BS Busters 001

The never-ending stream of gun-rag BS that gets posted on this website seems to be increasing at an exponential rate lately.  I can’t seem to go a single day without coming across a thread in the technical forums that has some steaming pile of horse manure posted as if it were fact.  Naturally, the posters of these excremental edicts fail to post any factual data to support what they are saying and anyone who disagrees with them is called a “dumbass” by the person shoveling the manure, based solely on the basis of his self-proclaimed intellectual superiority or self-anointed status.

This is a technical forum and the only thing that matters here are facts.  In God We Trust, All Others Must Post Data.  No one cares how many degrees you have, if you can’t support what you are saying here by posting factual data or relevant, credible references (and Wikipedia is not a credible reference source.)  The only thing that matters here are the facts.  It matters not one bit what you were told in the service, if you can’t support what you are saying here by posting factual data or credible references.  It doesn’t matter how many drug-busts you have carried out if you can’t support what you are saying here by posting factual data or credible references.  It’s irrelevant what manufacturer you claim to work for, if you can’t post factual data or credible references to support what you are saying here.  I don’t care how many competitions you claim to have won, if you can’t post factual data or credible references to support what you are saying here and I absolutely don’t give a rodent’s rump what gun-rag you write for, if you can’t post factual data or credible references to support what you are saying here.

In an effort to combat the misleading, mistaken, fabricated, intellectually fornicated and outright false information posted in these technical forums, I’m starting this “BS Busters” thread.  Anyone can contribute to this busting of BS on any AR-15 related topic, as long as you can contribute factual data or credible references.  For the first installment of this thread, I’ll be showing how a small application of science can contribute data towards busting some BS I’ve seen posted on the Internet.


Kaboom

There have been several reports on the Internet of “kabooms” in AR-15s. Invariably, the Internet Commando, who was not witness to the event, has not examined the remains of the event and basically has not a clue what he is taking about, chimes in to proclaim that the source of the kaboom was due to a bullet striking a previously “fired” bullet that was lodged in the barrel because that cartridge lacked a powder charge.  That is, the obstructing bullet was propelled into the bore to a point  ahead of the throat powered solely by the primer ignition.  

"This is Rumor Control. Here are the facts."

I loaded a Hornady 55 grain FMJ bullet into a factory primed, Winchester 223 Remington case.  No powder charge was loaded into the case.  The overall length of this “loaded” cartridge was 2.217”.  I then chambered this round into an AR-15 with a Centurion Arms barrel.  For the next step of this little experiment, I slowly ejected the round and measured the overall length of this chambered, but not yet fired round.  That measurement was 2.2175”.  This step was taken simply to rule out any gross forward movement of the bullet out of the case due to chambering.

Lastly, I rechambered the test cartridge and pulled the trigger; all that was heard was a “click.”  Again, I slowly ejected the round and low and behold, the bullet was still in the cartridge case; not lodged in the bore  ahead of the throat as the Internet Commando claims must happen.  The overall length of this “fired” cartridge was only 2.2185”.  Not counting the possible forward movement measured above due to chambering, this shows that the bullet only moved 0.0015” forward out of the case from the primer ignition.  As the jump to the lands in a NATO chamber can be 0.150”+ for a typical 55 grain FMJ load, we can see that the bullet was not even remotely close to contacting the lands, let alone becoming lodged into the bore forward of the throat, simply from the ignition of the primer.



The test vehicle.






The “fired” test cartridge.






The singed bullet base, illustrating that the primer did indeed ignite.





The fired primer.



It’s difficult to see in the above picture, but the primer backed-out of the case by a few thousandths of an inch during the firing process.  Before measuring the cartridge overall length after firing, I “reseated” the primer for a true overall length reading.



The reseated primer






Side by side for comparison.




.....






BS Busters 002

“55 grain bullets are unstable/overstabilized/inaccurate/less-lethal when fired from a barrel with a 1:7” twist.”

