There has been great consternation recently over barrels and chambers.
Some have barrels that seem to allow factory cartridges to drop right in, straight from the factory. Others have claimed that their barrels do not allow them to chamber factory ammunition, but do allow short seating of bullets, and seem to shoot very well.
There have been conflicting reports that manufacturers may be using SAAMI spec reamers, and not getting SAAMI spec chambers, or that the chamber design itself may be at fault.
Unfortunately, all of the above, and all the "remedies" are nothing but speculation from everyone involved.
There are some terms that are somewhat confusing:
Some refer only to the area occupied by the cartridge case itself as the chamber, while others define the chamber as the entire area filled by a loaded cartridge as the chamber. In the second case, this includes the area filled by the cartridge case, the area in front of the case (often called the throat, and which includes the angle that guides the bullet into the caliber sized, engraved portion of the barrel), and the area occupied by the ogive of the bullet.
SAAMI defines the dimensions of the case itself.
The drawings of the chamber are also defined by SAAMI, and in the case of the Grendel chamber, that includes the compound throat, and the designated angular changes within that throat. In order to properly be called a SAAMI chamber, all those dimensions must be consistent with the SAAMI drawing. In a typical chamber, the dimensions include an area ever so slightly larger than the bullet diameter, this is called the "free bore". This is an area prior to the caliber diameter area where the bullet is moving freely before it is forced into the caliber engraved barrel itself.
In attempts at ultimate accuracy, this freebore area may be nearly nonexistent, or the handloader may load his bullets long, thus engaging them into the rifling so that the bullet does not ever have that "free" jump before engraving. This is a bit of a gamble on the handloaders part, accepting that there is a pressure increase, but that the gain in accuracy is worth it. VLD bullets are typically loaded in this manner. Modern metals are so good and so strong that many long range competitive shooters "JAM" the bullets significantly into the lands and get away with it because of that strength.
Here are the facts about ALL chambers:
A proper SAAMI chamber will allow a proper SAAMI cartridge to chamber properly. This means it should not take excessive force for the cartridge to chamber. The bullet should NOT be engraved by the lands doing so. There is NO SAAMI chamber that I am aware of that allows a factory loaded cartridge to do so. The area directly in front of the case mouth may very slightly "kiss" or rub the bullet, but in doing so it should not deform or scrape the bullet. (Those seeking ultra accuracy often have a "tight necked" chamber built, where they must turn the neck of the cartridge itself to allow loading, but no SAAMI cartridge or design I can find is on the books in this manner.) Even when they do so, the area in front of the neck must remain open to the bullet itself, although as noted above, that area may be very short.
We have reports of barrels that do not allow loading of SAAMI factory ammunition.
There are TWO and only TWO possibilities:
1) The chamber is incorrect.
2) The ammunition is incorrect.
Number 2 is pretty easily checked. Try a cartridge from another case lot, or several different case lots, and several different loadings.
If ONLY the one cartridge doesn't fit, you can be relatively sure that the cartridge itself is out of spec.
If more than one, or multiples, don't fit, then there are only 2 possibilities:
1) You have multiple case lots of ammunition out of spec. (Highly unlikely, especially if you use different loadings and bullets.)
2) You have a chamber that is out of spec.
Some have barrels that seem to allow factory cartridges to drop right in, straight from the factory. Others have claimed that their barrels do not allow them to chamber factory ammunition, but do allow short seating of bullets, and seem to shoot very well.
There have been conflicting reports that manufacturers may be using SAAMI spec reamers, and not getting SAAMI spec chambers, or that the chamber design itself may be at fault.
Unfortunately, all of the above, and all the "remedies" are nothing but speculation from everyone involved.
There are some terms that are somewhat confusing:
Some refer only to the area occupied by the cartridge case itself as the chamber, while others define the chamber as the entire area filled by a loaded cartridge as the chamber. In the second case, this includes the area filled by the cartridge case, the area in front of the case (often called the throat, and which includes the angle that guides the bullet into the caliber sized, engraved portion of the barrel), and the area occupied by the ogive of the bullet.
SAAMI defines the dimensions of the case itself.
The drawings of the chamber are also defined by SAAMI, and in the case of the Grendel chamber, that includes the compound throat, and the designated angular changes within that throat. In order to properly be called a SAAMI chamber, all those dimensions must be consistent with the SAAMI drawing. In a typical chamber, the dimensions include an area ever so slightly larger than the bullet diameter, this is called the "free bore". This is an area prior to the caliber diameter area where the bullet is moving freely before it is forced into the caliber engraved barrel itself.
In attempts at ultimate accuracy, this freebore area may be nearly nonexistent, or the handloader may load his bullets long, thus engaging them into the rifling so that the bullet does not ever have that "free" jump before engraving. This is a bit of a gamble on the handloaders part, accepting that there is a pressure increase, but that the gain in accuracy is worth it. VLD bullets are typically loaded in this manner. Modern metals are so good and so strong that many long range competitive shooters "JAM" the bullets significantly into the lands and get away with it because of that strength.
Here are the facts about ALL chambers:
A proper SAAMI chamber will allow a proper SAAMI cartridge to chamber properly. This means it should not take excessive force for the cartridge to chamber. The bullet should NOT be engraved by the lands doing so. There is NO SAAMI chamber that I am aware of that allows a factory loaded cartridge to do so. The area directly in front of the case mouth may very slightly "kiss" or rub the bullet, but in doing so it should not deform or scrape the bullet. (Those seeking ultra accuracy often have a "tight necked" chamber built, where they must turn the neck of the cartridge itself to allow loading, but no SAAMI cartridge or design I can find is on the books in this manner.) Even when they do so, the area in front of the neck must remain open to the bullet itself, although as noted above, that area may be very short.
We have reports of barrels that do not allow loading of SAAMI factory ammunition.
There are TWO and only TWO possibilities:
1) The chamber is incorrect.
2) The ammunition is incorrect.
Number 2 is pretty easily checked. Try a cartridge from another case lot, or several different case lots, and several different loadings.
If ONLY the one cartridge doesn't fit, you can be relatively sure that the cartridge itself is out of spec.
If more than one, or multiples, don't fit, then there are only 2 possibilities:
1) You have multiple case lots of ammunition out of spec. (Highly unlikely, especially if you use different loadings and bullets.)
2) You have a chamber that is out of spec.
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