Soot on one side of the brass

[jonp]

I've been trying out some 452190's that my acp's don't like as target rounds in my 45Colt BH. Using low to mid-range loadings with both Promo and Unique I'm getting soot on one side of the brass only. The other side is clean. All the powder seems to be burning, no unburned flakes, and no leading. I've tried LPP, LPM and LRP.

Any idea why soot is on one side of the brass only?

[dubber123]

My guess is if you pay attention when you eject one, the soot will be facing to the outside of the cylinder, The 454190 doesn't really have a front band to keep it centered, and I bet they are laying on the bottom of the chamber. The soot flashes over the top side, where there is clearance. Less sizing of the brass, or hotter loads to expand them to seal will help.

[Loudenboomer]

I get the same thing with my 8 gr. unique charge under the 250 Keith in the 44 mag. (Very accurate) I suspect in my case not quite enough pressure to get a tight chamber seal and path of least resistance on the soot.

[BCRider]

I think you're right about the soot appearing along the same area for each chamber. But it could be due to a variety of reasons. One I like is that as the brass springs back in from the chamber walls as the pressure drops that gravity causes the upper edge to open first. The hot gases still in the chamber can then leak along the gap and deposit fouling soot on the outer side.

Cowboy action folks get this a lot. And the lower the amount of powder and pressure the more it seems to happen. I get some with my .38Spl pistol rounds and more with the rifle. Which makes sense because the rifle will hold pressure for longer as the bullet has farther to go.

Next time you're at the range take note of which "clock" of the cylinder the sooting occurs. Then for giggles load up and shoot a cylinder worth "gangsta style" and see if the fouling stays on the outside, which would be basically under the top strap, or moves to the side.

In the case of my 92 the extractor hooks on. If it's holding some pressure that would influence the soot patterning. If it is loose then perhaps it's gravity again.

[bangerjim]

Light loads will cause soot on your brass most times. I have all the time with my 38's and 45LC's loaded on the low end.

You are not getting full expansion of the brass in the chamber.

Nothing to worry about. Just wipe them off! And shoot away.

banger

[Markbo]

Wipe them off? Isnt that what tumblers were for...so we wouldn't have to clean brass by hand?

[bangerjim]

I can wipe off a couple hundred "sooties" a whole bunch faster than tumbling them for hours!!!!! You gotta inspect them anyway, right??????? What better way than a quick wipie down??? Takes only a couple twists of the wrist and they're good to go.

I tumble to get rid of corrosion and darkening, not low-load soot fouling.

banger

[tazman]

I can wipe off a couple hundred "sooties" a whole bunch faster than tumbling them for hours!!!!! You gotta inspect them anyway, right??????? What better way than a quick wipie down??? Takes only a couple twists of the wrist and they're good to go.

I tumble to get rid of corrosion and darkening, not low-load soot fouling.

banger

Very true. I use this procedure myself.

[GoodOlBoy]

yep non-brass expansion, IE not enough pressure for a good seal. Not dangerous, I get it all the time with cowboy loads (as has been said). You can anneal the brass to try to see it a bit less, but the end all and be all is just to go with it. Otherwise you can spend alot of time pulling out hair and gnashing teeth over a bit of nuthin.

GoodOlBoy

[big bore 99]

I agree. Just wipe them off and go. I get it on my 45-70 brass that were light loaded. With smokeless powders, I just throw them in the washing machine with a load of clothes. They come out plenty clean for me. Black powder loads are another story.

[Gastero]

Agree with non brass expansion due to a light load.

[CastingFool]

I have experienced the same issue with my .45 acp ammo. Haven't loaded for it in a while, will have to check my records, and try again.

[w5pv]

A little Kroil on a rag helps to shine and wipe away

[jonp]

I'm wiping them off and using them and I'm not worried about the soot. I get it with low target loads in all of my handguns. I am just interested in opinions as to why it is on one side of the brass only. If, as has been suggested and I agree with, that it is due to low pressure/non-expansion of the brass (after firing I don't have to resize them at all, they just slip right into the chamber) then why is it not all of the way around?

[williamwaco]

I can wipe off a couple hundred "sooties" a whole bunch faster than tumbling them for hours!!!!! You gotta inspect them anyway, right??????? What better way than a quick wipie down??? Takes only a couple twists of the wrist and they're good to go.

I tumble to get rid of corrosion and darkening, not low-load soot fouling.

banger

Ditto. Dampen a paper towel with mineral spirits. ( damp - not wet ).
Pick them up, wipe them, and insert them directly into the shell holder.

You can do this without ever putting the towel down. Takes very little time.

[stephen m weiss]

I wonder if all the powder IS actually burning and not just getting ejected after being heat degraded and busted up good. If you measure the powder flake sizes, what are they? I have never managed to get any Unique or pistol powder, but can do heat transfer scaling from my different powders and see how fast they should be burning away. I have been wondering if all that soot is not just thermally decomposed and condensed powder. Of course powder has to ablate into gas before it can 'burn'. At low temperature, it does something other than burn straight off.

Well, if it is, then reduced case volume will help by raising pressure and temperature and causing a more complete burn. It will also seal the case mouth completely, and cut the amount of powder required. Pressure at muzzle (for the same speed) will be lower so the gun will be quieter.

Oh, what is a high pressure load and speed for Unique and a low pressure load and speed for the same gun and bullet weight? That will tell if the powder is all burning. If it is, then the Ft-lb/grain will be constant at about 63.

[bangerjim]

I'm wiping them off and using them and I'm not worried about the soot. I get it with low target loads in all of my handguns. I am just interested in opinions as to why it is on one side of the brass only. If, as has been suggested and I agree with, that it is due to low pressure/non-expansion of the brass (after firing I don't have to resize them at all, they just slip right into the chamber) then why is it not all of the way around?

You are witnessing the non-linear expansion of the powder. The case is shoved to one side or the other of the chamber. Not much! Just enough to let blowback in around that side of the case. Full loads will general not do that because of the complete expansion of the brass 360° in the chamber.

I have always observed when I resize my light load 38's and 45LC's, there is not much resizing taking place there! Not like a full load expansion.

And add that to this:

And I tend to see it more on the TOPS of the brass in my revolvers (38SPL's 45LC's) due to gravity probably pulling the brass and heavier boolit down and allowing the slight blowback.

We are talking a very teeny tiny itsy bitsy space here. so don't loose any sleep over it! You are not doing anything wrong or damaging your guns. Just shoot them and wipe 'em down. Or tumble them if you have hours and hours to waste.

bangerjim

[fast ronnie]

This seems to confirm what I've been seeing with working up loads for a wildcat I have. (7 x 50r belm) I just finished annealing them and going to step up horsepower. By the way, does anyone out there use this wildcat? Designed by Mike Belm. case is 5.6 magnum necked to 7 mm. I'd like to hear from you if you have any experience with it. (please pm so I don't miss a post)