Statements such as the one above always seemed to be proclaimed by the Internet Commando without the slightest bit of hard data to support that these effects even occur, or that if they do occur, they do so to any degree that has any significant effect on the terminal ballistic properties or accuracy spectrum involved with AR-15s firing M193/M855 type ammunition.

By definition, an “unstable” bullet is one that will have a gyroscopic stability factor of less than 1.0 at the muzzle.  A typical 55 grain FMJ bullet will have a gyroscopic stability factor of approximately 3.7 when fired from a 20” barrel with a 1:7” twist.  [CaptainObvious] 3.7 is not less than 1.0. [/CaptainObvious].


The following demonstration compares the results of firing four 10-shot groups of the same lot of 55 grain Prvi Partizan M193 ammunition from two different barrels; one barrel with a 1:9” twist, the other barrel with a 1:7” twist. The first barrel used in testing was 16” Colt HBAR with chrome lining, a NATO chamber and a 1:9” twist. The second barrel used in testing was a 20” Colt HBAR, also with chrome lining, a NATO chamber and of course a 1:7” twist. The longer barrel with the 1:7” twist was purposely chosen for the increased muzzle velocity coupled with the 1:7” twist. Both barrels had free-float handguards.

Accuracy (technically, precision) testing was conducted from a distance of 100 yards following my usual protocol. The fore-ends of the weapons rested in a Sinclair Windage Benchrest and the butt-stock rode in a Protektor rear-bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was attached to the objective-bell of the scope. Naturally, the wind conditions were monitored using a Wind Probe. The set-up was very similar to that pictured below.





Four 10-shot groups of the PPU M193 were fired from the 1:9” twist barrel. Those groups were over-layed on each other using RSI Shooting Lab to form a 40-shot composite group. The mean radius of that composite group was 1.08”.

As with the 1:9” twist, four 10-shot groups were fired from the 1:7” twist barrel.  Those groups were also also over-layed on each other to form a 40-shot composite group; the results were nearly identical to those obtained from the 1:9” twist barrel.   The composite group had a mean radius of 1.01”. The two composite groups are shown side by side for comparison.






Testing performed by C.E. Harris at Aberdeen Proving Ground and later at Sturm-Ruger has shown that the “overstabilization” claim is largely inconsequential. The testing showed that “overspinning” quality light-weight bullets from a fast twist barrel does not become an issue unless you have a gyroscopic stability factor greater than 5.0 (which would require something along the lines of a 1:6” twist barrel launching a 55 grain bullet at over 3500 fps) or unless firing at an angle greater than 85 degrees.

After the U.S. Military adopted the 1:7” twist for the M16A2, C.E. Harris performed tests comparing the accuracy of light-weight bullets fired from 1:10” twist barrels and 1:7” twist barrels using 52 grain Sierra MatchKings. The accuracy testing was done from 200 yards, (well into the downward slope of the trajectory where the Internet Commando claims that all manner of evil befalls the “overstabilized” bullet), and the accuracy results from the two different twist barrels were also nearly identical.





Quality, modern lightweight bullets (40 to 55 grain) of typical copper-jacket/lead-core construction can shoot superbly from fast twist barrels.   Typical 55 FMJ bullets do not fall into the quality category.


The group pictured below was fired from a 1:7" twist Noveske barrel using 40 grain V-MAX bullets.






The 10-shot group pictured below was fired from a distance of 100 yards from a Noveske barreled AR-15 with a 1:7” twist.





The 3-shot group pictured below was fired from the same 1:7” twist barrel for the Internet Commandos in our viewing audience.







The next 10-shot group pictured was fired from a Krieger barreled AR-15 with a 1:7.7” twist using 55 grain BlitzKings.





Here's another example of just how well a 1:7" twist barrel can shoot light weight bullets. While the group pictured below was fired from a distance of only 50 yards, it's a 10-shot group fired from a chrome lined, NATO chambered Colt barrel with a 1:7" twist using 52 grain Sierra MatchKings.








A 14.5" Colt M4A1 SOCOM  barrel,with its NATO chamber, chrome lining and 1:7" twist can shoot quality 55 grain bullets quite well.






