Mystery stuff

16 May 2011, 07:23

Antlers

Mystery stuff

Ok, this is a new one for me. I've loaded some 300gr HDY FPs in my Heym 450/400 and they shoot to the same POI as my 400gr DGX loads.

Now the mystery - after shooting alot of these I noticed on picking up the brass that there were small squarish black spots embedded into the brass. The spots scrape off with a fingernail and they're very thin, but leave indentations. What is this stuff? My first thoughts were cellulose from the powder, but if that's it, why is this happening and how do I fix it? Never seen this before, but I bet some of y'all have.

16 May 2011, 17:28

MacD37

quote:
Originally posted by Antlers:
Ok, this is a new one for me. I've loaded some 300gr HDY FPs in my Heym 450/400 and they shoot to the same POI as my 400gr DGX loads.

Now the mystery - after shooting alot of these I noticed on picking up the brass that there were small squarish black spots embedded into the brass. The spots scrape off with a fingernail and they're very thin, but leave indentations. What is this stuff? My first thoughts were cellulose from the powder, but if that's it, why is this happening and how do I fix it? Never seen this before, but I bet some of y'all have.

Antlers, this sounds like the chamber pressure is not enough with the 300 gr bullets to expand the case fast enough to avoid unburned powder blowing back between the case walls, and the chamber walls. Just a guess on my part, however!

....Mac >>>===(x)===> MacD37, ...and DUGABOY1
DRSS Charter member
"If I die today, I've had a life well spent, for I've been to see the Elephant, and smelled the smoke of Africa!"~ME 1982

Hands of Old Elmer Keith

16 May 2011, 20:51

degoins

I've had unburned powder stuck on my cases like that.

16 May 2011, 21:44

quote:
Originally posted by MacD37:
quote:
Originally posted by Antlers:
Ok, this is a new one for me. I've loaded some 300gr HDY FPs in my Heym 450/400 and they shoot to the same POI as my 400gr DGX loads.

Now the mystery - after shooting alot of these I noticed on picking up the brass that there were small squarish black spots embedded into the brass. The spots scrape off with a fingernail and they're very thin, but leave indentations. What is this stuff? My first thoughts were cellulose from the powder, but if that's it, why is this happening and how do I fix it? Never seen this before, but I bet some of y'all have.

Antlers, this sounds like the chamber pressure is not enough with the 300 gr bullets to expand the case fast enough to avoid unburned powder blowing back between the case walls, and the chamber walls. Just a guess on my part, however!

I agree... I've seen it before with low pressure loads too.

DM

16 May 2011, 21:59

nitro450exp

Hello,

Try a faster burning powder or crimp harder or even use a magnum primer if you aren't already.

Nitro

"Man is a predator or at least those of us that kill and eat our own meat are. The rest are scavengers, eating what others kill for them." Hugh Randall
DRSS, BASA
470 Krieghoff, 45-70 inserts, 12 ga paradox, 20 ga DR Simson/Schimmel, 12 ga DR O/U Famars, 12 ga DR SXS Greener

16 May 2011, 22:11

500N

If you go with a Magnum Primer, start your load development again
as a Magnum primer can be the equivalent of 2 - 3 gs of powder.

I would try a couple of cartridges and crimp them quite hard
to see if that at least stops the blow back of unburnt powder.'

Then go from there.

16 May 2011, 22:50

Bob Nisbet

I'm no expert in this area, but was thinking that if you take cases that were fired with full weight bullet and loads, then only do neck sizing, you may eliminate the problem.
The cases will have been blown out to match your chamber and only doing neck sizing will probably mean the brass will not leave a void for unburned powder.

17 May 2011, 09:05

Antlers

quote:
Originally posted by MacD37:
quote:
Originally posted by Antlers:
Ok, this is a new one for me. I've loaded some 300gr HDY FPs in my Heym 450/400 and they shoot to the same POI as my 400gr DGX loads.

Now the mystery - after shooting alot of these I noticed on picking up the brass that there were small squarish black spots embedded into the brass. The spots scrape off with a fingernail and they're very thin, but leave indentations. What is this stuff? My first thoughts were cellulose from the powder, but if that's it, why is this happening and how do I fix it? Never seen this before, but I bet some of y'all have.

Antlers, this sounds like the chamber pressure is not enough with the 300 gr bullets to expand the case fast enough to avoid unburned powder blowing back between the case walls, and the chamber walls. Just a guess on my part, however!

Hey Mac, this sounds likely. I am using magnum primers, but wasn't crimping - I'll give that a try.

Thanks to all who replied!