some general rifle cartridge questions

[thomis]

I've been working up several pet loads for my two hunting rifles, and I've come up with some questions/ observations.

I started at the minimum charge for the Sierra 125 grain (.308 Win) in my Featherweight using IMR 4064. Groups are closing up significantly as I near the max charge. So I went ahead and loaded up a few last night at max charge. The powder came all the way to the top of the case. I know this can be normal but it's the first time I've ever done it and it kind of makes me nervous. In seating them, I could even feel the pressure of the compressed charge in the press and backed off a little, unable to seat to the desired COL. I went ahead and seated one of them all the way down and it took a lot of pressure. Honestly, I'm afraid to fire this cartridge.

Another observation...crimping the bullets that have a cannelure. This may or may not be necessary, and I don't know when exactly it is necessary. But some of the bullets I've been loading lately (150 Hornady .308 for one) has a cannelure, so I've been giving the cartridges a light roll crimp. I'm using the seating die to do this and it works just fine once you get the die set right. Which makes me wonder, why do they sell a separate die for this job?

One bullet I have on hand but I can't find a COL online for is the Hornady A-Max 168 grain bullet. If I had a Hornady manual, I could look it up but...I don't. I wish the bullet manufacturers would post COL's on their websites, or at least give some guidance in that regard. Someone with a current Hornady manual could please provide this?

My other hunting rifle is a .243 Winchester. I've been loading several different cartridges for it, including some Berger bullets. I posted a thread a few days ago and got some good info, but...If someone could share what they have successfully used as a COL for the Berger (6mm/.243) 95 grain VLD, that would be great!

Thanks for the help!

 

[LivewireBlanco]

What is your COL and how many grains is that max load?

 

[beatledog7]

Hornady #8 says OAL for the 168gr A-Max is be 2.800". Be advised that's not always going to be you best load, but it's a good place to start.

 

[ironworkerwill]

a crimp is advisable in auto loaders and especially chain loaded guns like a 30-30. most all other applications are not required.

 

[thomis]

Livewire,

According to http://data.hodgdon.com/cartridge_load.asp

The max charge for IMR 4064 is 50.1 grains for the Sierra 125 grain SP with a COL of 2.70"

 

[308win]

I have found that my .308 shoots best with max loads.

 

[gamestalker]

I've worked up to max compressed charges in numerous cartridge applications with no ill effects what so ever. If you've done things right, as in working up to that charge, and sticking to published data, you'll be alright.

OAL is determined by the chamber your loading for. I like to seat close to the lands, but this does cause pressures to go a bit higher, thus the importance of working up charges, and to do so with the same consistent seating depth throughout the process. Not doing it this way can result in a sudden unexpected rise in pressures. To reiterate, anytime you change anything in the process, seating depth, bullet, or primer, you need to work up all over again from square one. Just because two bullets weight the same doesn't mean they will run the same pressures, even if they are seated at the same OAL.

As for crimping, it is totally unnecessary to crimp bottle neck cartridges, with some exceptions for certain auto loading actions, and tubular magazines. I've never crimped a bottle neck cartridge other than a 30-30 lever action that was obviosly tubular magazine fed. So my suggestion is keep the process simple, as crimping bottle necks often causes more grief and issues than it could ever benefit.
GS

 

[308win]

Crimping for my .308 wasn't a solution.

 

[Grumulkin]

I've been working up several pet loads for my two hunting rifles, and I've come up with some questions/ observations.

I started at the minimum charge for the Sierra 125 grain (.308 Win) in my Featherweight using IMR 4064. Groups are closing up significantly as I near the max charge. So I went ahead and loaded up a few last night at max charge. The powder came all the way to the top of the case. I know this can be normal but it's the first time I've ever done it and it kind of makes me nervous. In seating them, I could even feel the pressure of the compressed charge in the press and backed off a little, unable to seat to the desired COL. I went ahead and seated one of them all the way down and it took a lot of pressure. Honestly, I'm afraid to fire this cartridge.

Another observation...crimping the bullets that have a cannelure. This may or may not be necessary, and I don't know when exactly it is necessary. But some of the bullets I've been loading lately (150 Hornady .308 for one) has a cannelure, so I've been giving the cartridges a light roll crimp. I'm using the seating die to do this and it works just fine once you get the die set right. Which makes me wonder, why do they sell a separate die for this job

1. Published COAL is based on the accepted SAAMI spec as well as the length of the bullet. Your COAL may be different. Your COAL must provide for 3 things. First, the cartridge must not be so long that it can't feed through a magazine unless, of course, hour have a single shot. Secondly, there must be enough bullet in the neck of the case to hold it securely. This usually means a caliber length inside the neck though there are some short necked cartridges where the neck is a little shorter than a caliber length so this is impossible. Thirdly, it's usually best to have the bullet as close to the lands as possible without actually abutting against them. Exceptions to the third rule would be monometal bullets such as those made by Barnes that do best with a little jump to the lands.

2. As long as the pressure is OK, it doesn't matter if your shooting a compressed load. Just make sure you're paying attention to pressure signs and not blindly following a manual that says such and such a load is "maximum." I have seen instances where starting load data in one manual was a maximum load in another. It's best to compare loads from 2 or 3 sources and STILL evaluate pressure signs in your gun.

3. In general, you can entirely ignore the cannelure. I've loaded for semi autos up to 30/06 and can tell you that you don't need to crimp them. When you get up to stuff with more recoil like a 378 Weatherby Magnum, 460 S&W Magnum and the like, then you do need to crimp bullet if you don't wish them to move under recoil.

4. The reason separate crimping dies are sold is because with come cartridges, to get an adequate crimp to prevent bullets moving under recoil, you will collapse the case. The Lee Factory Crimp die is the best one to use if you wish to crimp.

 

[thomis]

Thank you all, I believe all my questions have been answered.
Much appreciated!

 

[greenmtnguy]

One bullet I have on hand but I can't find a COL online for is the Hornady A-Max 168 grain bullet. If I had a Hornady manual, I could look it up but...I don't. I wish the bullet manufacturers would post COL's on their websites, or at least give some guidance in that regard. Someone with a current Hornady manual could please provide this?

I have Hornady Reloading Manual 7th Ed. and it shows the 168 A Max #30502 bullet with a COAL of 2.800"

It doesn't list IMR4064 for it though It does show the heavier #30712 A Max bullet (180gr?????) with the same COAL and start load of 34.0gr of IMR4064, MAX LOAD of 41.3gr

Odd that they show IMR4064 for A Max bullet loads with 150gr bullets, and with 180 grain bullets, but not the 168grains in their manual. Probably just didn't get around to it?

 

[witchhunter]

You probably don't need to crimp with your bolt gun, I figure the COAL is the length that gives the best accuracy. Sometimes this is with the bullet touching the lands, sometimes it is somewhat shorter. I usually start about .010 off the lands if it will fit in the magazine. If it fits in your magazine and your chamber that should be your correct length. Don't be hung up on max length unless it won't feed or chamber.

 

[homatok]

Quote "As for crimping, it is totally unnecessary to crimp bottle neck cartridges, with some exceptions for certain auto loading actions, and tubular magazines. I've never crimped a bottle neck cartridge other than a 30-30 lever action that was obviosly tubular magazine fed. So my suggestion is keep the process simple, as crimping bottle necks often causes more grief and issues than it could ever benefit."

If you are filling your cases to the point that you need significant pressure to seat the bullet, you may want to load a few up, measure the OAL and set them aside for a few days/weeks and then re-measure the OAL. Allowed to stand for awhile, the compressed powder may well push the bullets further out than you loaded them.