Case separation in rifle chamber

[Chas B. Wolfson, SASS #11104]

 Recently a good friend was telling me that his wife's rifle had a case separation.  38spl case.

With that conversation in my mind, I got to thinking and the three watt bulb in my brain flickered on.

Is there any real, factual proof that the cannelure on a case is a primary factor to separation in the chamber?

In all the years of participation in this sport, Annie has had only one instance of this happening.  That separation occurred at the very base of the case where the body meets the solid part of the case.  And yes, she has always used nickel cases shooting BP due to easier case cleaning.  357mag in rifle, 38spl in pistols.

There is a lot of conjecture out there but is there any real substantiation?

Chas B 

 

 

 

 

[Gateway Kid SASS# 70038 Life]

I have very limited experience with case separation. None in my guns (knock on wood), but I have personally seen three in about 16 years. 
1. ALL were traditional brass, not nickel plated. 
2. Only 1 separated at the cannelure, the other two were nearer the base of the shell. All separated in the rifle. 
3. All were well used (older) brass that had been used for cowboy ammunition exclusively. Hence lower pressure but reloaded a lot. Don’t know how many times. 
4. Per the shooters involved none had been trimmed over their life cycle. I have never trimmed my own cowboy brass but I suspect for those who do that would be an opportune moment to see precursor damage to the case.
5. I DO inspect for cracks and shiny spots, anywhere on the case, on brass I get back at the unloading table, after I separate it from my dry tumbling media, as it is going through the reloading machine, as I put it into strips and lastly when I load my guns. BTW my alias to my alias is OCD Kid. 

6. ANY brass, nickel or traditional, that has even a tiny crack anywhere on the case hits the recycle bucket. I have plenty and it’s cheap insurance to avoid what could be a serious problem. 
Possibility that it could happen but I do what I can and so far been successful. 
YMMV

Regards

    
Gateway Kid

 

[Sarge]

My wife has had three in her .38spl. rifle in four years.  All three were cases with cannelures.  I now throw them out when I come across them.  Haven't had a separated case since.

[Garrison Joe, SASS #60708]

I've seen and helped remove three circumferential case separations in .38 special (firing) rifles.  Where a ring breaks off and sticks in the chamber.   2 were nickle plated cases, one brass.  All three occurred at a cannelure.   

 

I've seen many more longitudinal case splits, though, that seem to happen with nickle and brass cases in a mix that is similar to the cases that the shooter has loaded.  

 

If a case separation is a game killer for you, don't use nickle or cannelured cases in your rifle.  Shoot 'em up in revolvers. 

 

If you clean fired BP cases within a day and get all fouling and corrosion off the OUTSIDE of the case, there is no reason you need to be using nickle cases!   

 

good luck, GJ

[C. W. Knight # 47289L]

Chas, I have had two.  Both .38 sp, one was a RP with cannelure amidships, and the first one I don't know because we never found the base.  After the second I have never used any brass with mid case cann's.  I regulate those for pistols.  C.W.  

[I. M. Crossdraw, SASS# 8321]

I've had two and they are also 38 spl.  I load them on my pistol whenever I see a cannelure on the cases.  It is easier to extract split case from a pistol than a rifle.  There is no way to predict When it can happen but if it does, hopefully it's not on the day of a major match.  

[Go West]

I had two in .38 special nickel with cannelures that separated at that location. They ruined my match to say the least. I chucked all nickel cases that I found in my supply and any that found their way to me since and have had zero splits thereafter.  

Edited September 21, 2025 by Go West

[Chas B. Wolfson, SASS #11104]

 The following pics show where I have witnessed case separation.  The case body meets the base/web of the case.

[Garrison Joe, SASS #60708]

5 hours ago, Chas B. Wolfson, SASS #11104 said:

pics show where I have witnessed case separation.

 

Wow, that is not something I've seen before. 

 

First, is your chamber in good shape?  Examine with a good flashlight and look at chamber walls closely. 

 

Almost seems like your chamber is oversized - has it been heavily honed for some reason?

