Wanted to express my views on action length. With the advent of shorter fatter relatively high capacity cartridges, I am observing that they are actually better suited to longer actions, say 30-06 length actions than shorter ones. Such cartridges include the WSMs, Shermans, the PRCs, etc. The reason I think they are better suited to the longer action is that the longer action and magazine will better accommodate the very high BC bullets now available, since the bullet can be seated further out in the case and increase the usable powder capacity, providing greater optimization of the bullet jump as well. Limiting powder space and jump control simply degrades the potential of the short fat cases, which arguably are more efficient than longer cases with narrow powder columns. Case in point is my 300WSM. I have that rifle in a long action Savage, it feeds well and I can shoot our 175 gr BD2 bullet 3200 fps and the 195 gr BD2 at 2995 fps. From a short action that would be difficult to do if not dangerous with those bullets loaded to magazine length. Finding the same thing using a 6.5PRC. Would like to get some rational discussion about this subject from the obviously experienced reloaders on this site.
I did some extensive testing with bullet seating depth many years back and pretty sure the report was posted here on LRH. The test was with my 338 Allen Xpress which is my version of an improved 338 lapua. Now this is not a short action but the reason for the testing was because some were saying they could seat the 300 gr berger to well over 4" in their 338 edge rifles and easily match the 338 Allen Xpress……. i knew this was not correct, especially when considering brass life. The results however really did surprise me.
tested this bullet with a seating depth of 3.650" for use in detachable magazines such as the HS Precision, 3.820" for use in the extended mag lengths and then at 4.100" for single shot use which should have produced a HUGE advantage in velocity.
to start the test, i started with Retumbo which at the time was one of the better powders for the 338 Allen Xpress with the 300 gr berger. the test barrel was a 26" finish length, simply tested cutting throat lengths to different lengths.
going off memory, the short length produced around 2850 fps. mid length was a bit over 2900 and the long length was in the 2975 fps range so there was a 125 fps increase in velocity. This was as expected and it proved that a long seated 338 AX in a relatively short barrel was easily matching a long seated 338 Edge but doing it with 4" shorter barrel length….
anyway, after this test and reviewing the results, the short seated rounds ran out of capacity relatively quickly. So just for curiosity i decided to try some ramshot magnum which is a ball powder in similar burn rate to retumbo. Just to see, i through a same weight powder charge as the one used for retumbo and found that there was plenty of excess space in the case with same weight powder charge. This was simply due to magnum being a ball powder with much higher load density then the stick powder retumbo.
gave magnum powder a full work up and to my amazement, this powder topped out at the exact same 2975 fps as the very long loaded 4.100" version with retumbo…… i could actually use slightly more Magnum in the short 3.650" oal then retumbo used on the long seated version…..
so whats the point. Well, with the selection of powders we have today, there is very likely a combo that will work with a higher load density powder that will produce basically the same velocity as a different powder in a long seated application.
now if your using one specific powder, yes there will be a preferred oal to get the most velocity for a given situation but in a short seated application, there will be a best powder and there will be a totally different BEST powder for a long seated application. In the end, they often are extremely similar in end resulting performance.
as far as safety, we have heard often its dangerous to deep seat bullets….. not sure where this came from. I have never seen any danger at all in doing this. In all honesty, even a deeply seated bullet will have passed through the throat and into the bore before peak chamber pressure is reached. Never seen any issues over many thousands of rounds testing my super magnum wildcats or any other conventional chamberings.
if you want to use a standard receiver for a short action round, if it feeds, no problem at all. There are extended mags for most of the most common SA receivers which offer good oal that work well.
simply put, dont get to hung up on thinking you need to seat the bullets out as far as possible to get top performance numbers. That is not actually the case. Unfortunately today, getting any powder we want is a bit tricky for sure though.
