powder position vs chamber length?

[labnoti]

I've been getting some wide spreads on velocities with .38 special even when meticulously weighing the powder for each case. I've seen some data that indicates the .38 special is sensitive to powder position. We understand the .38 was originally a black powder cartridge, evolved through the .38LC for the 1851 Navy conversions. So the result is we have a long case that is only partially filled with most modern smokeless propellants.

I'm also seeing less velocity than I want from +P loads. I'm wanting to load a little hotter than .38 +P maximums, but would want to use a .357 rated gun.

The question is, is it better to use the short .38 case and fill it fuller, or go to the longer .357 case and have it still half-empty?

I understand for the factories, the longer .357 case was the answer to prevent a high pressure magnum load from being used in a standard .38 pressure gun. I have no such concern to "idiot-proof" loads for my personal use. But I wonder if it's better to have a long case that fits the cylinder relief better, or a short case that is easier to drop into the cylinder and which holds the powder more consistently, but fires the bullet past the relief ring in the chamber. Has anyone demonstrated problems with .38's in .357 magnum cylinders?

 

[Alaskan Ironworker]

It would personally make me nervous loading high pressure loads in a case that could fit in a low pressure gun. Its literally an accident waiting to happen! What if you forget? What if your kids or someone else uses it? Just things i coukd see happening to me! I always think about if i died tomorrow, what would happen to all my guns and reloads. If you want .357 power loads out of your .357, theres powders out there that will fill the case.

 

[labnoti]

.357 cases also take a longer ejector rod that pocket/ankle guns don't have, so the ejection is dodgy. I should have made it clear my question is specific to small j-frames. Because the short barrel, loose cylinder gap etc. conspire against .38 special performance on the j frame, the .357 models offer the promise of handling more pressure to make up for the shortcomings. But the .357 case length comes with drawbacks of its own.

Bulky powders won't be the answer. There are not enough powder choices to deliver the performance on all the criteria - pressure, velocity, muzzle flash, burn rate etc. - to add that one also. Loading full magnums could address powder position problems in .357 magnum cases for the platform in general, but again this is pertaining to airweight/airlite J frames and what would be light magnum loads, just above .38 +P

My research thus far indicates that velocity spread due to powder position is a bigger deal than the comparatively small problem with additional free-bore using .38 cases in a .357 gun, but I've done no testing.

 

[Alaskan Ironworker]

I should add; Free-bore has not been an issue for accuracy/velocity in either my Taurus raging judge .454, or my standard judge .45 colt, and they have about as much free-bore of any revolver out there.

 

[243winxb]

The question is, is it better to use the short .38 case and fill it fuller, or go to the longer .357 case and have it still half-empty?

The lead wadcutter bullet is made to fill the case, but not with +P loads. A more full 38 would be better, if its not a position sensitive powder.

38 special is sensitive to powder position.

Walkalong has threads on the subject in the reloading section. Try a search.

Some powders are worse then others. Has a magnum primer made any difference in your 38 spec? Ball powders need a mag primer.

 

[Zendude]

If you’re looking to load hotter than 38+P, I would go with 357 mag brass. The powder position should only be an issue if you’re wanting soft loads. If you’re loading regular strength 357 mag and still having velocity inconsistencies, then maybe try a different powder.

 

[labnoti]

I have only used small pistol magnum primers so far in testing, Remington 5 1/2.

I am specifically looking for a soft .357 magnum load or what could also be described as a .38 Special +P+ for .357-rated airweight/airlite j-frames. The question is whether to use .38 brass or .357 brass.

I've tried more than one powder, and I'll post the details in the reloading section later. For now, I'm looking for what direction to go in revolver and brass-wise.

 

[ATLDave]

Do you even chrono, bro'?

Joking aside, what kind of velocity spreads are you getting in the .357 case that has you concerned?

 

[Walkalong]

Any load that has a big velocity loss powder forward vs powder back will suffer the same fate in .38 Spl cases. Some powders are better than others and the operating pressure makes a difference.

My default advise is always to not load .38 Spl cases over +P .38 pressure. Never know what they can end up in when you are not control of them, and at some point in time that can happen.

So, that aside, I am serious that using .38 Spl cases for .357 loads with erratic velocity due to powder position won't help enough to notice. I have done a lot of powder back vs powder forward testing in .38 Spl and .357 cases. There is so little difference in the case length it simply doesn't help enough to worry with.

 

[labnoti]

Yes, I chrono. I'll post results later, hopefully today, because I'm waiting to get a box of factory hollowpoints for reference first. I don't have data for .357 brass. If I had all the data, I wouldn't need to ask. It's simple, I ask because it's easier than spending money for .357 brass and a couple days work loading and testing, if I'm only going to find out that the result is too powder-position sensitive.

 

[ray15]

I load some 38 special cases that are only 0.750" long. And although accuracy has not been hard to find, strangely enough I've not been able to get the Sd as low with the short cases as I have with full-length 38 cases. The best loads I've chrono'ed with the short case have a Sd over 20, where the +p max loads of Titegroup or BE86 in an unaltered 38 special case are in the 11-12 range. 38 special is strange beast, and I'm not sure I've tried a really good powder for it yet. Walkalong's True Blue experience is good, and I've also got my eye on the Shooter's World 'Auto Pistol' powder which appears, name aside, to be very well suited to 38 special. It's described as being like AA#5, but the load data looks better suited to 38.

Even more than most calibers, I'd like to know what sort of powder factory 38 special ammunition uses. I'm pretty sure something like BE86 is about optimal for 9mm luger but don't really know how much it leaves on the table in 38.

 

[PO2Hammer]

I am specifically looking for a soft .357 magnum load or what could also be described as a .38 Special +P+ for .357-rated airweight/airlite j-frames.

Best done in 357 brass.

Bulky powders won't be the answer. There are not enough powder choices to deliver the performance on all the criteria - pressure, velocity, muzzle flash, burn rate etc. - to add that one also.

Says who?
Unique does exactly that for me. It's the perfect fuel for 38+p+ power in 357 brass. N340 and HP-38 also work very well to and all 3 are not very position sensitive.

 

[labnoti]

"In our testing, standard .38 Special ammunition had consistency issues that we noted, due to the powder forward/powder back dilemma," Federal Premium Product Manager Justin Johnson said. "We were getting inconsistent pressures and velocities, and that could easily translate into a bullet not doing what it was designed for."

Federal's solution was to reduce case volume by seating the bullet deeper. Their solution was notably not to use an even longer .357 magnum case.

 

[Walkalong]

"In our testing, standard .38 Special ammunition had consistency issues that we noted, due to the powder forward/powder back dilemma," Federal Premium Product Manager Justin Johnson said. "We were getting inconsistent pressures and velocities, and that could easily translate into a bullet not doing what it was designed for."

I have had the same issue with trying to get a safe .38 Spl load with the 135 gr Gold Dot. The trouble is having all shots at/over the velocity threshold.

For example, and the best one yet. True Blue, but over book max. - 135 Gr GD
4" Model 10 HB
6 shots each
Powder Back Powder Forward Powder Level
HI 936 887 903
LO 844 826 828
AVG 903 847 869
ES 92 61 75
SD 32 24 25

Max, but not over, charge of 3N37 - 135 Gr GD
4" Model 10 HB
6 shots Powder Back Powder Forward Powder Level
HI 929 724 758
LO 873 640 677
AVG 893 680 732
ES 56 84 81
SD 21 29 29

 

[Jack B.]

I only load brass to levels that match the head stamp. 38 special never get loaded to +P or .357 Magnum levels. I think it is dangerous to load to higher levels than the max for the head stamp of a particular cartridge. Confusing them could be disastrous to you or someone else getting the improperly loaded cartridge. It's a rule that I impose upon myself.