Polish chamber

[99lover]

Anybody have a decent DIY method to lightly polish the chamber of a Model 99 in 300 Savage? I seem to be getting some sticky extraction at 2500 fps in mid level loads using Hornady 150 gr bullets. Not stuck bad but have to apply more than normal pressure on the lever to start extraction, also some marks on the case body which seems to show some rough areas in the chamber. Primers look fine. Load is 40 gr. of Varget.

[Robinhood]

I have used a shotgun bore mop coated with polishing bore paste like JB's on a cordless drill . Squirt some Kroil in there every so often. Take it slow and easy.

[J.Baker]

I have used a shotgun bore mop coated with polishing bore paste like JB's on a cordless drill . Squirt some Kroil in there every so often. Take it slow and easy.

That method works on guns where you have easy access to the chamber through the rear of the action, but not so well on a 99 unless you pull the barrel off the receiver.

[Mad Dog]

I wonder if you could get one of those Dremel extensions that bend to wiggle in there.

[Robinhood]

That method works on guns where you have easy access to the chamber through the rear of the action, but not so well on a 99 unless you pull the barrel off the receiver.


LOL, Yeah that is a problem. How about an aluminum cleaning rd screwed in from the muzzle end?

[99lover]

Ordered an 800 grit Flex chamber hone for 308 (Midway). Completely disassembled the rifle and used the hone per instructions. It did a great job and chamber looks perfect. However it did not help with the sticky extraction. Using reformed PPU 308 brass I can not go above 39 grains. Just can't get even close to RP 150 gr CoreLok (1614 fps). Best I can do with the PPU cases is about 2400 fps. (39 gr. IMR 4064 with Hornady 150 gr. SST bullets).
I took 5 cases of the reformed PPU cases and 5 cases of RP 300 Savage cases and made some measurements:
The PPU cases hold an average of 50.5 gr. of water.
The RP 300 Savage cases hold an average of 52.2 gr. of water.
RP cases hold 1.7 gr. more water.

The average weight of the PPU cases was 175.5 gr.
The average weight of the RP cases was 158.2.
The PPU cases weigh an average of 17.3 gr. heavier than the RP cases.

Would these differences in case volume and weight explain the behavior of the PPU cases showing earlier than expected pressure signs?

Sorry. This probably should be moved to the Ammunition and Reloading section. If it is a problem maybe the moderator could move it.

[Robinhood]

i commend you on your efforts. Just a couple of thoughts... Back in the day we would try a small base die. If you have a 0-1 mic or decent quality calipers, you could measure the base of the cases and see if previous loads may have expanded the base.

You could also consider annealing your brass if you have several loads with them.

(A Wilson trimmer case holder tells you a lot about your brass after sizing if you know what to look for.)

[99lover]

My desire for a small base die is what started this thread. I annealed the cases after I formed them to 300 Savage. I knew the PPU cases would behave differently from 300 Savage cases, but did not expect them to limit my loads to such low velocity.
I will use these cases and load for practice only. I am going to try and obtain some Win 308 cases and form them and see if they make a large difference.
I sure will be glad when factory 300 Savage cases become available.