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View Full Version : Video of scope base flexing



Tony Shankle
09-27-2010, 11:31 AM
Interesting!



http://www.youtube.com/watch?v=s5pVya7eask

333smitty
09-27-2010, 01:48 PM
Does the flexing occur after the bullet has exited the muzzle?

squeakie
09-27-2010, 01:58 PM
Does the flexing occur after the bullet has exited the muzzle?

the flex should start at the sametime the bullet enters the rifeling.
gary

wolf gray
09-27-2010, 02:12 PM
I think if somebody stuck a .50 cal in me and pulled the trigger, I would be flexing the whole time :)

Best.
Dan Batko

"Where are we going and why am I in this basket?

P.S. In a more serious vein, would a 6,30 or .22 flex at all? I'm sure that anything mounted on a
.50 cal rifle would have no choice but to flex.

TomD
09-27-2010, 03:03 PM
If it returns to zero it will have no effect on accuracy.

Jim S
09-27-2010, 08:35 PM
That is very exadurated by the cantilievered rail over a stamped reciever. watching the guy take the recoil is neat. You can see the initial recoil is relativly light, the bigger push comes as the gas is escaping the muzzle.

alinwa
09-27-2010, 09:51 PM
I can't agree with the previous post. Watch the video..... there's no "light" recoil happening. What you'll see is the gun driving steadily backward until it reaches the limit of dude's compression (clothes/muscle tension/flesh) and then dude MOVES.... and then the brake catches the rifle and saves the man from serious bodily harm.

IMO every rifle from a 22RF to a BMG flexes like this. Sure a big one flexes "more" but that's just relativity.

It's like the old whore joke:

"would you sleep with me for 20 bucks?

NO!

"for 1000?"

no

"for a MILLION??"

well.......

wolf gray
09-28-2010, 10:55 AM
Al,
Kind'a sounds like that one I heard a long time ago.
"Would you sleep with me for $20.?"
"No"
"How about a $1000.?"
"Hmmm"
"How about $50.?"
"Hmmp, what do you think I am?"
"We have already established what you are, we're just haggling about the price" !! :)

Best,
Dan Batko

"Where are we going and why am I in this basket?"

Dennis Sorensen
09-28-2010, 11:15 AM
There is a good possibility the flexing of the mount absorbs a lot of energy and actually reduces shock to the scope... now is that by accident or design?

AJ300MAG
09-28-2010, 12:11 PM
Skip the rail, watch how the objective end of the scope flexes!!!!

While back there was a show on tv where one of the .50 manufacture's wife plus two other women were firing .50's at Raton. One of the ladys was say a plus size. When she fired the .50 you could see the recoil start in her shoulders, travel back through her body and reverberate in her rump.... :D

Jim S
09-28-2010, 07:18 PM
I can't agree with the previous post. Watch the video..... there's no "light" recoil happening. What you'll see is the gun driving steadily backward until it reaches the limit of dude's compression (clothes/muscle tension/flesh) and then dude MOVES.... and then the brake catches the rifle and saves the man from serious bodily harm.



Al, Campare the ejected case from the side view and then the rear view, The bullet is long gone before the case comes out of the gun, the rear view shows the muzzle flash/case relationship well. There is a definate excelleration in the mans movements that is pretty easy to spot.

AJ300MAG
09-28-2010, 07:52 PM
Wonder if Al has ever put shots downrange out of a Barrett.... :rolleyes:

Jhart
09-28-2010, 09:21 PM
NICE.. looks like the thing kicks almost as hard as a 30BR... Makes a fella wonder doesn't it...

alinwa
09-28-2010, 10:16 PM
Wonder if Al has ever put shots downrange out of a Barrett.... :rolleyes:

No, not in semiauto mode.

I've fired the bolt action Barrett and an AR50 and even a 13lb McBro's Big 50.......I'm no expert on the BMG round but I do understand the concept of recoil and I stand by my contention. I contend that without a muzzle brake we'd see another flexural movement, that of the shooter leaving the frame!

Alla' that timing stuff is due to one thing, inertia. Hard to get 'er moving and hard to stop the movement but the brake definitely controls the recoil by catching the lump of exiting gas...... ain't much "rocket effect" left on the forward end, and no push after the brake IMO. Just because I don't advocate brakes doesn't mean I'm unfamiliar with them, I've got one of Benny Cooley's units setting on the lathe right now waiting to be bored out to .750 for a 338 Lapua Improved barrel.


BUT....... aside from all that. THERE'S NO SUCH THING AS GAS AHEAD OF THE MUZZLE PUSHING THE RIFLE BACK!! That gas is GONE, the recoil happened as you accelerated it up to vel. Want proof? Go into your shower, take down the flexible shower head dealie and turn it on. Hold it or hang it or set it on the handrail. Watch how it swings or slides because of the "rocket effect"..... Or go out to your garden hose, lock the head on "spray" and watch it rock back under pressure.

Now.... it's all rocked back/pressured up......... take your free hand and block the spray (you're gonna' get WET!) and move closer and closer to the sprayer head, try to "push" it further by pushing the water back.......

