.338 Lapua Magnum

desertstormvet · February 5, 2014, 10:47 AM

Guys...any help on reloading .338 LM would be appreciated. My first question is around COAL...drawings pulled from the internet and www.loaddata.com indicate a COAL of 3.681" (which doesn't fit in my Barrett MRAD); whereas, www.hodgdon.com indicates a COAL of 3.55" (for Hornady 250 grain SP) and 3.6" (for Sierra 300 grain BTHP). Finally, I purchased two boxes of Lapua Scenar cartridges (250 and 300 grain) and they both measured between 3.603 and 3.606". I've determined that 3.65" will fit in my MRAD, but I can't find any consistent reloading data. Any thoughts / recommendations? I'm not too keen on experimenting without some similar, known data.

Bart B. · February 5, 2014, 11:01 AM

The overall length of a cartridge is determined by what the rifle's chamber and box magazine dimensions are. What's listed in reloading data is only what they used; it's an example, starting point, etc. Your ammo can easily be different.

Yours should be loaded to about 1/16th inch shorter than magazine length if they'll be held in it. Providing they chamber easy, too. If you'll use them single loaded and not from the magazine, they usually can be a little longer.

To find out what the longest cartridge length can be for your rifle, with an empty chamber and the bolt closed, drop a cleaning rod down the barrel until its stops against the bolt face then mark a thin line on it even with the muzzle. Then remove the rod and the bolt, push one of your bullets into the chamber with something so it sticks in the rifling. Then put that cleaning rod back in gently until it stops against the bullet without it coming loose in the rifling. Make another thin line on the cleaning rod. Put everything back together.

The distance between those two marks is very close to the maximum overall length your cartridges can be; minus whatever distance you want the bullet to jump to the rifling. That works as a starting point. Make some dummy rounds with bullets seated for different overall lengths you want to try then test them as the feed from the magazine as well as chamber easily when single loaded. Once they pass the functional test, it's time to make live ammo.

Use the published load data starting about 7% below maximum charge weights, then work up to what you think's a safe level.

desertstormvet · February 5, 2014, 02:04 PM

Thanks for the recommendations...very insightful. I found through my initial effort that my max. COAL would be between 3.65 and 3.68". A couple more questions...the max. load per Hodgdon for a 250 grain bullet is for a COAL of 3.55". If I load for a length of 3.65", for example, and using the same powder/bullet combination, is Hodgdon's max. load still a maximum or can I go higher due to slightly more space (~0.1") available in the casing? I'm concerned about overpressure...and the ability to open my bolt and extract the cartridge after firing. Also, is there any recommendation on distance between the bullet and the rifling? All my research indicates that it should be as little as possible for improved precision.

Bart B. · February 5, 2014, 03:08 PM

It's usually not a good idea to change charge weights as case volume changes with bullet seating depths. Stick with the suggested powder charge weights.

While that 1/10th inch difference in the powder height in a case held vertical looks big, with the rifle horizontal, the space above the powder in a horizontal case for the same charge weights spread will be very small and probably not noticeable in shooting them. When the rifle is fired straight up or down, then that space makes a small difference.

Most bullets shoot most accurate with Minimum distance to the rifling. That helps center them when the round is chambered.

Brian Pfleuger · February 5, 2014, 03:24 PM

There is no "magic number" distance from the rifling that always shoots better. Sometimes, touching can be best because it ensures that any difference in neck tension are covered by the extra pressure it takes to get the bullet moving.

In a rifle, making a cartridge longer almost always raises pressure because the bullet gets less and less of a "running start" before contacting the rifling.

Use whatever OAL you'd like and start at the listed starting load and work up. You can expect to end up below the published max if you start your bullet in the rifling, although you'll have no idea what's happening unless you have a chronograph. Even that (speed) is not a direct pressure indicator but when you get close to the velocity indicated in the published data you know you're getting close on pressure.

desertstormvet · February 5, 2014, 04:24 PM

Thanks guys...maybe my last question. When I recently loaded for .338 LM, I used the Hodgdon load data, but maintained a higher COAL. When I picked up a cartridge, I could hear the powder moving. I heard alarm bells and shortened my COAL to better align with the COAL used by Hodgdon. Am I hearing that rattling powder isn't an issue???

