the barrel)
6. brass displaced into the barrel's extractor cut-out
7. stock cracks near the tang

That's all I can think of at the moment. Muzzle flash, hard recoil and loud report may also be consistent with a too-hot load, but are subjective and not necessarily signs of overpressure.
 
Joseph Dawson said:
What pressure signs should I be looking out for?
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There are none. Despite decades of people trying to apply bottlenecked rifle rules to revolvers, there are no reliable pressure signs to look for. Sticky extraction can have any of a number of causes. Trust your data and verify over a chronograph.
 
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