I can think of a couple of reasons why manufacturers don't do what's been suggested (the seating stem contacting the bullet at the point where the latter's outside diameter reaches that of the rifling's lands' internal diameter - I can't think of an easier way of avoiding using the misleading 'O' word).
First, you might, no say again WOULD, have a very long seating stem to accommodate the longer VLDs. The risk of the bullet bottoming out would be that much greater than in existing designs, and it's a real possibility with the present arrangements. Die bodies might have to be longer overall to accommodate such stems and I'm not sure what effect all this might have on bullet run-out in the finished round.
Secondly, I don't want ANYTHING metallic to touch and risk damaging / distorting that section of the bullet jacket. I've had fragile A-Maxes end up with a marked ring further up the jacket caused by seater stem contact. While many of us on this forum use bushing dies, mandrel expanders or whatever to give light neck tensions, we've got to remember we're in a minority of handloaders so far as the die manufacturer is concerned. Most people use standard dies and end up with a lot of neck-tension on their bullets even from the most expensive makes like Forster and Redding. The die manufacturer has to cater for them first.
Fair enough for anybody who wants to alter the seater stem conatct area with a bit of lapping on a bullet or get the manufacturer to produce a custom stem. It seems to me there's a risk of having a seater die that only suits one bullet model though - OK if you only ever load the one like the many .308W/155 Fullbore and Palma shooters who find a load with one of the three or four best models on the market and stick with it for the life of the barrel.
Personally, I agree with those who're saying seater stem contact point is a non, or at the worst, minor problem. The large variations I've found in some makes and batches of bullets in their bearing surface lengths concern me more and that's what I'll check out before I'd bother about the exact place where the seater stem contacts the bullet shoulder and start looking to make changes in it.
First, you might, no say again WOULD, have a very long seating stem to accommodate the longer VLDs. The risk of the bullet bottoming out would be that much greater than in existing designs, and it's a real possibility with the present arrangements. Die bodies might have to be longer overall to accommodate such stems and I'm not sure what effect all this might have on bullet run-out in the finished round.
Secondly, I don't want ANYTHING metallic to touch and risk damaging / distorting that section of the bullet jacket. I've had fragile A-Maxes end up with a marked ring further up the jacket caused by seater stem contact. While many of us on this forum use bushing dies, mandrel expanders or whatever to give light neck tensions, we've got to remember we're in a minority of handloaders so far as the die manufacturer is concerned. Most people use standard dies and end up with a lot of neck-tension on their bullets even from the most expensive makes like Forster and Redding. The die manufacturer has to cater for them first.
Fair enough for anybody who wants to alter the seater stem conatct area with a bit of lapping on a bullet or get the manufacturer to produce a custom stem. It seems to me there's a risk of having a seater die that only suits one bullet model though - OK if you only ever load the one like the many .308W/155 Fullbore and Palma shooters who find a load with one of the three or four best models on the market and stick with it for the life of the barrel.
Personally, I agree with those who're saying seater stem contact point is a non, or at the worst, minor problem. The large variations I've found in some makes and batches of bullets in their bearing surface lengths concern me more and that's what I'll check out before I'd bother about the exact place where the seater stem contacts the bullet shoulder and start looking to make changes in it.