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Centerfire Rifles - Manually Operated Lever action, bolt action or other non gas operated centerfire rifles.

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  #41  
Old 08-20-2020, 5:29 PM
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All I want to add is I bought a bohica upper as part of a group buy on Calguns. We all got our stuff, but the next week bohica was out of business and their new adventure doesn’t support the bohica models. You can’t even get a firing pin. I’m glad I bought a spare.

The whole experience left me with a bad feeling for the upper and the owner. Who knows if he even had product liability insurance. The firing pin issues are well documented. Some stuck in the bolt face as the steel used to make them was incorrect or improperly heat treated , or both . Kinda like a Uzi FS bolt but with different results in a bolt fed 50 DTC.

We will never know what really happened that day but I do know Bohica seemed like a shady company based on what I experienced.
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  #42  
Old 09-05-2020, 7:15 PM
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Just a medium length reply to a few people -

To pratchett - I appreciate the extensive editing exercise; others do to. Don't have any .458 SOCOM rounds. Has anybody noticed that unless done the way pratchett did it, there is no first line indent within these forum posts.

To LynnJr - As far as 100% verifiable reason for the Kaboom; I don't have one. I THINK it was the primer just waiting for anything to touch the previously mashed priming compound from bad seating being hit (even lightly) by the firing pin inertia (held back by a very weak spring) while the bolt is rammed forward to overcome the extractor force necessary to go over the case rim. It is difficult on mine; which is why I place the case head under the extractor before chambering.
I didn't say any fault was a short case length. I mentioned the shoulder to case head dim as a possibility before trying it in my own Bohica. Not a problem.
I'll put my Mechanical Engineering degree up against yours anytime and I've been reloading for almost 70 years.
Putting the "HAMMER" blow on the bolt handle bullcrap to rest.

To DueceMcGurk - The new owner of the Bohica in question acquired it from the ex-boyfriend (the one involved in the OOBD at Angeles Shooting Range) of the owner's (one and only) sister. Remember the off-roading trip?

As for spare firing pins; does anybody need a dimensioned drawing of one? A half way decent machinist can make one from a .250" x 6" long HSS drill bit blank or a good piece of stainless. I can provide; just ask.

Last edited by DUBLBZ; 09-05-2020 at 7:19 PM..
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  #43  
Old 09-05-2020, 9:23 PM
LynnJr LynnJr is online now
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Yes you can put your mechanical engineering degree up as it is useless.
As I suspected all along you haven't got clue one as to what happened.
.
"The sized and trimmed length of the case could also be an issue"
No it can't send that degree back and get a refund.

Love the title of your post but instead of the word final it should read just another guess based on nothing.
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Last edited by LynnJr; 09-05-2020 at 9:31 PM..
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  #44  
Old 09-05-2020, 10:17 PM
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I do have to say, this was a great reading experience on cgb
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  #45  
Old 09-06-2020, 8:24 AM
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DUB,
My weak attempt at humor.

Point is that big blocks of text are "uninviting" as they taught in copy writing class.

This will discourage some folks from reading and responding. Those may be the exact gunners you want to comment on your post. Pratch had a good example of a long, but readable, post.

Stay with us. We are on your side. But this is a tough crowd. Especially Lynn. lol
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  #46  
Old 09-06-2020, 7:39 PM
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Lynn isn't a tough crowd but when he reads I have been reloading for 100 years and I am a mechanical engineer but it may have been too much setback on a shoulder he calls BS.
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  #47  
Old 10-12-2020, 3:28 PM
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I assume the round went off as the bolt was being closed. This has not been stated positively.

I do not want to discount the sensitive primer theory, as I have an account of cartridges igniting in a court evidence bag. Primers are not be trusted, they are not nice and reliable like a light switch. Sometimes it takes very little to set one off.

Therefore, if there was someone on the bolt face, or the firing pin tip was sticking out, there could have been incidental contact.

1) Does this design have a positive firing pin cam and is the firing pin held back during bolt closure? If the firing pin is stuck forward inside the bolt, due to something, then the tip could have been sticking out of the bolt face.

2) What happens if the hammer is knocked off the sear? Does the hammer move the firing pin forward prior to bolt closure?

Quote:
but it may have been too much setback on a shoulder
If the cartridge is shorter than the chamber, I am of the opinion that is more likely to cause a misfire. If the firing pin barely touches the primer, because the case is too deep in the chamber, misfires will happen.

Now, if the case was too fat for the chamber, then you have a "crush" fit, and that could cause something strange to happen.