 

I'd "chamber cast" that chamber with CerroSafe alloy and see if it is over-diameter.   You can get that alloy from Midway or Brownells, and it melts over boiling water.  Follow instructions to make the casting and then wait correct time after solidification to measure the diameters.   A .38 special chamber should not be any larger than 0.385" diameter near the base of the cartridge.  Down to 0.381" would be the minimum chamber diameter (but you are not having problems at that end of chamber size, where chamber is tighter than normal).

 

The base end of the case is of course fairly thick, the walls are thin and can expand into an oversize chamber.  Looks like your sizing die is reducing most of the case down to normal diameter, and the bottom of sizer die stops where that line and slight bulge shows on the cases in your pic.  About three or four cycles of major expansions (during firing) then reducing diameter (when sizing) could be work hardening your brass and leading to an early separation right at the transition from head of case to thin wall.

 

good luck, GJ 

[Chas B. Wolfson, SASS #11104]

1 hour ago, Garrison Joe, SASS #60708 said:

 

Wow, that is not something I've seen before. 

 

First, is your chamber in good shape?  Examine with a good flashlight and look at chamber walls closely. 

 

Almost seems like your chamber is oversized - has it been heavily honed for some reason?

 

I'd "chamber cast" that chamber with CerroSafe alloy and see if it is over-diameter.   You can get that alloy from Midway or Brownells, and it melts over boiling water.  Follow instructions to make the casting and then wait correct time after solidification to measure the diameters.   A .38 special chamber should not be any larger than 0.385" diameter near the base of the cartridge.  Down to 0.381" would be the minimum chamber diameter (but you are not having problems at that end of chamber size, where chamber is tighter than normal).

 

The base end of the case is of course fairly thick, the walls are thin and can expand into an oversize chamber.  Looks like your sizing die is reducing most of the case down to normal diameter, and the bottom of sizer die stops where that line and slight bulge shows on the cases in your pic.  About three or four cycles of major expansions (during firing) then reducing diameter (when sizing) could be work hardening your brass and leading to an early separation right at the transition from head of case to thin wall.

 

good luck, GJ 

Brother, you are way over thinking this.  Brass has been reloaded numerous times.  Natural progression of stretch and resizing.

The examples shown are pulled from about 2000 cases.  Nothing wrong with three different rifle chambers or the sizing dies.

Just old age.

Thanks for your insight and remarks.  We all learn every day from others.

Chas B 

Edited September 21, 2025 by Chas B. Wolfson, SASS #11104

[Assassin]

No nickle or cannelured cases in rifles.

Nickle plated brass is a problem. Two different metals, they expand at different rates. That is the reason nickle plated cases split more frequently. They usually separate at the cannelure, I've seen a couple split about 1/8" above the rim. Too much head space could possibly lead to splitting near the rim because the case has no support. Cold weather, nickel  does not expand in low pressure loads. I chronographed nickle and brass cases in 20 degree temps. Nickel was sometimes 150 fps slower than brass. Once I added powder or warmed the cases the velocity stabilized. 

[Garrison Joe, SASS #60708]

 

5 hours ago, Chas B. Wolfson, SASS #11104 said:

Nothing wrong with three different rifle chambers or the sizing dies. Just old age.

Well, guess if you have no curiosity to try to find the cause, you will just have to endure a few ruptured cases.  Or figure out when you have to discard cases after several firings.  Best be carrying a broken shell extractor for .38s.  GJ

[Boggus Deal #64218]

I’m with Joe here. Several different firearms, brass loaded untold number of times. Never seen this. Cases split lengthwise from tiny splits at the neck to full length. Personally, thankfully, not had a case separation in the chamber. Seen quite a few. 

[Texas Red]

Chas,

All I've seen or witnessed involve  cannelure casings all were 38 or 357's.  I do experience a lot of horizontal splits wit 32 H&R mag brass & APP.

