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My 20 Vartarg custom

600 Yard Performance - - - My notes show I shot on a practice day at the 600 yard range using my one-in-12 Hart-barrelled "live varmint" 20 VT. I used F-Class rests and target. We took turns pulling and pasting targets in the pits and I don't have the target as the targets were reused. My notes say after 2 sighters "very few 9s - about a minute of angle." This is with my 39 grain Sierra hunting bullets. Oh, and I had chronographed the load and confirmed the scope's elevation calibration, but it took 2 3/4 minutes more elevation than the ballistic tables would have predicted.
Even using the heavier 55gn Bergers, it really falls apart quickly at 600yds when the wind is changing. Yesterday's results at 500 were some of the best I've seen so far and were partly due to excellent conditions with mild and steady wind.
 
600 Yard Performance - - - My notes show I shot on a practice day at the 600 yard range using my one-in-12 Hart-barrelled "live varmint" 20 VT. I used F-Class rests and target. We took turns pulling and pasting targets in the pits and I don't have the target as the targets were reused. My notes say after 2 sighters "very few 9s - about a minute of angle." This is with my 39 grain Sierra hunting bullets. Oh, and I had chronographed the load and confirmed the scope's elevation calibration, but it took 2 3/4 minutes more elevation than the ballistic tables would have predicted.
Just curious. So last week I tried the VarTarg on Shot Marker electronic targets at 600. The Sierra program would lead one to believe there is sufficient velocity at 600 to trigger the Shot Marker. Nope. Two of 5 shots registered - 1175 fps at 600 from a load that chronographs 3450 at muzzle. If I manually input a BC of .205 the drop and velocity match what was observed.
 
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Just curiuos. So last week I tried the VarTarg on Shot Marker electronic targets at 600. The Sierra program would lead one to believe there is sufficient velocity at 600 to trigger the Shot Marker. Nope. Two of 5 shots registered - 1175 fps at 600 from a load that chronographs 3450 at muzzle. If I manually input a BC of .205 the drop and velocity match what was observed.
I've not tried the 39s or the 40 vmax at 600 but I'm not surprised that they didn't hold up that far. They do work fine at 400 yards but that is the farthest I've gone. The 55 are way more LR capable and I've shot them in a 1000 yard benchrest match with qualified success. They grouped about 18 inches on a day when the guys shooting 6mm were shooting 8-10inch groups; a rough day wind-wise.
 
20210815_20VT.jpg
Quick little update: the 20 Vartarg is still shooting excellent with no noticeable erosion in the barrel. The numbers in this picture are seating depths. The blue, 2.608" seating depth (comparator installed, but not zeroed), would have been a stunning 0.75" group at 450yards had I not jumped the flag and broke the shot with the wind blowing too hard. Still pretty respectable ~2" groups at 450 yards!
 
View attachment 1273543
Quick little update: the 20 Vartarg is still shooting excellent with no noticeable erosion in the barrel. The numbers in this picture are seating depths. The blue, 2.608" seating depth (comparator installed, but not zeroed), would have been a stunning 0.75" group at 450yards had I not jumped the flag and broke the shot with the wind blowing too hard. Still pretty respectable ~2" groups at 450 yards!
Nice shooting! Let's say that blue group is 3/4". Bergers :)
 
Thought I would drop in and give a little update. Target you see has my 6.5x47 on top and the little 20 Vartarg on bottom. 600 yards with strong gusty winds requiring 6 MOA left on the scope. 2.25" for the groups without one flying out. The 20 Vartarg with 55gn bergers shoots smaller in bad weather than I expect it should every time.
IMG_20220519_170546051.jpg
EDIT: Had to fix this picture - rotated and cropped!
 
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Do you have a guesstimate of speed at that distance?
I can’t get away from speed it seems. All I feed mine is 32-34 grain, I will save the 55’s for the 20BR.
 
It's 3100fps at the muzzle and probably in the ballpark of 2000fps at 600 yards. Still supersonic and stable at 1000 yards.
 
Hmmm. With a MV of 3100 f/s, and a ballistic coefficient of, oh, 0.3, a wild guess as to what the Berger would produce, The Sierra program predicts 1500 f/s at 600 and below 1000 at 1000 yards. Do you get different numbers? As a reference, my 6XC with a MV of 3000 f/s registers 2100-ish at 600 and 1600-ish at 1000 on the ShotMarker with Sierra 107 MKs. Sierra shows BCs of .5 or so for that bullet. I like what you're doing with the fast twist .20. Keep the information coming.
 
