Lee Challenger and dies rifle crimping


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JGPena
February 21, 2011, 01:29 PM
ok newbie handloader here. Just getting setup and I did a test bullet seating for .308 winchester. from my understanding cartridges for semi auto rifles should be crimped. These loads will be for a M1A/SOCOM16. When I seated the bullet for the correct length of the cartridge, there is no crimp applied. I had previously test seated another bullet and it was seated too far into the casing, but it did create a crimp. what might I have done wrong that a crimp wasn't made for the correctly seated cartridge? Im using standard Lee dies. Is it the press or dies?

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243winxb
February 21, 2011, 01:37 PM
The crimper is fixed in the seating die. The more you screw it into/down in the press, the more it crimps. Bullet Seating Adjustment

The trick is to set the bullet seating depth first, then the crimp. This is done as follows; With an empty, sized case in the shell holder, hold the ram at the top of its stroke. Turn the bullet seating die body down over the case until you feel it come to a stop. This will be when the case mouth contacts the crimp shoulder inside the die. Mark this position by turning the lock ring down against the turret or press frame. Now adjust your bullet seating depth. Once you have the bullet seated to the desired depth, back the bullet seater adjuster out about 1 turn. Now turn the bullet seating die body in to apply the desired crimp. Once this is established, hold the ram at the top of its stroke and spin the bullet seater adjuster down until it stops.

It is a good idea to carry this out with an empty case, so that after you have seated the bullet, you have a perfectly safe "dummy" cartridge (or gauge) to repetitively set seating depth and crimp on future occasions.

Once you have this "dummy" gauge, all you have to do is place it in the shell holder, raise the ram to the top of its stroke, turn the bullet seating body down until it stops, and then turn the bullet seating depth adjuster in until it stops. Since the crimp and the seating depth were already set, the die will return to very close to the same settings.

243winxb
February 21, 2011, 01:42 PM
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 other—and in our opinion, better—option is increased neck tension. This, in turn, leaves us with two more options depending on what type of equipment you’re using. The object of either is simply a tighter grip on the bullet. Using conventional sizing dies, (i.e., those utilizing an expander ball) this is accomplished by reducing the diameter of the ball itself. This can be done by chucking the expander/decapping rod into a drill and turning it down slightly with fine emery cloth or a stone. The goal here is to decrease the diameter two or three thousandths (0.002" to 0.003") under bullet diameter. This is a trial and error process, and must be done slowly. The end result is an expander ball that opens the case neck up somewhat less than the as-issued item. This, in turn, increases the grip of the case neck on the seated bullet.

A better alternative to achieve the same effect is the use of a bushing die, such as those from Redding Reloading. This is by far the best solution, not just for Service Rifles, but for a broad range of reloading applications. The basis for this system is a fairly conventional sizing die, at least where the body and shoulder of the case is concerned. In the neck area, however, the die is fitted with a removable bushing. Available in .001" increments (as measured at the inside diameter of the bushing), they can be matched with a specific batch of brass to provide optimum neck tension. This tension can be increased or decreased by simply moving up or down in bushing size. The one drawback to this system, if it can be called a drawback, is the absolute necessity of sorting cases and loading them in batches. This, of course, is how virtually all loading should be done anyway.

ranger335v
February 21, 2011, 01:55 PM
"Lee Challenger and dies rifle crimping.... Is it the press or dies? "

JC, it's the loose nut at the end of the lever! Follow the good instructions in 243's first post.

I strongly disagree with the contents of the "exteriourballistics" site in his second post tho. What is normally being called "bullet tension" isn't. In fact, having a neck smaller than about 1 thou from the bullet is meaningless to bullet grip, it only increases the required seating effort. Stretching a neck more than about a thou simply exceeds the brass' elastic limits and only the last thou of elasticity will remain no matter how small the neck originally was. But having a neck smaller than it really should be does increase seated runout and that is NOT good for accuracy.

Actually, I suspect the "need" to crimp autoloader bullets is greatly over stated, at least I haven't found it to be needed and I DO NOT load with "high bullet tension."

Good luck!

JGPena
February 21, 2011, 02:58 PM
ah, gotcha, loose nut, lol. Thanks for the info. Sorry if ths info is in the Lee manual. I looked over the steps to reload that are in the manual, and I didn't notice anything about it in that section. I will look through the book more before I actually start making working cartridges. Thank you

243winxb
February 21, 2011, 03:45 PM
Sorry if ths info is in the Lee manual. The Lee link below, FAQ has the info. http://www.leeprecision.com/cgi/faq/index.cgi Good Luck.

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