Yesterday I tried a new to me powder, the Norma RP-15, it's the sporting version of Norma MRP.
I used 56 grains of the powder, the listed starting load for MRP, and some 150 grains Norma semispitzers that have been laying around. R-P cases and Remington LR primers. I usually end up a grain under listed max with MRP and my box of RP-15 seemed slightly faster with the only pressure sign a flat(ish) primer.

The problem was quite a bit of soot on the throat and a couple millimeters down on the shoulder. I often get some soot on the 270 cases but not this much. My theory is that the brass is the same as 30.06 or 35 whelen, and the smaller caliber leave more metal in the throat.

What can I do to get rid of my problem?

I do not have any neckturning equipment, I dont want to increase the load and I dont have another powder suitable for the 270.

Cases were necksized and used maybe 7 times with a couple of full sizings. Have they hardened?

No, its just a low pressure load. Seven loadings with full-house 270 data would probably bethe end of the case life due to loose primer pockets.

I don't think there is much you can do if you don't want to raise pressure and it isn't hurting anything except cosmetics.

If you are getting soot on the neck and shoulder of the cases after firing them you either have a very low pressure load that is not exerting enough pressure on the neck of the case to form a proper seal between the case neck and the chamber or you have some cases with very hard necks that are not forming a proper seal or a combination of the two. You say the cases were fired approx 7 times. I would bet the necks are too hard. Anneal the necks and your problems will disappear.

As a mtter of discussion and not saying that's wrong, wouldn't there be some neck-splitting if the brass were that hard?

I suppose one easy way to find out is to buy a box of new brass or factory ammo and try the load on them.

Tigertate,
Maybe, but not necessairly, these things are not written in stone..

In 99% of these cases however it is a low pressure load, or the use of an improper powder..

By the same token if he heats that load up and the necks are hardened, then he will almost surely get some split necks..

As yet I don't have any definitive test data but there are indications that cases with excessive lube will allow gas between the necks and the chambers. This is more pronounced with lite loads and dirty powders like WCC846. This may be a Bardahl negative. Oh my** roger

Yes the cases are on their last trip to the range. A friend is borrowing the gun for his first moosehunt and the ammo was meant to give him some extra training at the range. I have one time fired brass and 160 gn partitions for the hunt. I'll load some of them to see if the problem is in the cases.

I dont think pressure is low since the primers are as flat as they are and MRP is the ultimate 270 powder. I have had oversized primerpockets and one big bang with gas in the magazine and 270 win etched into the face of the bolt earlier. Its either a fast barrel or a tight chamber because I get around 100 fps over reloading manual listed speeds, probably the last since I end up below max. listed loads. I dont have a chronograph at the moment to check these loads.

I'm not really happy with the primer reading method since I find the readings differ so much from gun to gun, in the 375 H&H I get extractor marks and brass shavings with no flat primers.

quote:

Originally posted by Atkinson:
Tigertate,
Maybe, but not necessairly, these things are not written in stone..

In 99% of these cases however it is a low pressure load, or the use of an improper powder..

By the same token if he heats that load up and the necks are hardened, then he will almost surely get some split necks..

That's what I was figgerin. If the pressure is high and the brass is hard, neck splits are almost a given.

MRP is not necessairly a great powder for the .270, its a bit slow and that may be your problem..

If you have it try IMR or H 4831, RL-19 or IMR 4064 and you won't have that problem..If you blowing primers, you had better back off..

900 SS ----- Some powders leave much more soot in the throat than others. Good shooting.

+1 Aneal

All good advice above.....

I tend to what Ray is saying though, anneal the necks and try a "quicker" powder. Manuals offer all sorts of data for powders with so-called similar burning rates and actually IMR or H-4831 is one of the all time favorites in the .270 Winchester.

I finally got to the range again. With 59 gn MRP , one time fired Norma cases, rem large rifle primers and 160 gn Partitions the soot problem almost disappeared.

The new "problem" is that I only got about 2" groups with the Partitions and the other "soot" load kept under 1". Not much of a problem for moose and under 100 meters anyway. I wont try to solve that this season.

The 225 Accubonds in 35 Whelen also kept around one inch. I dont think I'm capable to shoot better without a better rest. I'll try those for moose, but I'm worried the bullets are a bit to light for caliber on moose. Hopefully I'll post a happy report sometime in october.

Personally I don't anneal brass, after it reaches that point, especially in the common calibers like .270 wherein brass is cheap, I just toss them and start with the new stuff..Annealing is a inexact science anyway.

+1 H4831!