So I get back home finally and look at the other box of bullets I have left and guess what I find...Lands and grooves. So it is a factory crimp as stated. Guess if I shut up and listen I might learn something. Thanks guys.

I think I will take it to the gunsmith tommorrow and get a chamber cast. It doesn't make sense that it is land and grooves since there is no problem closing the bolt. Thanks for the ideas and keep them coming. This is way out of my league but unfortantly the type of things that keep happening to me. (The strange and unusual.)

It sounds like the barrel has no throat/leade. Time for a chamber cast.

George

It's not the factory crimp. You can clearly see lands and grooves from the mouth back for about 1/16th an inch or more.
The gun is a 270 WSM in a MRC action and barrel. Ammunition is 150 grain power point factory Winchester. Three shots went into around on inch or a little more. Was not difficult to load or extract. No pressure signs on the case. This box had been shot before without noticing these impressions. Same accuracy.
Nothing unusual about the reloads other than not finding a good recipe yet. 130 TSX over 70-72 (for today's testing) grains of magpro without pressure signs. Horizontal stringing out to three inches but vertical of an inch or less. Most importantly, no signs of lands or grooves engraved into the case neck.

Mike - Without more information it's hard to say positively but I'm gonna make a guess. Could it be that you are seeing the remains of a factory crimp? Many factories use what is called a segmented crimp, that is, it is not continuous around the mouth but does have the appearance of high spots and low spots or, lands and grooves. Look at one of the loaded rounds and see if it does have the segmented crimp. If not, get back with more info such as caliber, brand of ammo, rifle, etc.

Ray

I recently shot some factory ammunition and noticed that there was lands and grooves impressions left on the last bit of the neck. I would say about a sixtenth of an inch. I have fired this same box without this problem before and also shot some reloads today. Does anyone know what or why this happened? Is it dangerous?