Originally Posted by speedy2k4
PM's always had a shorter bolt assembly than the DM series. Meaning less chamber volume and slightly higher operating pressure.
When the DM9 came along it featured the same bolt length as the previous PM8, but with additional milling inside the body to increase chamber volume.
Unless you are talking about something different, it's not a myth and was always pretty obvious. Of course there were many people who would pay the extra $500 or w/e to buy the DM, and throw a tophat mod on not realizing that they were making it perform exactly like the PM always did.
So, in other words, I am under the false impression that the same bolt could be used in the PM7 as what is used in the equivalent DM's? It was my impression that they were interchangeable. If I'm wrong, then it looks like this is where the misunderstanding comes from.
I will say that a change in bore length makes a lot more sense then the "internal milling" that I was picturing in my head. I was looking at my PM7's bolt and was thinking that there was no real way to increase the diameter of the dump chamber while keeping the rear cap's dimensions the same (in other words making the ID of the dump chamber bigger then the ID of the rear cap's bore). I guess you COULD do it by sticking the body on a lathe and having a special tool remove material from the dump chamber's walls... but that kind of effort didn't make sense in relation to the gains that you would receive from it.
I know the your statement is wrong in regards to the PM8, the same bolt for the PM8 works in the DM9-11, but I don't own one of the earlier DM's so I can't confirm.
You'll have to forgive me for approaching problems like this with a health dose of skepticism. There are plenty of myths floating around in the paintball community that appear equally "obvious" to the people that subscribe to them.