Hammer Bullets - Neck Tension and Crimping

[BigDon]

I didn't used to crimp until I had a hammer bullet get stuck in the freebore of my rifle on a late season elk hunt. The cartridge neck has less grip on a hammer bullet than a bullet without grooves so it is way easier for the bullet to pull out. This may be less of a risk with a cartridge that doesn't have any freebore, but since hammer bullets are generally 0.0005" larger than nominal bullet diameter (i.e. when you order a 0.308" bullet it is actually 0.3085"), I think getting a bullet frozen or jammed in your freebore is a very valid concern. The crimp is cheap insurance to help keep that bullet in the case neck until you pull the trigger. Also, this is another good reason to use more neck tension with a hammer bullet. I currently use a mandrel that is 0.0035" smaller than nominal bullet diameter on hammers.
I have crimped every load since that incident last year and hope that I don't have the same experience on my two upcoming late season elk hunts. I'm also taking some extra steps on this trip to keep moisture out of my action during whiteout storms so hopefully that also helps.

Sticking a bullet usually means you're too close to the lands. Hammers traditionally like jump - about .050 to .080. I'm good with crimping - but if you don't stick the bullet in the lands to begin with, you shouldn't be having bullet pull issues.

 

[cbuck516]

Sticking a bullet usually means you're too close to the lands. Hammers traditionally like jump - about .050 to .080. I'm good with crimping - but if you don't stick the bullet in the lands to begin with, you shouldn't be having bullet pull issues.

This was set at 0.050" jump. The rifle was a 300 PRC which has a freebore that is 0.3088" diameter and 0.232" long. Using a hammer bullet that is 0.3085" in diameter does not give a lot of room for error in harsh environmental hunting conditions.

 

[David_h]

This was set at 0.050" jump. The rifle was a 300 PRC which has a freebore that is 0.3088" diameter and 0.232" long. Using a hammer bullet that is 0.3085" in diameter does not give a lot of room for error in harsh environmental hunting conditions.

I've read that about PRC freebore. Im currently going with 0.088 jump in my 300 PRC with Lee Factory crimp on 199gr HH. I wonder if chamber had some carbon or fouling to unseat bullet?

 

[cbuck516]

I've read that about PRC freebore. Im currently going with 0.088 jump in my 300 PRC with Lee Factory crimp on 199gr HH. I wonder if chamber had some carbon or fouling to unseat bullet?

Very possible. It wouldn't take much to wedge a bullet in there. This was a trip where we were often in single digits and in and out of vehicles and tents so the chance of there being some condensation in there that froze is also a very real possibility.
I would also add that I never really tested to see how hard it was to pull those bullets out of the uncrimped case. After I had that incident in the field, where I was 4 1/2 miles from my truck I tested one of the other cartridges with a multitool, and was pretty amazed how easily it was to pull the bullet out by hand.

 

[BigDon]

Very possible. It wouldn't take much to wedge a bullet in there. This was a trip where we were often in single digits and in and out of vehicles and tents so the chance of there being some condensation in there that froze is also a very real possibility.
I would also add that I never really tested to see how hard it was to pull those bullets out of the uncrimped case. After I had that incident in the field, where I was 4 1/2 miles from my truck I tested one of the other cartridges with a multitool, and was pretty amazed how easily it was to pull the bullet out by hand.

Couple more comments - Condensation? That's why we tape muzzles. Pull a bullet out by hand? You've got neck tension issues. Something is wrong here. Crimping is good - but is not the fix for light bullet/neck tension. Crimping is just covering up the base issue here.

 

[cbuck516]

Couple more comments - Condensation? That's why we tape muzzles. Pull a bullet out by hand? You've got neck tension issues. Something is wrong here. Crimping is good - but is not the fix for light bullet/neck tension. Crimping is just covering up the base issue here.

