45-120 Case Cracks/Separation

Status
Not open for further replies.
MEHavey

MEHavey

Member
Joined
Jul 27, 2010
Messages
5,032
Location
virginia
I've had a (Farmingdale) Shiloh Sharps 45-3¼ since `81; and over years of sporadic shooting have experienced several unexpected case separations about an inch above the head. All of these loads are Black Powder (GoEx 1Fg and/or Swiss 1½), and with both RCBS and HDS (Huntingdon) cases.

Today another case (HDS) case separated, and I can see still another loaded case that has all the signs of getting ready to go on next firing: (Bright ring partially marked w/ blue sharpie)

45-120-Case-Crack-sm.jpg

Anyone else experienced this with long BP loads/cases such as this 3¼ ?
(I've had none w/ four other 45-70's and two 45-90s -- just this cartridge/rifle)
 
IIRC this is caused by excess headspace. On firing the case stretches to conform to the dimensions of the chamber. In a correctly headspaced gun that amount of stretching is nominal and the case can withstand it over multiple cycles of resizing and firing. If the amount of headspace is excessive, the case stretches beyond its "elastic limits" and thins at its weakest point, eventually resulting in a separation.
 
LaneP said:
IIRC this is caused by excess headspace. On firing the case stretches to conform to the dimensions of the chamber. In a correctly headspaced gun that amount of stretching is nominal and the case can withstand it over multiple cycles of resizing and firing. If the amount of headspace is excessive, the case stretches beyond its "elastic limits" and thins at its weakest point, eventually resulting in a separation.[/QUOTE

It is not a headspace issue. Rimmed cartridges use the rim for headspace and to secure the case in place for firing. Not sure what the issue is. I shot quite a few 45-70 in a Ruger No 1 and my brother has a 1895 Marlin and we have never seen that. Will be interesting to see what experiance straight wall guys have to say.
Click to expand...
 
I have talked to several BPCR shooters and found that BPCR cases are stretched forward, up the throat. One shooter in fact told me that if the case and the chamber were not clean and dry his cases would move about 0.1" into the throat of his rifle and have rifling marks! This is totally contrary to the smokeless powder experience where the high and fast pressure curve of smokless powder actually locks the case into place during initial combustion, causing sidewall stretch when the case stretches back to the bolt face.

Maybe you have not been wiping the chamber between shots, or have a highly polished chamber.
 
Rimmed cases headspace on the rim so IMO it’s not a head space problem. Perhaps the case have worked hardened to the point they no longer expand in the chamber, resulting in a rolled crimped bullet pulling the case forward as it exits. Annealing the cases from time to time may help. Adjusting the resize die to size only the upper portion of the case walls may help.

In my hunting days I checked the brass on high power rounds from time to time with a paper clip sharpened to a point and bent 90 degrees on its tip. The resulting probe could be inserted in the case and dragged up the case wall. The tip would catch on any depression forming that would indicate a thinning. This technique was outlined in an early reloading manual. Lyman if I remember. I also resized cases enough to re enter the chamber.
 
Last edited:
I see sort of the same thing with my 45\70 brass, annealing the cases slows it down. My own problems are with pin holes in case sides about halfway down the case.
 
i thought i replyed on this but if it wasnt deleted i must not have. the only time i had case seperation is if i didnt clean my cases to as new. their can be no crud or ruff spots inside a case or it can seperate. also i annelled some cases once too soft and ruined them. my 45/70 cases are 25 to 30 years old and still keep going. the nickle has worn off of the those kind. im such a old school that all the primer holes are drilled out to a larger size. talked to the guys that make reloader 7 and they said it wouldnt bother that powder at all. i use blackhorn 209 powder now and it is a dream to shoot in a 45/70. my stevens 44 and 1/2 remake is a dream to shoot. super accurate with a gain twist smith from canada barrel on it.
 
Catman42 said:
i thought i replyed on this but if it wasnt deleted i must not have. the only time i had case seperation is if i didnt clean my cases to as new. their can be no crud or ruff spots inside a case or it can seperate. also i annelled some cases once too soft and ruined them. my 45/70 cases are 25 to 30 years old and still keep going. the nickle has worn off of the those kind. im such a old school that all the primer holes are drilled out to a larger size. talked to the guys that make reloader 7 and they said it wouldnt bother that powder at all. i use blackhorn 209 powder now and it is a dream to shoot in a 45/70. my stevens 44 and 1/2 remake is a dream to shoot. super accurate with a gain twist smith from canada barrel on it.
Click to expand...
You using a magnum primer for the bh209
 
OK... after much mucking around with a zillion variations that went not only nowhere, but killed three more cases (10-thou stretch&worse every shot), I went back to simplified assembly from 35 years ago:

- Annealed necks using 750 Tempilaq
- Cleaned/sonic'd/walnuted the cases
- Trimmed to 3.25" perxactly
- Used Lyman BlkPwdrGold* Lube cut as a 0.2"-thick/quartered disk as grease cookie
- Sandwich the cookie between 2 0.060" veg cards hand-pressed home
- put a "release" 0.030 card above cookie sandwich
- Shoot cases Unsized
- Hand-insert bullet: just enough friction w/ paper patch to retain
- Kicker duplex charge of 10gr 4759
- Enougth GoEX 1Fg to result in an UNcompressed charge column giving me ~⅓" shank depth (~89-90gr -- 152 volume setting on the Harrells)
- Wiped 1x-&-out Damp Patch, followed w/ 1x-&-out dry between shots . . .

* Only use I've found in the 15 years I've happened to have the tube of it -- normally use DLG in the grooved&Lubed game

Sharps450-120-1982-Paper-Patch-Load-Ld-Trgt-sm.jpg
 
Last edited:
yes i use magnum primers, but i dont want to misslead anyone. my cases are old and back then many of us drilled out the primer holes to a larger size. i guess you can say i like to make sure the burn is fast and good. i never crimp as my gun is a single shot. i also free bored the back of the barrel for about 1/2 inch. that way my paperpatched bullet can start up into the barrel with out hurting the paper on the bullet. the bore is .4585 and the free bore is .459. it is a gain twist barrel that ends in 1/22, slower than most. shoots 425 weight bullets very very well. i chose a slower twist so i wouldnt have to shoot heavier bullets and still get accuracy. ive tried the trail boos cowboy powder and that shoots well also. i like the 209 powder the best. reloader 7 shoots very well also but hurts the shoulder some where the others dont. my action is very strong, they say but dont really know this for sure that it is stronger than a high wall winchester.
 
Status
Not open for further replies.

Similar threads

F
  • Locked
Incipient case head separation?
Replies
1
Views
426
GP100man
G
PCCUSNRET
  • Locked
7.5 x 55 Swiss Case Separation
2
Replies
45
Views
3K
PCCUSNRET
PCCUSNRET
P
  • Locked
Here it comes---I can't wait!
Replies
21
Views
1K
Jim Watson
J
Joshua M. Smith
  • Locked
Checking for Incipient Case Head Separation?
Replies
11
Views
870
Sport45
S
BrotherMaynard
  • Locked
460 S&W Mag Case Separation
2
Replies
27
Views
820
BrotherMaynard
BrotherMaynard
Back
Top