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No. 4(T) Results with R-P Cases

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Category: Reloading
Forum Name: Reloading .303 British
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Printed Date: December 08 2023 at 5:44am
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Topic: No. 4(T) Results with R-P Cases
Posted By: britrifles
Subject: No. 4(T) Results with R-P Cases
Date Posted: October 09 2022 at 4:52am
Anyone have an issue with R-P cases affecting accuracy?  I would not think so.  Of all the variables affecting accuracy, cases seem to have the least affect, at least I thought so until now.

I’ve been using a batch of 100 R-P cases with my Dad’s No. 4 (T) for a number of years, they probably have about 15 reloads on them now.  I’ve had some great results, but more often than not, I experience one or two fliers in a 10 shot group.  

As a control, I’ve tested the rifle with known good ammo, Canadian Dominion Arsenal DAC 1951 VIIz ball ammo.  This ammo consistently produces 10 shot groups of about 1.5 MOA shot off the bench in this rifle and other No. 4 rifles I have. 

Here’s an example of the group results, first with my match load:  174 gr SMK, 40.0 gr Varget, R-P case, WLR primer, 3.05 inch OAL.  Two fliers (maybe 3) to the right. 

Here’s one even worse, same load. One flier way off to the right. 

Next, the DAC ‘51 Mk 7z.  This is fairly typical for this ammo, sometimes a bit better.  There are ten shots here, one hole is a double. 

These are only some examples, but after shooting many rounds of my match loads with R-P cases and a few hundred rounds of the DAC ‘51, it’s quite compelling, on average, the service ammo shoots much better in this rifle than my match loads with the R-P cases.

I started marking the R-P cases that were associated with the fliers.  My plan is to check the weight of those cases and measure rim thickness to see if they are outliers.  I’m also going to load up some new PPU cases, I’ve had good success with PPU cases in all my No. 4 rifles.  

P.S., here is an example from last year of a good group result with my match load, with the R-P cases, but no fliers.  Group is about 1.5 inches extreme spread.  Shot on the MR 31 target (Mid Range 600 yard target reduced for shooting at 100 yards).  

Posted By: Goosic
Date Posted: October 09 2022 at 8:07am
This might sound weird to you but, I can FEEL and HEAR the difference between a normal round and a flyer and 9 times out of ten that flyer is a result of a ruptured case.  I have Herters, PPU, and a No Name brand of cartridge case that I use for my .303 target shooting sessions and as long as everything is identical, (powder charge weight, powder used, primers, bullet weight and type, and OAL) accuracy stays rather consistent between the bunch. 
Between the Herter's, PPU, and the No Name cases, the No Name brand is as close to what the original cases would have been with the Herter's coming in next and the PPU cases falling in last but having the best overall case conformity of the lot. All of my cases are fire formed to the rifle and my Go-To reloading tool is my Lee Loader Whack-A-Mole kit. The barrel on my Maltby is a 5 groove BSA Shirley made item that was still in its mummy wrap when I purchased it and as of this writing, currently has 550 rounds through it. The cases on the other hand have been used in other rifles in the past until recently and have since been solely dedicated to this one rifle. The three brands of cases have been reloaded at least 10 times now and are starting to show signs of stress. This is where the FEEL and HEAR comes into play. When I am target shooting I will shoot a group of ten shots at a target and move on to the next target after a 15 minute break. Every shot will typically FEEL and SOUND the same, (Recoil&Report).
A ruptured case will intensify both the recoil and report of that shot, throwing that shot high and to the left. I only shoot in small batches of 50 rounds per session and will typically leave that session with an average of 4 ruptured cases and 1 perfect ten shot grouping. For me, it is not exactly about what is the better brand of case but rather how long can I reload that case until it subsequently destroys itself and throws my ten shot accuracy  group off kilter...

Posted By: britrifles
Date Posted: October 09 2022 at 1:25pm
Yes, it’s pretty easy to detect a rupture case when firing by the sound and recoil.  I’ve experienced this with Canadian military cases I’ve reloaded too many times (about 40 to 50).

This batch of 100 R-P cases have only been fired in my Dad’s No. 4 (T), I’ve not used R-P cases in any other No. 4 rifle I have.  I’ve not seen any indications of case web cracks yet with these cases, and no head separations/ruptures. 

