I'm looking to start working up a 338 LM load using 300gr Sierra MKs and Retumbo. Hodgdon says 85-94. I'm thinking somewhere in the 90-95gr area but that's a lot of ground to cover with expensive components. Does anyone have a favorite load that they would like to share?
- Thread starter Cira
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Re: 338 LM with Retumbo
90-92 grains was where I started and I am around the 92 mark now and am getting very good accuracy...
90-92 grains was where I started and I am around the 92 mark now and am getting very good accuracy...
Re: 338 LM with Retumbo
I'm using 93.5grs right now with the 300gr scenar...
I'm using 93.5grs right now with the 300gr scenar...
Re: 338 LM with Retumbo
Cira,
You asked what our loads were and you got a few answers....is there an exact load that shoots great in all .338LMs? Who knows? Thats why we reload....to find out.
A simple thanks would have been better than a smart ass reply.
Cira,
You asked what our loads were and you got a few answers....is there an exact load that shoots great in all .338LMs? Who knows? Thats why we reload....to find out.
A simple thanks would have been better than a smart ass reply.
Re: 338 LM with Retumbo
The Sierra book lists loads for Retumbo with 215 grain bullets and 250 grain bullets, but not for 300 grainers. Now I'm not saying Retumbo won't work, I'm just saying that it isn't listed under 300 grain bullet. Sierra's "Accuracy Load" is listed as IMR-4350 with 78.2 grains. I was actually going to do load development with it this morning, but the local bridge is out, so hopefully on Friday.
myerfire
The Sierra book lists loads for Retumbo with 215 grain bullets and 250 grain bullets, but not for 300 grainers. Now I'm not saying Retumbo won't work, I'm just saying that it isn't listed under 300 grain bullet. Sierra's "Accuracy Load" is listed as IMR-4350 with 78.2 grains. I was actually going to do load development with it this morning, but the local bridge is out, so hopefully on Friday.
myerfire
Re: 338 LM with Retumbo
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: PGS</div><div class="ubbcode-body">Cira,
You asked what our loads were and you got a few answers....is there an exact load that shoots great in all .338LMs? Who knows? Thats why we reload....to find out.
A simple thanks would have been better than a smart ass reply.
</div></div>
I'm very sorry, I think you misunderstood. I wasn't trying to be a smart ass. I had a little smiley at the end hoping it wouldn't come off that way. I understand load development and the work that goes into it. I was simply trying to narrow down my work up zone and save myself some time and money. But, as you say, loads and guns are so different that it's hard to do. My comment was more along that line, that there's no cutting corners in load development.
Thanks for all the helpful replys so far.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: PGS</div><div class="ubbcode-body">Cira,
You asked what our loads were and you got a few answers....is there an exact load that shoots great in all .338LMs? Who knows? Thats why we reload....to find out.
A simple thanks would have been better than a smart ass reply.
</div></div>
I'm very sorry, I think you misunderstood. I wasn't trying to be a smart ass. I had a little smiley at the end hoping it wouldn't come off that way. I understand load development and the work that goes into it. I was simply trying to narrow down my work up zone and save myself some time and money. But, as you say, loads and guns are so different that it's hard to do. My comment was more along that line, that there's no cutting corners in load development.
Thanks for all the helpful replys so far.
Re: 338 LM with Retumbo
Didnt see the smiley...sorry.
Looking back into my reloading log for my .338LM I went as high as 97.5grs but started getting stiff bolt lift as it got into spring and summer so I ended up at 93.5grs...velocity is still right at 2800fps with e.s. around 15 and sometimes even lower. Plus I have good easy bolt lift and no flat primers keeping my brass nice and healthy. Have shot this load out to 1600 meters with great results.
I would feel safe starting at 91 or 92.
Good luck and let us know how it works out.
Didnt see the smiley...sorry.
Looking back into my reloading log for my .338LM I went as high as 97.5grs but started getting stiff bolt lift as it got into spring and summer so I ended up at 93.5grs...velocity is still right at 2800fps with e.s. around 15 and sometimes even lower. Plus I have good easy bolt lift and no flat primers keeping my brass nice and healthy. Have shot this load out to 1600 meters with great results.
I would feel safe starting at 91 or 92.
Good luck and let us know how it works out.
