Re: Tac Ops Delta 51
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: brinkhdlow</div><div class="ubbcode-body">Hey Keith,
While I am waiting for Mike to build the super special Delta 51 (Holly $h!t, the suspense is killing me)
, I have been using a Remington 40-X. I will start by saying great gun, but one issue I have noticed with it is my cold bore is unpredictable. I can’t figure it out. I have been monitoring it for right at 7 to 8 months. I when I got the gun I had no idea how many round went through it, but since I have had it, I have sent right at 587 rounds through the tube. When the barrel warms up it will shoot sub ½ M.O.A. groups, but getting there is a guessing game. My C.B.S. tend to land 1 to 1.5 M.O.A. at about 7’oclock from my P.O.A. about 80 percent of the time. The other 20 percent is all over at about 1 to 1.5 M.O.A. from my P.O.A. Temperature is not the factor because I have tried to duplicate each shoot as close as possible in reference to Wind, Sunlight, Elevation, Temperature and so on. Any thoughts why it would be so unpredictable?</div></div>
There are a lot of variables that can account for the shifting POI, including a "cold shooter". Do you go straight for the .308 when you get to the range? If so, try warming-up with a few dry-fire follow-throughs before you go hot. Get behind the rifle, focus the scope on your target, and concentrate on the target as you squeeze the trigger slowly, holding the crosshair on the exact aiming point (theorietically the POI) throughout the firing cycle. Your crosshair should remain centered on the target until after the ring from the firing pin fades.
Now, consider is that the 40X is a factory gun. As such, you shouldn't your 40X expect to shoot to the same POI between CB and WB - most rifles won't. The 40X is a nice rifle but its' still a production rifle with a factory barrel which aren't stress-relieved. Another thing is that Remington only torques the barrels to around 40 ft/lbs., and as the receiver and barrel heat-up, the change in connection dimensions, combined with the low torque on the barrel causes a POI shift. Some gunsmith torque barrels to 60 ft/lbs while some might go to 80 ft/lbs or even 100+ ft/lbs. Tac Ops uses a much higher torque - 220-280 ft/lbs depending upon the rifle.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: brinkhdlow</div><div class="ubbcode-body">Also, I was reading another thread where you were talking about your X-Ray and how consistent your P.O.I. is between your Cold Dirty Bore and your Warm Dirty Bore. Do you notice any change what so ever in the P.O.I. from Cold Dirty Bore to Warm Dirty Bore and what P.O.A. P.O.I. change (if any) have you noticed in going from one extreme environment to another, i.e. Wyoming’s 100 degree plus temps to subzero temps
Thanks
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My rifle doesn't have a shift of POI between CDB and WDB. Since I shoot at ASR most often I always zero my X-Ray 51 there. Once I have a solid 100 yard zero for the lot of ammo or load I'm shooting I am GTG at ASR. I always check my (100 yard) zero before I start shooting, and as long as I dry-fired a few times before I chamber my first round of the day my CDB shot is always dead on the money. I also know that if I chronograph that lot or load (which I always do) and make a drop chart that I will be dead-on at <span style="font-style: italic">whatever</span> distances I shoot at ASR. Also, ASR and other ranges in SoCal don't have the dramatic temperature shifts you encounter in Wyoming. I've shot in the low 50-120F range and while there is some POI shift it isn't dramatic when matching loads are shot.
Note that I clean the bore very sparingly - I just keep the chamber clean and only clean the bore when absolutely "necessary" or if I start feeling guilty because I haven't cleaned it for several hundred rounds. This is a far cry from when I first started shooting some 38 years or so ago - I used to clean to bare metal but now I just clean the chamber and leave the bore fouled. If I clean to the metal it takes my gun 10-15 or more rounds before my POI is dead-on and I'm stacking the rounds on top of each other again. Fouling the bore is a waste of ammo.
I attribute my X-Ray's consistent POI between CDB and WDB to Tac Ops methods, exacting machining, and attention-to-detail - the function of every part and how it operates in relation to the rest of the system is considered. I mentioned that depending upon the rifle, Tac Ops barrel torque is between 220-280 ft/lbs. This is possible through Tac Op's use of a special receiver-to-barrel connection. Tac Ops machines special threads for the receiver-to-barrel connection that withstand higher torque. The superior clamping and higher torque eliminates loosening and movement as the barrel and receiver heat-up. The receiver and barrel are also tempered and stress-relieved. The stress relieved, high-torque connection does not allow the gross metalurgical and dimensional changes that occur without these processes.
Keith