I've been getting some radial marks on my case heads which I think are probably from a bit of metal or grit in a reloading die. I have never seen them on factory ammo but haven't done any extensive testing as range time etc. is difficult so development takes a long, long time. The rifle is a Blaser straight pull so it shouldn't be rotating the case on extraction. None the less I know there is a lot of knowledge on this forum (already posted this on a UK stalking forum) and so thought to post some pictures here and gather opinions. The load is within book max but none the less is the "hottest" load I've used. I picked it because it is accurate, I was working with a lighter load but suspect that the velocity was marginal to be deer legal here in the UK. Hence the move to a hotter load. Anyhow, here are the photos, all comments are appreciated:

My first thought: Check the bolt face.

My second thought: Check the shell-holder.

My third thought: Bad brass???


The primers don't show any signs of pressure...but they ARE marked with a radial pattern. All of them. So is the brass...marked with the same thin radial pattern (not the big scratches...just the minor ones).

You don't mention the reloading press you are using, but if it's any normal single stage press (hornady, rcbs, etc.) then the primer isn't likely to be radially scored that way at all. Moreover, the shell-holder (atop the ram) would be the culprit...not the die itself. The die itself is only affecting the shoulders and side of the brass. Moreover, the shell-holder has a hollow center - it wouldn't cause a primer to be scored as such...

Regardless of the rifle being a Blaser, that's the first place I'd look. It IS conceivably possible you got an unfinished bolt-head that still had machining marks?

Bad brass is my only other thought...but I retract that statement. It's both primers and brass. Primers are replaceable...so there's got to be a force acting against the base of the round.

Oooh, final, but not likely thought (because of how evenly concentric the rings are) - what do you store the rounds in when loaded? Plastic MTM box or something? Is it possible that is the culprit?

My best thought: bolt face.

PS: someone check me on this...but does that primer pocket look like it's cut a bit wrong? My brass has a normal radiussed cut to it...but this looks like it's got a step in it? I'm not familiar with Lapua brass...is it cut that way intentionally?

It is the bolt face at fault. Even if the bolt face rotated 60 to 90 degrees on the cartridge head you would only see the radial mark over 60 to 90 degrees on the case head.

The bolt face is impressing the 360 degree circular lines on the cartridge head and primer and the deeper scratch marks are also impressions from the bolt face. Poor workmanship or a bolt that has slipped through a polishing process.

Thanks for the reply Robert, my concern is over the deep radial "scratches" on the brass and not the radial markings on the primers. I suspect all primers have these but you only see them at this level of magnification/lighting and I'm pretty certain it is a function of the production process.

New brass is fine, and factory ammo fired in the rifle is unmarked so I'm pretty certain that something in the reloading process is marking the brass but I thought to ask here as a "sanity check" just in case someone thinks this might be a pressure problem or similar. There is no smearing of the lettering, as you can see, and I believe the scratching appeared while I was still shooting very moderate loads but I value all comments as I'm a relative beginner at this.

As you suggested I've checked the bolt face and all seems OK plus the fact that, so far, I've seen no marks on factory ammo leads me to think it is more likely to be a function of my relaoding process than of the rifle. However, there might be a flaw in my logic and it occured to me that if my reloads were high pressure then they might be doing something in the rifle to cause the marks that is not happening with factory.

I can't comment on the primer pocket other than to say that it might, again, be a function of the magnification of the photo. It is also the case, I think, that Lapua drill their primer pockets while many other manufacturers "punch" them out as this is, it is said, less expensive. I've no idea if that is true or not but it might explain what you are seeing.

quote:

Originally posted by eagle27:
It is the bolt face at fault.

Actually you might be right eagle27, the fine 360 degree radial marks on the primers can not be seen with the naked eye. The photos above must have approx 10X magnification and so these marks could be machining marks from the bolt face. However, these are not my concern as this is to be expected as all machined metal will have some marks on it no matter how fine. I am more concerned about the deeper scratching on the actual brass head of the case, where the lettering is and, in fact, cutting into the lettering in some places.

Burr on the bolt face. Take apart the bolt and examine with a 10X glass .You'll be able to see and feel a burr causing that deep a scratch. Polish it off .

I'm pretty sure that it isn't the bolt mete just because I haven't seen it on factory ammo. In saying that I don't shoot a lot of factory ammo these days so I will take the glass to the bolt just in case!

MY guess Hot load or Soft brass because factoy does not do it. Coming from the bolt face, i guess??

First, I cannot say for sure what is causing those big scratches in the case head. But from using both a single stage and progressive press, I don't see how the resizing and bullet seating operations could make radial scratches. My guess would be, perhaps, from the manner the case was fastened in a case trimmer, where a burr made the scratch when it shifted its hold.

IMO, those radial marks on the primers are imprinted from the machining marks on the priming button when you seated them in your press. I doubt they are there from the manufacturing process like the 'B' on these CCI BR4 primers.



BTW, being an R93 owner, I know its straight pull action would not make those scratches.

I don't think it is happening in the gun. The theory about spinning or slipping in the case trimmer seems the most plausible among those theories thus far advanced.

The radial pattern in the primers is from micro machining marks in the bolt face. By the tiny size of those marks it is clear that a defect in the bolt face large enough to cause the radial marks on the case head would be visibly obvious.

The bolt face needs to be polished if these marks bother you to much.
I have seen it in other rifles also.

quote:

Originally posted by Stonecreek:
I don't think it is happening in the gun. The theory about spinning or slipping in the case trimmer seems the most plausible among those theories thus far advanced.

By a process of logical elimination I think this has to be the most likely Stonecreek, now I need to do some testing with unmarked brass to see if I can replicate the marks with in the trimming process. Let's hope the real world is working in a logical way!

Thanks to everyone for their thoughts, at least no one said it was a pressure sign of some obscure source.

Be sure to let us know if you discover the cause of these marks.