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Forum Index > Rifles general discussion > New Theory to pick apart

New Theory to pick apart

09 Mar 2016
@ 12:58 am (GMT)

Paul Leverman

Being laid up, and not having the energy to do much of anything, I read through 33 pages of "Rifle General Discussions". Interesting stuff. One scenario that stuck in my fogged and drugged brain was the idea that shooting through electrical tape (I've also used pre-formed plastic caps for hydraulic fittings) would impair POI. So here are my thoughts on this:

Electrical tape is placed over the muzzle to prevent water/snow/debris from entering the muzzle. The chamber is loaded with our favourite 10million magnum load at +10' over light speed. Before that projectile even comes close the muzzle, the tape is blown off by the compressed air ahead of that projectile. There is no way that bullet will touch that tape.

There you have it. Feel free to argue/correct as you see fit. But please, refer to the first ten words of the third sentence in this post.

Replies

09 Mar 2016
@ 01:22 am (GMT)

Joshua Mayfield

Re: New Theory to pick apart
Paul, I subscribe to the same theory. But since I have zero experimentation to go along with my subscription I don't guess it counts for too much.
09 Mar 2016
@ 05:07 am (GMT)

Ben Grady

Re: New Theory to pick apart
Good point. But maybe while the electrical tape is flying through the air straight off the end of the barrel, the projectile hits it?
(and I was blaming those wayward shots on my shooting ability! hehehe)
09 Mar 2016
@ 05:12 am (GMT)

Mike Davis

Re: New Theory to pick apart
at 50 yards or less in the bush the tape wont matter stuff all,I believe its not recomended for .22 calibre centrefires as high degree of accuracy needed, on a recent thread on another site the question was asked about taping suppressors and one of the leading makers said yes do it. I do it but if remember remove it before shooting. never had any issues .
09 Mar 2016
@ 05:47 am (GMT)

Sebastian Shand

Re: New Theory to pick apart
I've always wondered if there would be any poi difference when shooting with tape over the muzzle, I think if there is it would be very minimal and probably not the same result each time. i have shot animals at 200metres and always hit where i was aiming which leads me to believe that maybe if it did have an effect you wouldn't see it unless shooting long range but to be honest everyone i know shooting at extended ranges has time to remove it.
one of these days i'll test it out but for now it will remain a mystery.
i think you may be on to something with the theory of hot gas traveling in front of the projectile may blow it out of the way before it reaches it. this could be easily tested with a slow mo camera if you know anyone who owns one that is slow enough to pick it up...
09 Mar 2016
@ 07:56 am (GMT)

Thomas Kitchen

Re: New Theory to pick apart
just a thought you could tape barrel then poke small hole through it? it might let the pressure out and let bullet it tape to see if there is a change in P.O.I
09 Mar 2016
@ 08:35 am (GMT)

Martin Taylor

Re: New Theory to pick apart
Zero effect at 100 on any one of 5, 30 cals or 9.3mm, PIO or group size. Didn't worry my 243 when l had it either.

I tape mine every time l hunt in the bush, only removing it on my dedicated LR rigs.
09 Mar 2016
@ 01:08 pm (GMT)

Warwick Marflitt

Re: New Theory to pick apart
I think you're right Paul
In a clean barrel......You have a piston (bullet) compressing the air inside a cylinder(barrel)against the resistance of the obstruction(the tape) The pressure generated inside the barrel will be equal to the strength of the seal of the stick of the tape on the barrel. This Could be tested with a tube taped off like you would your barrel, with an engine compression tester gauge fitted to the pipe and using a high volume blast of high pressure compressed air to see what pressure is required to pop the tape? This'll tell you the pressure inside the barrel And the maximum pressure reached at the tapes rupture
What about in a taped up dirty barrel.
In a dirty fired bore? maybe carbon and un-burnt powder residual with copper fouling may possibly be wedged by the air pressure in the tapered area where the bullet ogive meets the lands of the barrel? Causing a wedge of matter to jam and be smeared into the bullet and rifling ? (that's what water in the barrel does because it doesn't compress causing a barrel bulge.) Although I think the sudden displacement of the air rushing before the bullet will quite likely push the loose fouling ahead of the projectile, stretching and ballooning the tape until the pressure ruptures it releasing the compressed air, loose fouling and the bullet following and passing the crown of the barrel milliseconds later while the ruptured tape is still moving away from the crown.
I hope that my maths below is correct?
So 2500fps = 30,000 inches per second. If you divide that by the length of the barrel 22 inches you get 1,363ths of a second ( cut one second into 1,363 pieces) take one of these bits of a second? AND That's how much time it takes for the bullet to travel the length of a 22 inch barrel in theory!!!!
BUT..... actually the bullet was sitting still in the case, until you squeezed the trigger, releasing the firing pin into the primer it igniting the powder burning and creating pressure that forced that bullet out of the case into the lands and accelerating it from 0 mph to 1,704 mph in a distance of 22 inches . It puts a top fuel dragster to shame?
So that piece of tape gets stretched out of the way in a fairly short space of time.
I hope that my numbers are correct enough to give you some idea of what happens when you let one off? Please add to this or correct me if you think that I've missed something. Take care. ALWAYS IDENTIFY YOUR TARGET BEYOND ALL POSSIBLE DOUBT and have a great day.


