Gunboards Forums banner

bnz4 nice but cracked receiver

4K views 39 replies 23 participants last post by  Hambone 
#1 ·
Bad metal ?Dosent looked like it was dropped,late war matching rifle,great stock!Have it welded or nice wall hanger?Shoot it or not safe?Mint bore,crying shame,uuggg.:(
 
#7 ·
You have an original rifle with a reciever showing the stresses of late war production.
The crack in the reciever kept bubbas paws off of it for 65 years. Keep it or sell it, but get a cheap shooter instead of breaking it up. Seconds behind the guy who spoke for it on the trader.
 
#8 ·
Very interesting. By chance... Have you hecked the barrel very close for bulged areas?

It looks like the barrel is no longer seated properly to the reciever. (Gap between shoulder of barrel and receiver) I am thinking this might be an indication of excessive over pressure, like from round fired with an already plugged barrel. That is why I asked about barrel bulges. Often seen in such scenarios.

The crack in the receiver is right about where the third boltl lug is located, maybe indicating again excessive pressure, partly forcing the barrel to try to extrude out, and the 3rd bolt lug to crack the receiver? Or maybe just poor metalurgy. Interesting any way. Keep it together and hang it on the wall.

DO NOT SHOOT IT! Too dangerous to try. It might be interesting to check the head space on it for giggles. Cool find!
 
#12 ·
check out 'Mauser point blank range' (can someone post the link?)
this is the only way id shoot that one. lanyard. LOL. first is strip it of any good parts. and use RC bolt or something. then? Duck and Cover! just make sure you record it for the other members!
 
#15 ·
Receiver crack

The more I look at this the more I think this could be the result of someone trying to wrench off the receiver from the rear. The crack is rolling top to bottom as it would be if it was being twisted counter-clockwise. Mauser did not design these to be as strong on the rear half with the thumb-cut and stripper guide on the rear bridge they are easily broken The no barrel bulge observation does warrant a headspace check as Bill said. As for fixing it (I would) replace the reciever because a rifle that will not shoot is a paper weight. The argument of worth is only relevant if the rifle is for sale. All the Best. Sunfish
 
#16 ·
The rear receiver bridge is a non-stressed portion of the rifle. It would probably be OK to shoot but you don't know if the heat treatment/alloy was bad which means the stressed front ring could be waiting to go. Being matched, it still has value as a collector piece. Put it together as a wall-hanger and buy a RC to shoot.

To further answer your questions, since the rear bridge is non-stressed, it could be TIG welded but there goes the collectors value. If you could find someone who has access to a hardness tester, the hardness could be checked at various places to see if the problem was locallized to the rear bridge or if the whole receiver is suspect. As a mechanical engineer, I would think the front ring is OK since the metal is much thicker there. The crack is in the thinnest section of the receiver. Thin sections are difficult to heat treat especially when case hardening is used. Leave it in the case hardening bath too long and it is hard all the way through.
 
#17 ·
There are no wrench marks anywhere and if someone were trying to remove the reciever from the barrel they would certainly put the wrench on the front of receiver!I have see vice marks on the reciever of rifles that have had the barrel removed,there is no way a person would be dumb enough to put a wrench back there,no its stress fracture maybe from bad metal as was said or too hot a loaded round.Definatly war time crack,I have been advised this is a collector rifle,how many untouched k98 do you see? If I want a shooter I will get a refinished rc mixmaster,no problem!
 
#21 ·
Don't fire it.
Life is too short for that level of risk.
Sometimes a relic is just that/

What good is a poll?
"How long can I hold on to this gernade 'fore it goes off?"

If you pass it on, do somebody and your Karma a favor by dewatting it.

It will eventually make its way into the hands of somebody who won't suspect.

You did good by inspecting this thing.

Your choice.
 