Hmmm. With a MV of 3100 f/s, and a ballistic coefficient of, oh, 0.3, a wild guess as to what the Berger would produce, The Sierra program predicts 1500 f/s at 600 and below 1000 at 1000 yards. Do you get different numbers? As a reference, my 6XC with a MV of 3000 f/s registers 2100-ish at 600 and 1600-ish at 1000 on the ShotMarker with Sierra 107 MKs. Sierra shows BCs of .5 or so for that bullet. I like what you're doing with the fast twist .20. Keep the information coming.
I'm at 5000ft. Here's JBM:
1654293267354.png
 
IMG_20220604_213625989.jpg
I looked through my notes and decided that I should revisit Benchmark, as I hadn't tried it at 600 yards. The conditions today proved tricky. Light wind around 4mph peak, but it was gusting on and off and moving from 6 o'clock to 3 quickly. At 70 degrees and sunny, it was still a very pleasant day to be shooting.

I was surprised at how wide the node was! 19.6 up to 19.8gn stayed flat and then began climbing at 19.9gn. This was cracking along, requiring 1.5MOA less on the scope compared to my H4198 load from last weekend and I think it must be in the 3250fps range although I did not have a chrono set up. Despite the wind challenges, the yellow group is pretty decent at 2.5 inches. The top 20gn load started to show high pressure. Bolt lift started to drag on my Borden which was glass-smooth for the previous loads. If you want to try these loads out proceed with extreme caution! They took a 12inch drop tube and a slow pour for me to load them comfortably without crunching.
 
As square and true as Jim's actions are, and with a small diameter case head, if you are getting bolt lift drag You're kinda hot, right? I concur that you are right to caution your readers.
 
As square and true as Jim's actions are, and with a small diameter case head, if you are getting bolt lift drag You're kinda hot, right? I concur that you are right to caution your readers.

Yes. This action has really well matched primary extraction and the chamber design handles exceptional pressure without any of the traditional brass or primer signs most people look for. Extreme pressure presents as a change in bolt lift. No primer or case signs show up until the brass extrudes into the ejector which happens way later than in any other rifle I've owned. If you forge ahead, the primer pierces and bolt lift is still manageable although it will not be possible to size that piece of brass far enough to chamber again.

I'm comfortable pushing up to the listed loads and pressures because of how strong the action is, how small the case head is, and how large the barrel shank is. The whole setup is very strong - much stronger than the exact same action and barrel with, for example, a 30BR.
 
I should also add that it takes maybe 0.3gns to go from a slightly stiffer bolt lift to piercing the primer and trashing the brass in this rifle. My chargemaster light can swing 0.2gns between charges. I wouldn't use just it, or just a powder throw. I wouldn't push this hot without an A&D or better scale. It is also important to check the capacity of each case. You don't want to play at max pressure and load a case with 0.5gn less capacity to the same level. That too will push you over the top. Tiny cases like the Vartarg are much more sensitive. It's easier and safer to back off and shoot at one of the many safer nodes, like my H4198 load that is every bit or more accurate, even at 600 yards.
 
Shot at 600 today. It was heavy overcast, humid, and mild wind. The 20 Vartarg blew me away today:
IMG_20220625_142154822.jpg
Double checked my Benchmark node from 19.6 up to 19.8, and then tried 3 different seating depths. The purple group is 1.7". Absolutely stunning. 0.35 G1 BC, 3150fps, and it is outshooting my 6.5x47 by a significant margin.
 
How many rounds do you have on the setup now? I’ve been wanting to build a 20 TAC with 9 twist specifically for that bullet. But maybe I just need another 20 VarTarg.
 
How many rounds do you have on the setup now? I’ve been wanting to build a 20 TAC with 9 twist specifically for that bullet. But maybe I just need another 20 VarTarg.

About 1600. I didn't keep records originally in a way that I can easily count it up. I was still grouping things by 50s back then. At about 400 or so rounds in, I switched to a line by line accounting of every shot in excel for this and my other rifles.
 
Went out today, despite the brutal heat. 100 degrees, dry, strong gusty wind. Challenging conditions. My goal today was to evaluate my best H4198 load against my best Benchmark load and see if the extra speed is useful:
IMG_20220710_134222957.jpg
I shot a 5-shot group of H4198 then of Benchmark, and repeated for 4 groups total. I think that it's pretty clear that the nut behind the stock is very important in challenging wind, but this test tentatively suggests that yes, the Benchmark load is better. I never cease to be utterly blown away by this mighty little 20 Vartarg.
 
Went out at 600 yards this weekend. Hot, mid 90s. Switchy wind between 8 and 12mph or so. I took the H4198 load and the Benchmark load and shot fast groups and slow groups with a more exacting aim. I shot a fast H4198, then a fast Benchmark, then a slow H4198, then a slow Benchmark, and then repeated it again. I think the results are intriguing:
IMG_20220731_145843241.jpg
I've run this test before on other rifles and it's always been pretty conclusive. Shooting fast is smaller than picking your shots. I'm not sure I can pick a favorite here. The extra speed of the Benchmark only shows up as a couple inches higher up on the target. I will likely stick with the H4198 and save my Benchmark for something else.
 
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