strange powder burns on .303B neck

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I ve been working with cast in .303b for the past few weeks now with decent success. But I have noticed that some of the cases come out with powder burns on the neck but only 1/4 of the neck has it and the rest is still clean. would this suggest that the chamber is not aligned properly with the barrel?

im using 17gr of AA#9 behind a 185gr GCed cast boolit made entirely of range scrap. I have also noticed that after a number of firings the necks are starting to elongate at one side more than the other.

Rifle is a 1916 Enfield No 1 MK III* FTR 53

any thoughts would be greatly appreciated
thanks
Jeremy

and now for some pictures

loaded rounds ready for range (tumbled till pretty)



100 yards



burns on cases



The author shooting an SMLE from horse back (not as easy as it looks)

 
That's typical "blowback" from light loads. The reason they are not concentric is because the SMLE extractor pushes the case to one side of the chamber.
 
What's the powder charge loading range for AA#9 in this cartridge? If some are burned and some are not, you must be on the fine line. Can you bump it a half grain? Personally, I've never worried about burns or soot on the neck if it shoots good.
 
Nothing strange about it-it's what Cosmic says in post above.

You can possibly get it gone by tipping barrel upward before every shot.

My range RSO's really don't like when I do this but it's the only way to get even burning and good accuracy out of some of my loads with 2400 powder.

Trail Boss and Red Dot/Promo powders don't do that.


BTW-Neck sizing cases solves that problem too to some degree but you have to fireform those cases well first with say,jacketed loads.
 
17gr of AA9 is what I'm using. No tipping the rifle. CE Harris says the 2400 isn't position sensitive and the AA9 is right next to it on the burn chart. I tried 18gr and 19gr and it doesn't group AS well. Maybe I ll retry the 18 gr or even a 17.5 and see if that fixes it. The strange shaped next is more what I was curious about.

I've tried neck sizing only (with jacketed) and found I got better accuracy with full resizes.
 
Soot on the case necks is, as mentioned, little or no case expansion upon firing. Kind of hard to see in the pictures, but your's aren't as bad as some I've seen. Some look like they've been dipped in a carbon lamp.
Where'd the data come from? Accurate doesn't publish cast bullet rifle loads. At least not in the manual I have or on-line.
The hay burner object to the shot?
 
I ve just been using 2400 data. They're right beside each other on the burn chart. I started on the low end and kept an eye for over pressure signs. Recommended min load for 2400 with this boolit is 17gr. I started at 16 and tried up to 19. 17 gave best results.
 
Since you report that that load shoots good in your rifle I'd say it's not a big deal.

Couple things you can try is putting a small tuft of Dacron filler to keep the powder against the flash hole. Another thing is maybe try magnum primers in that load, the extra spark from the magnum primers may work.

Lastly perhaps apply a slight crimp to let pressures build more before the bullet exits the case.

I must say that I shoot cast in all of my 303's and some of them with Red dot powder do have soot sometimes. Also I have one Mosin that always has some soot on the neck after firing. All of my rifles shoot well with my load cast loads so I'm not really too concerned.
 
Yeah I'm not too worried about it. I've shot about 500 rounds of this load now.
I don't like using Dacron if I don't have to lol adds an extra step. I'm almost out of this powder anyways so I ll have to move on to something else since powder is like unicorns these days.

Oh, all these rounds are crimped using lee factory crimp die.
 
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