Last edited by slamfire1; 10-12-2020 at 3:32 PM..
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  #48  
Old 10-12-2020, 3:32 PM
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The angeles range one was a hangfire and dummy open bolt just as it cooked off. No hammer involved in that one. Very bloody mess.
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  #49  
Old 10-13-2020, 12:58 AM
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slamfire1 & edgerly779 - Yes, the round went off as the bolt was being closed. Damage to his hand indicated pushing the bolt handle, not lifting it as if opening. Not a hangfire. The shooter also described what was being done at the time of the detonation.

The Bohica design does not have any positive mechanical surface or device to keep the firing pin from contacting the primer during chambering. The tip of the firing pin sits flush with the bolt face, being held in that position (fully rearward waiting for a AR15 hammer blow) by a 7 ounce (200 grams) spring. The firing pin weighs 1.16 ounces (33 grams). From these factors, it only takes in excess of 6gs of forward impact deceleration of the bolt to allow the firing pin to contact what was a crushed and extremely sensitive primer. That is not much.

The bolt does have a cammed surface at the side of the slot for the hammer to strike the rear of the firing pin. From close inspection, it appears that the hammer can only contact the firing pin from approximately 80% closed to fully closed and locked. I plan on using a primed empty case to test where this point actually is. Starting at chambered but no locking rotation, and pulling the trigger. Incremental rotation toward full lock (after re-cocking of coarse) will eventually arrive at the position that allows primer ignition. I will publish here what I find out.

The cammed surface mentioned above does cause additional torque to be exerted at the bolt handle upon opening after firing due to camming the AR15 hammer toward the cocked position (not all the way). Finish cocking is achieved upon extraction.

The issue of case length was not in reference to it being too short. Being too long at the shoulder from inadequate sizing practice (or equipment/set-up) would make it very difficult to chamber. This ended up not being an issue, just an original possible problem to be looked at.
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  #50  
Old 10-13-2020, 5:18 AM
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Quote:
Originally Posted by DUBLBZ View Post
slamfire1 & edgerly779 - Yes, the round went off as the bolt was being closed. Damage to his hand indicated pushing the bolt handle, not lifting it as if opening. Not a hangfire. The shooter also described what was being done at the time of the detonation.

The Bohica design does not have any positive mechanical surface or device to keep the firing pin from contacting the primer during chambering. The tip of the firing pin sits flush with the bolt face, being held in that position (fully rearward waiting for a AR15 hammer blow) by a 7 ounce (200 grams) spring. The firing pin weighs 1.16 ounces (33 grams). From these factors, it only takes in excess of 6gs of forward impact deceleration of the bolt to allow the firing pin to contact what was a crushed and extremely sensitive primer. That is not much.

The bolt does have a cammed surface at the side of the slot for the hammer to strike the rear of the firing pin. From close inspection, it appears that the hammer can only contact the firing pin from approximately 80% closed to fully closed and locked. I plan on using a primed empty case to test where this point actually is. Starting at chambered but no locking rotation, and pulling the trigger. Incremental rotation toward full lock (after re-cocking of coarse) will eventually arrive at the position that allows primer ignition. I will publish here what I find out.

The cammed surface mentioned above does cause additional torque to be exerted at the bolt handle upon opening after firing due to camming the AR15 hammer toward the cocked position (not all the way). Finish cocking is achieved upon extraction.

The issue of case length was not in reference to it being too short. Being too long at the shoulder from inadequate sizing practice (or equipment/set-up) would make it very difficult to chamber. This ended up not being an issue, just an original possible problem to be looked at.
Thank you for the reply

Based on my web research, this is what I found the shooting was doing at the time of ignition

This

Out of Battery Bang when round fired before bolt fully closed


http://bulletin.accurateshooter.com/...-fully-closed/

lead to this:

Bohica Kaboom

https://www.ar15.com/forums/armory/-...301869/?page=4
I was not at the range when this happened but I spoke with the range staff last week and they pretty much explained exactly how this happened. The guy was using new reloads that weren't exactly fitting well into his chamber. Dude was slamming the bolt handle with his palm trying to get the cases to lock in. The guy was also slamming the bolt forward full force from the rearmost position back and forth trying to ram the cases into chamber in an attempt to squeeze the rounds in so the bolt could close. Finally, on one of the attempts of him doing this, the possibly stuck firing pin rams into the primer and explodes the round when he slams the bolt forward (zero lug engagement hence the KB) and shooter puts himself into a world of hurt.

That is why his left hand is all ****ed up, because he had his left hand gripped on the front magwell of the receiver for extra leverage when using his right hand to slam close the bolt.


