bigedp51 - I will not get into a pi$$ing contest with you. You've got some pretty pictures and obviously have access to all kinds of data, but your interpretations are simply wrong. (Having reloaded for a long time doesn't make you right. If it matters, I have been reloading almost as long as you and actually studied ammo design at a post-grad level.)
There is no particular magic about small-base dies or auto weapon chambering. It is common for full-auto and semiauto weapons to have slightly-larger-than-normal chambers. This is required mainly because such actions generally do not have the same torque as a bolt-action rifle. To avoid jamming, particularly in weapons which have been fired many times, feeding requires some extra help and that comes through a larger chamber. Another help for the reloader is a sizing die which makes the case a tad smaller than SAAMI specs. In other words, a case can be made that semi-auto rifles should be reloaded with SB dies.
On the other hand, brass put through a sizing die will be sized to that die's dimensions. It doesn't really matter (within limits of course) if the case is a touch oversize going in. While the brass will spring back a little bit, just as it does in the chamber after firing, it will only spring back from the relative size produced by the die's action and that amount of springback is considered by the die's designers. If x is a dimension in inches of a case meeting SAAMI specs, a case x + .001" will come out to SAAMI specs, as will a case x + .002", x + 003", etc.
Sizing dies are designed to handle brass fired from a variety of chamber sizes. .303 British dies, for instance, are designed to reload cases fired from a wide variety of chambers, some of them grossly oversized. Nobody suggests that a special 'small base' die is required for the .303. (To be sure, the .303 has a bunch of other problems, but we're not talking about headspacing, etc.) SB dies are only required for semi-auto (and sometimes pump) reloading.
Let's see what some of the manufacturers say.
Lee Precision:
Sierra:
For the OP's Remington 700 (or any other comparable bolt action rifle), small base dies are overkill. Ammo reloaded using properly-adjusted normal sizing dies will chamber just fine.
There is no particular magic about small-base dies or auto weapon chambering. It is common for full-auto and semiauto weapons to have slightly-larger-than-normal chambers. This is required mainly because such actions generally do not have the same torque as a bolt-action rifle. To avoid jamming, particularly in weapons which have been fired many times, feeding requires some extra help and that comes through a larger chamber. Another help for the reloader is a sizing die which makes the case a tad smaller than SAAMI specs. In other words, a case can be made that semi-auto rifles should be reloaded with SB dies.
On the other hand, brass put through a sizing die will be sized to that die's dimensions. It doesn't really matter (within limits of course) if the case is a touch oversize going in. While the brass will spring back a little bit, just as it does in the chamber after firing, it will only spring back from the relative size produced by the die's action and that amount of springback is considered by the die's designers. If x is a dimension in inches of a case meeting SAAMI specs, a case x + .001" will come out to SAAMI specs, as will a case x + .002", x + 003", etc.
Sizing dies are designed to handle brass fired from a variety of chamber sizes. .303 British dies, for instance, are designed to reload cases fired from a wide variety of chambers, some of them grossly oversized. Nobody suggests that a special 'small base' die is required for the .303. (To be sure, the .303 has a bunch of other problems, but we're not talking about headspacing, etc.) SB dies are only required for semi-auto (and sometimes pump) reloading.
Let's see what some of the manufacturers say.
Lee Precision:
If you have the Lee Pacesetter die set with a full length-sizing die, you shouldn't need a small base die. Other manufacturers make small base dies on the premise that semi-autos require cases sized to the minimum allowable case dimension for reliable feeding, but in reality most semi-autos have chambers cut on the large side for that same purpose.
Sierra:
Full length dies size the case back to smaller than fired dimensions, but not all the way back down to its unfired dimensions. This is the most common die found and usually used on most bolt action rifle ammo. With their terrific camming power, a cartridge can be easily forced into the chamber even if it is a bit snug. Semi-autos and pumps do not have this type of camming power, and as a result, require the case to be resized somewhat smaller than what the full length die can do. This is exactly the type of situation that calls for the small base sizing die.
For the OP's Remington 700 (or any other comparable bolt action rifle), small base dies are overkill. Ammo reloaded using properly-adjusted normal sizing dies will chamber just fine.
Last edited:
