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Old May 31, 2013, 11:15 AM   #1
Colorado Redneck
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IMR and Hodgdon 357 reloading data

Why does the data involve a 10 inch barrel? How many 357 shooters use a 10 inch barrel? I was in disbelief for a long time when looking at their web site for load info, and then someone here told us how to view the information about barrel length (hit the print button) and lo and behold, the extreme velocities for revolvers is obtained by using a barrel length that nobody I know uses. That is slightly misleading, to say the least.

I am aware that some silhouette shooters may use weapons like that, but it still seems intuitive that most---75% or more--hand gunners use barrel lengths 8 inches or less---mostly less.

Any insight or thoughts?
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Old May 31, 2013, 11:31 AM   #2
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'Cuz it bumps velocity up to nutty levels & so looks "Mo Bettrer" I guess?
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Old May 31, 2013, 12:03 PM   #3
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I suppose that the original .357 Magnum REVOLVER barrel length of 8 3/8", when added to a cylinder length of slightly more than cartridge length (1.610") looks a lot like 10" in round numbers. So, that may be where the 10" test barrel length originated.

But, even with a test barrel that matches the barrel + cylinder length of a revolver, the test barrel almost always produces higher velocities. Some folks thought that the main difference was the gap between the barrel and cylinder face venting powder gases. Some special "vented" test barrels were produced to try to address that effect. Lyman's manual used to publish some .357 Magnum load velocities from a 4" vented test barrel. But I don't really know if the whole barrel was only 4" long, or if there was 4" beyond the vent.

One reason that at test barrel produces higher velocities than most retail fire arms is that the test barrels are intentionally produced with dimensions that will maximize peak pressure. That means that pressures measured in test barrels will not be exceeded by pressures in guns sold at retail so long as those retail guns are within SAAMI dimensional specs. It also means that the lower pressures in retail guns will prodeuce lower velocities with the loads tested. (However, pressures in revolvers may not be so easy to bound in that manner.)

Some manuals try to give handloaders a more realistic expectation of what velocities the listed loads will produce by shooting them in an example retail firearm after the max pressures have been checked in a pressure barrel. That is helpful, but still not very helpful. The problem is that the velocities of the exact same .357 Magnum loads in various revolvers of the same barrel length can vary by as much as 200 fps, even between two revolvers from the same manufacturer. For a good demonstration of that variability, look at the table on page 771 of Speer Manual #14.

It should also be pointed out that the ACTUAL peak pressures in revolvers can be quite different than what the same loads produce in a test barrel with the same internal dimensions. Speer demonstrated that by making a pressure testing device to replace the cylinder in a standard revolver. The peak pressure in a revolver can actually be higher than in the test barrel. That appears to be due to the forcing cone that is in the revovler, but not the test barrel, even the "vented" test barrel. Sometimes, a bullet will slightly "rivet" in the forcing cone, expanding to more than the cylinder throat diameter where it is not supported by the cone, then getting squeezed down to bore diameter. That is where the pressure may peak in a way that the test barrel does not duplicate.

So, in reality, ammo that meets SAAMI peak pressure limits in a test barrel may exceed that pressure in real revolvers in some situations. From years of experience in measuring pressures in test barrels and designing revolvers to hold-up when the same loads are shot, we have an industry that produces guns and ammo that can be shot without fear of the guns coming apart, even if the acutal pressures in the revolvers are not really known with much accuracy.

But, trying to match test barrel velocities by increasing handload charges above published max loads is NOT safe, because that can produce peak pressures that are above what the test barrels produced, and above what our guns were designed for.

SL1

Last edited by SL1; May 31, 2013 at 12:09 PM.
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Old May 31, 2013, 12:36 PM   #4
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Quote:
I am aware that some silhouette shooters may use weapons like that, but it still seems intuitive that most---75% or more--hand gunners use barrel lengths 8 inches or less---mostly less.

Any insight or thoughts?
Two thoughts:

1- Marketing Toward the Low Information Voter/Headline Only Reader Crowd - they see a ludicrous speed for muzzle velocity, and want that. Product Sold....... much the same way many see the claim of 3,100 f/sec for a .270WIN 130 gr bullet ...... yet their own rifle has a 20" or 22" barrell.....

2-Possibly another case of a niche market skewing the perception of the larger sport- all the obsession with "sub-MOA" hunting rifles is one example. In benchrest or long range target shooting, such precision would indeed be necessary ....... but in 95% of real deer hunting situations, a 4MOA rifle in the hands of a competent shooter will suffice......
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Old May 31, 2013, 02:32 PM   #5
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It is very frustrating. I use Hodgdon and IMR powders almost exclusively and getting realistic data for my 4" .357s is difficult.
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Old May 31, 2013, 03:55 PM   #6
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Try some of the bullet makers data, they seem a bit less effected by length madness. I've seen a few that use 6" barrels in actual revolvers.
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Old May 31, 2013, 04:45 PM   #7
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Quote:
Try some of the bullet makers data, they seem a bit less effected by length madness. I've seen a few that use 6" barrels in actual revolvers.
This.

My Speer, Hornady, Nosler and Sierra manuals all list the make and model, barrel length, and twist rate of the firearm used to generate their data.
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Old May 31, 2013, 05:00 PM   #8
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I can see your frustration, I can even say that it's warranted, but I'm nearly to the point of snickering out loud if you somehow believe you've only now just seen this for the first time and only from Hodgdon.

Wanna stain your shorts? Make a quick run to Alliant's (crappy) web-searchable load data and find some of the velocities they list for .357 Magnum using their Power Pro 300-MP powder.

Now I have some of this powder and I've already made some safe loads with it, but my chrono has been shelved over the offseason. I'm hoping to get some genuine numbers on my next range trip.

I can tell you that I do -NOT- expect to see numbers like the ridiculous numbers that Alliant has published as possible "results" from .357 Magnum loads concocted with 300-MP.

I live in the real world and I'm not a used car salesman... like the guys who publish some of the velocities in some published sources.
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Old May 31, 2013, 09:27 PM   #9
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Quote:
Wanna stain your shorts? Make a quick run to Alliant's (crappy) web-searchable load data and find some of the velocities they list for .357 Magnum using their Power Pro 300-MP powder.

I can tell you that I do -NOT- expect to see numbers like the ridiculous numbers that Alliant has published as possible "results" from .357 Magnum loads concocted with 300-MP.

I expect to see higher numbers than those in my .357mag loads using a 125g bullet. Then again I'm using a 20" barrel so yeah :P


Test barrel length and type of gun(if one was actually used) should always be noted when you're working up loads. To me, it's just another aspect of finding a good, safe, reliable formula. Makes comparing powders a pain though.
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Old May 31, 2013, 10:58 PM   #10
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Most revolvers are maybe 4-6 inch barrels?

From reading many threads here in TFL it seems that most of the revolver shooters use 4-6 inch barrels. There are some that like longer barrels, particularly for 44 mag etc. but the majority seem to favor mid length barrels. Just my observations.

Anyway, shooting rounds from a K frame Smith 357 with 140 XTP bullets that leave the barrel at 1700 fps with 900 ft lbs of energy would be an exciting experience. It never seemed to me that this was realistic, as the old Hornady manual that was my first read about hand loading didn't show loads anywhere near that hot. And factory ammo (except Buffalo Bore) is a far cry from the top loads shown at Hodgdon. Not dissing Hodgdon--I like their products. Just seems strange to publish that kind of data.
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Old June 1, 2013, 05:57 AM   #11
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I have some thoughts

The data offered is always fore-worded with a caveat to "Start low and work up slow"


There are good reasons to follow THAT advice strictly.
My gun is different than theirs.
My tooling is different.
My components are different (even if same exact brand/etc., the lots will be different).
My test environment, and test equipment, is different.

Doesn't really matter what they use.
What matters is what happen with my stuff from my gun(s), ay?
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Old June 1, 2013, 08:58 AM   #12
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Quote:
...getting realistic data for my 4" .357s is difficult.
No it's not. For about a hundred bucks you can get a chronograph and get very good data for your 4" revolver.

Me, I don't worry much about it. I don't shoot handguns so far that +/-200fps makes any difference in trajectory and my target won't know the difference either.
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