Anyone notice this about Varget and IMR 4895?

[Nessal]

I loaded some .308 155grn A-Max with IMR 4895 in the past and at 40grn, I was getting less than half MOA at 100. Quite surprised at the results. I loaded some Varget and started the load at 40grains and worked up to 43grans. At 40grains, the grouping was COMPLETE CRAP. I noticed as I worked up the load, it tightened up considerably.

Does anyone have similar experience with using IMR 4895 and Varget?

 

[johndoe]

Re: Anyone notice this about Varget and IMR 4895?

Yes I have noticed that on some powders. Then all of a sudden
the accuracy can fall out of the bottom with a 2/10 grain increment.

 

[BobinNC]

Re: Anyone notice this about Varget and IMR 4895?

Did you start out with a clean or fouled barrel?

My procedure when developing a new load is to make 5 extra rounds with the starting load, to first foul the barrel. I pay no real attention to the grouping with those first five. Especially if my barrel was squeaky clean when I started.

Over the years I noticed that first few shots with a clean barrel almost never shot well. Even if the barrel is well fouled, when I change powder, bullets, et al, I always discount the first five, then fire for effect.

This is not a scientific analysis, and it is not powder or caliber specific, but just an observation I made over the last 38 years of reloading.

Bob

 

[JALVI]

Re: Anyone notice this about Varget and IMR 4895?

Ok. Heres my .02.

I have no clue as to what barrel length or anything for that matter, that you are running so I'm going of what info has been provided.

IMR & H4895, & Varget are two different powders, with different burn rates - 4895 being the faster of the two.

In this case, I think velocity in a given node is the issue here.

I'm going to use MY rifle as an example.

26" Bartlein, 11.25 twist,

All loads using Lapua brass, CCI BR-2 primers, and Lapua 155 Scenars, and 175 SMKs.

For <span style="font-weight: bold">175 SMK's</span> with a target velocity of <span style="font-weight: bold">2725</span> fps I was rollin a flat 44 gr of Varget.

Switch to the <span style="font-weight: bold">Lap 155</span>, with a target velocity of 2940 fps, I was rollin 44.5 gr H4895

TO ACHIEVE THE SAME VELOCITIES USING VARGET, I ROLL <span style="text-decoration: underline"><span style="font-weight: bold">46.7</span></span> GR VARGET.

Notice how your groups tightened up as you creeped up to 43 gr Varget???? Velocity.

This is just my 0.02. YMMV

 

[Nessal]

Re: Anyone notice this about Varget and IMR 4895?

I'll take a look at this again and see how it turns up. I didn't know IMR4895 has such a huge difference in burn rate than Varget. Thanks guys.