Varget running out of barrel?

[Bigbubba]

I thought I pointed that out - some of the pressure comes from converting the solid to a gas, more pressure comes from the heat of the reaction heating up the gas, thus increasing the volume of the gas even more - and since the volume of the cartridge case is constant, therefore increases the pressure.
With out commenting on the name calling or any of the other statements made here, the powder is burned up.
And going back to the statement in the OP, 50fps of velocity change is nothing significant, given the margin of error of the loading, the chrony, head spacing, etc.

Instead of arguing you should be loading......

 

[joe-nwt]

- powder choice is based on cartridge capacity, bore size and bullet weight, not barrel length (even to a lesser degree)
- the powder giving the highest MV in a long barrel will do the same in a shorter barrel and vice-versa

While I do agree with a lot of what you are saying, I have noticed, like acrashb has suggested, that recommended data for particular cartridges is not the same for standard rifle barrel lengths and those that are shorter, say in a Contender for instance. Most data for shorter barrel lengths tends towards the faster burning powders. If you would care to offer your opinion on this, I'm all ears.

And while I have witnessed unburned powder from handguns, I've never seen it from a rifle. Actually, I can't say I've really looked for it either. But I have tapped just-fired handgun cases on the bench, scraped the granules into a pile and they seem to burn just like powder, not some burning byproduct. Any thoughts on how unburned powder could stay in the case?

 

[Bigbubba]

Ever had a wood fire? ever had ash left over? ever tried to ignite it?
Try. Should answer your question

 

[acrashb]

Ever had a wood fire? ever had ash left over? ever tried to ignite it?
Try. Should answer your question

It's not ash. As stated, it's recognizably powder grains.

 

[beltfed]

- powder choice is based on cartridge capacity, bore size and bullet weight, not barrel length (even to a lesser degree)

This is contrary to the example I mentioned above with different load data between .223 rifle and .223 pistol in the same Hornady manual (6th edition)
For the rifle, they used a Remington 700 with a 26" barrel as their test subject and for the pistol they used a T/C Contender with a 14" barrel.
Again - same caliber, same bullets, same powders and different load data.
Check it out.

-I'm thinking that this is an "AR" thing - seems you guys think it operates according to its own unique laws of physics.

Some of us have the opportunity to compare the exact same ammunition and hand loads on the exact same guns with the exception of barrel length and can see ammunition behaving differently. Perhaps some of us are benefiting from seeing these differences...

 

[Powderfinger61]

I understnad that even factory loads have a residue that exits the barrel. Especially in short barrel handguns. We've all seen CSI i shows that can determine the distance a shot was fired (from residue shot patterns) and analize the composition and determine which manufacture produced the bullet.

The questing was " Is it possible that varget doesn't have enough time to burn completely in 20" once it is loaded this heavy?"

I will say the powder will be burnt, but you will have residue.

If there were no residue, i wouldnt have to clean barrels anymore.