I’m planning to use this rifle in CMP Vintage Sniper matches, so I need this rifle to consistently hold the 2 MOA 10 ring with high X ring count (1 MOA) on the MR target at 600 yds.   Hopefully with new PPU cases, this issue will be resolved, it will probably be a year until I have another opportunity to shoot the rifle. 

Posted By: Shamu
Date Posted: October 09 2022 at 5:10pm
Yes I can also feel a dud.
I call them sometimes before the bullet reaches the target at long range!
Other range users look at me like I'm crazy when I shout "ALIBI"
R-P used to be my Go To brand, but no more I'm afraid.
Now its HXP (if I can find them) Or PPU if anyone has any.

Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

Posted By: britrifles
Date Posted: October 12 2022 at 7:05am
I'm glad I bought 1000ish PPU cases a few years back when they were available.  I have several hundred new R-P cases too, but not so sure I want to use them unless I can figure out what is going on with the fliers on the No. 4(T).  

I did measure the rim thicknesses on the ones I marked as a flier, they are running at 0.058 to 0.060 which is on the thin side compared to PPU and military cases I have.  Have to weight them compared to the others.  

Posted By: Goosic
Date Posted: October 12 2022 at 8:06am
Originally posted by britrifles britrifles wrote:

I'm glad I bought 1000ish PPU cases a few years back when they were available.  I have several hundred new R-P cases too, but not so sure I want to use them unless I can figure out what is going on with the fliers on the No. 4(T).  

I did measure the rim thicknesses on the ones I marked as a flier, they are running at 0.058 to 0.060 which is on the thin side compared to PPU and military cases I have.  Have to weight them compared to the others.  
If you feel that you will not use them, I would be interested in purchasing them from you.. 

Posted By: britrifles
Date Posted: October 12 2022 at 8:34am
OK, I'll keep that in mind.  Although it's probably going to be a year before I can get back and retest the (T) with loads using PPU cases.  

Posted By: Goosic
Date Posted: October 12 2022 at 8:57am
No rush. I have pretty much relegated my rifle as a full-time hunting rifle anyways. The 7.62mm Enfield and my .243W Weatherby Vanguard are my Go-To target rifles now...

Posted By: britrifles
Date Posted: October 12 2022 at 9:27am
I think they are perfectly fine for that use, unless your shooting out past 300 yards.  

The annoying thing is that I've gotten ragged one hole groups at 100 yards for five or more shots; then a wide flier.  

I've gone all over the rifle multiple times and all is as it should be.  That fact that it shoots very consistently with 60 year old service ammunition makes me believe the issue has to be with these reloads with R-P cases.  There is always operator error, but I've shot enough of the service ammo to know that the likelihood that I am the source of the flier is pretty low.  

I thought for a while that perhaps the CMk4 six groove rifled barrel doesn't like 174 grain Sierra Matchkings, they are on the edge of stabilizing in the throat, but I pulled 20 Mk 7 bullets from the 1951 service ammunition, and seated a SMK and they shot great.  And the pulled Mk 7 bullets seated in the R-P cases gave that same 1/10 shot flier problem.  

If my theory turns out to be right, I could cull those cases that give fliers and all will be well. 

Posted By: britrifles
Date Posted: February 12 2023 at 6:21am
I’ve been scratching my head on this one for a while.  It was the recent discussion on case “crush up” that made me go back and look at neck thickness.  This might explain these fliers I’ve described on this post. 

The only rifle I currently use RP cases in is my Dad’s No. 4(T).  I did some initial load development with RP cases in my Long Branch Fulton regulated rifle which did give good results, but soon changed to Canadian military cases. 

What stands out in the batch of RP cases I’ve been using in the (T) is the relatively thin necks.  Rims are also thin.  

I could not come up with an explanation for is why the 1951 Canadian Dominion Arsenal factory loads shoot so much better than my handloads with RP cases?  My handloads have shot some pretty small groups, some examples of one ragged hole for 7 shots or more, but then the dreaded flier throws the group out to 3 inch extreme spread at 100 yds.

The average of ten RP case necks measured 0.011 inches vs DAC ‘51 at 0.014 inches.  Add to that, the Mk 7 bullet loaded in the DAC ‘51 is .312 inches vs .311 SMK in the RP case.  Now we get a difference in neck diameter of .007 inches.  That’s a lot.  And that could result in the .311 SMK bullet sitting .0035 inches lower in the chamber than the DAC 51 loads. 

