My 338LM seeting depth test, 300gr Scenar

[dstewart51]

Last week I found a good charge (for my loads and rifle) of VV N-570 with the 300gr Scenars to be right at 91.5gr. Pushes them down range at 2750fps and well with in safe pressure range. Ran tests up to 93gr and never saw any excessive pressure signs.

Some load info,
In my rifle I am measuring a once fired Lapua case to measure,
neck OD: .371" to .372" (new .368")
Head to shoulder: 2.191" to 2.192" (new 2.190")

So I found using the Redding Bushing "366" to give me a .365" OD that gives me close to .003" neck tension. And I have been bumping back the shoulder about .0005" to .001" to 2.191". Using the Federal Mag Match 215M primers I found I needed to use a primer pocket uniformer to get the primers to seat below flush.

Stopped off at the range this morning before work to test the effects of bullet seating depth on my Savage 110FCP, all targets @ 200y, slight breeze from the left.

So here is what I shot,
Bullet: 300gr Scenars
Case: Once Fired Lapua Brass, trim to 2.715", FL sized to 2.191", Primer Pockets uniformed
Primer: Federal 215M
Powder: VV N-570
Charge: 91.5gr
Ogive to Lands: -0.100" to -0.000"

The first shot of the -0.100" jump was low and off the target so I used my other two to sight it in. I was .5mil low. I noticed as my jump was reduced my velocity increased. I did not have my chrono out with me today so I cant say how much.

-0.075" jump = 1.125" 3 round group @ 200y

-0.050" jump = 1.5" 3 round group @ 200y (adjusted scope down .1mil for this group)

-0.030" jump = 2.0" 3 round group @ 200y (vertical stringing)

-0.020" jump = 1.5" 3 round group @ 200y

-0.015" jump = 1" 3 round group @ 200y (adjusted scope down .2mil for this group, best group of the day)

-0.010" jump = 1.25" 3 round group @ 200y

-0.005" jump = 1.75" 3 round group @ 200y

-0.000" jump = 4" 3 round group @ 200y

So I have a winner with my recipe at -0.015"! It was nice to see the groups shrink and then open back up.

 

[CanSniper]

Re: My 338LM seeting depth test, 300gr Scenar

Nice work up!! Thanks for the post.

 

[JimGnitecki]

Re: My 338LM seeting depth test, 300gr Scenar

Dstweart51: Putting tthe hyphen in front of each jump number implies a "negative" jump number = interference!

I assume you just used the hyphen as a "bullet", not as a an indicator of "negative" value for jump, right? Or, is this actually negative jump = interference (bullet into lands)?

Very nice job of testing. I have been thinking verys eriosuly of going with Vihtavuori N570, and your posting pretty much convinces me to go ahead.

The only negative I have heard is the very large kernel size, which causes Vihatvuori to caution that all N570 charges should be WEIGHED, not dispensed by a powder measure. That caution makes perfect sense - too many kernels would get "cut" in a powder measure dispensing scenario, and so would affect the burn rate.

Jim G

 

[dstewart51]

Re: My 338LM seeting depth test, 300gr Scenar

Jim, I see how "-0.015 Jump" could be viewed as a double negative. To me it makes sense, its shy of the lands or under length (-) and it has to make a jump. To me, its more of a double statement. Not sure if there is a Standard or not, its just how I do it.

Retumbo has to be weighed as well. The N570 kernels are ~.07gr and Retumbo is nearly the same. After the RCBS Chargemaster dispenses the charge I weigh it with a Redding beam scale and add or remove a kernel or two as necessary with some tweezers. Takes about as long for the Chargemaster to throw a charge as it does for me to fine tune and dump in to the shell so it doesn't add any extra time. Usually the Chargmaster is dead on, if not its only one or two kernels off.

My only complaint with N570 is, you will NEVER get a clean patch again. Almost no amount of cleaning will remove all the graphite out of the barrel. But unlike Retumbo, its graphite not carbon. The graphite helps protect the barrel and seems to minimize copper fouling as well. Does not seem to have any effect of accuracy, clean or dirty. It does leave a residue on the necks but it wipes off, also unlike Retumbo.

 

[JimGnitecki]

Re: My 338LM seeting depth test, 300gr Scenar

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dstewart51</div><div class="ubbcode-body">My only complaint with N570 is, you will NEVER get a clean patch again. Almost no amount of cleaning will remove all the graphite out of the barrel. But unlike Retumbo, its graphite not carbon. The graphite helps protect the barrel and seems to minimize copper fouling as well. Does not seem to have any effect of accuracy, clean or dirty. It does leave a residue on the necks but it wipes off, also unlike Retumbo. </div></div>

Speaking of copper fouling, IS that an issue with 338 Lapua, due to the velocity / energy combined impact? How often do you find you need to use a copper solvent?