Regards

TR

[Griff]

IMO, there isn't any factual, scientific basis for the belief.  However there appears to be a certain argument with the number of cases where no other explanation is held up as proof.  From a scientific viewpoint if the cannelure was the cause, it would seem to reason an absence of a cannelure would mean there is no reason for a case to separate... yet they do.  I have a large number of .38 Special cases that have both cannelure(s) and none, so old that they use large pistol primers and the nickel examples have the nickel plating completely, (or nearly so), worn off.  Having used them in 3 different handguns, and two rifles, I've never had a case separation.  I can unequivocally state that... I don't shoot a .38 Spl... But for the 8 years or  so that my son & wife competed, they did.  Between 2 & 3 matches a month each.   The firearms used were a pair of Rossi 1892s, and pistols are a pair of Colt SAAs  My used of .38 Spl was limited to my duty Smith & Wesson mdl 65 and it was fed a diet of new & inmate reloaded +P ammo.  Is there a particular brand or model gun that seems to have an increased incidence of case separations?  In my reading of such incidences on the Wire, my gut tells me that the Uberti '73 rifle accounts for the majority.  Ergo, does the Uberti '73 rifle chamber dimension exacerbate a "problem?"    Does frequent loading and full length resizing of increase the likelihood of case separations?  Probably.  And the further the case is moved by stretching in the chamber and then being resized back to nominal sizes also fatigues the metal.  Just how many times can this be done without risking a failure?  

 

I don't know.  But I can say it's exactly one time less than I've reloaded these two 45 Colts.

BTW, they're both from a Uberti '73... although they've probably been in any number of other rifles and handguns if they've been in my brass bin for their entire life.  

 

So... my advice, (which I'll probably not follow either), is to pick a number of times you'll reload a case, then toss 'em and replace your stock with fresh brass!  If you have a subsequent separation, reduce the number by 1, until separations disappear.

[Abilene, SASS # 27489]

I used to shoot a lot more large caliber, but more .38 for several years now.  I checked my records and I have reloaded 40K of .38's.  Totally mixed brass, some very old, with a lot of cannelures.  Never had a case separation.  But I loaned my '73 to another shooter for the last stage after his broke a firing pin, and he had a case separation in it using his ammo (yeah, I know).  So I know nothing about how old it was and I don't know if it had a cannelure, but it took a lot of effort to get it out.  I'm not losing sleep about it happening, but if I'm shooting the same .38 ammo in pistol and rifle, I will pick out the cannelured ammo at the loading table and put it in the pistols now.

[Garrison Joe, SASS #60708]

2 hours ago, Griff said:

one time less than I've reloaded these two 45 Colts.

.45 Colt cases tend to split lengthwise only.  Even though Winchester has long put cannelures on some loadings, and other companies have had intermittent production with cannelures applied. - .45 Colt never seems to break at the cannelure.

 

And, yeah, both Uberti and Marlin production rifles made in .45 Colt have maximum chamber sizes (and a few even larger), and often split old tattered cases.

 

good luck, GJ

[Major E A Sterner #12916]

I had a .38 in my 66 separate at the  cannelure  on the 1st shot first stage of Heluva Rukus about 10 year ago, since then I only use Starline brass in rifle. The worse part is the match photographer caught the broken case in the picture she took of me.

[watab kid]

ive only reloaded a few that have separated or ruptured over the years , in eevery case they have fired successfully and  not been an issue to extract , ive been working harder at my inspections before reloading since 

[SGT. ELI 35882 GUNFIGHTER]

I have removed a few for customers, they were all cannelure separations except 1. I removed quite a few 9mm separations for my USPSA customers that were all stepped brass cases separating at the step.

Between cowboy, wild bunch, 3 gun, and uspsa, practice I have fired 200,000+ rounds and never had one.

Edited September 23, 2025 by SGT. ELI 35882 GUNFIGHTER

[Eyesa Horg]

What is/was the objective of the cannelure? 

[SGT. ELI 35882 GUNFIGHTER]

41 minutes ago, Eyesa Horg said:

What is/was the objective of the cannelure? 

It identifies factory load specs, bullet weight, powder etc.

[Kingsley]

I was always under the impression that it was to help prevent bullet setback.

 

CC

[Garrison Joe, SASS #60708]

1 hour ago, Kingsley said:

I was always under the impression that it was to help prevent bullet setback.

Back in the 1920s and 30s, yeah.  Not since WW II ended has any factory counted on a deep cannelure for bullet retention.  GJ

[Kingsley]

There I go getting in trouble thinking again. Thx GJ.  
 

