Breechplug
For me, it is a feeling thing.... I can feel as I am pushing the load down the barrel whether it is to tight or to loose. Even then loose is not the end of the world. To tight on the other hand certainly can be.
I do not know who first suggested the weight/measure thing - might have been Phil... but the suggestion was it should take somewhaere in the neighborhood of 30/40 lbs of pressure to load a sabot, and I am going to use the word,
correctly...
There has been a lot made of a tight sabot - better accuracy - and there is some truth to that. But IMO more is made of this than necessary. Back when I was doing a lot of sabot testing - I was shooting an A&H and the normal sabot that I used was a HPH-24, because a HPH-12 would not go down with beating it down. The gun shot great with a 24 and either a .451 or .452 projectile, even a .4515 Seirra. Then Del sent me some HPH-3p-EZ'z to test before they were released to the market. I suggested to Del at the time they might be to loose for me as the 24's worked just fine in every rifle that I had. He asked that I try them and give him a report.
My decision was if I were going to test them I might as well test some other 'thin sabots' - so I picked up some Harvesters long & short and some of their new 'crush rib' sabots.
In the testing the all of harvesters and the 3p certainly loaded somewhat easier than the 24's, with the 'crush ribs' and 3p's noticeably easier, but not fall down the barrel easy.
They all shot relatively the same POI @ 100 yards -which really kind of amazed me - but the difference came in velocity across the chrono. The thinner sabots did loose around 100 to 150 fps second across the chrono.... EXCEPT the 3p's they maintained approximately the same velocity as the 24's.
When I talked to Del about it this - it was all about 'obturation' the MMP formulation of polymere is of course somewhat differnet than Harvester. The MMP formulation is more pliable - like seems softer... Take a couple of mmps and a couple of harvesters and throw them in a freezer for a few days. Take them out and see which ones you think are easier to bend. The 'pliabilty' of the polymere makes it easier for them to mold themselves to the bore and the pliabilty also make them 'obturate' to the bore - providing a very tight seal.
The abilty of either the Harvester or the MMP to 'obturate' actually gives them the abilty to work in my different bores with many different bore conditions - cause goodness knows my bore are not the same as yours and my 'tightness' is not the same as your 'tightness'
Gees! all lot of wind written here with not much said...