Jim G

 

[SavageLapua]

Re: My 338LM seeting depth test, 300gr Scenar

dstewart, I was just curious as to what you did for your load testing. Did you start on the lands or give it a jump? I built all my test loads at .010" jump... Once I found a load I was going to play with seating depth from there... Thoughts?

 

[dstewart51]

Re: My 338LM seeting depth test, 300gr Scenar

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JimGnitecki</div><div class="ubbcode-body">
Speaking of copper fouling, IS that an issue with 338 Lapua, due to the velocity / energy combined impact? How often do you find you need to use a copper solvent?

Jim G</div></div>

Its more a barrel specific function. From day one, I have not noticed much copper fouling at all in my rifle. Now, between 40 rounds or so I cant detect any copper traces. Could be the barrel is just broken in or it may have something to do with the graphite powder deposits, dont know.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SavageLapua</div><div class="ubbcode-body">dstewart, I was just curious as to what you did for your load testing. Did you start on the lands or give it a jump? I built all my test loads at .010" jump... Once I found a load I was going to play with seating depth from there... Thoughts?</div></div>

Well, when I start with any new powder or combo, I will start the charge 10% low with the bullet JAMMED .010" in to the lands and work my way up in charge 1% at a time. Watching for pressure I will find what I think is a safe charge range.

Now I know a worst case max charge. Then you can run a ladder test or load up sets at various charge levels and find a node. Im this case I didnt have very good luck with the N570 and the Scenar .010" jammed running a ladder test. So I ran 3 shot groups at .020" off the lands starting with loads about 5% under what I found to be a safe max up to my safe max. Thats where I found two charges that worked very well (91.5gr and 93gr). The 91.5gr charge was pushing the bullet down range plenty fast enough for me so I centered around that charge. Loaded up 3 round sets all at 91.5gr at 0.000" (at the lands) to -0.005", -0.010", -0.015", -0.020", -0.030", -0.050", -0.075" and -0.100".

This test shows its the bullet flys well if the jump is between 50 thou and 100 thou but best accuracy is at 15 thou and still good (better then the long jump) at 10 thou off the lands. Accuracy goes to hell if its seated at the lands so they need some jump. This is only valid for my rifle and the the exact recipe above.

I had a few extra prepped cases once I was done loading what I needed for the 300gr Scenars so I loaded up some 300gr SMK's at 10 and 20 thou off the lands. They didn't group anywhere near the Scenars with the same seating depth. Given a different charge they may have been able to group just as well.

 

[JimGnitecki]

Re: My 338LM seeting depth test, 300gr Scenar

Nice data, Dstewart51 !!

Thanks for taking the time to do it and to post it!

Jim G

 

[JimGnitecki]

Re: My 338LM seeting depth test, 300gr Scenar

Dstewart51: Have you done a 250 grain bullet load as well?

Jim G

 

[dstewart51]

Re: My 338LM seeting depth test, 300gr Scenar

No, only 300gr SMK's and Scenars. If anything next is going to be Berger OTM's. With all the combinations of powders, bullet makes and weights you can burn up a barrel up just testing, then you have to test in the new barrel. Not sure I will test the 250's or not yet.

I would like to do a 5x5 with the load above and see if its a consistent sub 3/4MOA. If it is and it holds up well at distance, Im done.

Ive always been a fan a big and heavy (does not apply to women). Thats why I only carry a 45ACP with 230gr, shoot 300gr out my 44Mag, 400gr out of my 475Linebaugh and 325gr from my 45-70Gov lever gun. I like the thump

 

[JimGnitecki]

Re: My 338LM seeting depth test, 300gr Scenar

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dstewart51</div><div class="ubbcode-body">No, only 300gr SMK's and Scenars. If anything next is going to be Berger OTM's. With all the combinations of powders, bullet makes and weights you can burn up a barrel up just testing, then you have to test in the new barrel. Not sure I will test the 250's or not yet.

I would like to do a 5x5 with the load above and see if its a consistent sub 3/4MOA. If it is and it holds up well at distance, Im done.

Ive always been a fan a big and heavy (does not apply to women). Thats why I only carry a 45ACP with 230gr, shoot 300gr out my 44Mag, 400gr out of my 475Linebaugh and 325gr from my 45-70Gov lever gun. I like the thump

</div></div>

I tend to go the higher speed / lower bullet weight route. I carry a commemmorative SIG SAO all s.s. handgun in 357 SIG (125g at 1350 fps). Hits, per our TX Highway Patrol troopers, like "a bolt of lightning" and stops the aggressor right now.

I plan to try 250g Matchkings and Scenars in the 338 Lapua TRG 42. I'll have to examine the Cd differences and also the relative uniformity.

Jim G

 

[GGGN]

Re: My 338LM seeting depth test, 300gr Scenar

This is a 5 shot group shot at 500 yards. I know it looks like 3 the first two are in the same spot that iss why the pot hole is larger. Shot with 300gn hybrids 90.5 of h-1000 set to fit in mag.

This is what they look like after they hit the steal