• The Shot You’ll Never Forget Giveaway - Enter To Win A Barrel From Rifle Barrel Blanks!

    Tell us about the best or most memorable shot you’ve ever taken. Contest ends June 13th and remember: subscribe for a better chance of winning!

    Join contest Subscribe

Range Report Load development

hereinaz

LS Wild - Thunderbird Long Range
Supporter
Full Member
Minuteman
Commercial Supporter
  • Mar 7, 2018
    1,827
    1,204
    Arizona
    I loaded for a Bartlein 26, heavy barrel, .300 win mag the other day at 100 yards. Loaded for a buddy some 210 Berger VLD over H1000 in .3 grain increments. As the loads went up, the point of impact moved down. Over the course of 1.5 grains, 6 different loads, they all fairly stacked on top of each other but trended down. I had a magnetospeed, and was watching the velocities and will load to velocity.

    Just curious how many others have seen where higher loads actually impacted lower?
     
    I'm not real great at explaining things, so I apologize in advance. That's fairly normal unless you have a really short sight height. If the sight height on your rifle is around 2-2.5" above the bore, which I'd say is pretty common, and the rifle had been zeroed at 100y, then the bullet should be crossing the line of sight for the first time at roughly 100y. When you increase the velocity of the round, it's crosses the 100y mark before it's crosses the line of sight, meaning it will hit lower on the target than the slower round. Again, I'm not real great at explaining things in writing, maybe someone else will chime in and give a better explanation.
     
    An increase in velocity produces a higher impact regardless of sight height above the bore, assuming you are using the same bullet and same zero settings on the scope. UNLESS you have some strange harmonics going on. But at 100 yards and with a heavy Bartlein barrel, the harmonics should be minimal. Many guys who develop loads for long-range competition swear on the benefits of the "ladder test." They use this procedure to find the "sweet spot" in barrel harmonics to minimize vertical dispersion at long ranges.
     
    Last edited:
    Maybe.

    Recoil works differently from what 'common sense' would lead folks to believe. I also originally believed that higher velocity would always result in a higher POI; but that was not the case, and there is strong physics to support it.

    Velocity isn't the only force at work here. There is also recoil.

    We adjust sights to put the POA and observed POI together. But as the rifle recoils, muzzle flip initiates, and the actual relationship between the POA and the bore line changes upward while the bullet transits the bore. So the pointing direction of the bore is not the same when the bullet emerges as it was when the sear released.

    The key point here is that a shorter transit time associated with higher velocity means that the bullet emerges sooner than it would at the original velocity at which the sights were regulated. So the barrel flip is reduced, the bore is actually pointing lower, and the POI shifts that way.

    One might believe that the recoil would cause more flip, raising the bore line; and that is true. But the transit time wins the race because of the vagueries of how the human body responds to recoil, and the net effect of both changes results in the lower POI.

    This phenomenon was first observed in the 1800's by revolver shooters, whose sights did not adjust and some means needed to be found to regulate elevation without the capacity to change sight settings. As 'common sense' dictated, they increased their powder charge to find a higher POI, and Whoa Nellie, the danged things shot lower. Puzzled, they added more powder, and now the danged thing shot lower still.

    It was the bore transit time at work.

    So some intrepid soul tried lower powder charges, and Voila, the desired POI raise followed very effectively.

    It's certainly counterintuitive, but once the entire process is understood, it all makes perfect sense.

    In an application where the rifle is rigidly supported/mounted, recoil cannot generate muzzle flip, and the 'common sense' explanation becomes the norm. Where rigid support is lacking, recoil causes muzzle flip, and it's transit time, not charge weight, that has the more effective consequence.

    Somewhere in the midst of all this, sight height is a factor. But it's not the crucial one.

    To further explain, and perhaps complicate, this issue, I refer you to this earlier post. The way this relates most is to emphasize the relationship between recoil, the human body's response to it, and the effects that bear upon where the bore is pointing.

    This is another reason why dispersion could vary between different shooters firing the same rifle; and a possible explanation of why BR shooters shoot so much better. It's not just about the equipment.

    Now could also be a good moment to review LL's excellent explanation about why his prone position may well be better than many of ours. Listen to The Man, he knows from which he speaks.

    Greg
     
    Last edited:
    I agree with your recoil assessment, especially when it comes to inconsistent recoil management. For example, shooting one group free-recoil and the next with the rifle into shoulder will lead to vertical issues. I can only assume that the OP is using consistent recoil management techniques. Additionally, I did not address the multitude of other issues that can cause vertical issues. for example:
    --is the barrel/action property bedded. (if the stock is touching the barrel, you are asking for problems)
    --did you adjust for parallax
    --did you let your ammo sit in the sun and get hot between groups
    --did you shoot one group with light wind and the next with a boiling mirage.
    --etc., etc

    Again, sight height is not a factor.
     
    I shoot nearly mostly only handloads, except when I'm looking for something to shoot in bulk without having to crank out large volumes of ammunition; one does get bored eventually, and sometimes, when the automated powder dispenser gets The Fidgets, kinda frustrated.

    I am currently looking closely at the RCBS version which uses a touch screen for control inputs. The membrane switch panel on my old one is going to die real soon, but not of murder; it will wither away from the harsh language and suppressed rage it generates in the operator. My Doctor told me to avoid stress; I need a better automated powder dispenser.

    When my Hornady Lok-N-Load isn't acting up, it starts serving me up the next charge while I'm seating the bullet, and I can advance the 550 another step, and have the next measured charge waiting for me.

    ...And..., I forgot to mention to the OP that what they are experiencing is not so abnormal after all.

    Greg
     
    Last edited:
    • Like
    Reactions: Stpilot12
    Yes, we are similar in our staged approach. I use a cheap Lyman digital for my 1st stage throw (it is a gen 6 with touch screen) set about 1 grain low and then do the final weighing on my Sartorius Entris with with a Dandy-2 electric trickler. YES I’m am anal. I can’t help it.
     
    I am currently looking closely at the RCBS version which uses a touch screen for control inputs. The membrane switch panel on my old one is going to die real soon, but not of murder; it will wither away from the harsh language and suppressed rage it generates in the operator. My Doctor told me to avoid stress; I need a better automated powder dispenser.

    I apparently spoke too late, because when I went to use the measure yesterday, it went completely belly up. And an hour later, after failing completely to resurrect the old RCBS electronic scale and bring the old Dillon mechanical powder measure back to lifer; I bit the bullet and ordered the RCBS measure. To add insult, etc., the Midway sale price of $199 which had been in effect the day before was back up to $249. I ordered it from Amazon who had it listed for $235, but when it rang up they had added tax, bringing it, you guessed it, back up to $249. The only break I got was Prime's free two-day shipping.

    Some days...

    Greg