Always learning something new

[eshorebwhntr]

Braise yourself, this has the potential to get very interesting ...

That made me laugh

Thanks FEENIX

 

[rjmarine]

there will be an optimum length barrel for each caliber and bullet style and weight
and for a given powder . each 1 of these items can be changed and there is a good chance it will change how fast or slow the bullet leaves the barrel. then you can also had 2 lets just say off the shelf rem 700 in 30-06 . shoot them both on the say bench same day same everything and you can end up with 1 of them being faster then the other and even sometimes by 100 fps.
so we can not through a blanket statement over the rifles we shoot saying all of them will be the best using a 26" barrel. it can and is different for each load. so what we end up doing most of the time is using a barrel in a length that will be a happy medium for that caliber and what we plan to use it for

some guys are very much hung up on getting the max muzzle velocity out of the rifle so he will go with the longest barrel he can thinking that will give him what he is looking for. but as your gunsmith told you that longer barrel will not always give you the max fps.

i myself like to choose a barrel length that looks and feels good on the rifle and work around what the final velocity ends up being.

those wacky guys on mythbusters did a show on something kinda like this
they were trying to get a ping bong ball to go through a sheet of plywood.
so they did a bunch or test to find there max fps. they tried many barrel lengths from short to very very long. they were using compressed air. forgot at what psi they settled on but they did find that the longest barrel did not give max fps
oh yes they also added in there a vacuum on there barrel which was a huge jump in fps

 

[Mikecr]

I find it hard to believe that MV would decrease even if the barrel were 40 feet long.
For one, there is always plenty of pressure behind a bullet, that has been fully engraved, leaving high spots of jacket behind, and having less obturation(less friction) with travel and as pressure drops.

I believe velocity gains from 2ft to 4ft would be way bigger than gains from 20ft to 40ft, but that there would still be gains (never loss).
You know there are some who believe that bullets continue to accelerate after muzzle release...
Probably find that in some old fart article out there.

 

[600BP]

Geez guys I wasn't trying to ruffle feathers here. Just a curious question. Maybe the smith was having a crazy moment. BUT with six IBS world records to his credit, I still think I'll let em install a barrel for me.

Regards
Erik

 

[RockyMtnMT]

I find it hard to believe that MV would decrease even if the barrel were 40 feet long.
For one, there is always plenty of pressure behind a bullet, that has been fully engraved, leaving high spots of jacket behind, and having less obturation(less friction) with travel and as pressure drops.

I believe velocity gains from 2ft to 4ft would be way bigger than gains from 20ft to 40ft, but that there would still be gains (never loss).
You know there are some who believe that bullets continue to accelerate after muzzle release...
Probably find that in some old fart article out there.

Try shooting a bullet with just a primer. It may make it out of the barrel.

Steve

 

[Bart B]

I find it hard to believe that MV would decrease even if the barrel were 40 feet long.

22 rimfire bullets shoot slower from barrels longer than around 20 inches. I see no reason to think center fire barrels don't have a length limit before their bullet leave slower.

You know there are some who believe that bullets continue to accelerate after muzzle release...

They do for the first inch or two. High pressure gas ejecta pushes them just like blowing a balloon sideways with a puff of air from your lungs. That gas leaves at least two or three times the speed bullets do.

Maybe the smith was having a crazy moment. BUT with six IBS world records to his credit, I still think I'll let em install a barrel for me.

Ones ability to fit good parts together to make an accurate rifle and ammo plus making wind corrections really well doesn't qualify him as an internal ballistics expert.

Once the powder "envelope" is exhausted in a barrel, the pressure inside is at zero. There'll be no muzzle blast whatsoever.

 

[600BP]

With all due respect sir. This was a simple question; nothing more. Nonetheless, you are correct. Someone who is talented enough to:
*Put together quality components
*Make quality ammo
*And make correct wind calls which earned them several records, is someone I would have faith in to install a rifle barrel. Thank you for reiterating why I was there in the first place.

Regards
Erik

 

[FEENIX]

Erik,

LL! Hang in there.

Ed

 

[Longrang3r]

I'm too tired (or lazy) to look it up tonight, but I seem to recall that Dan Lilja did this exact same experiment. He started with an overly long barrel (like 40" or so) and found that velocity increased as the barrel was cut 1" at a time. However, it then reached a point where velocity began to decrease again. I can't remember the caliber.

I believe this phenomena is true of all calibers with regards to barrel length. The 'tipping point' for barrel length changes with cartridge/powder and bearing surface of the bullet.

Found it! Maybe I'm not too lazy after all:

Long Barrel Velocities - Lilja

A very good read. It's amazing how much information is available on that site.