Myth Busting 9mm R-P "thin" case wall notion

[9mmepiphany]

(Note rounded rim edge of R-P "." headstamp brass)

I remember when I first ran across their rounded rim and thinking, "I wonder how they got worn like that?"

Just curious, do you know if there is a benefit/advantage to that rounded rim...The only thing I could come up with was to offer less "shock" to extractors when folks would load chambers by dropping rounds into the chamber rather then feeding them from the magazine

 

[LiveLife]

(Note rounded rim edge of R-P "." headstamp brass)

I remember when I first ran across their rounded rim and thinking, "I wonder how they got worn like that?"

Me too. I also went, "Wow, that's some worn brass" until I saw that they were all like that and brass looked new with sharp inside rim.

Just curious, do you know if there is a benefit/advantage to that rounded rim.

I am not sure exactly.

If you look at the comparison picture above, some newer headstamp brass put a bevel around the rim edge to likely help extractor get over/around the rim and Remington put smooth rim edge. I think if beveling/rounding of rim edge was meant to help with extractor, both would accomplish the job instead of being a 90 degree abrupt rim edge.

It sure makes it easy to identify the R•P "•" headstamp brass though.

 

[longdayjake]

So during the panic buying years Federal/Blazer/CCI/Speer were making such thin cases that people were having really bad setback issues with our bullets. Actually, I think it was a combination of thin brass and a certain brand of dies that was advertising "Looks like factory ammo" dies. What happens when you have really thin brass and dies designed to only size a casing down to the bare minimum amount? Bullet setback. Based off of your numbers it looks like R-P cases are right in there with the Vista Outdoors cases as far as being the thinnest. So, I think that is how the myth started. It was a die issue. Oddly enough, most guys immediately assume the bullet must be the issue when it's the only thing with any kind of diameter consistency.

 

[9mmepiphany]

Oddly enough, most guys immediately assume the bullet must be the issue when it's the only thing with any kind of diameter consistency.

We should hunt them down and beat them about the head and shoulders with sticks

It is pretty amazing that they would blame RMR bullets as they have been the most consistent bullets I have ever used. The only time I use other bullets is when RMR doesn't make that in-house bullet...but I am waiting patiently for a .452" 200gr SWC

Sidebar: my credit card screams whenever you add "seconds" to the site...they have really worked great (another 4k on the way as we speak )

 

[MarshallDodge]

For a while I was sorting my 9mm brass by WIN, FC, and R-P headstamp. I never saw any difference in reliability between them, and was shooting over 500 rounds a month at that time.

 

[LiveLife]

When RMR decided to sell their own headstamp branded 9mm brass, I thought it would be good to update the "Myth Busting Neck Tension and Bullet Setback" thead with RMR and other newer headstamp brass like SIG (Sig Sauer)/DRT (Dynamic Research Technologies)

So when I received the RMR branded 9mm brass order, I start data collection for part 2 of "neck tension and bullet setback" and measure 9mm brass at 4 points (12/3/6/9 o'clock) with additional headstamp brass to include RMR at .100"/.200" below case mouth.

But after data collection over several weeks part time after doing wife's "Honey Do" list of project chores, I get ready to do bullet setback test using Glock 22/23 and KKM conversion barrel I previously used and my darn Chromebook decides to do an update and BAM ... my new thread data is GONE. (I should have backed up the draft data on Google cloud ... )

So stay tuned as I redo another myth busting thread on neck tension and bullet setback.

BTW, I was able to post initial measurements of new RMR headstamp 9mm brass on the "Best 9mm brass" thread compared to Starline brass measurements for comparison (Only new data saved due to THR posting ... And FYI, I already asked @longdayjake if Starline made RMR brass and answer was "No") - https://www.thehighroad.org/index.php?threads/best-9mm-brass.918907/page-2#post-12642215

Thickness .100" below case mouth where taper crimp is applied:​

​

RMR: .011"/.011"/.011"/.012"​

RMR: .011"/.011"/.012"/.012"​

RMR: .011"/.012"/.012"/.012"​

​

Starline: .011"/.011"/.012"/.011"​

Starline: .013"/.011"/.010"/.011"​

Starline: .010"/.011"/.011"/.011"​

​

Thickness .200" below case mouth where 115 gr FMJ bullet base gets seated down to:​

​

RMR: .012"/.012"/.012"/.013"​

RMR: .012"/.012"/.013"/.013"​

RMR: .012"/.013"/.013"/.013"​

​

Starline: .012"/.012"/.013"/.012"​

Starline: .012"/.013".012"/.011"​

Starline: .012"/.012"/.013"/.013"​

​

​

 

[GeoDudeFlorida]

No disagreement regarding R-P 45ACP brass. Now that Alliant/Federal/CCI/Speer bought Remington Ammunition, perhaps that will be addressed.

But this myth busting thread is about 9mm case wall thickness and I have presented my objective, measurable, repeatable data along with bullet setback measurements to bust the myth that 9mm R•P/R•P "•" headstamp brass has thin case wall. (Thank you @Atavar for the "•" )

I’m the exception. I haven’t had problems with any brand of brass. Some may require more work or more attention to detail - some are really best used being converted to something else - but I haven’t had to toss any brass except what I ruined on the lathe reshaping them. Maybe it’s because my standards for shiny, pretty cartridges are lower and my degraded eyesight means I’m not as picky about accuracy.