My latest project for custom load work up is a custom 7 Rem Mag, Big Horn Action, custom stock with carbon fiber barrel pushing the 180 grain Berger VLD-Hunting bullets. The barrel is threaded for a suppressor, but my customer is still waiting on his can. So, I completed the load work up with my suppressor on his rifle. When doing a load work up and the rifle will be shot suppressed, the loads need to be worked up suppressed, so mine will fill the need just fine. Since this is a precision rifle, I want to test for groups at 200 yards with 2" shoot N see's.

First trip to the range last week and the first load tested, Load A (middle group) running 2764 avg fps and 12 ES (extreme spread). Right out of the gate, it shot a 3/4" group at 200 yards. What a first group!!! I knew we had a good rifle right off. I just needed to pick up the speed a little bit with the 180 grain VLD-H. Load B, C, D, and E didn't impress, and I knew I needed more speed to be in the 2900-2950 fps range for the next accuracy node. Fast forward to today- range trip #2 (see below).



Second outing today 4/6- since the groups weren't that impressive for Loads B, C, D, and E, I went ahead and put 2 wet patches down the barrel before I shot, followed by multiple dry patches to dry it out. First group, Load F, had a clean, cold bore shot (CCB) labeled top left. After the first shot, the next 4 shot right at 1" at 200 yards at 2890 fps and 23 ES (all 5 shots). Not bad at all. Let the barrel cool 15 minutes, and shoot Load G. Load G stacks them in there, sub 1" at 200 yards!!! 4 rounds in this groups with 2913 fps avg and 36 ES. That's what I was looking for! Loads H and I open up. I think Load G is our load! Load A would work well also, but I think we'll take the extra 149 fps and keep the good groups.




While I was letting the 7 Mag cool, for poops and giggles, I shot some of my 308 Winchester BULK 168 A-max ammo out to 700. I started at 600, and made 8 shots. First cold bore shot was just right off the plate. I made my wind correction and sent 7 rounds down range. 4.5 mils come-up and .6 mil wind hold. The first 6 rounds went into a nice cluster low right on the plate. The 7th and last round, the wind pushed me left. The first 6 rounds is in about a 5" group at 600 yards (plate is 2 moa at 600, so 12"). Not bad at all for $0.82 a round! I plinked with it out to 700 yards tagging the 1 moa and 2 moa plates there also (5.8 mils come-up). This ammo runs 2690 fps in my Surgeon rifle. This is the ammo I plink with the most in my 308. It's a lot of fun to shoot! And at $0.82 a round, it's easy on the wallet!

That sir, is some mighty fine shooting.

Wow that's incredible at that distance, well done sir!

Very nice and informative.

Thanks for taking us through the shot testing. This is very cool.

Can you educate me on what ES means?

Yes it is. Excellent.

Sure. ES is the extreme spread from the fastest to the slowest round in the shot string. For example, Load A shot very tight, and had a 12 fps extreme spread on all 4 shots. So there is only a 12 fps difference from the fastest to slowest all 4 rounds, which is VERY consistent. If you look at Load G, there is a 36 ES. I like to see about 20-25 fps ES. I didn't look at each shot on the chronograph on this group to see if one round caused the higher than normal ES. Most likely one round was higher or lower than the other 3. But the group being tight and knowing I needed to get the speeds in the 2900-2950 area for the next node was my goal. You can see all groups tested are in the 20's or less ES, except Load G, which may have an outlier round.

When you have a precision rifle with high end scope that is capable of very tight groups at long ranges, you want to feed the rifle good ammo that is tuned to the gun and is loaded in a manner that allows for tight tolerances. When loading my match grade ammo, I am throwing the powder charges accurate to .02 grains, which is to the kernel of powder (see video below). This keeps the ammo very consistent and provides a low ES. When you shoot at longer ranges, 600 yards +, and your ammo has a high ES, you will begin to see vertical groups. The vertical groups are simply due to different speeds of each round and one going faster than the other, causing a high or low impact (vertical groups). Having a tight ES allows the ammo to be consistent enough to be spot on target at longer ranges.

Here's a YouTube video I made to show the tight tolerances of my scales. All my match and hunting ammo is loaded single stage weighing the powder out to .02 grains. My BULK and 300 blk out ammo is not loaded this way, which are done on progressive presses.

Thank you, guys! And gal!!!

Also, here is a picture of my typical set up at the range. The first berm is at 100 yards used for zero'ing and getting on target. The second berm to the right is the 200 yard berm where I do most of my group shooting. The orange square object is my Lab Radar chronograph, which tells me the bullet speed on each shot. It is the coolest tool I own. It is a Doppler Radar chronograph, like they use for weather and long range tracking of bullets. It picks up the bullet about 4-8 feet in front of the muzzle.

Wow, very cool!

thanks for sharing

Meh.

Thanks for explaining that! Awesome work.

You're welcome!!

Good read, Chad. Had no idea of the science behind your work; very cool.

I am still trying to get through an early run of your 168 A-Maxes and am very happy with their performance in the field.

WOW - what a chronograph! Where do you get those & I assume they are a little more costly than a Chrony!

I've read & studied benchrest shooters a lot trying to unlock some of their secrets on how they shoot almost unmeasurable groups at 100 to 200yds. Many weigh but many more claim that powder volume is more important than powder weight. Of course the two are related & weight predicts the volume. Also, it seems most have very little concern about velocity ES. Your explanation make perfect sense especially how it would be more obvious & thus more important in long range shooting. Thanks for a very informative post - very interesting!