#22 ·
If it were dropped or struck there would be a gouge mark I would think?Sure is a conversation piece if nothing else!Its not a paper weight, people pay thousands of dollers for dewat examples , this rifle will shoot and if it werent for the collector value it could be welded for about 10.00 and be safe to shoot I bet.The crack is on the bolt guide on one side and not under pressure like the front of reciever.;)
 
#23 ·
Thanks for the opinions!I would think the ears on the bolt locked into the reciever grooves would take all the pressure from the fired round,those parts look great,if they were cracked or broken you might have a problem!Anyway wont shoot it,no need ,I would much rather have this than a dewat rifle myself.:)
 
#26 · (Edited)
....I would think the ears on the bolt locked into the reciever grooves would take all the pressure from the fired round,those parts look great,if they were cracked or broken you might have a problem!...
Under normal conditions the front lugs do take the pressure. A failure there, causes the pressure to transfer to the 3rd lug as a back up system to take the pressure.

If the front lugs have been badly fit, or machined out of tolerance so that they are not holding the pressure as intended, the thrid lug may have been actually doing the work instead. This would then put pressures to the rear receiver bridge area that is not normally experienced under proper conditions. A visual inspection of the bolt lugs will not tell you much in the case of the above scenario.
 
#27 ·
My first bnz41 KM was a minty example purchased in the late '70's or early '80's. It had a similar fracture in the same approximate location. My thoughts at the time were that either bad metal, an overloaded cartridge or that the rifle had been dropped or hit on that thin area. No physical evidence to suggest such a hit but it always stuck with me as an option.

As to bad slides on P38's. A long time ago - I snapped the slide of an engraved AC43 (byf) with a couple shots of light reloads. The subject P38 had cost me a nice K43 in trade and was sold as a pile of parts to a reenactor for a song. Ugh. I have since never felt compelled to throw any collector grade P38 into my shooters bag.
 
#28 ·
A crack like the one pictured is most likely the result of a combination of factors.
1. Poor metallurgy.
2. The steel may have been low in nickel making the receiver brittle.
3. The lack of stress relief during a hasty manufacturing situation.
4. The likelihood of work hardening during manufacturing.
The area of the crack is about the weakest part of a 98 action. Overall, I would say that there was substantial stress in the receiver that had not been relieved and it just did not hold together. A small stress riser like the shock of recoil or being dropped could have initiated the crack. Maybe it just could not hold together anymore. Metal that has been worked a lot does some strange things. It would be intresting to heat the reciever and see how much memory is left in it....it may bend up like a pretzel!!!!

I would not shoot it! If the weak parts give way, I would not bet my face on the strong parts!!!!

Just my 2 cents….
 
#29 · (Edited)
Safety lug does not engage the receiver bridge. It engages a radial slot in the floor of the receiver at the 6:00 position - but under the receiver bridge. If pressure forces the safety lug against it's reaction shoulder, it would not create a significant stress in the receiver bridge as the bridge has no way to react forces at it's 12:00 position. Tension stress would exist in the floor of the receiver.
This appears that it could be a delayed post-heat-treatment stress crack
I have a Randall Model 15 knife that was made in the 1960s and I purchased it in 1975 - been laying in a drawer ever since. Two years ago the blade cracked 1" back from the tip - never used, no forces on the blade. Just cracked by itself after 40+ years.
It could even be the result of Bubba holding the receiver in a vise at the bridge and cranking down too tight on it - except that no vise marke are present. What does the area under the bolt stop look like?

DON"T SHOOT IT!!!!!
 
#32 ·
Safety lug does not engage the receiver bridge. It engages a radial slot in the floor of the receiver at the 6:00 position - but under the receiver bridge....
Correct.

My point was that under normal conditions this rear receiver bridge AREA sees no stress from firing pressures. But if the front lugs are out of spec, or if in the case of catastrophic failure of the front lugs this would then transfer stress from firing pressures to this rear bridge AREA. Thus indicating that firing pressure stress could also be a factor in the damage.

There could be any number of factors coming into play that caused this, metalurgy, heat treatment, sudden impact or other higher than normal stress, temperature, or any combination of the above.
 
#30 ·
Definitely don't part it out. I wouldn't shoot it either though. I'd be happy to have it in my collection as is. I think it's worth well over what you originally paid. Don't get me wrong, I'm not looking to get into rusty relics, but Kar.98k's with catastrophic failure of one component such as this are interesting.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top