Interesting 357 magnum chrono results


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TargetTerror
May 12, 2008, 08:20 PM
So I finally got around to chronographing my .357 mag and 38 special loads in my 6 inch 686 and 2 1/4 inch SP101. Here are the results. The chronograph was ~10 feet away from the muzzle. I was using WSPM for 357, WSP for 38. All cases were mixed headstamp, untrimmed, with a heavy crimp from a Lee FCD:

686
38 Special, 125gr Zero JSP, 5.1gr Unique - 890fps Avg velocity, 220 m/e

357 Magnum, 158gr Montana Gold CMJ, 12.5gr 2400 - 1076fps Avg velocity, 406 m/e

357 Magnum, 158gr Zero JSP, 15.1gr H110 - 1175fps Avg velocity, 484 m/e

357 Magnum, 158gr Zero JSP, 15.5gr H110 - 1168fps Avg velocity, 477 m/e


SP101
38 Special, 125gr Zero JSP, 5.1gr Unique - 764fps Avg velocity, 204 m/e

357 Magnum, 158gr Montana Gold CMJ, 12.5gr 2400 - 945fps Avg velocity, 312 m/e

357 Magnum, 158gr Zero JSP, 15.1gr H110 - 1070fps Avg velocity, 400 m/e

357 Magnum, 158gr Zero JSP, 15.5gr H110 - 1045fps Avg velocity, 380 m/e

357 Magnum, 158gr Magtech JSP loaded ammo - 1025fps Avg velocity, 367 m/e


I was surprised at the velocities for the 686. I would have thought them to be a bit higher. I was even more surprised at how little loss in velocity I get out of the SP101 - only ~100fps from almost a 4 inch shorter barrel! That is astounding. The Magtech's are also pretty astounding - they are just about a full-house 357 magnum load, and I will definitely continue to carry them.

I was also surprised at the performance of H110. Because velocity fell off in both guns as I jumped from 15.1 gr to 15.5 gr, 15.1gr seems to be right around max pressure. I'm not quite sure why velocity would actually decrease. I think my crimp was uniform, but admittedly one might have been more aggressive, I don't know.

Final note: try not to flinch when firing a snubbie with a full house load. The metal poles on the chronograph don't like getting hit :)

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Grandpa Shooter
May 12, 2008, 08:49 PM
Good to see some numbers. I carry SD in a Taurus 605 snubbie. They are stout but not uncontrollable.

Doesn't surprise me that the snubbie gives good velocities. Never quite understood why people expect drastic drops.

DWFan
May 12, 2008, 10:36 PM
Having loaded for the .357 Maximum for years, I can tell you that powders can do strange things at or above maximum loads. Velocities can drop, rise or deviate so much that shooting a tight group is impossible. It's seldom that maximum loads are the most accurate loads.

ArchAngelCD
May 13, 2008, 01:37 AM
I was also surprised at the performance of H110. Because velocity fell off in both guns as I jumped from 15.1 gr to 15.5 gr, 15.1gr seems to be right around max pressure. I'm not quite sure why velocity would actually decrease. I think my crimp was uniform, but admittedly one might have been more aggressive, I don't know.
I'm sorry to disagree with you but 15.1gr H110 doesn't produce the Max pressure in a .357 Magnum case. According to Hodgdon you can charge all the way up to 16.7gr H110 with a 158gr Jacketed bullet. Next time you load up some .357 Magnum rounds try a charge of 16.5gr and see how high the velocity is. From a 6" barrel you will get right around 1250 fps yet still be below the new SAAMI pressure standard of 35,000 psi.

TargetTerror
May 13, 2008, 11:47 AM
I'm sorry to disagree with you but 15.1gr H110 doesn't produce the Max pressure in a .357 Magnum case. According to Hodgdon you can charge all the way up to 16.7gr H110 with a 158gr Jacketed bullet. Next time you load up some .357 Magnum rounds try a charge of 16.5gr and see how high the velocity is. From a 6" barrel you will get right around 1250 fps yet still be below the new SAAMI pressure standard of 35,000 psi.

