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Schrodinger's headspace - a problem that isn't? (Read 9691 times)

FredC KCA Official Member Offline Krag Enthusiast! Posts: 759 Location: Dewees, Texas Joined: May 31^st, 2013 Gender:	Re: Schrodinger's headspace - a problem that isn't? Reply #15 - Mar 31^st, 2020 at 1:51pm	Print Post
	Parashooter wrote on Mar 31^st, 2020 at 5:14am: butlersrangers wrote on Mar 31^st, 2020 at 3:33am: . . . My generous FTR chamber allowed the cartridge case body to be stretched to the side-walls and forward toward the chamber-neck. This movement of brass, ballooning to the side and stretching to the front, likely caused my .303 brass to fail at the web area of the case wall. . . .303's loaded to stiff normal pressure in neck-sized cases can fail at the head because of the rear-locking action's flexibility, allowing some rearward movement of the bolt face on firing at full pressure. This allows the case head/wall junction to stretch, thin, and fail. Flexibility was going to be my first guess also. I have not worked with any 303 actions but I sort of remember a reputation. Maybe during the rebuild a mismatch in the locking lug/lugs happened that made it even more flexible. Parashooter, The demo with the scribed lines on the case is comforting, when fire forming cases it is good to know that you are not stretching the case contributing to head separations.


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butlersrangers KCA Forum Member Offline Krag Enthusiast! Posts: 6330 Location: Michigan Bi-Peninsular&Proud Joined: Oct 7^th, 2009	Re: Schrodinger's headspace - a problem that isn't? Reply #16 - Mar 31^st, 2020 at 3:05pm	Print Post
	Parashooter's graphic is quite educational. I always appreciate his input, knowledge, illustrations and observations. It is interesting how 'fire forming' re-located the .303 case shoulder and shortened the overall case length. I wish, I still had some of my wrecked .303 brass, to see what the case diameter measured just above the 'incipient separation ring'. I may be very mistaken, but, I can envision a cartridge case failing by being overly stretched 'sideways'. This might happen if the chamber is generously large radially and not adequately restricting expansion of the case wall at its juncture with the solid case web.??? (p.s. - I am not arguing or debating, just trying to better understand my experience).


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FredC KCA Official Member Offline Krag Enthusiast! Posts: 759 Location: Dewees, Texas Joined: May 31^st, 2013 Gender:	Re: Schrodinger's headspace - a problem that isn't? Reply #17 - Mar 31^st, 2020 at 3:25pm	Print Post
	BR, I think the head and rim are still moving after the forward brass expanded and sealed. Head space and flexing of the receiver or bolt most likely. Looked at you gauge photos again, it does have a recess to clear the firing pin. With your gauge, firing pin damage is a non issue. KCA is an informative place you just keep learning things here.


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butlersrangers KCA Forum Member Offline Krag Enthusiast! Posts: 6330 Location: Michigan Bi-Peninsular&Proud Joined: Oct 7^th, 2009	Re: Schrodinger's headspace - a problem that isn't? Reply #18 - Mar 31^st, 2020 at 3:46pm	Print Post
	Yes, whoever made my 'knock-off' head-space gauge thought things through. Actually, it can be easily 'hooked' under the extractor, to retain it against the bolt-face, and be feed smoothly into the chamber. (No wear or tear and convenient at gun shows). But, as we both have said, it is best to strip the bolt and focus on 'feel' of gauge.


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FredC KCA Official Member Offline Krag Enthusiast! Posts: 759 Location: Dewees, Texas Joined: May 31^st, 2013 Gender:	Re: Schrodinger's headspace - a problem that isn't? Reply #19 - Mar 31^st, 2020 at 4:16pm	Print Post
	butlersrangers wrote on Mar 31^st, 2020 at 3:46pm: . Actually, it can be easily 'hooked' under the extractor, to retain it against the bolt-face, and be feed smoothly into the chamber. (No wear or tear and convenient at gun shows). Had not even thought of that, to quote Paladin "have gauge, will travel"


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psteinmayer KCA Forum Member Offline Krag Enthusiast! Posts: 2391 Location: Ypsilanti, Michgan Joined: Aug 30^th, 2011 Gender:	Re: Schrodinger's headspace - a problem that isn't? Reply #20 - Mar 31^st, 2020 at 9:32pm	Print Post
	This talk of problems with .303 case failures makes me a little nervous. I just loaded 100 new Winchester cases (Hornady 150 gr SST, 36.0 grains H4895, CCI-200) for my new Lithgow. Should I be concerned???


