New to .338 Lapua reloading

Roblonsberry

Private
Minuteman
Dec 30, 2021
20
8
Canada
I am purchasing my first long range setup in 338 Lapua.
I have some experience reloading but not with a large caliber.
I have H4350 for 250 grain bullets. Problem is I can’t get my hands on magnum primers up here in Canada. I have large rifle CCI though.
Since I use these on my 6.5 creedmoor with 41.5 grains of h4350, will it be ok to use on the 338 since the powder weight is nearly doubled?
I’d love to use Retumbo or h1000 but it’s impossible to find here. Hours searching online with no luck. I spent a whole day driving to ma and pa type gun stores to no avail.
 

6.5SH

Old Salt
Full Member
Minuteman
Jul 24, 2020
4,111
6,338
You can't just double a charge for another cartridge and expect it to work.
The max on a fast for that cartridge powder is going to be well under what you think and will give poor results due to a less than optimal fill rate.

Look at the widely available load data then try to find something closer to the burn rate you need. Any of the 4350 range powders ain't it.
 

Dogtown

Ke = (mv^2)/2
Full Member
Minuteman
Jun 21, 2007
5,162
2,012
CONUS
Ramshot LRT will be the easiest to find, but it’s slow in that cartridge.

For 250s, here are some good powder options...

1664202080254.png



And if you were wondering why using H4350 would be a bad idea?
1664201747330.png

It's a best practice to keep your Fill Percentage somewhere in the 90s. You can do the 80s, but it starts to get a bit iffy and DO NOT GO INTO THE 70s because that can lead to a detonation (all powder burns at once vs linearly from the primer to the neck).

If you're shooting 250s in an average .338LM barrel length (26-28") you should be easily in the 2850-2950fps range. With H4350 you're really only safe in a slim window of charges. In Kurdish we'd say that's "Nah bash!"
 

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Roblonsberry

Private
Minuteman
Dec 30, 2021
20
8
Canada
I haven’t settled yet. The firearm is going to take a lot longer than I was quoted.
Going to be well into next year before I get to start testing.
 

Kazman1960

Private
Minuteman
Nov 25, 2022
4
0
p0n1k0
I haven’t seen any RL26 but will try this if I can get some. Thanks
Not sure if you have access to this powder , IMR4831 . Thats my go to powder for my .338 Lapua .
In fact , this is my goto for most of my Magnum loads as well as a load in my 6.5 Creedmoor that my Remington tends to favor .
 

Alaska

Private
Full Member
Minuteman
Mar 11, 2013
126
21
In a big magnum Lapua H1000
H1000 @ 91.0 to 92.0
300gr Berger tactical
Lapua Case and Fed 215M primers
 
Last edited:

Roblonsberry

Private
Minuteman
Dec 30, 2021
20
8
Canada
Ironic I just got it out it to test. Was having issues with my chrono mount but it seemed to have a node around 91. No pressure signs either.
going to make up another batch and try again next weekend.
 
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Roblonsberry

Private
Minuteman
Dec 30, 2021
20
8
Canada
I will when I get the bugs in my chrono figured out. My mount kelts loosening so I missed a fair bit of data. Seems to be a node around 88.2 and 90.2 Groups were slightly sub MOA
 
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Alaska

Private
Full Member
Minuteman
Mar 11, 2013
126
21
Ironic I just got it out it to test. Was having issues with my chrono mount but it seemed to have a node around 91. No pressure signs either.
going to make up another batch and try again next weekend.
300gr Berger OTM Tactical