A 1:7”  twist rate does not have a negative effect on the terminal ballistic properties of M193 and M855.  From Dr. G.K. Roberts . . .

"The U.S. Army Wound Ballistic Research Laboratory conducted terminal performance testing using 5.56 mm 55 gr M193 FMJ ammunition fired in 20” barrels of 1/14, 1/12, 1/9, and 1/7 twist rates. No difference in terminal performance was noted between shots made with the different twists. Similar testing was conducted with 5.56 mm 62 gr M855 FMJ ammunition fired in 1/9 and 1/7 twist barrels. Again, no difference in terminal performance was noted."











….




BS Busters 003

“5.56mm NATO cases have thicker walls and therefore less case capacity than .223 Remington cases.  


The data below speaks for itself.





….

You would have to use every possible combination of case,  primer, bullet, and crimp to prove anything.  All you proved was that the conclusion you sought happened one time with your one particular handload.

The point of this thread; you didn't "get it."

Maybe it was a light charge.  Load rounds with progressively heavier charges till you see how powder it takes to move the bullet..you could even come up with a grains per inch of barrel table.

I like the idea of the thread..BS Busters...LOL

Now, where is Gecko45?

I'm not sure you understand 'proof'.

This proves that it doesn't happen for that specific combination.....doesn't mean it absolutely cannot ever happen.

Reading comprehension, you lack it.  Show us exactly where the word "proof" appears anywhere in my original post.

Considering the overall diameter of the .223 round is usually .224, the round is bigger than the bore.

Show me anywhere in the wide world of small rifle primers, one that is strong enough to propel an oversized bullet into a smaller bore.

Molon is merely dispelling rumors with a common load, I'm sure he could figure out how to fit a .50 BMG primer on there and make it work, but your average rifle primer ain't gonna do the trick.

Cool thread. I like it.

Well this might not be the kind of BS your looking for but its been said numerous times that more than 8 or so rounds of 5.45x39

cannot fit in a standard pmag let alone feed reliably.


Here's my unscientific proof:

Video Link

ETA: mag was not modified in any way.

I'm curious what impacts a light load causing a bullet to be lodged in the barrel a) before the barrel gas port hole and b) after the gas port hole has when firing a subsequent round, in case anyone wants to step up to evaluate

Great idea for a thread Molon

Lately I've noticed more and more people discuss the "knockdown power" of one round versus another. I'd love to see a reality based discussion demonstrating that a hit from a 223/9mm/12ga etc is not like a hit from an RPG or a TOW missile-Hollywood notwithstanding. Being shot with a 12ga slug is not going to pick you up off your feet and throw you across the room.

Posted Via AR15.Com Mobile

Placeholder. I'll post "Gas Ring Bullshit" tomorrow.



So I went to the range this morning to determine the validity of the "Gas Ring" myth, the myth being that the rings must NEVER be aligned.  I've heard this for years and was even told this in Basic at Ft Benning in 1993.  I think most know it's total crap but I wanted to know for sure.  I used an old Frankengun that I've had for five or six years.  These days it's mostly for my 15 y/o to shoot with a Ciener kit.  



Sorry for the Iphone pics but it's what I had.



So we start with all three rings.  Bolt was still kinda grimy from the last time I shot it and I did not lubricate for the test.





Fired three rounds.  No problems.







So I remove a ring.





Bang bang bang.  No problems.





Interesting, so I take off two rings.  Only one left on the bolt.







Whaddaya know, three more rounds with no problems.


Conclusions:  There are no real conclusions to draw from a test that can really have a lot of variables.  The BCG was not lubricated or cleaned; the ammo was 55 gr FMJ Remington LE223 (green box).  Obviously this was not very intensive but I'm pretty certain that if the gun will function on one ring, it will sure as hell run on three if the gaps are aligned.  Now obviously I would recommend periodic replacement of the rings and if one is missing or stretched then you should probably replace it.  But blanket statements regarding basic function of the weapon with ring alignment or missing rings is potentially incorrect.

