So I recently took a chance on a Kimber Montana chambered in .270.

I bought from a good buddy because it was a known shooter, and in that regard it has not disappointed. Its groups 145 ELDs at 3/4 MOA. It also carries like a dream, which is nice because I'm about 30 lbs past my fighting weight and the country I hunt has about 3,000 feet of elevation on a given day (Hells Canyon). It also accounted for a decent little buck a couple of days ago...


I digress however.

It was scratching the bejesus out of the brass until I sacrificed a round and cycled it through a couple of hundred rounds, which helped immensely. Today though, I noticed that it's chopping off the tips of the ELDs when feeding from the magazine. Any suggestions on what to modify to remedy the situation short of seating deeper? I don't want to change the seating depth as I'm terrified to lose the considerable accuracy.

After looking at the photo a little closer, now I'm wondering if it's just being flattened by being "mashed" into something while it's feeding?...

Looks like the tips are just deforming in the mag box under recoil...

^^^^^^^
This!

You're right, I grabbed the wrong bullet for the first photo. That first photo was one from the magazine when I shot the buck.


The one on the left hasn't been cycled through the rifle. The one on the right was cycled from the magazine, and deformed the tip if ever so slightly and it has NOT been in the rifle while being fired. This photo better shows the "chopping" of the tip effect I was alluding to in first post. Maybe it doesn't matter, it just doesn't strike me as ideal for accuracy?....



Dave

Mine was doing the same w/150LRAB's. I ran them in another .010 deeper. No trouble maintaining accuracy and now they cycle without beating up the tips.

I don't know about your Montana but Mrs Blacktailer's Super America is not generous with magazine length. If I try to set COL by spacing off of the lands, it is a single shot because the loaded rounds will not fit in the mag much less cycle. Try setting COL a little shorter as horse1 said and you will probably fix the problem.
BTW where are your loads as compared to max OAL spec?

My Forbes 270 doesn't care too much about seating depth. Maybe your Montana won't either. Worth a shot anyway.

If there are no other obvious solutions I'm missing, I guess I'll just seat them a little deeper and see what the rifle tells me.

Dave

I'm going to hazard a guess. They are either getting slammed on the bottom or top of the chamber in feeding. Feed slowly and watch.

If they are getting slammed on the bottom look up the threads on how to modify the ejector for .223ai. You reduce the underside slightly so the rounds ride higher. Which in turn helps them feed straighter.

That's what I would be doing.