SmallCaliberCentral

I have visited this subject before but what will or could happen if the bullet is on seated just enough to hold bullet. I've tried to pull it out by hand and move it by hand but it stays put?

I'm wanting to get as close to the lans as possible. I'm testing a new coating (not on the market) and it needs to be as close as possible or I will have to order a barrel and have cut to specs need.

FYI: if needed, I'm using 40 gr Berger

40 gr Brand A OG lenght 1.98 COL 2.350

40 gr Brand B OG length 2.031 COL 2.379 New Coated bullet

Most information I've read about seating suggests seating the bullet 1/3 of the length in the case...

I've had a custom AR upper built and the gunsmith questioned me about the bullets I was planning to reload and he custom cut the chamber for that grain bullet. It prevents me from shooting the 50gr Bergers as they would be too long and well into the lands (probably wouldn't fit the magazine either).....

Were it me, I would go to the expense of having a barrel with the chamber custom cut to the specs you need. That will allow you to get the maximum potential out of your intended load, but the downside is that it may restrict you to just that combination for best results..

Very interesting.

What kind of new expierimental bullet coating comes with a requirement that it be as close to the lands as possible???

The answer to your question is the gun will go bang and the bullet will come out the muzzle.
Of all the 40's the Berg is the shortest bearing surface. That will make it more difficult to reach the lands. I'm not sure but I think you might have an easier time getting to the lands with a flat based 32 compared to the 40 Berg.
My 204's always preferred a healthy jump so DTL is not a major concern of mine.

PS I did'nt take the time to measure my lot of 40 Bergs to see how much bearing surface is in the case with your numbers. Lots vary anyways.

How much bearing surface is in your case with your bullets?