Molon- based upon what you have done so far, do you think a small amount of powder, as opposed to none/ primer only, could create the bullet in barrel scenario? (Forgive me if for some reason the question I asked has revealed that I have no clue what I am talking about.  )

Even if it was possible, I must ask, why would bullet 2 striking bullet 1 stuck in barrel create enough back pressure to kaboom the upper? The hypothetical bullet 1 "stuck" in the barrel due to no (or insufficient) powder should not be STUCK at all. It would be sitting there due to insufficient pressure and while not pretty, should just get blown out with the second bullet *assuming* it were to happen at all.

If the condition being tested *did* occur, the rifle wouldn't cycle.  At that point, you should stop and figure out what is going on, right?

Great point.

Molon,  I like the thread and everything else you have done for our group.  I meant no disrespect, just a little humor.
R/
Mike

So go ahead and enlighten.  Am I supposed to use a magnum primer and an uncrimped case to show the opposite result?  I lack 223 reloading equipment but I'm sure someone here does.

Ever heard of a 22 CB round?  Rimfire, no powder.  223 diameter bullet is larger than the barrel bore.    I know it's not a small rifle primer but....    

Smartass

10/10 for the rant.  

And excellent write up.

I like the thread.. and the idea of a BS buster thread.

But really...

This is a very specific case of BS here.  Lets see some more common BS things dissected.

But wait....that is a COLT....and that field piece was all MILSPEC..... How can that be?????
I will stick with HIGHPOINT and VULCAN from now on....

Again, just being a wise guy, no disrespect to OP or anyone else intended.  Have a great / safe weekend all.

Updated my post above.  Hope you don't mind Molon.

Interesting...

Why anyone would waste their time arguing with Molon is beyond me.  

Save your breath.  Molon is very knowledgeable about this stuff and, trust me, if you thought of it, he has too.

The .22 CB has a soft lead bullet as opposed to a FMJ, but that primer sure makes it squirt out the barrel. I was shooting some Aguila Colibri 20gr powderless .22 in my backyard before I realized they were going THROUGH the cedar fence on the other side of the yard. Yikes!

The neighbor's Escalade was parked over there, but fortunately wasn't hit. Made me think twice about playing with those things, though. Later found out a friend of my brother's uses them for rats, rabbits and squirrels with deadly results.

.
.

I'll be honest, I have never read a thread where someone claims an obstruction-caused kaboom was due to no powder charge. That scenario wouldn't allow the gun to cycle past the faulty round, must less blow up the gun on the ensuing round. I suppose some could argue the second shot is after a tap rack bang, though.

Posted Via AR15.Com Mobile

A barrel obstruction will cause your hand guard and barrel to split. The muzzle could also have split or there could be a hole out the side.
A kaboom where you see debris flying down the magazine or having the receiver split is a gun firing out of battery, or an over pressured unsafe handload.

Maybe not to many handgunners here, but I stuck a bullet with a 500 S&W magnum once. Reloaded cartridge with 39gns of Hodgen H110 using a 350 gn Hornady HP. I was using Federal LP magnum primers. In my case the cartridges fired normally in warm weather but when the temp dropped I was getting hangfires, which got to a point of a main powder charge not igniting properly causing a stuck bullet.

My solution was to up the temp and use  Large RIFLE primers. No more gremlins.

I agree with Molon. I don't think a bullet can move far enough to stick a bullet without some powder charge to help it along. A sure sign of no powder is the primer backing out.

http://www.youtube.com/watch?v=tWygoxV_ApM&feature=player_embedded

It's possible for the right circumstances for the bullet to act as the bore obstruction.  It's not always a case of one bullet stuck stationary in the bore and a second bullet impacting it.

While it was with a handgun, I have personally experienced a bore obstruction due to a primer only round.  If I had not been paying attention it could have been devastating.

Molon. Good luck. The bullshitters are numerous and there allies are many.

I'll probably get bashed for this, but here I go...

