Todays groupr test. 300WM LRAB 190gr FAIL

Kelly Timoffee

Kelly Timoffee

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So, wind or not I was heading out, you hardly get days with no winds.

First is 7828.



Velocities...

72 2885
72.5 2930
73 2936
73.5 2993
74 3069
74.5 3123
75 3158
75.5 3162
76 3093
76.5 3095

Retumbo



73 2802
73.5 2807
74 2828
74.4 2854
75 2861
75.5 2871
76 2889
76.5 2889
77 2953
77.5 2961

Wind picked up around 7:15 , kept shooting until I was done at around 8.Shooting was done at 250 yards.Barrel cooled between shots.

Definitely piss poor results regardless of wind.
 
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Retumbo looks like it will work in the 2850 fps range

Try a faster burn rate like RL22, H4831, IMR 4955, RL19, RL23, Ramshot Hunter, StaBALL 6.5, Viht N560
 
todbartell said:
Retumbo looks like it will work in the 2850 fps range

Try a faster burn rate like RL22, H4831, IMR 4955, RL19, RL23, Ramshot Hunter, StaBALL 6.5, Viht N560
Click to expand...

What do you think about the 7828 in the 74, 74.5 , 75 gr load? 1/2 MOA vertical on that but yes, the retumbo over all looks better.

Wish we had better powder supply in these parts.

Reloader 17 is showing best accuracy on Nosler site.
 
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I would try moving up with Retumbo if you have any case room left. I am using 75 grains of Retumbo in my 308 Norma behind the 210 LRAB.
No pressure signs, 2850 fps, and sub-moa out to 400 meters. Dave.
 
Kelly Timoffee said:
What do you think about the 7828 in the 74, 74.5 , 75 gr load? 1/2 MOA vertical on that but yes, the retumbo over all looks better.

Wish we had better powder supply in these parts.

Reloader 17 is showing best accuracy on Nosler site.
Click to expand...

That 7828 narrow span could be good, speeds are looking pretty warm. Retumbo just looks like you can do no-wrong.
 
Eagleye said:
I would try moving up with Retumbo if you have any case room left. I am using 75 grains of Retumbo in my 308 Norma behind the 210 LRAB.
No pressure signs, 2850 fps, and sub-moa out to 400 meters. Dave.
Click to expand...

Thanks Dave , I actually had a 78 and a 78.5gr cases marked and ready to fill and stoped at 77.5 once I started to compress , that was at a COAL of 3.540” , these long bullets sure give challenges.Chamber is cut to 3.550” , so I’m pretty much tapped out.

I may load up a couple just to see how compressed they actually are.
 
todbartell said:
That 7828 narrow span could be good, speeds are looking pretty warm. Retumbo just looks like you can do no-wrong.
Click to expand...

I like how the 7828 velocities also seem to increment nicely 74-75gr.No pressure signs, easy extraction on every load today.

And yes, The Retumbo does look fairly forgiving, I don't mind the lower speeds as you know these projectiles will hold their giddy up pretty good down range.** I just looked back at some previous ladders , the Retumbo is half of the vertical dispersion of all the other powders.

And now that I look at it again, the retumbo velocities seems to step nicely in the 74-75gr range.

I know one shot velocities isn't very reliable and a chrony isn't infallible but I do like the incremental pattern.

I think I'll load both powders and try a few groups, if I get two powders that group then even better.
 
The 338 looks like you need to go back farther! How far is this test at?
Retumbo is good at 76.3. Load that as the middle and do .3 grains on either side to confirm a node. 76, 76.3, and 76.6 should all have the same vertical.

7828 I don't see anything if I look at the fps and target together.
 
Lead hammer said:
The 338 looks like you need to go back farther! How far is this test at?
Retumbo is good at 76.3. Load that as the middle and do .3 grains on either side to confirm a node. 76, 76.3, and 76.6 should all have the same vertical.

7828 I don't see anything if I look at the fps and target together.
Click to expand...

The 338 is plenty far enough , that was my initial ladder with the new barrel many years ago.Just putting that up as an example of a ladder test that went well.

I’m less concerned about velocity at this point and more concerned about nodes , if I see a node that is shooting Sub MOA with varying charge weights then I’d say there is something to pursue.

I take the chronograph as an extra tool.Like with this test , it’s shows an overall picture , with the retumbo it shows to me that over all speed is comparably slow for the chambering and with the 7828 that at the top end of the charge weights it’s becoming inconsistent.It will also show me if it may be time to stop at a particular charge weight if I see velocities getting too high or erratic.I’ll place more relevance on the velocities once I start doing group tests and can determine deviations.
 
Eagleye said:
FWIW, Kelly, Retumbo does not seem to mind being compressed, even quite heavily compressed loads do
not display any erratic characteristics. Dave.
Click to expand...

Thanks Dave, I have limited experience with it, only in my 338.

Here is my so called plan....

I'm going to do a few group tests with the Retumbo in 75.5 , 77.5 , and I'll probable also do 78-79 as those will be the compressed loads to see what they do.

In 7828 I'll do 74.5 and 75.

Not really scientific but I will know if the powders are working.

If it's calm I'll stay at 250 yards, if not I'll back back to 100.(250 is my intended zero for this rifle anyways)

Even though it was windy on this test I still think it shows viable options.
 
Kelly Timoffee said:
Thanks Dave, I have limited experience with it, only in my 338.

Here is my so called plan....

I'm going to do a few group tests with the Retumbo in 75.5 , 77.5 , and I'll probable also do 78-79 as those will be the compressed loads to see what they do.

In 7828 I'll do 74.5 and 75.

Not really scientific but I will know if the powders are working.

If it's calm I'll stay at 250 yards, if not I'll back back to 100.(250 is my intended zero for this rifle anyways)

Even though it was windy on this test I still think it shows viable options.
Click to expand...

You also seem to have an accuracy node at about 72.5-73 gr of IMR 7828
 
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