The design of the rifle allows movement of the firing pin before the bolt is fully in battery. This means the firing pin can, through inertia, impact the primer before the lugs are in battery. Free floating firing pins sensitive primers, are the most common cause of slamfires in automatic weapons. I have had them in Garands and AR15's, lots and lots of reports of slamfires in SKS's. If the shooter was ramming the bolt hard, to crush fit rounds to the chamber, I think incidental contact between the firing pin and bolt to be the most likely cause of the out of battery incident.

I do want to note, I got to talk slamfires with one of the best Long Range Shooters in the US. He has every medal, a number of National Championships, and has been shooting rifles since the early 1960's. He showed me the palm of his right hand, and I have a picture, where he received 32 stitches from a NM M14. He was shooting a NM M14 at 600 or 1000 yards, prone slowfire, he had placed the round in the magazine and tripped the bolt. This is the way you are supposed to load the thing, from the magazine, to slow the bolt's forward movement. This is because in the Garand mechanism, the firing pin is totally free floating and will rebound off the primer. Slowing the bolt will therefore reduce, but not eliminate, the potential of a slamfire due to a sensitive primer




For the National Champ, during loading slow fire prone, the round caught on the feeding ramp and the bolt stopped. He then bumped the operating rod to get the round to chamber. The round ignited, no doubt due to a tiny bump from the free floating firing pin on the primer, and the operating rod cut through his palm. He said it blew the stock apart and the magazine from the rifle. No doubt he was more concerned about his hand and getting medical help, than a forensic analysis of what bit him.

He was firing LC Match ammunition, so it was factory ammunition with the proper primer sensitivity.

I am not going to mention his name, due to all the hateful A**holes who don't believe in slamfires, and therefore might attack the old man while he is living. Some day I will post a picture of his palm, with the scar still visible from the cut he received in the early 1970's.

If you look at good bolt action design, the firing pin is positively held back during chambering. Based on what I know about primers and firing pins, I consider the Bohica a defective and dangerous design, and if it was not for others taking pictures and posting, we would never have know about this.
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  #51  
Old 10-13-2020, 6:29 AM
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I don't know of anyone who doesn't believe in slamfires.
The debate usually centers around what was the actual cause without all the speculation and guessing.

Broken firing pins or protruding firing pins protruding from the boltface are usually but not always the suspected culprit.
Is the picture of my right hand close to your picture?
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  #52  
Old 10-13-2020, 8:48 AM
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Quote:
Originally Posted by LynnJr View Post

I don't know of anyone who doesn't believe in slamfires.
The debate usually centers around what was the actual cause without all the speculation and guessing.

Broken firing pins or protruding firing pins protruding from the boltface are usually but not always the suspected culprit.
Is the picture of my right hand close to your picture?
Very similar!

Lynn: I assume that is the scar left by a slamfire, which weapon? Garand, M14, M1a, or M1 carbine?

In so far as slamfires, I should have clarified that the opposition against slamfires is multi-fold.

Firstly, the American public was taught, by the Army, through the NRA, that the only causes of slamfires were due to "a worn out receiver bridge and high primers". This was a deliberate misdirection, and shifted the problem as only due to user misconduct. I have been able to trace this back to the early 60's in American Rifleman articles, and it was when Civilians were first getting their hands on NM Garands, through the DCM, and when the M14 was in a life and death struggle with the Colt AR15. The civilians were undoubtly doing dumb things like neck sizing, (I was in the Springfield Armory pavilion on Commerical Row, at Camp Perry and an older shooter walked up and was proudly discussing his neck sized long range ammunition! This was around 2000. Some people are so lucky) and using "match" primers, which were the most sensitive primer around. And then, the Garand mechanism is wholly dependent on primer sensitivity to keep from slamfiring, in battery or out of battery, so given that confluence of issues, the public was taught there was no such thing as primer sensitivity, and the only allowed causes of slamfires was due to worn out guns and bad reloads. The M1 Garand and the M14 were perfect, there were no design flaws, no design risks, the things were perfectly designed, perfectly made, just the most perfect weapons ever, and to suggest there were systemic risks (which all mechanisms with free floating firing pins share!) was communistic.

It turns out, high primers are the most likely cause of misfires. If the anvil is not seated firmly in the pocket, the primer will misfire when struck. While there are shallow primer pockets, and people will try to seat primers without removing the military primer crimp, the high primer misdirection is more or less the moot in the shooters eye, compared with the beam in Army's eye.

Of course, until 1999 mil spec primers were not available to the American public, so there was not much shooters could do to buy the less sensitive mil spec primers. Maybe that was a part of the decision to lie about the causes of slamfires. And those explanations more or less were dogma within the shooting community until a tidal wave of AR15's arrived on the scene (mid 1990's) and suddenly, lots and lots of in battery slamfire reports are occurring with AR mechanisms, with factory ammunition, and the things don't have a receiver bridge.