I had a bullet get lodged in the bore from just the primer with no powder charge what so ever.  About 10 years ago, my buddy and I were out shooting.  I fired a round out of my .22-250 and we both said it sounded funny.  I removed the bolt and looked down the bore.  Sure enough, the bullet was lodged in the barrel.  I ended up knocking the bullet out later with a cleaning rod.  This was a reloading error on my part (I'm a lot more careful now).

The scenario is a bit different: bolt action and standard large rifle primer.  But my point is, it can happen.  Never tried it with a .223/5.56 though.

Isnt that what killed brandon lee..a bullet stuck in the bore and then pressure from blanks being fired and it killed him?but like was mentioned pistol rounds have a smaller volume than a rifle round case.

BS Busters 002 added to the first post of the thread.

Tag

I had a factory squib load in 9mm (Remington or Winchester ammo) once that lodged the bullet in the barrel of a Ruger P89. Fortunately it wasn't far enough forward that the next round would chamber. It did however cycle the handgun, eject the spent casing, and attempt to load the next round. Maybe that was because of blow back instead of DI?

Back on subject, would the next bullet really push the first one out of the way? I just can't see that happening. Hard to believe it would explode the barrel but that is what I would think would happen.

Also thanks again Molon for everything you contribute to this site. I actually look forward to reading your write-ups, too bad there is not a subscribe to author feature.

That's one of my favorite bits of BS I see tossed around far too often.  Glad you are consolidating some of this into one post, Molon, thanks, and subscribed!

I agree with C jan about he "knockdown power" myth. i know mythbusters did an episode on that and busted it, but here is a link to an article that i think helps resolve the old 9mm vs 45 debate. http://www.hipowersandhandguns.com/9mm%20vs%2045.htm

I have also fired a cartridge with no powder in it... by accident!  I had a failure to fire at the range, and I took home the cartridge to inspect.  The primer was bulged, and the 75 gr PPU projectile was singed on the bottom.  

Here is some "data" published and circulated by at least one gun manufacturer. This may be one source where the myth is generated.



What would happen if a rifle was fired with an obstructed bore? I suspect mainly barrel damage. Having never experienced it though, I can't say.

As far as the possibility of a bullet being sent down a bore that is obstructed with another bullet in a AR type rifle, there are at least a couple perfect storm scenarios where this could occur. Would it cause the type of KB usually described involving ARs? Probably not. But again, having never experienced an obstructed bore, I can't say.

I have had one KB many years ago. Mag blew out, upper bulged, bottom of BCG, blew out, bolt damaged. Barrel and lower were not damaged. Typical AR KB. It appeared from looking at the cartridge case that ignition occurred before bolt was fully engaged. I replaced upper and BCG and have put thousands of rounds through it since.

Molon, thanks for the effort of seeing what a round with no powder would do.

I think Molon, or someone else here has also busted that myth with a cut out.  The firing pin won't connect with the hammer until the BCG is forward enough where the bolt's locked

 

That very well could be true. I believe I've read that myself. I was just speculating from the condition of the case and the bolt being lodged halfway in the lugs. It appeared ignition occured with the case not fully in the chamber. I had to pound it and the bolt out. Maybe Molon could shed some light on it. I've always wondered about the true cause of this particular incident.

Here is an excellent picture from Ned Christiansen showing why an OOB firing is next to impossible with an AR-15. In the picture below, the bolt is completely locked in battery, but the bolt carrier has not quite yet fully seated. You can clearly see in the picture that the firing pin is not even close to coming into contact with the primer. In Ned Christiansen's own words, the "firing pin is blocked from contacting the primer by a step in the carrier that stops the firing pin's flange. Again–– bolt is completely locked and FP cannot touch the primer. Misses it by a long shot, by design."

This is the most refreshing topic I've read in this forum in some time.





Molon -timely as well, as I was just reading about gyroscopic stability/lethality this evening; do you happen to know the gyroscopic stability of the 1:7/75 gr. combination. The chart I have, as printed in Duncan Longs' "The AR-15/M16" (1985) lists the 1:7/62gr. FMJBT (SS 109/M855) with a GS factor of 2.5, but nothing heavier.