Cutright wrote:I have the gauge and the case. However the (edited)COL when it meets the lands is far longer than the magazine will allow, so I've just been loading at factory length
You have just rediscovered the downside of the AR15 platform. Different bullets with their individual ogives will engage the lands at different COL. I should clarify that "engaging the lands" is a somewhat misnomer. Many bullets engage the taper of the throat, at the end of the leade, before actually engaging the lands, which begins shortly beyond that point. I'll give you a rare example in the 450b. The Hornady 300gr XTP Mag does not have a ballistic tip that extends its length. As such, in my chamber it engaged the lands with the COL only being 2.22. I suspect that would be applicable to any non-ballistic tip hollow point, that is long such as occurs in the 300 grainers, but I only checked it using the XTP Mag. Additionally, due to its dense nature, the short, 230gr, round nose FMJ engages the throat at a COL that places it totally outside the case. IE it is clear of the case before it starts obturating to fit the bore. In my mind's eye, I believe it is really important for the leading edge of the bullet to be supported by the throat before it is no longer supported in the rear by the case. Otherwise, it can be slightly misaligned when it enters and exits the bore. It may be why I have poor luck with groups when shooting the 230gr round nose fmj.
There is however another alternative to being limited so much by the inside dimension of the magazine. Back in 2011, I wrote up a how-to thread, for modding a magazine to allow for COLs up to or slightly longer than 2.40. Amazingly, the thread and images are still intact over at the Olympic Arms website. Here's the
Link to it.
Hoot
EDIT: I must apologize because in revisiting the article referenced above, some of the images have fallen victim to Tiny Pic hosting expiration policies. The missing images would have shown my method for accurately slitting the front of the mag. cbass16 (original idea source) slit his free-hand and although it was not cosmetically as nice as my result, it still worked fine.
2nd EDIT: I found the backup images from that link. If anyone is interested in reproducing my work, let me know and I can send them to you. In the mean time, I'll try editing that old article over at oa2.org.
Posted: Mon Jan 25, 2016 5:38 pm