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butlersrangers KCA Forum Member Offline Krag Enthusiast! Posts: 6330 Location: Michigan Bi-Peninsular&Proud Joined: Oct 7^th, 2009	Re: Schrodinger's headspace - a problem that isn't? Reply #21 - Mar 31^st, 2020 at 9:47pm	Print Post
	Paul - Shoot some rounds and observe your brass. FWIW - My WW-2 Lithgow S.M.L.E. doesn't appear to show problems.


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FredC KCA Official Member Offline Krag Enthusiast! Posts: 759 Location: Dewees, Texas Joined: May 31^st, 2013 Gender:	Re: Schrodinger's headspace - a problem that isn't? Reply #22 - Apr 1^st, 2020 at 12:28am	Print Post
	I can not see a problem with 308 bullets and Krag pressures in the solid not springy Krag. You all did it with no problems during the great ammo shortage. I ordered 25.06 Remington cases during that time and could not get any. Finally got Lapua match .222 cases as Remington was also unavailable. Stupid hoarders.


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butlersrangers KCA Forum Member Offline Krag Enthusiast! Posts: 6330 Location: Michigan Bi-Peninsular&Proud Joined: Oct 7^th, 2009	Re: Schrodinger's headspace - a problem that isn't? Reply #23 - Apr 1^st, 2020 at 1:20am	Print Post
	Fred - Psteinmayer is concerned about his re-loads (in .303 British) for an Australian made Short- Magazine Lee-Enfield Mk-III, (manufactured at the Lithgow arsenal). He is worried he could have an experience, like I did, with my BSA rifle.


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Parashooter KCA Forum Member Offline Kragmudgeon Posts: 514 Location: Connecticut Joined: Feb 4^th, 2010	Re: Schrodinger's headspace - a problem that isn't? Reply #24 - Apr 1^st, 2020 at 1:42am	Print Post
	psteinmayer wrote on Mar 31^st, 2020 at 9:32pm: This talk of problems with .303 case failures makes me a little nervous. I just loaded 100 new Winchester cases (Hornady 150 gr SST, 36.0 grains H4895, CCI-200) for my new Lithgow. Should I be concerned??? No. That's about a 25000 psi (piezo) load per QuickLOAD. You'll be lucky not to get sooty cases! See (You need to *Login* to view media files and links) for more info.


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butlersrangers KCA Forum Member Offline Krag Enthusiast! Posts: 6330 Location: Michigan Bi-Peninsular&Proud Joined: Oct 7^th, 2009	Re: Schrodinger's headspace - a problem that isn't? Reply #25 - Apr 1^st, 2020 at 4:15am	Print Post
	'Parashooter' - Thanks for your excellent work on explaining head-space and forces acting on a rimmed 'bottle-neck' cartridge.


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FredC KCA Official Member Offline Krag Enthusiast! Posts: 759 Location: Dewees, Texas Joined: May 31^st, 2013 Gender:	Re: Schrodinger's headspace - a problem that isn't? Reply #26 - Apr 1^st, 2020 at 1:17pm	Print Post
	butlersrangers wrote on Apr 1^st, 2020 at 1:20am: Fred - Psteinmayer is concerned about his re-loads (in .303 British) for an Australian made Short- Magazine Lee-Enfield Mk-III, (manufactured at the Lithgow arsenal). He is worried he could have an experience, like I did, with my BSA rifle. WHOOPS! I was remembering all the members using 303 cases during the shortage. Sounds like you got an outlier on your remanufactured model. No use even speculating why it had all the separations with reloads since you do not have it anymore.


