4064-40gr. 168BTHP. A guess, cause the Hornady Book neglects this bullet, in 4064. Also shot Varget, at 44.7 gr. Supposed "fast" load. Over "Max", by the book. Shot 1" group, with the Varget, at 100, on the bull. Shot the 'Light" 4064 load, and it shot 2" ABOVE the bull. Same lot of prepped brass, same COL, same everything, except the charge weight and powder.. Shouldn't the lighter charge shoot below the bull?My head spins on the physics. Kept me up half the night, trying to figure it out. Help?
"Strange" range results.308
- Thread starter JoshcBoucher
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Re: "Strange" range results.308
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: joshboucher</div><div class="ubbcode-body">4064-40gr. 168BTHP. A guess, cause the Hornady Book neglects this bullet, in 4064. Also shot Varget, at 44.7 gr. Supposed "fast" load. Over "Max", by the book. Shot 1" group, with the Varget, at 100, on the bull. Shot the 'Light" 4064 load, and it shot 2" ABOVE the bull. Same lot of prepped brass, same COL, same everything, except the charge weight and powder.. Shouldn't the lighter charge shoot below the bull?My head spins on the physics. Kept me up half the night, trying to figure it out. Help? </div></div>
You neglected to factor in the burn rate but even with that factored in (they're pretty close) you should have seen the lighter charge lower on the target but a difference of 2" at 100yrds is far more than the different powder can account for especially considering you downloaded it by 4.7gr, all things being equal (as you mentioned) I'd suspect some other outside factor.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: joshboucher</div><div class="ubbcode-body">4064-40gr. 168BTHP. A guess, cause the Hornady Book neglects this bullet, in 4064. Also shot Varget, at 44.7 gr. Supposed "fast" load. Over "Max", by the book. Shot 1" group, with the Varget, at 100, on the bull. Shot the 'Light" 4064 load, and it shot 2" ABOVE the bull. Same lot of prepped brass, same COL, same everything, except the charge weight and powder.. Shouldn't the lighter charge shoot below the bull?My head spins on the physics. Kept me up half the night, trying to figure it out. Help? </div></div>
You neglected to factor in the burn rate but even with that factored in (they're pretty close) you should have seen the lighter charge lower on the target but a difference of 2" at 100yrds is far more than the different powder can account for especially considering you downloaded it by 4.7gr, all things being equal (as you mentioned) I'd suspect some other outside factor.
Re: "Strange" range results.308
100 yards isn't far enough away for you to determine "drop" differences between different loadings - unless they are WAY, WAY different in speed.
Research the concept of the OCW load development method. It's entirely possible your Varget loading has the bullet exiting the muzzle with the barrel whipping down, while the 4064 has the bullet exiting while the barrel is whipping up. Thus, even though the 4064 load maybe going 500fps slower, it may still impart the target higher by a couple MOA.
Repeat the the test at 1000 yards though, with the same bullet, and you'll CERTAINLY see the slower loading impact lower.
100 yards isn't far enough away for you to determine "drop" differences between different loadings - unless they are WAY, WAY different in speed.
Research the concept of the OCW load development method. It's entirely possible your Varget loading has the bullet exiting the muzzle with the barrel whipping down, while the 4064 has the bullet exiting while the barrel is whipping up. Thus, even though the 4064 load maybe going 500fps slower, it may still impart the target higher by a couple MOA.
Repeat the the test at 1000 yards though, with the same bullet, and you'll CERTAINLY see the slower loading impact lower.
Re: "Strange" range results.308
Maybe. Maybe barrel harmonics, maybe recoil differences...i.e., the slower load allows more barrel time so the muzzle drifts back and up while the bullet is in the barrel due to recoil forces causing the bullet to impact higher on the target.
Maybe. Maybe barrel harmonics, maybe recoil differences...i.e., the slower load allows more barrel time so the muzzle drifts back and up while the bullet is in the barrel due to recoil forces causing the bullet to impact higher on the target.
Re: "Strange" range results.308
this might be an explantion
http://www.varmintal.com/amode.htm
maybe your muzzle was "pointing down" when the bullet left the barrel with the hotter load
this might be an explantion
http://www.varmintal.com/amode.htm
maybe your muzzle was "pointing down" when the bullet left the barrel with the hotter load
Re: "Strange" range results.308
Thanks for the thoughts, guys. I'm still low, on the learning curve. I had no idea barrel harmonics had "that" much of an effect. My surprise. I was working up loads for the Varget, in .2 grain increments, for the second testing session, and starting the same, for 4064. Back to the books.
Thanks for the thoughts, guys. I'm still low, on the learning curve. I had no idea barrel harmonics had "that" much of an effect. My surprise. I was working up loads for the Varget, in .2 grain increments, for the second testing session, and starting the same, for 4064. Back to the books.
Re: "Strange" range results.308
From my experience, that is a very light load of IMR 4064 and would expect it to shoot higher. I can't prove why by any means but light loads usually shoot higher for some reason, probably barrel time/recoil related.
From my experience, that is a very light load of IMR 4064 and would expect it to shoot higher. I can't prove why by any means but light loads usually shoot higher for some reason, probably barrel time/recoil related.
Re: "Strange" range results.308
Harmonics + burn rates + different chamber pressures.... A little difference across multiple items adds up. I would also chrono if at all possible, numbers may surprise you.
Harmonics + burn rates + different chamber pressures.... A little difference across multiple items adds up. I would also chrono if at all possible, numbers may surprise you.
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