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Powderman · December 30, 2013, 08:59 PM

Others have posted this, and I will mention it as well: The crimp is the culprit.

Most seating dies have the crimp shoulder already built in. This is usually a ROLL crimp. If you try to put a heavy crimp on bottleneck rifle cartridges, you will buckle the shoulder.

As others have also said, case/neck tension is what holds the bullet in place.

That being said:

Here's a word of caution for those who reload .223 or 5.56 ammunition.

Remember--the original spec that the military standardized called for a 55 grain FMJ, leaving a 20" barrel at around 3200 fps, plus or minus 50 fps. With the 55 grain bullet or lighter, case neck tension does the trick.

When you go up to the 62 grain or heavier bullets--and you load from the magazine--you might well end up with problems. The bullet seated to the proper OAL will push past the neck's bearing surface, down into the case.

The AR15's feeding system has the potential to beat up a cartridge. This is especially true if you're using a carbine, or if you have mated a carbine barrel and a rifle upper--or the other way around. This creates what is known as the dreaded "carfle"--a hybrid carbine and rifle does doesn't work very well.

In these cases, the bullet can be jammed back into the case upon feeding. Sometimes, these will let you know what's happening by refusing to chamber; you'll see the bullet pushed back into the case.

If you DON'T see it, and a round like that chambers, you will have a serious overpressure problem.

The solution?

If I am loading 55 grain bullets or lighter, I will seat with no crimp. These work fine.

If I am using heavier bullets, I use the Lee Factory Crimp die. Adjust it to crimp right into the cannelure of the bullet, and you'll do fine. You do not have to "gorilla grip" the bullet--a slight crimp will do fine. (Unscientific method--adjust the crimp die until you see a light impression on the mouth of the case.

Of course, if you're using heavy match bullets, your best results will come from single loading each round. But...be careful of your overall seating length.

December 30, 2013, 08:59 PM	#29
Powderman Senior Member Join Date: September 7, 2001 Location: Washington State Posts: 2,166	Others have posted this, and I will mention it as well: The crimp is the culprit. Most seating dies have the crimp shoulder already built in. This is usually a ROLL crimp. If you try to put a heavy crimp on bottleneck rifle cartridges, you will buckle the shoulder. As others have also said, case/neck tension is what holds the bullet in place. That being said: Here's a word of caution for those who reload .223 or 5.56 ammunition. Remember--the original spec that the military standardized called for a 55 grain FMJ, leaving a 20" barrel at around 3200 fps, plus or minus 50 fps. With the 55 grain bullet or lighter, case neck tension does the trick. When you go up to the 62 grain or heavier bullets--and you load from the magazine--you might well end up with problems. The bullet seated to the proper OAL will push past the neck's bearing surface, down into the case. The AR15's feeding system has the potential to beat up a cartridge. This is especially true if you're using a carbine, or if you have mated a carbine barrel and a rifle upper--or the other way around. This creates what is known as the dreaded "carfle"--a hybrid carbine and rifle does doesn't work very well. In these cases, the bullet can be jammed back into the case upon feeding. Sometimes, these will let you know what's happening by refusing to chamber; you'll see the bullet pushed back into the case. If you DON'T see it, and a round like that chambers, you will have a serious overpressure problem. The solution? If I am loading 55 grain bullets or lighter, I will seat with no crimp. These work fine. If I am using heavier bullets, I use the Lee Factory Crimp die. Adjust it to crimp right into the cannelure of the bullet, and you'll do fine. You do not have to "gorilla grip" the bullet--a slight crimp will do fine. (Unscientific method--adjust the crimp die until you see a light impression on the mouth of the case. Of course, if you're using heavy match bullets, your best results will come from single loading each round. But...be careful of your overall seating length. __________________ Hiding in plain sight...