I have to disagree with that assessment. Because velocity actually decreased slightly when I went from 15.1 gr to 15.5 gr, that tells me that I'm at or right around max pressure for this load in both of MY guns. Any other gun, even the same make and model, might be able to handle a higher load of H110.

I also don't know where you are getting your Hodgon data. The manual I have lists 15.6gr as max, Nosler lists 15.9 gr as max, and Sierra lists 16.3gr as max. Some of these loads were with different primers, which might account for the difference. Based on the results I got chronographing my loads, I definitely will NOT be trying higher loads in either of these guns.

JG2000
May 13, 2008, 12:10 PM
I think Arch Angel is getting his data from the Hodgdon web site. They show 16.7gr of H110 as max with a 158gr XTP. I've always had better results from 110 when it was near max or compressed, just seems to ignite better. That may be what your seeing. Was there unburned powder in the barrel after you shot those rounds? Just a thought.

TargetTerror
May 13, 2008, 02:45 PM
Touche. That is very curious, as that is WAY over what any other manual I've seen lists for H110. No, there was no unburned powder in the cases after firing either load. I think (but admit I may be wrong) that the 15.5gr load had slightly flattened primers. Extraction was fine with both loads.

ArchAngelCD
May 13, 2008, 09:45 PM
TargetTerror,
I got those charge numbers directly from the Hodgdon load data site. I know you said the velocities went down when you increased the charge and I have no doubt they did so but if you increase the charge a little more the velocities will go up again. As a matter of fact, these are the numbers I have for different charges of H110 when shot from a 6" M686 using a Hornady 158gr XTP bullet:
15.0gr - AV=1200.6 fps
15.3gr - AV=1196.6 fps
15.6gr - AV=1203.0 fps
15.9gr - AV=1205.2 fps
16.1gr - AV=1241.2 fps
16.3gr - AV=1242.4 fps
16.4gr - AV=1231.4 fps
16.5gr - AV=1251.6 fps
16.6gr - AV=1238.2 fps
16.7gr - AV=1258.8 fps

As you see the numbers can go up and down more than once and while decreasing velocities when a charge is raised is an indication the pressures may be peaking it's not always the fact.

hoptob
May 14, 2008, 12:39 AM
Very nice series, Arch! Thanks for posting. Do you have any explanation why adding H110 does not increase velocity between 15 and 16 grains? Just can't understand how this can be happening.

TT, if you're looking for a hotter factory load, try Rem R357M2. It runs 1130 fps in my SP101 (2.25"). Speer #8 starting 38spl load for SR4756 pushed 158 gr. Rem SJHP to 1160 fps.

Mike

SSN Vet
May 14, 2008, 03:02 PM
unless I can ever spring for a Marlin 1894, I have little interest in hot .357 loads. :p

Bullet
May 14, 2008, 10:18 PM
I bet if ArchAngelCD chronographed his loads again you’d see different numbers. The SD's and ES can be more than some of the differences shown.

ArchAngelCD
May 15, 2008, 01:37 AM
I didn't shoot those rounds. The data came from a very trusted source and I'm totally sure it's accurate or I wouldn't have posted it.

Bullet, I agree SD numbers are important but I don't have them available. I totally agree high velocity means little if the SD is something like 100 fps. I will normally sacrifice some velocity for low SD numbers because low SD will usually produce more accurate ammo. When you get single digit SD readings you know you have found the sweet spot for the ammo/handgun combination you're shooting. (holds true for rifles too)

Ben Shepherd
May 15, 2008, 07:04 AM
Your results are not suprising. Go shoot those through a smith snubbie. You'll see a velocity drop like you were expecting, I'd bet.

Some of us that have put a lot of rounds over chronos have noticed that as a general rule rugers shoot faster than smiths. Just has to do with how they're built.

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