Introduction and set up notes for DTA HTI in 375 CT with NF ATACR MOAR, Spuhr, LRA bipod

[secondofangle]

I have been lurking for 5 years now but have posted very little. I recently had the good fortune to shoot with some guys from DTA and came back and immediately sold my McMillan Tac-50 and got a DTA HTI in 375 CT. The purpose is just to satisfy my dilettante interest in long range shooting and maybe kill a deer at LR or ELR at some point - ans shoot at groundhogs in the meantime. I will post some notes and photos below for others setting up the same equipment. I got the HTI chassis and NF scope and LRA bipod all from Eurooptic. I like those guys. Other than the "adult over 21 years or older present at the delivery address for signature" requirement that had me traipsing all over town chasing the UPS truck tonight to get the scope, that was a great transaction.

The DTA is AWESOME, and the wife even agrees. So much more managable than the BigMac. At 5'8", I can stand holding the rifle muzzle down with arm extended and the barrel does not touch the ground. It's balanced and wonderful. AND, unlike the BigMac, I can check it in a case and not be over 50# without removing the bolt or the bipod or buttstock or something. AND, I can get a 50 BMG conversion if I want to go back to the ultimate hard hitter. (I also have a Barrett 82A1 to play with for kicks for now.)

At the advice of members on the Hide and ar15.com and longrangehunting.com, I chose the Spuhr base/rings in High (1.48" IIRC), 34 mm and 44 MOA cant. Worried that it would not be tall enough, I tried to order the ultra high (1.89") but mile high shooting said they have not yet received their first shipment, and Midway let me order it but sent me the High (Part number 4802) instead of what I ordered (Ultra high, part number 4804), so I had to send it back and they also don't have 4804 yet it appears - inventory error.

The NF ATACR with MOAR reticle JUST BARELY fits. I can run about 6 sheets of paper between the sunshade and the rail, but not more. This is fine, and is good for cheek weld, but does not allow any sort of lens cover to be affixed to the scope. This is with the scope back as far in the mount as I could mount it, see photos. I won't comment on the scope more until I use it in daylight, but to be honest I'm an old school MOA SFP guy and a NF fanboy, so my opinions shouldn't carry much weight around here anyway, if my reading of most posts is any guide.

The leveling device that comes with the Spuhr mount is indeed helpful, if only to prevent the scope from rotating while you're tightening the rings. (GOD is that frustrating!) I confirmed leveling with independent levels on the top rail and a plumb line 25 yards out in the garage. (Wife not happy that this project took place on the kitchen table.) I used red locktite on all the screws and torqued the ring screws to 20 inch pounds and the cross bolts to 5.25 NM.

I'm a huge fan of the Spuhr mount so far. Seems totally awesome. But, as others have noted, the level is not visible when in the shooting position with cheek weld, so I may end up adding a scope tube mounted level at a later time if this remains an issue on the range and in the field.

The LRA bipod is also well made and bombproof, but I wish it canted right and left further and that you could apply tension to make canting under tension but not totally locked down (and that it was not $450). If this is an issue in the field, I'll try an Atlas next.

I adjusted the trigger to the minimum travel and pull weight. I'm accustomed to Jewell triggers. This trigger is very nice, but it's no "jewel". It is similar to the Timney on the Tac-50 which was set at 3.5# (impossible to adjust mine lower) and had minimal creep and travel. At the lowest setting on the DTA HTI, my RCBS (junk) trigger pull gauge measures exactly 3#. But it feels fine, and I accepted the bullpup trigger when I got this, so it's GTG as far as I'm concerned so far.

After I set the scope up leveled and with proper eye relief, I did a manual bore sighting at 25 yards. If that is close at a 100 yard zero, I will have 91 MOA elevation travel remaining to work with in the scope. Add 20 MOA for holdover with the MOAR reticle at full power, and 40 MOA at 12.5 power (and I guess 80 MOA at 6.25x if my math serves me) and I can easily get to 3000 yards with a 350 grain projectile with BC 0.80 and a nominal 3100 FPS.

Now, don't think that that is my intention - hey, I'm just a newbie plinker! But if you WERE "shooting for" 3000+ yards, this setup could get you there and beyond. (Incidentally, my Ballistic program for iPad maxes out at 3000 yards.)

I got some ammo from DTA (DTM). The 352 grain copper solid that supposedly goes 3080 with BC 0.89 IIRC in the Brass that starts with B, I forget. I also got some ammo from CheyTac, 350 SMKs in Jamison brass. In the next few days I will test those loads on the range and chrono them. Locally I have only 800 yards to work with and there's a wind advisory up to 60 MPH for the next 48 hours so we'll have to see. When I have useful results to report, I'll follow up on this thread.

Thanks guys for being such a great source of information the past few years!

~SOA

PS - being a newb, I can't figure out how to post the pics from photobucket.....help solicited....

