Cannalure and seating depth
OK, I admit, I buy the best priced .308 bullets because all I do is blast with them. The problem is the cannalure is all over the place with the different lots I buy. This last lot of 2000 was advertised as 146 gain U.S. mil surplus. When loaded into a 30.06 case (trimmed to specs.) to the overall length of about 3.330", the cannalure is abouve the case mouth by 1/16". I can seat the bullet deeper but then will get bullet jump. Questions are....can I crimp case on bullet below the cannalure and be ok? If not, then can I seat bullet deeper into case and fire it safety in say a Garand? Thanks in advance.
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For a Garand,best to crimp in the cannalure, seat the bullet deeper, adjust your powder charge if loading near maximum. 0 -
For "just blasting" it hardly matters. For what it's worth, bullets are designed for specific cartridges, including the location of the cannelure. The bullets in question are designed for the .308, I'd assume. So the cannelure might not be in the ideal spot for a 30-06. 0 -
seat them where you want, the cannelure means nothing unless you want to crimp them. I don't crimp anything 0 -
quote:Originally posted by JustC
seat them where you want, the cannelure means nothing unless you want to crimp them. I don't crimp anything
The cannelure is a quaint item often ignored for a reason. Seat the bullets to the depth you want to get the OAL correct and blast away.
NOTE; be careful to not shove the shoulder back during seating, the feel of the ram pressure while seating will tell you if you are applying too much force. As long as the shoulders of the case are not bulged you will be fine.0 -
quote:Originally posted by JustC
seat them where you want, the cannelure means nothing unless you want to crimp them. I don't crimp anything
i started doing what JustC says
only ones i crimp are the ones that seem a little loose when i seat them, most are only on pulled bullets0 -
Reloading for Semi-Autos and Service Rifles Read all at link http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm
Neck Tension
When we stop to consider the vigorous (read, downright violent) chambering cycle a loaded round endures in a Service Rifle, it becomes pretty clear it suffers abuse that would never happen in a bolt-action. This is simply the nature of the beast. It needs to be dealt with since there is no way around it.
There are two distinctly different forces that need to be considered: those that force the bullet deeper into the case, and those that pull it out of the case. When the round is stripped from the magazine and launched up the feed ramp, any resistance encountered by the bullet risks having it set back deeper into the case. Due to the abrupt stop the cartridge makes when the shoulder slams to a halt against the chamber, inertia dictates that the bullet will continue to move forward. This is exactly the same principle a kinetic bullet puller operates on, and it works within a chamber as well. Some years ago, we decided to examine this phenomenon more closely. During tests here at Sierra's range, we chambered a variety of factory Match ammunition in an AR-15 rifle. This ammunition was from one of the most popular brands in use today, loaded with Sierra's 69 grain MatchKing bullet. To conduct the test, we chambered individual rounds by inserting them into the magazines and manually releasing the bolt. We then repeated the tests by loading two rounds into the magazine, chambering and firing the first, and then extracting and measuring the second round. This eliminated any potential variation caused by the difference between a bolt that had been released from an open position (first round in the magazine) and those subsequent rounds that were chambered by the normal semi-automatic operation of the rifle. Measuring the rounds before chambering and then re-measuring after they were carefully extracted resulted in an average increase of three thousandths (0.003") of forward bullet movement. Some individual rounds showed up to seven thousandths (0.007") movement. Please bear in mind that these results were with factory ammunition, normally having a higher bullet pull than handloaded ammunition.
To counteract this tendency, the semi-auto shooter is left with basically two options: applying a crimp or increasing neck tension. The first option, crimping, brings up some other issues that can be troublesome. In general, crimping degrades accuracy. Most match bullets are not cannelured (which also seriously damages accuracy potential), a requirement for correct application of most crimps. Still, there are taper crimp dies available from most of the major manufacturers. Lee offers their "Factory Crimp" die as an alternative, which seems to be one of the better options for those bullets without a cannelure. That having been said, crimping is still, at best, an occasionally necessary evil. Avoid it if at all possible. The Lee Factory Crimp Die if not uses correctly will damage bullet and brass. IMO.
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