Powder burns on reloaded casings

[cpapastr]

On my first batch of hand loaded 9mm, I noticed all casings had powder burns around the mouth. Can anyone tell me if this results from the load being too hot, not enough crimp or is normal for hand loads. Thanks!

Need more input:
I increased the powder load and burns on the casing worsened. Here are my specifications:
9mm, 115gr. Ranier copper-plated bullet
Mixed headstamp range brass
Bullseye powder--Speer guide shows minimum load at 4.2gr., maximum at 4.7gr--First batch I used 4.4; second batch was 4.5gr.
OAL per Speer is 1.135 (range was 1.134 to 1.137
Case mouth after crimp was .378 and base was .386 (these are the same as factory S&B and PMC)

Powder burns are extensive (slightly more at the 4.5 load) but concentrated mostly to the left of a scratch in the base of the case running lengthwise (I assume from the extractor). Some of the burns turn the brass to a nickel color near the mouth. On some cases there are multiple scratches on both sides of the burn on the base of the case running lengthwise and on some there are also small lengthwise scratches 2/3 of the way to the mouth.

I've shot the loads in a G17, G19 and Kahr K9 with the same results. At this point, I'm wondering if I need to increase the crimp or lighten the load. My search of Web forums yielded the same advice as members below. Any further thoughts would be appreciated.

[ray1970]

I'm going to say its pretty normal. If anything, the pressure is a bit low causing the case not to expand sufficiently to seal to the chamber.

Hopefully someone more knowledgeable than me will come along shortly.

[Jamnanc]

Mine do too. Seems worse with dirtier powders. That's what the tumbler is for. Plus your probably paying way more attention to the fired cases than before so you notice soot you didn't before.

[spqrzilla]

Dark soot along the case usually means that a load is not fully obturating the case. In other words, low pressures. But it depends on the powder, bullet weight etc. If the load isn't on the light range, then if the velocity is irratic I'd up the crimp a bit.

[SA Friday]

See this a lot in fast burning double based powders that generate a lot of heat ------- Titegroup

Normal.

[spleify]

Yep pretty normal

[Zombie Steve]

Yep. Not running enough pressure to seal the brass up in the chamber. If everything else (i.e. load data) makes sense, take 'em up a little hotter and you'll see it go away.

[cpapastr]

Thanks all!

[cstone]

I get it in .40 with Power Pistol. I've never worried about it. The rounds are hot enough to cycle all of my semi-auto pistols and my Kel Tec Sub2K.

[cpapastr]

Casing burns increased with an increased load. Specifications are included in the edited first post above. I'd appreciate any further insight.

[Zombie Steve]

I definitely wouldn't crimp more. It's pretty easy to put a crease in a plated bullet. I generally get away with a taper crimp at .380". Your gun might require a little more.

...and a tenth of a grain of powder probably isn't going to make a bit of difference.

You might try a different powder... something in the medium burn rate range like Unique. Bullseye is one of the fastest out there.

If it runs the gun and it's getting where you want to be in terms of accuracy and velocity, I really wouldn't lose any sleep over it.

[cpapastr]

Thanks Steve!

[paddywagon]

It is very normal. I find that it seems to depend on chamber as to how much. I have a 9mm Colt subgun that the cases are half black when ejected and on several of my HK pistols there is very little discoloration.