Thanks. Very strange it seems to me, but it is a small part and if anything was going to break, I suppose that would be it.

I will be interested to learn what Atlas says. I have never had any warranty issues with them, but the customer service requests have all been handled completely satisfactorily.

Next day, with my other ARCA-clamp Atlas. I should first state that many moons ago in some matches I struggled with inadequate Atlas bipod height. Generally it was due to downward-shooting positions, but there's a match in western Colorado where the targets are placed high on a hill. This was before I installed 11" long ARCA rails -- the bipod only attached at the front end of the stock. With ARCA rails, I can slide the bipod back towards the magwell, which increases elevation by a lot. Anyway, I bought Atlas extensions, which I found increased bipod height too much. So I cut the Atlas extensions with a hacksaw to about half length -- and that's what I've been using for a few years. However, this means the lowest setting is fairly high, and I switched from small rear bags to larger ones. Eventually to a Game Changer on its side for a rear bag, which really isn't what it's designed to be. Nevertheless, this allowed my to reduce the bags I carried for PRS-type matches.

I probably need to test again with (a) no leg extension in the Atlas bipod, (b) sliding the bipod along the ARCA rail for major elevation needs, (c) use smaller bags. One thing I do like about the longer bipod legs is a slightly more upright torso position behind the gun in prone. With my chest off the ground a bit, I don't have to cock my head back so hard to achieve the best scope sight picture.

*****
I shot everything with the 1/2 length leg extensions, with bipod at its lowest setting. Same targets, same distances. Winds were kinda like the previous day, but a bit harder to judge. Winds were generally from my right down range, but were almost always from my left at the shooting location. Both days were shot late in the afternoon, after about 5 hours with a chainsaw. 5 round groups.

Bag A. No name on it -- it was one of my first bags. Fairly small, filled with light compressible beads. I had a seamstress open it up and add a few more mid-weight, less compressible beads. A decent bag for low bipods. But haven't used it much in years. I wasn't totally comfy with it at this bipod height.
- 412 yards - 3.5" vertical & 11" horizontal. .81 MOA vert
- 465 yards - 4.5" vertical & 10" horizontal. .92 MOA vert
- 527 yards - 6.5" vertical & 12.5" horizontal. 1.18 MOA vert
- 585 yards - 8.5" vertical & 8" horizontal. 1.39 MOA vert
Not great results. I noticed that shots were beginning to land a little lower than dope. DA was good -- 8800 feet that day and my dope card was for 8500 feet. Winds weren't strong enough to have much vertical effect. Especially with a too-small or too-squishy bag, I tend to throw rounds high. This is odd.

Bag B. A small TAB bag. Mid-weight fill, bag is fairly full. I used this for a few years off and on, but found that it really wasn't adaptable to higher buttstock positions.
- 412 yards - 6" vertical & 6" horizontal. 1.39 MOA vert
- 465 yards - 7" vertical & 4" horizontal. 1.44 MOA vert
- 527 yards - 2.75" vertical & 9" horizontal. .50 MOA vert - the only group where I felt the bag was just about right.
- 585 yards - 8" vertical & 6.5" horizontal. 1.31 MOA vert
All targets needed 1/4 to 1/2 more elevation than predicted dope.

Bag C. A Wiegad square-ish forend bag. Light fill, not very compressible, filled full, 3 different thicknesses depending on orientation used.
- 412 yards - 3.5" vertical & 5" horizontal. .81 MOA vert
- 465 yards - 5" vertical & 4" horizontal. 1.03 MOA vert -- I put the first four rounds in a 1.5" vertical group, then sent round #5 high. Dipshit.
- 527 yards - 7" vertical & 3" horizontal. 1.27 MOA vert
- 585 yards - 4.5" vertical & 11" horizontal. .73 MOA vert

Bag D. The cylindrical RedTac bag that worked well a week or so earlier. I may have extended the bipod legs one notch last time. I felt that this bag was a little big for the lowest setting. But I felt more consistent with this bag than with A,B,C above.
- 412 yards - 3.25" vertical & 6" horizontal. .75 MOA vert
- 465 yards - 2.75" vertical & 2.25" horizontal. .56 MOA vert Pic of the target follows.

- 527 yards - 4.5" vertical & 8" horizontal. .82 MOA vert
- 585 yards - 5.25" vertical & 8.25" horizontal. .86 vert

Notice the picture above -- it's low on the target. By the end of the day I was adding 1/2 to 3/4 MOA elevation on all targets. Possible reasons include:
- I'm an idiot, tired, or having a bad day. All possible, but low impacts aren't my normal dipshit issue.
- The scope's zero is changing. Possible, but not likely. Still, I should confirm at 100 yards.
- The barrel is losing velocity. I didn't have my chrono with me, but should check this. All Corbon ammo used for the past few weeks is from the same production lot. The Bartlein barrel now has 6,600 rounds. That's not a lot for Bubba who's blasting torso-sized targets at 100 yards, but it's beyond the expected lifetime for an F-class 308. I think I have about 200 rounds of this ammo left, then it's back to FGMM 175 or Hornady 168.