Also, around the same time, a whole host of military semi auto's, such as FN49's, FAL's, SKS's, AK47's, etc, came on the market. And they are slamfiring with commercial ammunition with sensitive commercial primers. These models were very scarce prior to the middle 1990's, and the internet was just coming on line. The internet allowed shooters to share their experiences direct with other shooters without the stalwarts in the NRA filtering the news.

Given the number of slamfires reported with all models of semi auto rifles, over time, the Army explanation of slamfires having nothing to do with primer sensitivity, and being solely due to shooter misconduct, appeared less and less believable. But it is still out there, just go to the M14 forum and you will still run into militant deniers. They are a hateful bunch, fully supported by forum management, and I have avoided that forum for years.

Last edited by slamfire1; 10-13-2020 at 8:51 AM..
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  #53  
Old 10-13-2020, 3:59 PM
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There was another 50 caliber rifle about 15-20 years ago that had firing pin issues.
The pin would fail allowing it to protrude from the boltface and eventually igniting the round off out of battery.
I don't want to guess at the name and get it wrong.
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  #54  
Old 10-13-2020, 5:57 PM
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Quote:
Originally Posted by LynnJr View Post
There was another 50 caliber rifle about 15-20 years ago that had firing pin issues.
The pin would fail allowing it to protrude from the boltface and eventually igniting the round off out of battery.
I don't want to guess at the name and get it wrong.
I researched slamfires, found in a book about the Vickers machine gun that they had to re design the feed mechanism because primers were being bumped by something as the rounds were being fed into the chamber area. The occasional sensitive primer would go off, causing all sorts of problems when the round exploded outside of the chamber.

Primers are tricky things, if the dwell is not perfect, that will cause advanced primer ignition mechanisms to malfunction. If weak ignition causes a slow pressure build up, the timing will be off on an advanced primer ignition gun, and possibly result in the cartridge being extracted when pressures are high enough to rupture the case sidewalls. Probably similar issues on chain guns, can you imagine a hangfire round being extracted in a chain gun? Probably cause a major malfunction.

Lynn, what was the cause of the scar on the hand picture?
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  #55  
Old 10-16-2020, 8:57 PM
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Default Yes on Slamfire

I read all the previous reports on this. Also talked to the shooter.

Yes the bolt was being aggressively closed to chamber a round.

That led me to initially wonder if the reloads had been sized/shoulder set back correctly while converting 50BMG to 50DTC.

I tried one of those original reloads in my Bohica by fitting the case rim under the extractor first. Chambered fine. Length not a problem. Knowing my extractor was a tough run up over the case rim, I think that was his problem. Couple that with the mal-formed very sensitive primer and the low impact level to allow the firing pin to move forward, and it detonates yielding a slamfire.

As I mentioned in the original post, I also have personal experience with Slamfires (AKS). Inserting a spring where there was none fixed that. The Bohica would most probably benefit from a stronger firing pin spring and weaker extractor spring.

Given the above potential changes, I still think that without the mal-seated primer, this event would not have happened.
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  #56  
Old 10-17-2020, 9:21 AM
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I think the rifle I was referencing was a Hesse/Vulcan but don't quote me on that.

On the Bohica was the firing pin the standard length pin or the 0.100 short or generation 2 pin length pin?
I ask because they shortened the pin for a reason.
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Old 10-17-2020, 9:47 PM
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My pin is 5.561" long. At the rearward position, the front of the pin is right at the face of the bolt. The event shooters Bohica was an earlier version than mine. I do not know what the two different lengths were, but as you say there was a shorter version where the tip was most probably set back into the bolt (maybe for this very reason), his was undoubtedly the long version. It was totally destroyed in the event so can't verify.
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Old 10-17-2020, 10:15 PM
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The firing pin in mine only travels about .06" forward from the face of the bolt, then stops. The shortened pin must have the grove cut in it for the rear motion limit C-clip moved forward the .100" length change, pulling the front of the pin back into the bolt the aforementioned .100". This means a change to the spring and shortening .100" at the rear of the pin where the AR hammer strikes it. Can't have the rear portion more accessible to the hammer where the cam surface is.
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Old 10-18-2020, 3:30 AM
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Old 10-20-2020, 9:11 AM
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Mixed crowd here.

Some contribute to the discussion, others that cannot just find something to complain about.

Sounds like politics today.

Does anyone have dimensions of the shorter firing pin in this subject?
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