Let’s say you have a 16 inch barreled AR and shoot XM193 at around 3,000 FPS. 3,000 FPS for 16 inches works out to 0.0004 seconds of dwell time in the barrel per round.
If your barrel lasts for 10,000 rounds, then you could say that your barrel life is around 4 seconds.
Thought someone might find that interesting. It’s not really news but it’s neat if you’ve never thought about it in that way.
LOL yes that is an interesting fact:p
That is interesting. I have never thought of that before. So…if a new 16" barrel is $230 than it costs you about $207,000 to shoot for an hour?
This had been brought to my attention a number of years ago, very eye opening. The inside of a firearms barrel is a very intense environment for sure, but probably more so than most think.
Great now I really feel like I’m getting my money’s worth…
Dwell time is much longer than that. The bullet has to speed up to 3000 before it leaves the barrel.
AR barrel life is much longer than 4 seconds.
I think some of the 7mag or 300 win mag barrels have a 4+/- sec life though.
LOL I knew this would happen sooner or later. It happened sooner than later. I’m not exactly a rocket surgeon so I don’t know how to figure out an exact number. I would definitely like to see somebody work it out though. Even if it is a few more seconds it’s still amazing (to me at least) to think about.
^^Debbie Downer over here with real facts.
Someone might want to check my math as I did this quickly. The “x^2” means x squared.
Given:
v(initial) = 0 m/s
v(final) = 914.4 m/s (3000 fps)
d = 0.4064 m (16")
a = ?
t= ?
v(final)^2 = v(initial)^2 + 2ad
(914.4 m/s)^2 = (0 m/s)^2 + 2a(0.4064 m)
836127.36 m^2/s^2 = (0.8128 m)*a
(836127.36 m^2/s^2)/(0.8128 m)=a
a = 1028700 m/s^2 or 1.03 * 10^6 m/s^2
v(final) = v(initial) + a*t
(914.4 m/s) = (0 m/s) + (1028700 m/s^2)*t
(914.4 m/s)/(1028700 m/s^2)=t
t = .0009 s
10,000 rounds = 9 seconds
EDIT - REMARK: This assumes constant acceleration in the barrel which is probably a simplification
^^WOW^^ That is impressive. I have a hard enough time with the checkbook. It is amazing the diverse group of people on here. David
I believe MarkM’s sig line is appropriate for this thread!
Even if it is… that is 104,898.207g :fie:
Another eye opener.
BTW Your math is good. My math is easier. If we have delta v on given distance with constant acceleration then average v=v0-dv/2 
Then with known distance we get time. Gives same result at the end. (I had always tendency to oversimplify, that is why they kicked me out from Physics at University)
BTW2 But we know, we do not have constant acceleration due to changing pressure curve that changes force applied.
Not bad for a napkin calculation.
According to this, the real answer is .0008s.
Now THIS is my kinda physics experiment!!! :haha:
Lol.
That is pretty crazy to think about it like that
What the hell are you guys typing!!! I’m pretty sure whatever it is, it’s violating the forum rules for geekness…
I’m getting the feeling you’re into chemistry or bio-chemistry along with guns, bullits, n’ stuff!?:blink:
Ugghhh I just finished the last final exam of my college senior year today and I come to the forum for a little relaxation and light reading…and I see this :eek:
Wow…Though isn’t the bullet accelerating exponentially during that trip, so the dwell time is slightly longer than that?
Thank you, I needed to be reminded about my weak math skills 