case length in 40 S&W shrinking?

[prs]

My reference books and the chart included with my Lee 4 die set all give a nominal case length for 40 S&W as 0.850". My brand spanky new Starline cases measured 0.844" and the average lenth of a random sample of 10 well used cases from my model 23 Glock range from 0.839" to 0.8435 with a mean length of 0.842". These are cases that have been shot many times (mild loads, frequent annealing).

So, I speculate that the published length is a max or "trim if exceeds" lebgth. Is that correct?

My brass seems to be getting shorter with use which seems contrary to Hoyle. Since this is a tough case design and since I run it one way through a Lee carbide factory crimp die "backward" (bulge buster case mouth first) and only let the full length resize die work that portion of brass occupied by my boolits, maybe the only reasonable expectation is for it shorten rather than lengthen.

Other deatails of my set-up includes an "M" die for .401 lead boolits, just enough "crimp from the seating die to remove the bell and step created by the "M"die, and a very slight taper crimp applied by the crimp devuce out of the Lee 40 S&W factory crimp die, but with that crimp device installed in a 45 Colt fcd body so that there is NO final sizing of my rounds. OAL = 1.139" Finished rounds do not have that "hour glass" shape, but rather have a VERY SLIGHT bottle neck appearance.

Any way, since this cartridge spaces on the case mouth, am I OK being a bit short of nominal case length? The cartridge sets well in my factory Glock barrel with head just the slighted amount below the end of the chamber bolster. If not, maybe I could start running them through the buster rim first to stretch them?

My load is a plinker/training round (I am inexperienced with shooting self loaders). I am using Lee TL401-175-SW with a full (but not compressed) charge of TrailBoss that loafs along at 725 fps very consistently. The primer firing pin dimples show far less pressure evidence than do factory 180gr jhp and, unlike the factory loads, there really seems to be no bulge to "bust", but I do anyway. Accuracy is certainly not a problem with my off hand shooting at cowboy type steel plates from 25' to 100', recoil is practically nothing and the report is very mild. A fun round to shoot that has alowed me to use an iron that was relegated to just dresser drawer ballast.

I am even contemplating adding another self loader to my stable; perhaps the Ruger SR1911.

prs

[geargnasher]

WHOA! You annealed your .40 S&W brass???? I don't know of a way to do that without making the cases dangerously soft unless you drew the mouths in your casting pot for a couple of seconds, but even that is not only iffy, but totally unnecessary since you have all of the right tools (M-die expander and FCD with oversize body die, etc.) to do the reloading job correctly for cast boolits.

When pistol brass is fired it gets shorter, and if the firing pin still reaches the primer every time, I wouldn't spend a second worrying about it. You might try adjusting your seating depth to make the cartridges a bit longer and see if you can make the cartridges headspace on the boolit rather than case mouth, but if you're happy with the way it shoots and it feeds and functions fine, don't worry about brass. I have some 45 ACP brass I've been shooting for 15 years, some if it may have been reloaded 50 or more times in FL carbide dies and I haven't culled a split case yet (except for ONE notable example with much newer brass that split during a PB Bocker test). With your tooling and techniques and low-pressure loads, your .40 brass should last just about forever as well. And if it doesn't, you can get a couple thousand 1F range pickups for about $50-75 delivered.

Gear

[44man]

Gear is right, why anneal?
Brass expands to fit the chamber, it will shorten but I would not be doing anything else to make it shorten more.

[prs]

Thanks Gear & 44! I will nix the annealing. I was doing that the same way I do revolver cases and it is tedious or requires finesse', but still quick with these shorties.

Why do pistol cases shorten? The firing pin will still set the round forward on the case mouth when it strikes. Ignition and pressure build will still expand the case walls outward to grip the chamber, no? The only way to go is backward with the unsupported part of the case toward the face. I am not questioning the facts, just curious.

prs

[44man]

Thanks Gear & 44! I will nix the annealing. I was doing that the same way I do revolver cases and it is tedious or requires finesse', but still quick with these shorties.

Why do pistol cases shorten? The firing pin will still set the round forward on the case mouth when it strikes. Ignition and pressure build will still expand the case walls outward to grip the chamber, no? The only way to go is backward with the unsupported part of the case toward the face. I am not questioning the facts, just curious.

prs
That brings in another question?????? Why are you annealing revolver brass? That is the quickest way to remove accuracy and have boolits pull not only from recoil but from the primer when fired.
Brass has to expand to fit the chamber, brass has to come from somewhere. Pressures are not high enough to make brass "flow" like a rifle neck. Anealing pistol brass might make the size die compress the grain structure

[BulletFactory]

I trim at .840, and even at that length, only about half of the casings ever touch the cutter. I only trim them once during thier life cycle, mine shrink too.

[geargnasher]

Thanks Gear & 44! I will nix the annealing. I was doing that the same way I do revolver cases and it is tedious or requires finesse', but still quick with these shorties.

Why do pistol cases shorten? The firing pin will still set the round forward on the case mouth when it strikes. Ignition and pressure build will still expand the case walls outward to grip the chamber, no? Expand, yes. Grip the chamber? Not as much as you'd think. Like 44Man said, it's not quite the same as a rifle. Even rifle brass will shorten quite a bit if FL sized and fired in a large chamber at low pressure. As the brass expands to fit the chamber, it shortens, like squeezing a balloon. The only way to go is backward with the unsupported part of the case toward the face. The brass will slip back in the chamber rather than stretch, the pressure, especially with Trailboss pushing a 175 grain boolit at 700-something FPS, isn't nearly enough to make the case grab the chamber enough to stretch lengthwise.I am not questioning the facts, just curious.

prs

I may be going overboard here with caution, especially since I wasn't the one doing the annealing, but I'd chunk every last one of those annealed cases in a Flat Rate Box and offer them for sale or trade to one of the guys who uses them for swaging bullet jackets. If somebody, maybe you one day, handloads them fairly warm for an older generation Glock with the unsupported chamber, it might be inviting a Kaboom. You'll have to make that call for yourself.