Brian Pfleuger · February 5, 2014, 04:29 PM

Almost all loads in almost all cartridges are not compressed. The only loads that will not "rattle" are compressed loads and are normally designated in data with a c after the charge weight, as in "104.8C"

Bart B. · February 5, 2014, 10:13 PM

.308 Win. match ammo's been loaded with about 96% load density (amount of the space occupied by powder inside a case with the bullet seated; 4% of those cases inside space didn't have powder) that's easily heard shaking loose in cases while inside a quite room shaking the rounds. That stuff tested well under 3 inches all day long at 600 yards. I doubt it matters with 33 caliber cartridges, either.

Go figure.

Jimro · February 5, 2014, 10:58 PM

Quote:

Thanks guys...maybe my last question. When I recently loaded for .338 LM, I used the Hodgdon load data, but maintained a higher COAL. When I picked up a cartridge, I could hear the powder moving. I heard alarm bells and shortened my COAL to better align with the COAL used by Hodgdon. Am I hearing that rattling powder isn't an issue???

Definitely not an issue with extruded stick powder. Best accuracy with a stick powder can be found anywhere from 80% case fill to 100%.

Ball powder should be ok, although my personal preference is to keep case fill very high to ensure proper ignition with a ball powder. But as long as you aren't shooting at extreme downhill angles you shouldn't experience ignition issues even with a ball powder.

Jimro

desertstormvet · February 15, 2014, 09:40 AM

I went to the range with my hand loads…WLRM primers, Lapua brass, Retumbo powder (varying loads from min to max), and Hornady's version of 250 grain BTHP. Of the 25, 9 did not fire. My assumption is that my primer seating depth was a bit too much for the rifle; however, this is my first use of Winchester's primers. Does a primer failure rate of 33% seem excessive? I think so and am assuming my primers will need to be flush. Since it's a bolt rifle, that should be OK. Thoughts?

Jimro · February 15, 2014, 11:23 AM

Primers should be "bottomed out" in the pocket. If they aren't the firing pin can push them down to the bottom with the first strike instead of setting them off.

Jimro

1stmar · February 15, 2014, 09:01 PM

Primers should be seated below flush. Did you try to refine the rounds that did not go off?

jwrowland77 · February 15, 2014, 09:25 PM

One thing I learned about using Lapua brass is that the primer pockets need to be uniformed, and to be completely sure that the primer pocket is completely uniformed.

February 5, 2014, 10:47 AM	#1
desertstormvet Member Join Date: May 26, 2013 Posts: 60	.338 Lapua Magnum Guys...any help on reloading .338 LM would be appreciated. My first question is around COAL...drawings pulled from the internet and www.loaddata.com indicate a COAL of 3.681" (which doesn't fit in my Barrett MRAD); whereas, www.hodgdon.com indicates a COAL of 3.55" (for Hornady 250 grain SP) and 3.6" (for Sierra 300 grain BTHP). Finally, I purchased two boxes of Lapua Scenar cartridges (250 and 300 grain) and they both measured between 3.603 and 3.606". I've determined that 3.65" will fit in my MRAD, but I can't find any consistent reloading data. Any thoughts / recommendations? I'm not too keen on experimenting without some similar, known data.

February 5, 2014, 03:08 PM	#4
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	It's usually not a good idea to change charge weights as case volume changes with bullet seating depths. Stick with the suggested powder charge weights. While that 1/10th inch difference in the powder height in a case held vertical looks big, with the rifle horizontal, the space above the powder in a horizontal case for the same charge weights spread will be very small and probably not noticeable in shooting them. When the rifle is fired straight up or down, then that space makes a small difference. Most bullets shoot most accurate with Minimum distance to the rifling. That helps center them when the round is chambered. Last edited by Bart B.; February 5, 2014 at 03:23 PM.

February 5, 2014, 03:24 PM	#5
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	There is no "magic number" distance from the rifling that always shoots better. Sometimes, touching can be best because it ensures that any difference in neck tension are covered by the extra pressure it takes to get the bullet moving. In a rifle, making a cartridge longer almost always raises pressure because the bullet gets less and less of a "running start" before contacting the rifling. Use whatever OAL you'd like and start at the listed starting load and work up. You can expect to end up below the published max if you start your bullet in the rifling, although you'll have no idea what's happening unless you have a chronograph. Even that (speed) is not a direct pressure indicator but when you get close to the velocity indicated in the published data you know you're getting close on pressure. __________________ Nobody plans to screw up their lives... ...they just don't plan not to. -Andy Stanley

February 5, 2014, 04:29 PM	#7
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	Almost all loads in almost all cartridges are not compressed. The only loads that will not "rattle" are compressed loads and are normally designated in data with a c after the charge weight, as in "104.8C" __________________ Nobody plans to screw up their lives... ...they just don't plan not to. -Andy Stanley

February 15, 2014, 11:23 AM	#11
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	Primers should be "bottomed out" in the pocket. If they aren't the firing pin can push them down to the bottom with the first strike instead of setting them off. Jimro __________________ Machine guns are awesome until you have to carry one.

