Create two loads with identical POI

Slowbalt

Slowbalt

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Hi, is there a trick, or a formula to developing two different loads that would have an identical POI at a specific range?

I wish to develop Load#1, which is my hunting load, (let's pretend in .308 with a 180gr Partition and zero it at 150yds).

I'd like to have Load#2, which has the exact same POI at a training range (let's say 50 yards, using cast bullets and a light powder charge) in order to train cheaply and with very reduced noise/recoil/expense.

How?
 
Only by keeping velocities identical up to the point of impact.

Bullet drop on heavy/light bullets is identical. Velocity is what gets the bullet to the point of impact fast enough before gravity pulls it lower.

Your best option is to set up your target at a distance on the range that will duplicate shooting at the center ring.

I don't worry about shooting for center, when shooting cast bullets for practice purposes and practising target aquisition/firing control.

I set up the rifle for the hunting load.

When I shoot with cast, the tightness of the group is much more important than where the group impacts on the paper, even with similar weight bullets as the hunting bullets.

Everything changes, especially harmonics when the loads change.

If you're getting a satisfactory group with cast bullets at closer ranges, be happy and make sure you clean out every bit of lead fouling, before going back to jacketed bullets or your jacketed groups are going to go awry pdq
 
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My 308 nosler 168 custom competition bullets I reload have the same POI as my 168 barnes ttsx that I reload for hunting. using different weights will make it hard you will have to experiment but for me the same varget charge with two different bullets of the same weight hit the same POI or close enough that I don't see the difference
 
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? Drop a rock and a feather they hit the ground at the same time you need to have the 2 bullets going about the same speed try shooting at 150 yards as zero than when you shoot cast at 50 yards use the drop as your new holdover don't readjust the scope I hope this helps
 
You'll likely see a large POI shift from a low speed cast load to a regular high velocity load. In my son's 6.5 Grendel, the difference in POI at 100m between his TrailBoss loads (1250 fps) and full loads (2500 fps) are about 12moa vertical

If the practice load is full velocity, the POI can be very close. In my 260 Rem, 140gr Partitions @ 2750 fps MV hit to the same POI inside 300 meters as the 147gr ELDm @ 2675 fps. Same in my 338-06 between 225gr Accubonds and 230gr ELDx
 
OP is proposing to zero a full power hunting load at 150 yards and a second, milder practice cast loading at 50 yards. I presume without adjusting sights or scope. So far as I know, that is just something to try - I have not read of any way to predict or pre-calculate such a thing. I am like todbartell - rifle gets zero'd with the full power hunting load, then discover what is required hold-off for other loads in it. I have rifles that throw second or third loads up, down, left or right - have to actually shoot to see. I do not have much experience at it, but was always told to me to scrub every bit of copper residue out of a rifle bore before shooting lead bullets in it - so what I have always done - I have never knowingly shot lead cast in a barrel fouled with copper jacket.
 
Supposing one does not wish to adjust windage and elevation, having different bullets hitting at same POI is a (very) happy finding through load development. I have a Browning BAR 30-06 which will shoot a 150, 165, and 180 grains to the same POI at 100 yards, all around 1 moa. Jack O'connor said once that a 30-06 that can shoot a 150 and 180 to the same POI is a rifle which should be cherished and used sparingly. Mine shoots 3 weights instead of his two. What can I say?
 
A similar situation was asked of me to have one full power load and a second load for grouse or other small game.
I suggested making head shots with his full powered loads but his concerns were noice and recoil.
It strikes me those are the same when shooting big game.
The OP is looking for "Practice Loads" at 50 yards.
This may take considerable experimentation with different powders and varying the amount of powder used.
That said, when trying different bullet/powder combinations, where that round goes from previous POI is unknown.
With my 338 WIN MAG, my longest head shot on a grouse was 38 paces. Only one blew up when it flushed as the trigger was pulled.
 
I found that 180 gr Nosler partition and 180 Sierra game king loaded atop the same powder charge, primer, and case have a common point of impact in my .30-06. Loaded to same length, ogive near enough to identical. Works great to keep practice happening without the premium cost. As far as I can tell, running reduced loads and hoping for a common point of impact could be tough, as it may require a common weight projectile and velocity to be as noted by others. You might get lucky, but ....

There's major saving in finding a bulk bullet or common cup and core offering that is close to a premium bullet in shape and weight. Biggest saving in is projectile cost.
I wouldn't be switching between jacketed and cast without a complete copper fouling removal, as others have noted.


