Does a bullet or blast wave accelerate before reaching maximum speed?

[brbrown]

Could someone please clarify if my understanding of the following is correct or not?
When a bullet is fired from a gun or a bomb explodes, I thought I had read somewhere that, in the first few microseconds, the speed of the bullet or bomb blast is slow at first then increases to a maximum, eventually slowing down if nothing other than air resistance or gravity impedes its progress.

 

[S_Happens]

What is the confusion? It's pretty easy to see with the bullet that it starts from zero velocity. That's pretty slow. Any noncontinuous change in velocity would require an infinite acceleration. It follows that it must start "slow" and increase to a maximum. This maximum is very near the end of the muzzle, which means a very short distance and a very short time.

When you use subjective terms like "slow," "at first," and "eventually" it's easy to become confused, because they don't really define anything.

 

[AtomicJoe]

If you had a very long barrel it would start slowing down in the barrel.

 

[sophiecentaur]

How long? How much fuel / propellant?

 

[brbrown]

What is the confusion? It's pretty easy to see with the bullet that it starts from zero velocity. That's pretty slow. Any noncontinuous change in velocity would require an infinite acceleration. It follows that it must start "slow" and increase to a maximum. This maximum is very near the end of the muzzle, which means a very short distance and a very short time.

When you use subjective terms like "slow," "at first," and "eventually" it's easy to become confused, because they don't really define anything.

Hello S Happens. Thanks for the reply. I don't really have any confusion. I just wanted to make sure I was right before I pursue another related matter. Thanks for the help.
Hello Atomic Joe and Sophiecentaur, I can see those points would have an effect but not needed for my purpose. Thank you both. Brian