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butlersrangers KCA Forum Member Offline Krag Enthusiast! Posts: 6330 Location: Michigan Bi-Peninsular&Proud Joined: Oct 7^th, 2009	Re: Schrodinger's headspace - a problem that isn't? Reply #27 - Apr 1^st, 2020 at 3:14pm	Print Post
	Its hard for me when discussing Krag (.30-40) head-space, which is relatively trouble free, to avoid looking at a similar cartridge (.303 British) with a "reputation", and a particular 'like new' Lee-Enfield rifle that was problematic. 'Comparing Apples and Pears' 'after The horse has left the barn', maybe ... but, I found it educational to ponder & discuss. The thread allowed some improvement in understanding 'head-space' and offered some practical solutions, in the end. Hey, Schrodinger! Why is that box of your's making cat sounds?


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psteinmayer KCA Forum Member Offline Krag Enthusiast! Posts: 2391 Location: Ypsilanti, Michgan Joined: Aug 30^th, 2011 Gender:	Re: Schrodinger's headspace - a problem that isn't? Reply #28 - Apr 1^st, 2020 at 9:36pm	Print Post
	Parashooter wrote on Apr 1^st, 2020 at 1:42am: No. That's about a 25000 psi (piezo) load per QuickLOAD. You'll be lucky not to get sooty cases! See (You need to *Login* to view media files and links) for more info. That's good to know... although sooty cases doesn't thrill me either, LOL. I consulted several load manuals and data before settling on that load. I wanted to keep it light starting out since I've never dealt with an SMLE before (and I'm a heck of a lot more cautious these days). Perhaps after firing these first hundred, I'll bump the charge up a little.


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Parashooter KCA Forum Member Offline Kragmudgeon Posts: 514 Location: Connecticut Joined: Feb 4^th, 2010	Re: Schrodinger's headspace - a problem that isn't? Reply #29 - Apr 1^st, 2020 at 11:22pm	Print Post
	psteinmayer wrote on Apr 1^st, 2020 at 9:36pm: ... although sooty cases doesn't thrill me either, LOL. I consulted several load manuals and data before settling on that load. I wanted to keep it light starting out since I've never dealt with an SMLE before (and I'm a heck of a lot more cautious these days). Perhaps after firing these first hundred, I'll bump the charge up a little. I suspect you'll want to increase the charge significantly just to fully fireform your cases. Here's a QL table predicting results with H4895 - Cartridge : .303 British (SAAMI) Bullet : .312, 150, Hornady SP 3120 Cartridge O.A.L. L6: 3.075 inch or 78.11 mm Barrel Length : 24.0 inch or 609.6 mm Powder : Hodgdon H4895 Predicted data by increasing and decreasing the given charge, incremented in steps of 1.163% of nominal charge. CAUTION: Figures exceed maximum and minimum recommended loads ! Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time % % Grains fps ft.lbs psi psi % ms -11.6 82 38.00 2312 1781 28477 6126 92.3 1.465 -10.5 83 38.50 2341 1825 29413 6221 92.8 1.444 -09.3 84 39.00 2369 1869 30379 6315 93.4 1.423 -08.1 85 39.50 2397 1914 31377 6407 93.9 1.404 -07.0 86 40.00 2426 1960 32408 6497 94.4 1.385 -05.8 87 40.50 2454 2005 33471 6585 94.9 1.366 -04.7 89 41.00 2482 2052 34570 6671 95.4 1.347 -03.5 90 41.50 2510 2099 35706 6755 95.8 1.328 -02.3 91 42.00 2538 2146 36877 6837 96.3 1.310 -01.2 92 42.50 2566 2194 38088 6916 96.7 1.291 +00.0 93 43.00 2594 2242 39340 6993 97.0 1.272 +01.2 94 43.50 2622 2291 40632 7068 97.4 1.254 +02.3 95 44.00 2650 2340 41970 7140 97.7 1.235 ! Near Maximum ! +03.5 96 44.50 2678 2389 43351 7209 98.1 1.218 ! Near Maximum ! +04.7 97 45.00 2706 2439 44780 7275 98.3 1.200 ! Near Maximum ! +05.8 98 45.50 2734 2489 46256 7339 98.6 1.183 ! Near Maximum !


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