I said condensation not precipitation. There is moisture in the air even in very dry conditions. When you go from a very warm environment like a warm tent or a truck to a much colder environment there is potential for condensation. There is always air inside of your barrel and inside of your action so there is always potential for condensation under the right conditions.
I would encourage you to test this for yourself and see if you can pull out a hammer bullet in an uncrimped case. I think you might be surprised how easy it is.

 

[BigDon]

I said condensation not precipitation. There is moisture in the air even in very dry conditions. When you go from a very warm environment like a warm tent or a truck to a much colder environment there is potential for condensation. There is always air inside of your barrel and inside of your action so there is always potential for condensation under the right conditions.
I would encourage you to test this for yourself and see if you can pull out a hammer bullet in an uncrimped case. I think you might be surprised how easy it is.

Valid point on condensation. I do test bullet pull - ever since I had the same stuck bullet problem as you on on an elk with a Barnes X back in 1986. Never have had the problem since.
In 1985 I has a load that wouldn't chamber in the field - that the day before had chambered fine. That issue was a compressed load reacting to the compression pressures - and it actually forced the bullet slightly out of the case over night. So I don't do that anymore either. Live and learn...

 

[C-130 Dude]

When crimping, you start with a crimp and use the same crimp as you go up in your charge looking for pressure.
When you find pressure, it is prudent to drop back one full grain (or slightly more) and shoot groups.
If you start with a light crimp (I start with "0" to 1/8th crimp using B'Bean's method) - you typically do not see much change in pressure or velocity as you increase crimp (with Hammers). What you will see is a decided preference in a certain amount of crimp with the same powder charge. Many use crimp amount as the final tuning method (I do). Much like changing bullet seating depth in the old lead bullet days.
As you change crimp amount, you will likely see swings in ES and SD.

I can't tell you how many times folks have come to me with crimp indused over pressure issues. They powder charge at maximum then crimp. Then wonder why they experience over pressure. The problem almost always comes down to over crimping. If you've crimped cases, you know just how touchy getting just the right amount can be. Adjusting your die a little bit at a time can have dramatic results. Go slow and test.

 

[Seabeeken]

IME, my rifles shoot under .5 and some under .1 with .0015-.002 neck tension and no crimp. I do crimp for my AR but it is so minimal that it barely leaves a mark on the neck. I also use Lee case lube inside necks to aid consistent bullet release and prevent bullet weld. This is just the way things work well for me

 

[Seabeeken]

I said condensation not precipitation. There is moisture in the air even in very dry conditions. When you go from a very warm environment like a warm tent or a truck to a much colder environment there is potential for condensation. There is always air inside of your barrel and inside of your action so there is always potential for condensation under the right conditions.
I would encourage you to test this for yourself and see if you can pull out a hammer bullet in an uncrimped case. I think you might be surprised how easy it is.

I've only ever seen condensation on my rifles when I've brought them from the cold outside into a warm building. I typically leave it outside and or locked up in my cold vehicle. Never saw condensation when taking it outside from a warm building. Same as a glass of ice cold water sitting on a table in a warm building sweating

 

[cbuck516]

I've only ever seen condensation on my rifles when I've brought them from the cold outside into a warm building. I typically leave it outside and or locked up in my cold vehicle. Never saw condensation when taking it outside from a warm building. Same as a glass of ice cold water sitting on a table in a warm building sweating

You are right, I said it backwards. When the temperature of the material gets below the dew point, there is potential for condensation.

 

[BillLarson]

Careful with that crimping. You can over pressure quick if your loading max charge weights.

And on a jacketed bullet you can crimp too much and separate the core from the jacket and cause out of balance in bullet....

 

[dougduey]

I always set up the Lee Crimp Die as per the instructions, which said to turn it in 1/2 turn deeper after you set it to touch the shell holder. I'd always work up my loads from there. Now that I've put a couple of new barrels on, I needed to rework up some pet Hammer loads. This is when I've started playing with the crimp. I start at a 1/8 turn and find a good load. Then I go to 1/4, 3/8 and 1/2 turn. I've found that 1/4 to 3/8 seems to be the sweet spot for crimp