Re: 338 LM with Retumbo
Just as a side note, I would go with a larger spread between loads for initial testing. .3 grains is not much.
Good luck,
myerfire
Just as a side note, I would go with a larger spread between loads for initial testing. .3 grains is not much.
Good luck,
myerfire
Re: 338 LM with Retumbo
I started working this up and I would like to ask for a little more advice. I went with the following loads.
300gr Sierra MK seated at 3.68
Lapua Brass
Fed Large Rifle Magnum Match primers
Retumbo
90
90.5
91
91.5
92
92.5
93
93.5
94
94.5
Everything over 91 started showing signs of the firing pin hole in the bolt face on the primers (primer flowing into the hole). No sticky bolt. Ultimately, they all grouped like crap. Best group I could get was .98 MOA with the 93.5 load. (I've got my 308 load shooting a pretty consistant .3-.5 so I hope it's not me.
I got a chance to measure my chamber and it's 3.76 so I was thinking of trying a 3.74 seating (which still fits my magazine).
With enlarging the case empty space by seating longer, I should reduce the charges, correct? Is there a rule of thumb for how much based on the precentage or something?
Any advice would be appreciated on what load weights and seat depth to try next.
The other piece of info is that this is a fairly new gun and the brass I used was first time. Maybe just try the same loads again?
I'm lost
I started working this up and I would like to ask for a little more advice. I went with the following loads.
300gr Sierra MK seated at 3.68
Lapua Brass
Fed Large Rifle Magnum Match primers
Retumbo
90
90.5
91
91.5
92
92.5
93
93.5
94
94.5
Everything over 91 started showing signs of the firing pin hole in the bolt face on the primers (primer flowing into the hole). No sticky bolt. Ultimately, they all grouped like crap. Best group I could get was .98 MOA with the 93.5 load. (I've got my 308 load shooting a pretty consistant .3-.5 so I hope it's not me.
I got a chance to measure my chamber and it's 3.76 so I was thinking of trying a 3.74 seating (which still fits my magazine).
With enlarging the case empty space by seating longer, I should reduce the charges, correct? Is there a rule of thumb for how much based on the precentage or something?
Any advice would be appreciated on what load weights and seat depth to try next.
The other piece of info is that this is a fairly new gun and the brass I used was first time. Maybe just try the same loads again?
I'm lost
Re: 338 LM with Retumbo
You can certainly take your best group from the list, 93.5 grains and play around with the COAL. In general, closer to the lands should be more accurate, but in reality, it doesn't always work that way. I would try various OALs and see if you can improve the groupings. I would recommend going down/up by increment of 0.025". Good luck
You can certainly take your best group from the list, 93.5 grains and play around with the COAL. In general, closer to the lands should be more accurate, but in reality, it doesn't always work that way. I would try various OALs and see if you can improve the groupings. I would recommend going down/up by increment of 0.025". Good luck
Re: 338 LM with Retumbo
How far are you shooting? It seems that sometimes these Lap-mags don't really stabilize til 300-400 yds. I believe the flow around the firing pin might be a factor of the size of the hole in the bolt rather then pressure. If you have no other signs soldier on. .5 grain is just over a 1/2% increase,very small increment on initial load development. On this size case I use 1 gr. for initial work.
How far are you shooting? It seems that sometimes these Lap-mags don't really stabilize til 300-400 yds. I believe the flow around the firing pin might be a factor of the size of the hole in the bolt rather then pressure. If you have no other signs soldier on. .5 grain is just over a 1/2% increase,very small increment on initial load development. On this size case I use 1 gr. for initial work.
Re: 338 LM with Retumbo
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pimpgun</div><div class="ubbcode-body">How far are you shooting? It seems that sometimes these Lap-mags don't really stabilize til 300-400 yds. I believe the flow around the firing pin might be a factor of the size of the hole in the bolt rather then pressure. If you have no other signs soldier on. .5 grain is just over a 1/2% increase,very small increment on initial load development. On this size case I use 1 gr. for initial work. </div></div>
I was only shooting at 100 yards.
So how does this sound for a Saturday at the range?