09 Mar 2016
@ 01:13 pm (GMT)

Warwick Marflitt

Re: New Theory to pick apart
Bugger! My cup of teas cold...
09 Mar 2016
@ 02:55 pm (GMT)

Ricardo Laborin

Re: New Theory to pick apart
And instead of dumping $100K on an engineering degree, let's read these pages....Amazing. Thank You.
09 Mar 2016
@ 03:10 pm (GMT)

Bryan Webster

Re: New Theory to pick apart
Over the years while hunting elk and moose I have always used electrical tape over the muzzle. I also tried it on my 7mm Rem Mag at the gun range on several occasions (had to show my two sons that it harmed nothing in accuracy.

From a cold bore shot on three separate occasions it did not affect accuracy of the rifle at 200 yards where shot one had the tape cover then shots two and three did not. The groups were still in the 1/2 moa right where they were supposed to be.

That being said, I only did that one three separate occasions which means too few reps to be statistically valid but for me it was good to go.
09 Mar 2016
@ 08:31 pm (GMT)

Paul Leverman

Re: New Theory to pick apart
Let's have a look.

1 atmosphere = 14.696psi

7mm bore (for arguments sake)= 3.1416 X 3.5mm X 3.5mm= 38.484mm= 0.059 sq.in

Static pressure in bore = 0.867psi

Tape specs (from random manufacturer website)

Elongation = 2%

Tensile Strength = 45 lbs/in

Adhesion to Steel = 60 oz/in

Distance bullet has to travel to compress the air in 24" barrel to exceed the tensile strength of tape: 3.0622"

Distance bullet has to travel to compress the air in 24" barrel to exceed the adhesion bond to steel:
too small for me to calculate.

Very unscientifically calculated, ripe with errors and miscalculations that would make Albert roll over in his grave, the tape would blow off before the bullet went 4" down the bore.

I really need to get outside.

10 Mar 2016
@ 07:59 pm (GMT)

Bryan Webster

Re: New Theory to pick apart
you also assume the bullet pushes the tape out, however my guess is the sudden air being displaced would be the cause
10 Mar 2016
@ 08:59 pm (GMT)

Nathan Foster

Re: New Theory to pick apart
Just one caveat here. Many years ago, a friend of mine had a .222 that showed some disruption of accuracy with muzzle tape. It seemed to be the exception to the rule.

Almost as if the pressure pushed the tape forwards and ballooned it, but was not enough to get the tape to either fully rupture without bullet contact or if it did rupture as a result of pressure only, it did not get the tape out of the way in an even manner (gas column uneven). Very odd.
10 Mar 2016
@ 09:17 pm (GMT)

Paul Leverman

Re: New Theory to pick apart
Odd, yes. But there is always an exception. I'm sure if you were to try this on a rimfire, or even the .17 cals, you would find that the exception would turn out to be the norm. Didn't they use to say you could fire a .22 with the muzzle underwater due to the low pressure? That's for someone else to try, though, not me. I'll stick to something less risky like trying to case harden a bolt.
10 Mar 2016
@ 10:00 pm (GMT)

Warwick Marflitt

Re: New Theory to pick apart
Haha brilliant Paul !
The burning powder pushes the bullet. The bullet pushes the air. The air pushes the tape.

10 Mar 2016
@ 10:32 pm (GMT)

Paul Leverman

Re: New Theory to pick apart
Hey Warwick, you have lots of time and not much to do. How would you like to carry out an experiment with that fancy camcorder/camera of yours? It's fairly high speed, isn't it?

Tell you what you do. Set up your shooting stand with sandbags, pads, etc., all your normal paraphernalia. Set up your camera on a tripod, so it focuses on the muzzle. Push the start button to start recording. Fire one round at your regular target/backstop. Play back the recording and post it here. Oh, I almost forgot. Instead of tape on the muzzle, tie a condom onto it.
13 Nov 2018
@ 12:50 pm (GMT)

Todd Free

Re: New Theory to pick apart
Need to get this mob to film it in slow mo to see what actually happens.

https://www.youtube.com/user/theslowmoguys/about
 

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