I sent the Atlas bipod for repairs, and it's supposed to be on its way back. I have not yet received an invoice, so I believe there will be no repair cost. In the meantime, I used my second Atlas ARCA bipod and I removed the leg extensions. The lowest setting is a bit too low for these targets, so I extended the legs a notch or two. First up is the non-name bag that I used for awhile, years ago. I felt more comfy with this bag with a lower bipod. I still think the bag is slightly underfilled, but it's not horrible. It was warm for October, with a relatively infrequent breeze from the east. I measured headwinds of 0-7 mph, fishtailing between 11 and 1 o'clock.

412 yards, 2-7/8" vertical and 4-1/8" horizontal. Vertical dispersion of .67 MOA. Not bad.



465 yards, 5" vertical and 5-1/2" horizontal. Vertical of 1.03 MOA. I didn't feel quite to comfy with this shooting position & target. No pic.


527 yards, 2-3/4" vertical and 4-3/4" horizontal. Vertical of .50 MOA, yeehaw.



585 yards, 4-3/4" vertical and 4-1/4" horizontal. Vertical of .78 MOA. Not bad, but I still didn't feel 100% comfy with the bag. Neverthess, I think these targets show that the no-name bag has some potential for times a smaller bag is better.

Next up was the small TAB rear bag. One of the first bags I purchased. It definitely worked better than using my fist as a support, but bags have become much better. The TAB bag is a true minimalist's rear bag.

But...it worked at 412 yards with the bipod legs collapsed. I didn't feel all that comfy, as my shoulders and head were really close to the ground. 1.5" vertical and 4" horizontal, which is just .35 MOA vertical. Another yeehaw.



The TAB bag's small size didn't do much for me on the other targets.

465 yards -- 4.5" vertical and 4" horizontal, for a .92 MOA vertical.

527 yards -- 5.5" vertical and 6" horizontal, for a 1.00 MOA vertical.

585 yards -- 6" vertical and 8" horizontal, for a .98 MOA vertical.

I really don't see using the TAB bag going forward. It's not big enough for either a rear bag, or a front bag on a barrier. Maybe to the dump, maybe to the box of "there might be a use for this thingie somewhere down the road".

Next day.. I planned to shoot with a few different rear bags, but the weather ultimately allowed only one -- the cylindrical RedTac bag. Winds started at 4-8mph, switching from my 11 to 1 o'clock. As a storm approached from the south, the winds increased with each of the 4 targets, finishing at 6-10mph from my 2-3 o'clock. And the temps dropped around 15 degrees by the last target.

I used the Atlas bipod without the leg extensions, set on the second notch. The RedTac bag was essentially at its minimal height in this setup. I still felt that my shoulders & head were a little low, but it seemed doable. The first target at 412 yards didn't go as well as planned. 5.5" vertical and 2" horizontal. I dropped the first shot 3 inches lower than the rest of the group -- ugh. I shot a 6th round and put it with the confines of the 2nd through 5th shots. Probably cold shooter, not helped by running a chainsaw all morning.

465 yards -- 2.5" vertical and 6" horizontal, which is .46 MOA vertical. That's more like it.



527 yards -- 3.75" vertical and 6" horizontal, which is .68 MOA vertical. I felt comfy with the position and the bag.



585 yards -- 1.5" vertical and 13" horizontal. The winds were getting wonky. FWIW, a 10mph crosswind produces 18 inches of bullet drift at this distance. Yep, that's an amazing 1/4 MOA vertical dispersion. I could shoot many times and not be able to repeat this "holding the waterline" so well. I felt my technique was dead on -- no reticle movement during & after breaking the shot. I was watching for impact, but I felt I could have seen bullet trace if I was looking for it. Bullet flight time was .69 seconds to the target, but it just felt like a long time. As if I'm staring at the target -- when is that thing going to impact?



I think the RedTac bag is my standard rear bag going forward. I may also keep the no-name bag handy for really low shooting positions.

This message has been edited. Last edited by: fritz,

quote:

Originally posted by sigfreund:
I will be interested to learn what Atlas says. I have never had any warranty issues with them, but the customer service requests have all been handled completely satisfactorily.

B&T repaired the Atlas bipod and sent it back to me. As their website states, no charge for repairs. The bipod looks and feels good. I tested it in the house with some dry firing. Back in business again for ARCA rail use...with a trusty original and a newer one as backup.

I also found a couple more small-ish rear bags. I'll give them a try sometime.

Good to learn about the Atlas.
And some fine shooting results—to say the least.

And now for a different type of "rear bag". I left a number of equipment items behind this day, including bags. At a shorter distance I tried a short section of a branch, which I didn't care much for. I then went with an empty Pepsi bottle, topped with a pair of leather work gloves. Not optimal, but OK for a single target. There was a fair amount of futzing around to get the elevation correct, and to not have the gloves slip off the bottle.

GAP Crusader 308, Hornady Amax 168 Black. Winds of 5-15+ mph from my 4 o'clock, I held right of the plate's 3 o'clock point. 650 yards, 11 rounds, 4.75" vertical and 10.25" horizontal dispersion. About .7 MOA vertical dispersion. This barrel has over 6800 rounds, and I'm surprised it hasn't gone tits up yet.