February 5, 2014, 11:01 AM	#2
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	The overall length of a cartridge is determined by what the rifle's chamber and box magazine dimensions are. What's listed in reloading data is only what they used; it's an example, starting point, etc. Your ammo can easily be different. Yours should be loaded to about 1/16th inch shorter than magazine length if they'll be held in it. Providing they chamber easy, too. If you'll use them single loaded and not from the magazine, they usually can be a little longer. To find out what the longest cartridge length can be for your rifle, with an empty chamber and the bolt closed, drop a cleaning rod down the barrel until its stops against the bolt face then mark a thin line on it even with the muzzle. Then remove the rod and the bolt, push one of your bullets into the chamber with something so it sticks in the rifling. Then put that cleaning rod back in gently until it stops against the bullet without it coming loose in the rifling. Make another thin line on the cleaning rod. Put everything back together. The distance between those two marks is very close to the maximum overall length your cartridges can be; minus whatever distance you want the bullet to jump to the rifling. That works as a starting point. Make some dummy rounds with bullets seated for different overall lengths you want to try then test them as the feed from the magazine as well as chamber easily when single loaded. Once they pass the functional test, it's time to make live ammo. Use the published load data starting about 7% below maximum charge weights, then work up to what you think's a safe level.

February 5, 2014, 02:04 PM	#3
desertstormvet Member Join Date: May 26, 2013 Posts: 60	Thanks for the recommendations...very insightful. I found through my initial effort that my max. COAL would be between 3.65 and 3.68". A couple more questions...the max. load per Hodgdon for a 250 grain bullet is for a COAL of 3.55". If I load for a length of 3.65", for example, and using the same powder/bullet combination, is Hodgdon's max. load still a maximum or can I go higher due to slightly more space (~0.1") available in the casing? I'm concerned about overpressure...and the ability to open my bolt and extract the cartridge after firing. Also, is there any recommendation on distance between the bullet and the rifling? All my research indicates that it should be as little as possible for improved precision.

February 5, 2014, 04:24 PM	#6
desertstormvet Member Join Date: May 26, 2013 Posts: 60	Thanks guys...maybe my last question. When I recently loaded for .338 LM, I used the Hodgdon load data, but maintained a higher COAL. When I picked up a cartridge, I could hear the powder moving. I heard alarm bells and shortened my COAL to better align with the COAL used by Hodgdon. Am I hearing that rattling powder isn't an issue???

February 5, 2014, 10:13 PM	#8
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	.308 Win. match ammo's been loaded with about 96% load density (amount of the space occupied by powder inside a case with the bullet seated; 4% of those cases inside space didn't have powder) that's easily heard shaking loose in cases while inside a quite room shaking the rounds. That stuff tested well under 3 inches all day long at 600 yards. I doubt it matters with 33 caliber cartridges, either. Go figure.

February 15, 2014, 09:40 AM	#10
desertstormvet Member Join Date: May 26, 2013 Posts: 60	I went to the range with my hand loads…WLRM primers, Lapua brass, Retumbo powder (varying loads from min to max), and Hornady's version of 250 grain BTHP. Of the 25, 9 did not fire. My assumption is that my primer seating depth was a bit too much for the rifle; however, this is my first use of Winchester's primers. Does a primer failure rate of 33% seem excessive? I think so and am assuming my primers will need to be flush. Since it's a bolt rifle, that should be OK. Thoughts?

February 15, 2014, 09:01 PM	#12
1stmar Senior Member Join Date: March 21, 2012 Location: Connecticut Posts: 2,378	Primers should be seated below flush. Did you try to refine the rounds that did not go off?

February 15, 2014, 09:25 PM	#13
jwrowland77 Senior Member Join Date: March 23, 2012 Location: Conway, Arkansas Posts: 1,398	One thing I learned about using Lapua brass is that the primer pockets need to be uniformed, and to be completely sure that the primer pocket is completely uniformed.