It's better to not have to rezero between practice and practical loads, and to have practice ammo that has the same recoil, report, and point of impact as your practical hunting loads, without the cost. YMMV....
 
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if you are using a duplex style reticle, i've had some luck with having the big game load sighted per normal and using the top of the thicker post section for low velocity cast loads. i've used the hammond game getter in a 300 mag with swaged 32 pistol bullets that hit very well at 25 yards.
Done this way it may not be at the distance you are thinking of but might be usable ie point of aim (top of post) at 40 yards or 70 and adjust from there.
just about any normal hunting rifle with cast and experimenting with 10 grains+- unique would do what you want.
 
I use 9.0 gr Bullseye and a Berry's 150 gr plated bullet in a 30-06. Same poi at 50 yds as 180 partition at 100 yds. Very cheap to load and quiet.
 
The only way I can see to do this is to load your cast bullet with a range of powders charges, min to max (say, 3 of each) and shoot them at 50 yards. Look for the load that hits the aiming mark, or close to it.

I would try 2 powders, like red dot and Blue dot.

The harmonics of the barrel may fling the bullets where you want with one of the loads.

I have done tests like this trying to get a double barrel rifle to superimpose.
 
The only solutions I see other than testing different powder charges and projectiles would be:
Quick detach scope bases and a second optic, although this kind of blows the practise budget to smithereens.
Adding weight to the barrel and harmonically tuning the practise load.
 
Is there a reason the sights can’t be adjusted? Write down how many clicks to get back to the hunting load, and test fire at the end of the last session before a hunt.
 
Slowbalt said:
Hi, is there a trick, or a formula to developing two different loads that would have an identical POI at a specific range?

I wish to develop Load#1, which is my hunting load, (let's pretend in .308 with a 180gr Partition and zero it at 150yds).

I'd like to have Load#2, which has the exact same POI at a training range (let's say 50 yards, using cast bullets and a light powder charge) in order to train cheaply and with very reduced noise/recoil/expense.

How?
Click to expand...


you can make one load that hits the same point that your hunting load hits. This assumes it has the exact right velocity for this and has no sideways change.


Another option is that you make your test load. zero it at 50m and write down how many clicks you needed. when you are done training you can dial the opposite amount of clicks back.

this assumes you never miss or miscount clicks and that your scope has accurate clicks
 
Ravage said:
My 308 nosler 168 custom competition bullets I reload have the same POI as my 168 barnes ttsx that I reload for hunting. using different weights will make it hard you will have to experiment but for me the same varget charge with two different bullets of the same weight hit the same POI or close enough that I don't see the difference
Click to expand...

I had the same experience with a Tikka Dirty '06: Speer 165s and 165 TTSX.
 
Going back to OP's question and example - 308 Win - 180 grain Partition full power, sighted in at 150 yards - wants a cast light load to also hit dead on at 50 yards, without adjusting sights or scope. Still not sure that I would know how to predict that - for sure I know of no formula to pre-calculate that - but some guys have two or more loads that get to the similar spot. For sure, I am in a bit of quandary about mixing jacketed and cast lead in same bore without thorough cleaning in between. Many moons ago (1990's) I started to do up loads for my son to learn with - in a 308 Win - they were Speer 110 grain half jacket - but I had no concern about adjusting scope to hit where he was aiming, then adjust back to take that same rifle deer hunting with full power 165 grain bullet loads. Maybe easiest solution to OP is to get over the issue about adjusting sights or scope - they have adjustments - made to be re-set from time to time??
 
Potashminer said:
Going back to OP's question and example - 308 Win - 180 grain Partition full power, sighted in at 150 yards - wants a cast light load to also hit dead on at 50 yards, without adjusting sights or scope. Still not sure that I would know how to predict that - for sure I know of no formula to pre-calculate that - but some guys have two or more loads that get to the similar spot. For sure, I am in a bit of quandary about mixing jacketed and cast lead in same bore without thorough cleaning in between. Many moons ago (1990's) I started to do up loads for my son to learn with - in a 308 Win - they were Speer 110 grain half jacket - but I had no concern about adjusting scope to hit where he was aiming, then adjust back to take that same rifle deer hunting with full power 165 grain bullet loads. Maybe easiest solution to OP is to get over the issue about adjusting sights or scope - they have adjustments - made to be re-set from time to time??
Click to expand...

Yes, I rezero regularly with ammo changes. Or get a scope with a reticle, or adjustable locking turrets. Makes different ammo use easy.
 
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