 

[secondofangle]

LRA bipod: "Lock it, then you Cant no More..." and other DTA HTI stories

DTA_zps6ce12ea3.jpg Photo by secondofangle | Photobucket

So I went to the range the other day and tested this rig and made the following observations:

Accuracy with 350 SMK from Cheytac was 1/2 MOA right away as I had hoped. I did not group the 352 solids loaded by DTA/DTM. Both were registering on my chrono out about 12 feet at 5500 feet elevation and 35 degrees at 3100, but they were on the 800 yard gong at 12 MOA, so I'm thinking 3200 FPS is the actual velocity.....or other factors are off and I'm using a velocity correction.

Recoil is downright pleasant. I would compare it to my 17# braked 300 RUM with A5 stock. It's nothing compared to 50 BMG (I've shot the HTI in 50 and it was NOT pleasant.)

BUT, the recoil rattled loose the picatinny rails to which the LRA bipod is attached, so I had to tighten that. Also, the trigger fell off. No kidding. I had to reinstall and tighten down the side screw which in the manual on page 27 it says is for pull weight but I'm almost sure it's for overtravel. I had previously adjusted the trigger and put 15-20 inch pounds on the side screw, but maybe that was not enough. The trigger shoe is alloy and attaches via a slot to the mechanism above via that one 2.5mm allen head screw on the right side of the trigger shoe.

When I got home, I locktited all the trigger screws and all the picatinny rails with red locktite. Hopefully problem solved. (I also talked to DTA and they were very helpful and offered to look at the rifle if I brought it in, but being a holiday week and with an upcoming hunting trip, I declined - unless it happens again!)

The trigger is good. It is set at 40 oz, which is about as low as I can get it without unscrewing the rear screw so much that I'm worried it will work out. It's no jewell trigger, but I'm satisfied with it.

The NF ATACAR lived up to my expectations and is clear and bright and wonderful, but then, I've always thought the same of my NXS scopes too. My spotter is a Swaro ATX 95mm, and I could see through the ATACAR on 25 X about as well as I could see through the swaro on similar magnification.

It took 3 shots to zero the scope and after I did, I found that I have actually 105 MOA of elevation travel. Add 20 to that for holdover on high, and 40 MOA to that for holdover on 12.5 MOA and I can dial at least to well over 3000 yards under a variety of altitude, temperature, BC, and velocity assumptions.

The scope, which I leveled with the Spuhr mount and level and also independent levels on the rail and a plumb bob in the garage AND a horizontal level in the garage, tracked straight up 20 MOA to 20.94" on my leveled target at 100 yards. I would have gone higher, but it was cold, I was out of target, and rounds cost $6.40 each so I wasn't about to go overboard with vertical testing.

The only thing I'm not sure about is the best bipod for this rig. The LRA is very solid and I "like" it aesthetically and in terms of construction, but there are 2 real world problems. #1 is that I do NOT like the "lock it and then cant no more". I like canting under tension. I just do. SO I found myself monkeying with the locking lever a lot and it's a short rifle but that lever is still a reach and I could easily imagine being VERY frustrated in a hunting or tactical situation having to mess with that lever to level for a shot.

#2, and perhaps more important is that the LRA is not very tall. Combined with the bullpup design, in which the butt end of the gun is elevated such that the gun is almost level when unsupported and with the monopod fully retracted, it makes it VERY difficult to make inclined shots, such as at the 800 yard gong which is about 200 feet higher than the benches at the range. I had to fully extend the LRA legs and then place them on sandbags which sucked and required adjustment after each shot as the sandbags were sinking under the bipod legs. I don't know how to solve this problem in the future other than take a 2x6 (or 4x6) with me to the range - but again, this poses serious problems for the tactical shooter or hunter who wants to shoot up an incline.

I think this setup requires a higher bipod, but I don't know what that is. I just received an Atlas bipod today (3" leg extensions on the way), but honestly I don't think it's enough bipod for this rig (it's actually shorter than the LRA when installed, and the legs extended are a bit wobbly even without the leg extensions. I'm gonna keep the Atlas for an AR platform in 308 to which it seems perfectly suited.) I just think I need something a bit bigger or sturdier for this rifle which is I'm guessing weighs about 24# with the bipod, Spuhr, scope, magazine all attached (advertised weight is just under 20# IIRC.)

I'm looking at the Versapod 50 BMG bipod and the model 180-MZ-252 made for the M249 SAW (Link: 180-MZ-252 Versa-Pod® Model 252 VersaPod Bipod Rest). But they're hard to find in stock, and I can't get any good photos, reviews, or specs like the weight of the thing, which is all steel and I bet heavy. The DTA is heavy already and I don't want any more unnecessary weight. As a former McMillan TAC-50 owner, I can confidently say that the heavy duty bipod market is an unfilled niche.

I cleaned the rifle in the usual fashion, but with no bore guide (I used my hand and a rag as a crude one) because DTA HTI guides are not in stock anywhere, and possom hollow and the likes do not yet appear to make one for 375CT.

Next week I'm going out for a long range hunting trip and I can report on some field observations after that.

Cheers!