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110BA accuracy tips, and Retumbo and 300 SMK's (338 Lapua)

 
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  #1  
Old 04-14-2012, 10:49 PM
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110BA accuracy tips, and Retumbo and 300 SMK's (338 Lapua)

I shot some more 338LM today, and among other powders I tested some more Retumbo.

I have become a bit more accustomed to the Savage 110BA's idiosyncracies... what is purported to be a "state of the art" stock is not honestly to my liking, it's too "AR-ish" to suit me. But it does work, when you get used to it.

My preference is for the center of gravity on the rifle to remain as close to the bore-line as possible. With the AR type pistol grip stock, I find that the heavy rifle (it weighs about 20 pounds scoped and prepped) wants to toggle left to right, seeming top heavy, in my opinion.

This top heaviness, combined with a Harris "S" bi-pod, (which allows the rifle to rotate clockwise and counter-clockwise in the bi-pod saddle) makes it feel unstable when shooting off the bi-pod and rear bag. The rifle seemed to want to topple left or right.

I installed a bi-pod locking lever, which replaces the knurled screw that comes on the Harris S, and situated that lever to really tighten the bi-pod down. This way it doesn't swivel at all... without the pod lock, you can't really get the knurled knob tight enough to stop the rotating of the rifle.

So I would highly recommend the pod lock lever if you're using a Harris S model bi-pod.

You will also want the Harris model with the notched legs, instead of the legs that you have to tighten the knurled knob down to hold them where you want them. This rifle is too heavy for you be able to count on those legs not collapsing in, to some degree, either on recoil or as you're preparing for the shot.

I think the non-swiveling (not the S model) bi-pod with the notched legs might be the best option for the rifle.

We know that for every action there is an equal and opposite reaction. For the action of a 300 grain bullet speeding down a 9 twist .338 inch bore at 2700 fps, the reaction is for that bullet, *to some measurable degree* to turn the rifle in the direction of the twist. If you don't have the rifle stabilized against rotating (as is the case with the S bi-pod), you're going to get poor accuracy and a wandering POI. Ask me how I know... I found this out through trial and error, never having had a rifle that wanted to do this sort of thing.

But lock that bi-pod TIGHT against letting the rifle rotate and accuracy is greatly improved, and POI stays where it should.

Here is a target I shot today at 105 yards, using the OCW of 89.3 grains of Retumbo, Lapua cases, CCI 250's, at 3.690" total OAL. Cold clean bore and four follow up shots...

The CCB shot was around 2680 fps, while the next four shots were all within 5 fps of 2700 fps. This load is going to work.

Cold clean bore shot to right, other four shots in the oblong hole in box.



The Retumbo, like all the other Hodgdon extreme rated powders I've worked with, really wants maximum load density. I think the coating they use to make the powder more temperature stable also makes the charge harder to light than with conventional powders--so you need a large enough charge to make sure it can't pour forward, away from the primer flash, perhaps making ignition inconsistent.

The next higher node with this powder and bullet combo is at 92 grains, but I had flat primers and ejector swipes at that level. At 89.3, all seems well and good.

Dan
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Old 04-15-2012, 09:09 PM
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Re: 110BA accuracy tips, and Retumbo and 300 SMK's (338 Lapua)

here's the same load at 600 yards, shot today...



I think it'll do even better than this, as I was having to lay downhill, which made it necessary to extend the bi-pod legs all the way out... a little shaky, for sure... but this is right at 1/2 MOA, so I can't complain.

Primers look good, bolt lift is nice and easy... so for the Savage chamber, this node should be a winner (89.3 grains Retumbo with 300 SMK's). It makes 2700 fps from my rifle, with a very tight ES from what I've seen so far.

Dan
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Old 04-16-2012, 12:49 PM
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Location: manitoba, canada
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Re: 110BA accuracy tips, and Retumbo and 300 SMK's (338 Lapua)

hey there...

sounds like our 110BA's like to be fed the same recipe!

300 gr Sierra mk
89.2 gr retumbo
cci 250 primer
Oal 3.702"
2755 fps

I also put the pod lock on my harris and haven't looked back...

i have got some pretty good groups with it out to 1000yrds... the best was a 5 shot group between 1/4 and 1/3 MOA....

how many rounds have you put through it? if you are just getting going i bet as you get that barrel broken in it'll tighten up your groups even more...

mine started to shine after i had about 300rds down the pipe...

orch
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Old 04-16-2012, 07:51 PM
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Re: 110BA accuracy tips, and Retumbo and 300 SMK's (338 Lapua)

That's good to hear, on the break in time, that is.

I might put the bullet a little closer to the lands and see if that makes things even better.

I've got about 120 rounds down the tube as of now. Just checked for copper after the last 30 round session... barely got a trace this time. So things are looking up.

What velocity are you getting from that 89.2 Retumbo load? I'm getting right on 2700 fps...

Dan
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Old 04-16-2012, 09:01 PM
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Join Date: Jul 2011
Location: manitoba, canada
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Re: 110BA accuracy tips, and Retumbo and 300 SMK's (338 Lapua)

2755fps.....
I'm seated out about 10thou further than u are..... Assuming our chambers were cut identicle to one another so both our chambers have the same amount of free bore that could account for the extra 55fps... But I am sure there are a couple other veriables at play that could be giving me the extra 55 fps...

Definetly try playing with the seating depth now that u have found your node for powder charge... I found my sweatspot for my powder with it seated at 3.714" and was getting pretty good groups then I set the overall length down to 3.702" and the thing went from "pretty good" to awesome... Lost about 20 to 30 fps but who cares if the groups shrunk by almost 25%!

Orch
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  #6  
Old 04-16-2012, 09:08 PM
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Re: 110BA accuracy tips, and Retumbo and 300 SMK's (338 Lapua)

thanks orch... will give that OAL adjustment a try. appreciate the word...
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