Here is the other odd thing.  Using my Hornady case headspace length gage, ten fired DAC cases all measured the exact same length to the shoulder datum, 1.8515 inches.  The RP cases are all over the place, they varied by 0.007 inches.  So, some were likely headspacimg on the rim, and some on the shoulder. 

My plan is to load new PPU brass with the Hornady .312 Match bullet.  This won’t quite give the same neck diameter as the DAC cartridges, but much closer (0.002 inches smaller vs 0.007 inches smaller with the RP case and .311 bullet).

Going to be a while until I can test out this theory. 

Posted By: britrifles
Date Posted: February 13 2023 at 5:48am
Found another surprising thing with the fired RP cases.  These cases have been neck sized multiple times, some more than others. Using a Hornady case headspace gage, I measured a very large variation in case length to the shoulder.  

Here are 35 cases, measured and sorted by headspace length.  Note, this is not really “headspace” since the .303 headspace is measured from the face of the bolt to the back of the chamber.  But, it does represent an indication of when a case will begin to headspace on the shoulder rather than the rim.  

Each vertical column in the photo, the case increases in head to shoulder datum length in increments of 0.001, starting at 1.840 inches on the left column to 1.852 on the far right.  

Now for the interesting part.  I measured 10 once fired cases from the DAC 1951 Mk 7z lot that gives very good accuracy and they were all the same, 1.852 inches.  

Perhaps the RP cases were not annealed after forming and the shoulder does not consistently blow out to fill the chamber.  I can’t think of any other explanation for this.  The end effect might be inconsistent position of the cartridge in the chamber, then coupled with the thin rims and thin necks, inconsistent bullet alignment to the bore. 

Posted By: Zed
Date Posted: February 13 2023 at 1:17pm
Initially I had all RP cases. But changed to PPU when starting to have failures with the RP.
The last batch of RP that I bought were not the usual standard. I had some cases already split form manufacture in the batch. Seems irregular thickness and or metal quality. I only use PPU now, but still have the RP cases as a secondary stock now.

It's nice to be important, but it's more important to be nice!

Posted By: Doco Overboard
Date Posted: February 13 2023 at 1:33pm
Something you could try is to put the poor performing cases up against a protractor to determine of there are any glaring anomalies.
Then, look just above the junction web of the cases for anything that may look different or that stands out.

Posted By: britrifles
Date Posted: February 13 2023 at 1:39pm
Zed, I’m sure I’m making this harder than I need to, but the engineer in me wants to understand root cause.  If the PPU cases shoot good, and the tests with these R-P cases don’t reveal the problem, they are going in the scrap pile.  If the tests prove conclusive on the cause, then I’ll know what to look for next time this happens.

I bought these R-P cases more than 20 years ago.  I still have another unopened bag of 100 cases.  

One other discovery in the investigation is that annealing the necks and resizing in a full length die has pulled the neck out of concentricity with the case body.  I don’t have a concentricity gage, but you can see the bullet wobble as you roll a cartridge on the table.  That’s another thing not conducive to accuracy.  Cases neck sized in my Lee Collet die don’t do this. 

Posted By: Shamu
Date Posted: February 13 2023 at 3:33pm
I used to swear by R-P cases back in the 80's.
Then, a few years back, 2011 from my records, I started discovering odd things myself.
I had a sudden rash of odd case separations. Not in the usual 1/4" forward of the web but much further! These were the same dies & settings I had been using too. It was indicating "imminent failure" at the first reload!
Nothing else had changed, same rifle same load, same bullet & so on.
I've had case separation occasionally but it was after several reloads & nowhere near as commonly or as widespread

Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

Posted By: britrifles
Date Posted: February 13 2023 at 4:28pm
Shamu, my problem may be an indication of what you experienced.   Case failures that far up lead me to suspect a material hardness issue, i.e too hard with low ductility. The fact that my R-P cases don’t seem to consistently “blow out” completely at the shoulder might be another symptom of the same basic problem - inconsistent brass hardness.

I went back thru my reloading notes and suspect I bought these R-P cases around 2005 (I though it was earlier than that, but I used Canadian Mk 7 cases prior to that). May have even been later. 

I think these are headed for the recycle bin. 

Posted By: Zed
Date Posted: February 14 2023 at 11:14am
here's two RP cases, the lower one is the newer batch. Very thin at the neck area.

It's nice to be important, but it's more important to be nice!

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