Shot my first ten handloaded rounds this weekend. Goods news is they all fell within 1.25"....but examining the cases after firing I am wondering if I may have done something wrong in the process. The cases seem to have a larger than normal amount of powder burn around the neck, not just near the case mouth. The load was a standard (I actually loaded it down a bit) load. The rifle is a Sig 270, the case is Winchester, CCI large primer, 51g of IMR 4350, Hornady 130 SP (2730). Any info on what the beginning signs of overpressure might be and if I should be concernced about this would be much appreciated.

Thanks
Brian

[QUOTE]Originally posted by bjk:
[B]. The rifle is a Sig 270
B[QUOTE]

Isn�t that a Sauer rifle with the locking lugs at the rear end of the bolt? It locks the lugs into the rear bridge. Here in sweden most handloader prefer not to use these rifles, as the bolt flexes slightly backwards at firing. This causes the cases to lengthen a bit and shortens the life of them. Perhaps that little movement is reason for the burned powder around the neck.

Yours,

Fritz

[This message has been edited by Fritz Kraut (edited 11-05-2001).]

Depending on how hard the brass was it's possible that your cases didn't expand to fit tight against the area of the case mouth.
This can happen with a combination of light loads and brass that's hardened some. Also, make sure you have no oil left in that area after cleaning. It's been my experience that slower powders like 4350 will burn cleaner and more consistant at closer to
max loads also. Someone else may also chime in with other ideas I have missed.

Powder residue around the necks and down toward the shoulder is a sign of low pressure. The brass has failed to fully obturate and seal off the throat from chamber gases. Not a dangerous condition. As the previous writer says, it could be in part due to harder than average necks.

Pay no attention to the theory that the rear-locking bolt is at fault. (I, too, prefer front-locking bolts, but this is not the source of your smudged cases.)

Ditto Stone Creek - Brass thickness around the case neck, hardness of the brass, chamber dimensions, and pressures all come into play. The best place to begin looking for pressure signs is the primer; that's assuming you don�t have a heavy bolt lift, etc. If you are on the low end of the pressure & load curve, powder residue is caused by blow by before the brass conforms (obturates) to the chamber. This is no big deal, however, could be a sign to anneal your case necks. If your cases are unusually tough or work hardened, annealing is the best solution.

bjk __

Another thing to consider is that the pressure is reducing at some point before the bullet leaves the barrel and is too low to keep the case mouth in close contact with the chamber walls allowing some "smut" to enter the gap and foul the neck. It "de-obturates" prior to the bullet leaving the muzzle.

All of the factors described in the above posts will have some effects on this condition.

Good shooting.

Robert

I will echo the others. While I think IMR 4350 isn't the best propellant in the 270 Win with 130 grainers, 51 grs. of any of the 4350 series is a fairly mild load.

Yeah, any rear-locking bolt action will flex a little more than a typical Mauser-type front locking bolt, but I think the situation you describe is mostly because of fairly low pressure.