I'll agree that there's a very small rearward component generated when the leftover gas in the barrel acellerates rapidly after the bullet's gone. This is because energy builds as the square of velocity and the velocity of the gas goes up rapidly when unconstrained by the bullet but it ain't much. IMO It doesn't account for the surge you see in the vid. Wanna' test this one? fireform some cases using only powder. I routinely fireform .308 sized cases using 40-50gr of shotgun powder. It shoots flames 20ft in the air, and recoils about like, oh, 40-50 grains :)


I contend that that tha'r Barrett has just ejected eight hunnerd-n-fiftysome grains of mass (gone) and the 30-50gr left in the barrel doesn't materially add to the recoil impulse. The real recoil comes from running an eighth of a pound up to 2700fps...... and that the surge noted is the result of the distribution of the original impulse, not from a "jet effect."

i could be wrong :D

al

alpacca45
09-30-2010, 06:50 AM
Al,
I'm not sure how many grains of powder a .50 BMG takes, but it is going to be a bit more than 40 to 50 grains.

I totally agree with the rest of what you are saying, the bullet is going to be the heaviest thing which is accelerating up the bore, along with around half the mass of the powder gas.

I'm not sure how much science goes into brake design (I guess not much) but there should be some interesting possibilities there, with jet thrust as well as the simple impulse from reversing the diretion of the gas

STBE Harris
09-30-2010, 12:32 PM
I believe if you watch the muzzle of this small cannon you will see flexing in the barrel too!!

STBE

wolf gray
09-30-2010, 02:30 PM
Yea,
This thing definitely needs a TUNER ! :)

Best,
Dan Batko

"Where are we going and why am I in this basket?"

Vern
09-30-2010, 06:37 PM
Al if you watch the video from the rear view you can see the muzzle flash while the bolt is barley even open.
However on the other end of the scale for recoil you are right about what would happen to him without all of the springs and surpressors.
Seems there was a guy in nam that tried the John Wayne thing of picking a 50 up off of a tripod and firing it from the hip.
As I understand it the first shot shattered his hip.

alinwa
09-30-2010, 10:35 PM
OK, 2 things :)

The ref to " 40 or 50 grains..." well I guess you just gotta' go reread what I said.

re shooting the BMG without a brake. Elmer Keith wouldn't do it......

Let me repeat what I just said, Elmer Keith wouldn't do it! And if there was ever a tougher hombre packing a firearm I don't know of him, Keith was One Bad Boy.

I ran a bunch of Berger 210's up to over 3300 the other day, NO brake, 7lb gun. I'd forgotten just how much I hate recoil.

My hatred was reaffirmed :D

As far as sending rounds downrange from a contraption such as pictured, I can't see myself involved. It's like the whole AK/SKS thing...... just flanging lead, even BIG lead, is not my thing. Besides that, this whole culture of middle-aged overweight guys shaving off their hair and putting on colored clothing and a scowl and walking arms akimbo just makes me chuckle. These are the same guys who buy shirts "I survived the Chelmsford Intersection" or "Hurricane Helga Survivor" as though not dying from self-induced paranoia makes one a hero ;)

al

Jim S
09-30-2010, 10:51 PM
Al, I respectfully disagree, what propels a jet? Rapidly moving/expanding gas pushing against AIR. The recoil impulse is relativly short compared to the thrust from a jet but it acts the same and hits a peak very rapidly. If that energy from a rifle shot continued at the same force for one minute my guess is that an unbraked rifle would sail backwards 100 or more feet.
http://www.youtube.com/watch?v=RMit5FMqp6E&feature=player_embedded
Watch the attached video of the Muscle brake, the gas exiting the side ports is very concentrated and the majority is directed 90 degrees from the bore. Lay your hand in that"thrust" and you would likly pull out a fist full of stumps. The job of the brake is to reduce the recoil from the gas, there is no way to reduce the recoil caused from the accelerating bullet. That gas is the fuel that produces energy. Instead of fire forming with cream o wheat that produces no resistance in the bore, fire form with a 5 grain slug of somthing with the same resistance as a bullet engaving the lands and producing friction as it moves down the bore, then you would see recoil similar to that of a bullet being fired because now we have a similar containment and explosion at the muzzle as the fuel escapes.

The muscle brake is a bit different in design, that directs the gas, and that eliminates the concussion effect to the shooter. Only problem with that is it requires a few different sizes of brakes/baffle/port dimension. To work on the many different sizes of cartriges.

John Kielly
09-30-2010, 10:57 PM
Besides that, this whole culture of middle-aged overweight guys shaving off their hair and putting on colored clothing and a scowl and walking arms akimbo just makes me chuckle. These are the same guys who buy shirts "I survived the Chelmsford Intersection" or "Hurricane Helga Survivor" as though not dying from self-induced paranoia makes one a hero
al,

Sounds like you need another handful of Psyllium husks in the breakfast cereal. :D

John

alinwa
09-30-2010, 11:01 PM
Al, I respectfully disagree, what propels a jet? Rapidly moving/expanding gas pushing against AIR.
http://www.youtube.com/watch?v=RMit5FMqp6E&feature=player_embedded


.


So we never really made it to the moon??? ;)

al