CC

[Kingsley]

sitting in the hollers of Alabama with almost zero net access. But finally was standing in correct spot and wamo, connected. 
 

Ok. Bullet retention verse bullet setback, to me are two opposite items. They both are similar, but not the same.  Retention being the force holding the bullet in place. Setback is when that retention fails and the bullet gets pushed back into the case.
 

With the cannelure stamped/pressed into the brass, hopefully it acts like a ledge that the bullet cannot be setback.  
 

but there I go thinking again. 
 

CC
 

 

[Garrison Joe, SASS #60708]

10 minutes ago, Kingsley said:

hopefully it acts like a ledge that the bullet cannot be setback.

  

I'd say "There you go hoping again."   

 

Tons of experience among shooters who need better bullet location security within a case to prevent recoil collapsing in tubular magazines and  to increase chamber pressure and get more complete powder combustion have found a tight rolled crimp is one of the best ways to achieve this.  Even though there are some commercial cannelure rollers available to handloaders  - no one that I have read here  has posted that they take that approach.  And certainly trying to count on a factory-applied cannelure to hold a cowboy action bullet, usually shorter and lighter than what the factory originally loaded, would not securely fix a bullet in place at all.

 

good luck, GJ

[Kingsley]

🎣  There I going hoping to get the words of wisdom, and I do.  Thank you Mr. Wizard....  

[Cpt Dan Blodgett, SASS #75655]

Normally only use brass cases.  The exception being when I love to make things difficult I will shoot 45 Colt Pistols and mag or 44-40 rifle. I then shoot nickel brass to make it really obvious which rounds go where. Nickle also Good for rounds left in cartridge belt for long periods 

[watab kid]

12 hours ago, Cpt Dan Blodgett, SASS #75655 said:

Normally only use brass cases.  The exception being when I love to make things difficult I will shoot 45 Colt Pistols and mag or 44-40 rifle. I then shoot nickel brass to make it really obvious which rounds go where. Nickle also Good for rounds left in cartridge belt for long periods 

yup , i always use brass cases , i do have a loaded stage of nickle that were made just to be in the beltloops - i dont carry a lot of extra weight on my belt anymore - back then i was young and less aware of the efforts of the days shooting , im light in my carry these days but i do have that on the cart just in case we shoot an extra stage some day , havent in five years so i guess im toting the extra weight for nuthin ......? yet , its happened before 

[Cinch]

I discard .45’s with a cannelure. Had a few decide to stay in the chamber on several guns. A .45 rifle brush got most of them out. Some took cerrosafe.

 

I had a 45-90 that the reamer ran several thousandths too deep and the case would come apart at the web. Had to be set back, timed, and the reamer run again. 
 

It seems that sizing dies wear out cowboy brass. It isn’t pressure for sure.

[Cpt Dan Blodgett, SASS #75655]

10 hours ago, watab kid said:

yup , i always use brass cases , i do have a loaded stage of nickle that were made just to be in the beltloops - i dont carry a lot of extra weight on my belt anymore - back then i was young and less aware of the efforts of the days shooting , im light in my carry these days but i do have that on the cart just in case we shoot an extra stage some day , havent in five years so i guess im toting the extra weight for nuthin ......? yet , its happened before 

I pack an extra 10 lbs ever where I go damn see food diet!

[watab kid]

9 hours ago, Cpt Dan Blodgett, SASS #75655 said:

I pack an extra 10 lbs ever where I go damn see food diet!

i can see it all now , a cart with shrimp cocktail and sushi ............

[Cowtown Scout, SASS #53540 L]

2 minutes ago, watab kid said:

i can see it all now , a cart with shrimp cocktail and sushi ............

I believe he ment SEE food and not SEA food 

9 hours ago, Cpt Dan Blodgett, SASS #75655 said:

I pack an extra 10 lbs ever where I go damn see food diet!

 

[watab kid]

54 minutes ago, Cowtown Scout, SASS #53540 L said:

I believe he ment SEE food and not SEA food 

 

i thought the bulge in my cheek was visible , or as rossana rossana danna would say "never mind"

Edited October 25, 2025 by watab kid