RiverRider
Handloader
- Dec 9, 2008
- 1,436
- 71
I swapped into a Kimber 84M in .243 last summer. It's one of the sexiest little rifles I've ever seen. The first time out it showed me it could shoot, but my handloading development was stymied by extremely difficult extraction.
I'd always stop at very low charges because of the extraction difficulties. I began to think that it was my brass...I'd laid in a bunch of once-fired 7.62 NATO brass, necked it down, turned the necks, and annealed it. The weird think was I could sometimes replicate the stickiness by chambering a case that I had just full-length sized, which led me to begin thinking the case heads has been expanded just enough to give me problems.
I figured I needed some fresh, unfired brass. To my dismay, I could not find any .243 brass locally. Then I decided I should be able to neck down some new .260 brass and it would be no different from fresh .243 brass. I did this, and I was once again confronted with very difficult extraction even with very mild loads (100-grain Partitions ov 42.0 grains of H4831SC).
Polishing the chamber seemed fix it, but by now I am deciding I no longer have any real use for a .243 so I put the rifle up for swap. I figure I'd better make sure the extraction issue is truly resolved. So I cycle five empty cases through it and the difficult extraction once again makes an appearance and I take the rifle off the market.
I sat and fiddled with the rifle for several hours over the next few days and finally concluded that the extraction issue had nothing to do with the lugs, the extractor, or the chamber. I began to suspect the area of the breech between the lug recesses and the feed ramp. Some empty cases would bind the bolt up and some would not, and I began to realize that the bolt face would hold the case head in the same position time after time but slight variations in case dimensions made some cases stick more fiercely than others. It finally dawned on me...
The area I have circled in red was where the problem resided---that, plus the area above it which is not so visible or easily photographed. The tolerances were just a bit too tight (or there may have been a burr, possibly). Honing with a wooden dowel wrapped in 400-grit sandpaper spun slowly in an electric drill took care of the problem. I just got back from the range and fired 18 handloads without experiencing a single extraction problem.
Now maybe I can actually develop a load without always wondering if everything I am firing is too hot!
I'd always stop at very low charges because of the extraction difficulties. I began to think that it was my brass...I'd laid in a bunch of once-fired 7.62 NATO brass, necked it down, turned the necks, and annealed it. The weird think was I could sometimes replicate the stickiness by chambering a case that I had just full-length sized, which led me to begin thinking the case heads has been expanded just enough to give me problems.
I figured I needed some fresh, unfired brass. To my dismay, I could not find any .243 brass locally. Then I decided I should be able to neck down some new .260 brass and it would be no different from fresh .243 brass. I did this, and I was once again confronted with very difficult extraction even with very mild loads (100-grain Partitions ov 42.0 grains of H4831SC).
Polishing the chamber seemed fix it, but by now I am deciding I no longer have any real use for a .243 so I put the rifle up for swap. I figure I'd better make sure the extraction issue is truly resolved. So I cycle five empty cases through it and the difficult extraction once again makes an appearance and I take the rifle off the market.
I sat and fiddled with the rifle for several hours over the next few days and finally concluded that the extraction issue had nothing to do with the lugs, the extractor, or the chamber. I began to suspect the area of the breech between the lug recesses and the feed ramp. Some empty cases would bind the bolt up and some would not, and I began to realize that the bolt face would hold the case head in the same position time after time but slight variations in case dimensions made some cases stick more fiercely than others. It finally dawned on me...
The area I have circled in red was where the problem resided---that, plus the area above it which is not so visible or easily photographed. The tolerances were just a bit too tight (or there may have been a burr, possibly). Honing with a wooden dowel wrapped in 400-grit sandpaper spun slowly in an electric drill took care of the problem. I just got back from the range and fired 18 handloads without experiencing a single extraction problem.
Now maybe I can actually develop a load without always wondering if everything I am firing is too hot!