J E Custom
Well-Known Member
In the past few years there have been lots of questions on load problems encountered with loading.
Everyone tries to trouble shoot the problem for the poster and after lots of discussions sometimes the poster finds the problem. In most cases the poster should not have had the problem If he/she
knew what there chamber dimensions actually were.
There are basically two types of chambers, SAMMI and Non- SAMMI chambers.
With the SAMMI chambers, the chambers are held to certain dimensions so factory ammo (That is also held to nominal dimensions) can be safely fired in it.
Non SAMMI chambers (Also called wildcats)are anything that Is not within SAMMI design specifications. These can range from simple changes in one dimension, to multiple/major changes
that totally alter the design function of the chamber. Chamber Reamer makers cannot alter these dimensions on a SAMMI reamer. He can, on a wildcat if requested by the owner and it is normally given a non SAMMI name so it will not be confused with a Spec. chamber.
It is the responsibility of the re-loader to understand the cause and effects of these changes and in many cases hear in lies the problem. lots of people hear the changes on the internet that someone has made and what success they have had by making the changes and cant wait to build a rifle with these changes. Having a SAMMI chamber does not mean that you cant have accuracy, In fact it is normally just the opposite. SAMMI chamber are designed to be safe and can be loaded to extreme accuracy with good ammo.
My opinion is that "NO ONE" should load for a firearm without knowing what chamber they have
be it SAMMI or wildcat or even somewhere in between (I have seen many so called SAMMI chambers that were not ether because the reamer was worn and did not cut a dimensionally correct chamber or someone modified the reamer/chamber and did not identify the changes on the barrel.
I meet people all the time that don't own a good loading manual with load data and definitions and say/think they can get all they need on line. This leads to many of the problems we see today. I recommend that any beginner start with a SAMMI chamber, Factory ammo and enjoy. Next start slowly and get into reloading (After buying all of the things you need including a good re loading manual and reading and understanding all of the aspects of reloading and the terms we use all the time and there meaning and their purpose).
Next Log on to = SAAMI And look up The cartridge to be loaded. The top drawing is the SAMMI Spec. for ammo. the second/bottom Drawing is the SAMMI chamber dimensions for that cartridge. print or make notes on key dimensions.
Armed with this information, measure a fired case if you have one to see if your chamber closely matches the fired case (It may be slightly different because of brass Spring back) pro die makers
often want 2nd or 3rd fired brass to build custom dies to be able to closely match your chamber
and do minimum sizing.
If your brass closely matches the SAMMI dimensions, you should be good to go as long as you load SAMMI Spec. ammo. If it does not then you must know what the difference is and how to deal with it.
Loading for anything other than a SAMMI chamber should only be attempted buy someone with experience loading wildcats that understands what each change means and the effect it has on the cartridge.
Long winded, but hopefully it will keep someone out of trouble and generate more questions before trouble shows it's ugly head.
J E CUSTOM
Everyone tries to trouble shoot the problem for the poster and after lots of discussions sometimes the poster finds the problem. In most cases the poster should not have had the problem If he/she
knew what there chamber dimensions actually were.
There are basically two types of chambers, SAMMI and Non- SAMMI chambers.
With the SAMMI chambers, the chambers are held to certain dimensions so factory ammo (That is also held to nominal dimensions) can be safely fired in it.
Non SAMMI chambers (Also called wildcats)are anything that Is not within SAMMI design specifications. These can range from simple changes in one dimension, to multiple/major changes
that totally alter the design function of the chamber. Chamber Reamer makers cannot alter these dimensions on a SAMMI reamer. He can, on a wildcat if requested by the owner and it is normally given a non SAMMI name so it will not be confused with a Spec. chamber.
It is the responsibility of the re-loader to understand the cause and effects of these changes and in many cases hear in lies the problem. lots of people hear the changes on the internet that someone has made and what success they have had by making the changes and cant wait to build a rifle with these changes. Having a SAMMI chamber does not mean that you cant have accuracy, In fact it is normally just the opposite. SAMMI chamber are designed to be safe and can be loaded to extreme accuracy with good ammo.
My opinion is that "NO ONE" should load for a firearm without knowing what chamber they have
be it SAMMI or wildcat or even somewhere in between (I have seen many so called SAMMI chambers that were not ether because the reamer was worn and did not cut a dimensionally correct chamber or someone modified the reamer/chamber and did not identify the changes on the barrel.
I meet people all the time that don't own a good loading manual with load data and definitions and say/think they can get all they need on line. This leads to many of the problems we see today. I recommend that any beginner start with a SAMMI chamber, Factory ammo and enjoy. Next start slowly and get into reloading (After buying all of the things you need including a good re loading manual and reading and understanding all of the aspects of reloading and the terms we use all the time and there meaning and their purpose).
Next Log on to = SAAMI And look up The cartridge to be loaded. The top drawing is the SAMMI Spec. for ammo. the second/bottom Drawing is the SAMMI chamber dimensions for that cartridge. print or make notes on key dimensions.
Armed with this information, measure a fired case if you have one to see if your chamber closely matches the fired case (It may be slightly different because of brass Spring back) pro die makers
often want 2nd or 3rd fired brass to build custom dies to be able to closely match your chamber
and do minimum sizing.
If your brass closely matches the SAMMI dimensions, you should be good to go as long as you load SAMMI Spec. ammo. If it does not then you must know what the difference is and how to deal with it.
Loading for anything other than a SAMMI chamber should only be attempted buy someone with experience loading wildcats that understands what each change means and the effect it has on the cartridge.
Long winded, but hopefully it will keep someone out of trouble and generate more questions before trouble shows it's ugly head.
J E CUSTOM
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