Velocity deviation using H110 in 357 revolver

[KenFromNY]

I noticed something interesting this weekend and thought maybe I'd post to see if anyone had any ideas.

I loaded up some 357 mag using H110 and 158gr bullets. In my 17" Henry, (the intended gun for these loads) the velocities were fairly consistent: [Min: 1654, Max: 1691, Std Dev: 18.8] Just for fun, I tried shooting some of the same batch out of my 6" S&W 686. The velocities from the revolver were all over the place: [Min: 1124, Max: 1316, Std Dev: 68.7] And yes, as expected, there was quite a bright muzzle flash from the revolver.

The only hypothesis I could come up with to explain the revolver's poor velocity consistency was that, given H110's relatively slow burn rate, the powder hadn't completely burned up by the time the bullet exited the revolver muzzle and the rate of combustion was variable enough to elicit large velocity deviations. In the longer barrel on the Henry, all of the powder had time to finish burning so the net energy was more consistent.

Anyone else have a theory?

 

[Jdague12]

I think that sounds realistic.

What powder do you like for 686? I reserve the H110/W296 for my Henry and load Titegroup for my 686 4”. Just curious.

 

[redcon1]

Inconsistent roll crimps due to variations in case length?

 

[LaneP]

Not sure but with H110, stay at or above the starting load with a firm roll crimp and good neck tension. With H110, 158 gr Rem JHP and a 6-inch bbl (Ruger Security Six) I am at 1360 fps with 16.2 gr. I chrono'd those some years back for 6-shot average but (doh) never recorded the individual shot velocities. Definitely don't remember anything too crazy though.

 

[AJC1]

I believe you are correct. I stay in the power pistol burn rate area and use mag powder in the carbine. It's worse in my 4"

 

[bigpower491]

I haven't personally chronograph ny loads out of my 6 inch model 83 Freedom, but I'm finding that Accurate 9 shoots better than 296 with 158 XTP. Found that out today as a matter of fact. Next session I'll have to set the equipment up and run em side by side.
But looking at the targets it certainly looks like my better groups came with the faster powder.

 

[Fyrstyk]

H110/WW296 requires a firm roll crimp to get the most consistent velocity. I have found that the Profile crimp die from Lee works really well on my loads in revolvers using WW296 or H110.

 

[cfullgraf]

Yes, uniform case length and a good roll crimp is needed to get consistent velocities out of a revolver with W296/H110.

And yes, W296/H110 has a small powder charge range for safe, effective use.

When I was shooting IHMSA handgun silhouette in the 1980's, my load was 158 grain jacketed soft point over W296. I never grouped them or measured velocities, but hits on the targets were very reliable at all ranges. So, the velocities could not be too variable.

 

[KenFromNY]

Just to respond to a few of the comments:
1. Brass was new Starline.
2. Crimped using Lee factory crimp, 3/4 turn after contact.
3. The lever gun and revolver shots were from the same batch of ammo, so there shouldn't have been any differences.
4. I didn't say in the original post, but these were Hornady XTPs with 16.4gr H110.

@Jdague12: I mostly shoot 38 special from the revolver and also like Titegroup for these.

 

[LaneP]

Ha! I found my hand written individual velocities from my load of Rem 158 gr JHP, 16.2 gr H110 from a 6" Ruger Security Six recorded in Nov 2010. At that time I was hand writing the shot velocities in a spiral notebook, then transferring the average to an Excel spreadsheet. They were: 1358, 1357, 1358, 1352, 1350, 1380.

I also recorded the same load in a 4" S&W 686: 1244, 1239, 1231, 1214, 1205, 1214

 

[WrongHanded]

Magnum primers?

 

[Varminterror]

Have you regulated all throats on the revolver? #1 contributor to inconsistent velocity in a revolver with otherwise solid combustion (mag primers, firm crimp, full cases).

 

[lordpaxman]

I’ve read the powder burns pretty much completely by the time the bullet’s an inch in the barrel. I wouldn’t compare a rifle and a revolver though, the rifle is a relatively closed system where the revolver with it’s cylinder gap and shorter barrel won’t take advantage of all the pressure produced. It’s apples and oranges.

 

[Rule3]

I’ve read the powder burns pretty much completely by the time the bullet’s an inch in the barrel. I wouldn’t compare a rifle and a revolver though, the rifle is a relatively closed system where the revolver with it’s cylinder gap and shorter barrel won’t take advantage of all the pressure produced. It’s apples and oranges.

What I thought as well

The powder is complete burned, just that a long barrel on a rifle allows the gas to remain behind the bullet for a longer period.

A whole heck of a lot of H110 has been used in revolver loads!

 

[n2omike]

H110 likes to be loaded to high pressure. If you aren't near max, it won't burn consistently and your the velocities will be all over the place.

 

[KenFromNY]

Yes, federal small pistol magnum primers. H110 is the only powder I use that definitely requires magnum primers.

@LaneP - Thanks for posting your values. Those are some impressively consistent values. My chronograph might not be as consistent as yours. I just have a low end Caldwell. But it should be close enough. Per your data, and other comments, there doesn't seem to be any reason that H110 can't have consistent velocity in a revolver.