In my previous post, I mentioned an article from the Berger website regarding how to get the best accuracy from a Berger VLD. I decided to give it a shot (pun intended) since I wasn't having any success with them thus far. Basically the idea is to start at the maximum COAL (cartridge overall length) also referred to as JAM (because the bullet is jammed into the lands) and work backward from there in .040" increments. Here is the link to that article: http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
This blog covers two range sessions.
Based on the article, I loaded up 3 loads for my 300 win mag. The article shows 4 but I already had data on one of the lengths so I didn't need to do that one again. Also I deviated from the article in that instead of doing two 3 shot groups, I did one 5 shot group for each load.
DISCLAIMER/WARNING FOR NEW RELOADERS: This load data should be worked up to and is for ONE particular rifle (mine). If you try this load in your gun, it may not feed and worse, it may feed but blow up your rifle causing injury or death. Be very carefull when extending your Cartridge Length over the reloading book published values as there can be dangerously huge increases in pressure.
Here are the COALS I loaded.
Group A. 3.596 (JAM)
Group B. 3.556 (.040 JUMP)
Group C. 3.466 (.120 JUMP)
I previously had tried some loads at around 3.500 so I excluded the 3.510" load.
All loads were same minus COAL:
Bullet: Berger 190VLD
Powder: H1000 78gr
Primer: CCI #250
Brass: Full length resized federal. 300 WM
First Range Session
All groups were fired at 200 yards. I setup 3 targets and alternated shots between the 3 targets. In other words, I fired one bullet from group A at target 1, then fired 1 bullet from group B at target 2, etc. This is to ensure that there is a fair accuracy comparison between the three loads. It also rules out changes in temperature of the barrel and external conditions (weather).
Group A: 3" group Avg 2970FPS.
Group B: 1.625" group Avg 2960FPS.
Group C: 4" group Avg 2950FPS.
Two things I noted, one which I didn't expect. The velocity went down slightly as the COAL was decreased. I expected the opposite to happen. I will have to read up on this a bit. The second was the drastic difference in accuracy between Group B & C. I was very happy with group B as it was roughly .8 MOA and a good starting point.
2nd Range Session
Working off of the best group from the previous session and with basically the same load I came up with these lengths to test:
Group A. 3.545 COAL (.051 JUMP)
Group B. 3.550 COAL (.046 JUMP)
Group C. 3.560 COAL (.036 JUMP)
Group D. 3.567 COAL (.029 JUMP)
Group A. 2.3" group (5 shots @200yards)
Group B. 1.25" group (5 shots @200yards)
Group C. 2.15" group (5 shots @200yards)
Group D. 2.0" group (5 shots @200yards)
I am very pleased with 1.25" group at 200yards. I don't see the need for any more expirementation at this point. All that is left for me to do is "prove" the load. What I mean by this is that I need to shoot a bunch more of this load to see what the actual accuracy average is. I do this by shooting a few 10 shot groups. I find a 10 shot group is much more telling about the accuracy of a load than a 5 shot group. Several 10 shot groups provide really good proof that the load is as accurate as I claim and not just a fluke or stroke of luck.