Gear

[Grandpas50AE]

I was told many years ago by a very experienced reloader (back in the early 70's) that straight-walled and slightly tapered pistol cases will shrink due to the sizing die pushing the metal back towards the head area, and there is no bottleneck or case restriction to make them stretch when fired. I have noticed that this happens on .41's, .44's, .357's, .45ACP's, .38 Spcl's, .38 Supers, etc. and what I was told seemed to make sense.

[prs]

The reason I have been annealing the case mouths is becasue working the brass hardens it and hard brass is prone to splitting at the mouths. I have had no splits with 40 brass. I rarely have any with 45 Colt revolver brass. I load NO hot rounds, so I will nix the annealing and just let them work harden. My annealing is NOT the cherry red process some go through, but rather just enough to heat discolor the upper case in the flame. So, that is a step I can eliminate. Cool.

prs

[runfiverun]

you also need to read up on how annealing is properly done.
not cutting on you.
but you should have the proper education on what you are trying to do. look here.

http://www.annealingmachines.com/model_360
you can also read up on it at the 6mmbr forum which i don't have a link to.

[Iron Mike Golf]

...So, I speculate that the published length is a max or "trim if exceeds" lebgth. Is that correct?...prs

Yes, that's the max length. Trim-to length is min length.

[williamwaco]

WHOA! You annealed your .40 S&W brass???? I don't know of a way to do that without making the cases dangerously soft unless you drew the mouths in your casting pot for a couple of seconds, but even that is not only iffy, but totally unnecessary since you have all of the right tools (M-die expander and FCD with oversize body die, etc.) to do the reloading job correctly for cast boolits.

When pistol brass is fired it gets shorter, and if the firing pin still reaches the primer every time, I wouldn't spend a second worrying about it. You might try adjusting your seating depth to make the cartridges a bit longer and see if you can make the cartridges headspace on the boolit rather than case mouth, but if you're happy with the way it shoots and it feeds and functions fine, don't worry about brass.
I have some 45 ACP brass I've been shooting for 15 years, some if it may have been reloaded 50 or more times in FL carbide dies and I haven't culled a split case yet
(except for ONE notable example with much newer brass that split during a PB Bocker test). With your tooling and techniques and low-pressure loads, your .40 brass should last just about forever as well. And if it doesn't, you can get a couple thousand 1F range pickups for about $50-75 delivered.

Gear

This is not strictly comparable but in about 1968, I bought a batch of once fired .38 special cases.

I continue to keep this batch separate primarily because it is so old. When they are all empty, I reload them all. This batch has been loaded aproximately twice a year for 43 years. They have been reloaded with the same set of RCBS carbide dies. They have been "almost" full length resized. To this good day they have no lengthwise scratches from the resizer. I am beginning to get split necks on firing with about three or four percent.

Oh I forgot,
they have never been trimmed,
they are still under max case length,
and
I have never annealed a case in my life.





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[geargnasher]

Williamwaco, gotta love low-pressure cartridges! I have culled a few .45 ACP cases due to the rims getting too many dings in them from the ejector and extractor, but that's it. I never have seen one get close enough in length to reach the cutter on minimum setting.

Gear

[44man]

The reason I have been annealing the case mouths is becasue working the brass hardens it and hard brass is prone to splitting at the mouths. I have had no splits with 40 brass. I rarely have any with 45 Colt revolver brass. I load NO hot rounds, so I will nix the annealing and just let them work harden. My annealing is NOT the cherry red process some go through, but rather just enough to heat discolor the upper case in the flame. So, that is a step I can eliminate. Cool.

prs
Good man, you will be surprised how long brass lasts.
Any split brass I have had was always new brass with the first loading.

[41 mag fan]

I've got 44 mag brass from the 70's and 80's. Like WilliamWaco with the 38sp cases, they get shot 2 maybe 3 times a yr. Been trimmed twice, and still are good to go.
I keep them separate from my newer brass, and basically load them at 44sp loading data.

[MattOrgan]

I am guessing that the reason cases in pistols and revolvers shortens over the years is because of the case head slamming against the recoil shield or breech face. This action keeps loaded rounds from allowing the primer to back out upon firing. I base this on some Western 45 ACP cases I have been loading since 1975 or 1976. They have been fired so often that the head stamp has been pounded almost flat from many reloadings. The stamping is nearly illegible at this point. These cases are failing routinely now. I can tell when they make the "crunch" sound upon sizing. They were the first pistol caes I ever reloaded and until I read this thread I never really that about them. As others have posted I have never annealed or trimmed a pistol/revolver case.
They last so long that it seems like a real waste of time. Even my 45 Long Colt cases generally last 7 or 8 loadings before they develop mouth cracks.

Of course this is just my opinion, I may not have any idea what Im talking about.

[williamwaco]

Williamwaco, gotta love low-pressure cartridges! I have culled a few .45 ACP cases due to the rims getting too many dings in them from the ejector and extractor, but that's it. I never have seen one get close enough in length to reach the cutter on minimum setting.

Gear


Gear, That is exactly why I love the .38 special and the .357 Magnum. I have never dinged a case with the extractor.

The .45 ACP is a different matter. I lose them so often I am not sure how often they get dinged.


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