All 93.5 grains:
5x 3.68 COAL - Shoot them at 100 yards
5x 3.68 COAL - Shoot them at 300 yards
5x 3.71 COAL - Shoot them at 100 yards
5x 3.71 COAL - Shoot them at 300 yards
5x 3.74 COAL - Shoot them at 100 yards
5x 3.74 COAL - Shoot them at 300 yards
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pimpgun</div><div class="ubbcode-body">How far are you shooting? It seems that sometimes these Lap-mags don't really stabilize til 300-400 yds. I believe the flow around the firing pin might be a factor of the size of the hole in the bolt rather then pressure. If you have no other signs soldier on. .5 grain is just over a 1/2% increase,very small increment on initial load development. On this size case I use 1 gr. for initial work. </div></div>
I was only shooting at 100 yards.
So how does this sound for a Saturday at the range?
All 93.5 grains:
5x 3.68 COAL - Shoot them at 100 yards
5x 3.68 COAL - Shoot them at 300 yards
5x 3.71 COAL - Shoot them at 100 yards
5x 3.71 COAL - Shoot them at 300 yards
5x 3.74 COAL - Shoot them at 100 yards
5x 3.74 COAL - Shoot them at 300 yards
Re: 338 LM with Retumbo
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cira</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pimpgun</div><div class="ubbcode-body">How far are you shooting? It seems that sometimes these Lap-mags don't really stabilize til 300-400 yds. I believe the flow around the firing pin might be a factor of the size of the hole in the bolt rather then pressure. If you have no other signs soldier on. .5 grain is just over a 1/2% increase,very small increment on initial load development. On this size case I use 1 gr. for initial work. </div></div>
I was only shooting at 100 yards.
So how does this sound for a Saturday at the range?
All 93.5 grains:
5x 3.68 COAL - Shoot them at 100 yards
5x 3.68 COAL - Shoot them at 300 yards
5x 3.71 COAL - Shoot them at 100 yards
5x 3.71 COAL - Shoot them at 300 yards
5x 3.74 COAL - Shoot them at 100 yards
5x 3.74 COAL - Shoot them at 300 yards
</div></div>
Now you are talking.... Good luck at the range.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cira</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pimpgun</div><div class="ubbcode-body">How far are you shooting? It seems that sometimes these Lap-mags don't really stabilize til 300-400 yds. I believe the flow around the firing pin might be a factor of the size of the hole in the bolt rather then pressure. If you have no other signs soldier on. .5 grain is just over a 1/2% increase,very small increment on initial load development. On this size case I use 1 gr. for initial work. </div></div>
I was only shooting at 100 yards.
So how does this sound for a Saturday at the range?
All 93.5 grains:
5x 3.68 COAL - Shoot them at 100 yards
5x 3.68 COAL - Shoot them at 300 yards
5x 3.71 COAL - Shoot them at 100 yards
5x 3.71 COAL - Shoot them at 300 yards
5x 3.74 COAL - Shoot them at 100 yards
5x 3.74 COAL - Shoot them at 300 yards
</div></div>
Now you are talking.... Good luck at the range.
Re: 338 LM with Retumbo
Your call, any rounds sent down range using good technique are good rounds on a new rifle. Personally I only shoot 100 in passing. If it won't shoot at 400+ I have no time for it.
The down side to the LM is very soon most ranges loose interest. Shooting under 600-800yds. gets boring. !000+interesting,1200-1600 Yesssss. As one of the more experienced shooters said " taking up crack or heroin would have been a lot cheaper than long range shooting"
Best of luck on the new adventure!
I just reread prior posts, no one has asked the question. What twist is your barrel?
1:12 may not stabilize the 300"s. Have you done any load work using 250"s?
Your call, any rounds sent down range using good technique are good rounds on a new rifle. Personally I only shoot 100 in passing. If it won't shoot at 400+ I have no time for it.
The down side to the LM is very soon most ranges loose interest. Shooting under 600-800yds. gets boring. !000+interesting,1200-1600 Yesssss. As one of the more experienced shooters said " taking up crack or heroin would have been a lot cheaper than long range shooting"
Best of luck on the new adventure!
I just reread prior posts, no one has asked the question. What twist is your barrel?
1:12 may not stabilize the 300"s. Have you done any load work using 250"s?
Re: 338 LM with Retumbo
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pimpgun</div><div class="ubbcode-body">Your call, any rounds sent down range using good technique are good rounds on a new rifle. Personally I only shoot 100 in passing. If it won't shoot at 400+ I have no time for it.
