Ring Around the Case

[2aBaC̶a̶]

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Or wrap a scotchbrite pad around a cleaning brush.

 

[Smittiac]

Gun Brushes, Rifle Brushes, Gun Cleaning Brushes

Are you looking for gun cleaning brushes? Brush Research offers high quality Flex-Hone® tools to be used as gun brushes, rifle brushes and more. For more information, contact us today.

m.brushresearch.com

Or wrap a scotchbrite pad around a cleaning brush.

Scotchbrite pads are always in my cleaning area lol probably the best thing since CLR for carbon.

 

[918v]

After discovering those other marks on the closeup, I think I should amend my statement to "There were no marks that I could easily see."

On extraction, the case rotates a bit. If it grabs too much after firing, then where it's grabbing would rub against the case. Perhaps the rubbing was occurring on previous firings, but wasn't enough to easily catch (like the other marks).

I'm open to other explanations/theories, but the cut case isn't showing any signs of irregular case stretching, and nothing matching the external marks. The chamber is definitely small (at least .0025 under Saami).

You’ll know soon enough.

 

[Wildbill 2020]

Sometimes imminent case separation is visible that way. Curious to hear what your planned case dissection shows.

That is magunum case I’ve been told not to reload more than 4 times on magunums cause of the stress but I’m 10 years in reloading may be getting weak in that spot instead of above the ring

 

[poppadoer]

When in doubt,throw it out.Life's good.

 

[STLSteve86]

Isn’t there a problem with the saami chamber of the 300 prc to tight? After the 3rd firing the brass is not able to be resized down enough and causing clickers

 

[1moaoff]

That is magunum case I’ve been told not to reload more than 4 times on magunums cause of the stress but I’m 10 years in reloading may be getting weak in that spot instead of above the ring

I think that's older theory than modern. The quality of brass, the load, chamber, sizing and annealing will all play a part in that.

 

[LongRangeAggie]

What was the conclusion? @Rocketmandb

I am having issues extracting some of my once fired brass from my Christensen MPR 300 PRC with not hot loads and get the same marks on brass that you were getting, I'm thinking I have a tight chamber or my RCBS Matchmaster die isn't sizing it enough? Might get it polished and see if that helps. Happens with both ADG and Hornady brass.

 

[Rocketmandb]

What was the conclusion? @Rocketmandb

I am having issues extracting some of my once fired brass from my Christensen MPR 300 PRC with not hot loads and get the same marks on brass that you were getting, I'm thinking I have a tight chamber or my RCBS Matchmaster die isn't sizing it enough? Might get it polished and see if that helps. Happens with both ADG and Hornady brass.

I, and others, have come to the conclusion that there are a number of small reamers out in the market now. Definitively the reamer my smith used on this chamber is small. I've measured brass coming out at .529", which means the chamber was likely cut at something like .530" or just under. I had a custom die built for my last chamber, but even it is not small enough to effectively size. This smaller chamber is causing me to use smaller powder charges to get the same velocity as I did in my last one (new = 73.4 gr of RL 26, old = 74.2 gr of RL 26 to get the same).

Interestingly, the same reamer was used as on my last chamber, but the smith bought a better lathe in between - less wobble - slightly smaller. I'm getting a new custom die made, so not a big deal, but the biggest bummer is that I am right on the cusp of being able to use Berger 245s at the same velocity as the 230s - and the same velocity node. The smaller chamber is the difference maker there, as @b2lee has been able to make his 300 PRC (with its normal-sized chamber) work with them.

I'm wondering if there's anything the smith can do to "polish" .001" back out of the chamber. I think that would get me where I want to be with the 245s.

 

[LongRangeAggie]

I, and others, have come to the conclusion that there are a number of small reamers out in the market now. Definitively the reamer my smith used on this chamber is small. I've measured brass coming out at .529", which means the chamber was likely cut at something like .530" or just under. I had a custom die built for my last chamber, but even it is not small enough to effectively size. This smaller chamber is causing me to use smaller powder charges to get the same velocity as I did in my last one (new = 73.4 gr of RL 26, old = 74.2 gr of RL 26 to get the same).

Interestingly, the same reamer was used as on my last chamber, but the smith bought a better lathe in between - less wobble - slightly smaller. I'm getting a new custom die made, so not a big deal, but the biggest bummer is that I am right on the cusp of being able to use Berger 245s at the same velocity as the 230s - and the same velocity node. The smaller chamber is the difference maker there, as @b2lee has been able to make his 300 PRC (with its normal-sized chamber) work with them.

I'm wondering if there's anything the smith can do to "polish" .001" back out of the chamber. I think that would get me where I want to be with the 245s.

Yeah that's what I'm thinking it was, small reamer from Christensen. I am only pushing the 245s about 2770 with N570 and getting some hard to eject cases with ejector marks when that is way under Berger's load data.

I am going to go by my gunsmith tomorrow and see what he can do, I'll report back.

 

[Rocketmandb]

I am going to go by my gunsmith tomorrow and see what he can do, I'll report back

Please let me know - I haven't called my smith on this as he's in the middle of a major shop move, but I'd like to know what you find out.

 

[b2lee]

What a lot of folks I've talked to have done is...they've taken the last .250" of the chamber and started at +.002 and blended it back in to the normal chamber...effectively giving you an extra 2 thou at the web to help in extraction.

I've had issues ejecting brass lately...but that was due to being 8x ADG and maybe 12x Hornady....so yea....past its expiration date...and instead of being 0.532...it is 0.5325 to 0.533.

 

[clcustom1911]

For some reason, every case from my last range trip has a ring around it. I can't feel it at all, case is smooth. Same location on every case, though a couple are less pronounced (case on right side below). This is the 6th firing of these cases through the same chamber. Never appeared before.

Any ideas what is causing this?

View attachment 7513781

Autopsy. Cut one in half, lengthwise to check for internal stretching. Safety 1st.

 

[Rocketmandb]

Autopsy. Cut one in half, lengthwise to check for internal stretching. Safety 1st.

Did that already - no weak points in the case.

 

[LongRangeAggie]

Please let me know - I haven't called my smith on this as he's in the middle of a major shop move, but I'd like to know what you find out.

Finally got around to getting my gunsmith to re-chamber my barrel. I shot about 10 225 eld-m this past weekend and got a couple that were a little stiff on extraction, so I am weary that it solved the issue. I will load up some rounds and test again to see if it's still an issue.

I am thinking that primary extraction may be the issue, as I have heard that being an issue with Christensen's rifles. Called LRI, who performs bolt timing services, and they said they have 3 of them in right now for that service. So I am going to send it to them and see if that fixes it.

Will report.