OK, Boom-Boom, your post is kinda like taking a drink from a fire hose. Under stand you "studied" a lot, what about a basic course in "H ow to Avoid.....".
My problem is that I use voice dictation and sometimes it comes out as stream of conscience. When talking, I have new thoughts and unfortunately try to be comprehensive sometimes.
Here are things to look to avoid in milsurps.
A) receivers that have been excessively D&T'ed, welded, Enfields that have been marked DP except as parts rifles, rifles converted using parts from several sources such as Bannermans mongrel Krag/Springfield/Enfield abominations. Any DP marked receiver should be carefully examined by an expert before conversion into a firing rifle. If you do not know what lug setback is, don't know how to use gauges to check headspace, or where they drilled holes to dewat these, get an expert opinion.
B) rifles and or receivers that have been rechambered in modern high pressure cartridges--century old receivers are generally not wise candidates for the latest supermagnums. Metallurgy was crude even while the craftsmanship was great.
C) rifles that have the original markings obliterated that are chambered in mystery cartridges. You might have liked Mystery Date as a game as a child, not so amusing in rifles.
D) badly pitted receivers or receivers that have thumb cuts to allow feeder clip feeding (see some GEW 88/05 models for example). In an exciting event occurence, this is a spot for the receiver to break into pieces, perhaps at high speed.
E) Corroded or rusty bores--there is dark and pitted and then there is rusty and corroded. The first might clean up and if the pits are in the grooves rather than lands, then it might be fairly accurate until it fouls. The second type might involve a bullet slowing down or stopping in the bore due to friction and then pressure spike--kablooey where your barrel turns into a flower or grenades.
In a similar vein, bulged barrels or those with extensive external pitting, or various holes where Bubba tried to mount a barrel sight , etc.. These now have weak spots that can make firing high power rifle rounds an exciting event. This is not your low powered 10,000 psi, a .22 LR at about 22,000 psi but even the lowly 30-30 generates nearly 40000 psi.
F) Barrels, bolts, and receivers that have various sorts of notches, machining operations, or heat discoloration from grinding, welding, etc. The widespread use of indiscriminate welding, Dremels and grinders have been used by Bubba to resolve all sorts of ills. Some folks think it smart to heat barrels to red hot to remove them from receivers--it is not. Want to know about heat treatment, read up on it or ask an experienced welder about how heat affects unknown alloys.
G) Krags or other rifles where the person brags on having lapped the bolt so that the bolt lugs and bolt handles both bear loads. Generally that means that they have went right through the heat treated bolt lug exterior into the softer core. Not good.
H) Various weird rifles not found in common reference books that are alleged to be coming from places such as China, Vietnam, Iraq, Afghanistan, etc. Often these sort of look like something in the magazines or books but have strange features not present in them.
Khyber Pass is one such place that has a kitchen industry of making odd home made variants of the various arms that have passed through Pakistan. The Philippine Islands also have a lot of backdoor gun crafting of popular models in that country. You might encounter quaint practices such as using rusty nails as firing pins, pot metal bolts that bend when firing, non working safeties, and no concept of modern heat treatment on some. Like the looks, keep it as a wall hanger. When you have misspelling of Mauser as Wauser or English lettering that has a few backward letters, then the hint is that yours might have been made in some back alley.
I) For a shooting rifle, it is best to avoid rifles where the nation was too cheap to buy new rifles to fire newer and more powerful cartridges. Thus, some were rebarrelled, rebored, some had chamber inserts, etc. Many of these used rifles simply as a badge of authority or war reserve so they were fired little. There will be some folks on forums that swear that they have put 100,000 rounds through them or that some laboratory test where a defunct company paid for testing receivers to destruction.
My question is how much is your face, hands, eyes, or even life is worth. By the time of copays, deductibles, and balance billing, firing rifle using a cartridge that was outside of its specified making where the rifle was subject to dubious storage and use is for those who love risks.
J) There are some rifles that have known issues and anyone firing them should at least educate themselves on the pros and cons.
a) Ross Rifles of 1910 (little issue of incorrect reassembly of the bolt)
b) Some makes of the GEW 88's as some of these were not manufactured correctly either heat treatment etc. Some ersatz versions were made in China for warlords and some of these crappy parts show up used on auctions or even gunparts.com
c) low number 1903's--there is a whole set of flamewars over this very issue--if you have one (old guns.net can give you the year of mfg and whether you have a low number Springfield or Rock Island receiver that might not be safe to fire with brittle receivers and bolts. Get informed and then decide whether or not firing a potential grenade is worth it. Most are probably fine. There is also a known problem with some WWI era barrels being made with burnt steel that burst upon firing--see Avis barrels.
d) some reports of cracked receiver rings in 1917 Rifles, probably caused by rebarrelling with a few alleging improper heat treatment (Eddystone makes are often cited but other Remington and even Winchester have had a few cracked receiver reports). Whether it is from scarcity or not, I have not seen any reports of such on the earlier P14 series--it is possible the English inspectors were more thorough.
e) Japanese training or school rifles where some had cast iron receivers and were not to be fired with live ammo or some school rifles were service rifles not fit for live fire anymore. If you see 00 stamped in front of the regular serial number, and odd defacements of the mum, then you probably have a school rifle. My example was an early T38 where the receiver had stretched with a very worn barrel. Someone had butchered the stock and was apparently firing it until it was sold as a Bambi Killer. I bought it in person because it was a neat cheap rifle. I keep it around as a lesson.
f) Chilean sleeved long Mauser 95's in .308--lousy job and many reports of separation have occurred.
g) Steyr 95's deacs where the bolt was spot welded underneath to the receiver.
h) late WWII wartime 98k Rifles made by slave labor might not be the best idea to fire. Some contractors had some issues with heat treatment. Some folks put Japanese last ditch Arisakas in a similar situation.
i) Carcanos in 8x57 made as emergency conversions, Volkstrum rifles, or the Vetterli converted to 6.5 Carcano. Emergency conversions mean probably unsuited for safe firing.
j) Krags, cracked bolt lug due to Army attempts to up the .30-40 Krag performance with more power and with only one lug, you don't want that. There was a reason that a lot of new old stock Krag bolts were floating around until just recently--the Army screwed up and needed a lot of replacement bolts in a hurry.
I got more but I am already running long. Peace out man.