The down side to the LM is very soon most ranges loose interest. Shooting under 600-800yds. gets boring. !000+interesting,1200-1600 Yesssss. As one of the more experienced shooters said " taking up crack or heroin would have been a lot cheaper than long range shooting"
Best of luck on the new adventure!
I just reread prior posts, no one has asked the question. What twist is your barrel?
1:12 may not stabilize the 300"s. Have you done any load work using 250"s? </div></div>
My 338 LM barrel is 1:10 which should be fine.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pimpgun</div><div class="ubbcode-body">Your call, any rounds sent down range using good technique are good rounds on a new rifle. Personally I only shoot 100 in passing. If it won't shoot at 400+ I have no time for it.
The down side to the LM is very soon most ranges loose interest. Shooting under 600-800yds. gets boring. !000+interesting,1200-1600 Yesssss. As one of the more experienced shooters said " taking up crack or heroin would have been a lot cheaper than long range shooting"
Best of luck on the new adventure!
I just reread prior posts, no one has asked the question. What twist is your barrel?
1:12 may not stabilize the 300"s. Have you done any load work using 250"s? </div></div>
My 338 LM barrel is 1:10 which should be fine.
Re: 338 LM with Retumbo
Update...after this weekend's shoot
It turned out to be seating. Same results with the 3.68 seating. The 3.68 seating would put like 3 touching then 2 others touching but off 3/4-1" off. The 3.74 seating (.02 off the lands) was perfect. Best group was .388 MOA. So it wasn't the charge, the distance or the twist.
So my load is 93.5 Retumbo with 300gr SMKs seated to 3.74.
I also chronoed it at 2640 out of a 26" barrel. That was a little less than expected considering the comment above about the same load at 2800 fps. Anyone have an opinion on that?
Update...after this weekend's shoot
It turned out to be seating. Same results with the 3.68 seating. The 3.68 seating would put like 3 touching then 2 others touching but off 3/4-1" off. The 3.74 seating (.02 off the lands) was perfect. Best group was .388 MOA. So it wasn't the charge, the distance or the twist.
So my load is 93.5 Retumbo with 300gr SMKs seated to 3.74.
I also chronoed it at 2640 out of a 26" barrel. That was a little less than expected considering the comment above about the same load at 2800 fps. Anyone have an opinion on that?
Re: 338 LM with Retumbo
Cira the first thing i do when i start loading for a new gun is find out its max. Like going up a grain at a time untill you get to 93 or 94 and go .5 at a time after that. Some barrels wont create the pressure you need right away to get close to those velocities. So I check the cases for a couple signs of pressure. I measure the case head and when you start to get about .004 growth i would say your close to max. Then i start about 1-2 grains under that and down for development. What deserthk was saying .025 will start to get you close but the jump can change how well it shoots real fast. I look for the lowest SD and start to change the jump or jam from their. I dont usually go more then .005 at a time. Then i will fiddle around a little by going .5 or .3 both ways and using that good seating depth you found. Just remember the throat will change after the first few hundred rounds and then you gonna have to do more fiddling after that. After the first few hundred rounds it will calm down and you can usually just chase it after that. My new BR gun this year had no rounds at the start and after the 200 i shoot all year just in the comps and it has 500 through it... it can rack up quick.
Cira the first thing i do when i start loading for a new gun is find out its max. Like going up a grain at a time untill you get to 93 or 94 and go .5 at a time after that. Some barrels wont create the pressure you need right away to get close to those velocities. So I check the cases for a couple signs of pressure. I measure the case head and when you start to get about .004 growth i would say your close to max. Then i start about 1-2 grains under that and down for development. What deserthk was saying .025 will start to get you close but the jump can change how well it shoots real fast. I look for the lowest SD and start to change the jump or jam from their. I dont usually go more then .005 at a time. Then i will fiddle around a little by going .5 or .3 both ways and using that good seating depth you found. Just remember the throat will change after the first few hundred rounds and then you gonna have to do more fiddling after that. After the first few hundred rounds it will calm down and you can usually just chase it after that. My new BR gun this year had no rounds at the start and after the 200 i shoot all year just in the comps and it has 500 through it... it can rack up quick.
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