Create two loads with identical POI

[Slowbalt]

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?

[RickinTN]

The best I can come up with is trial and error. I've never heard of a trick to avoid the work.
Good Luck,
Rick

[kevin c]

I don't shoot anywhere near well enough to speak from personal experience, but I'm thinking RickinTN is right. So many variables in each load to consider.

I'm not a rifle guy, but why would it matter? So long as the practice load groups well, wouldn't noting and changing the scope/sight settings when appropriate do the same thing: allow you to use the practice load at the range desired and hit the same target as the hunting load?

[tazman]

What you want is very gun specific. By that I mean, you normally need to get lucky in that the firearm will put two different loads in the same spot.
I have two rifles that do that. It wasn't planned. It just happened. Those same two loads shoot to different impact points in other rifles.
I have one really odd rifle in that it puts nearly all loads I have tried in it into a 2 inch circle at 100 yards. Being a 30-06 hunting rifle, that is completely adequate.
The other is a Savage 223 varminter. It puts 69 grain match and a 50 grain spitzer into the same 1.5 inch group at 200 yards using the same powder charge. The other nearly identical rifle won't do it.
None of the other many rifles I have owned over the years would do that.
Some would not put two different loads within 6 inches of each other.

[JimB..]

Trial and error, on the other hand it’s easier to just learn what the difference is and accept it. Measure groups and deviation from POA during practice, if groups are good and deviation consistent then you’re good.

[MT Gianni]

Ken Waters in Pet loads claimed that the 280 Remington had the unique ability to group accurate loads of different weight bullets very close at 100 yards. I have seen that with 175 and 140 gr bullets. It was unique enough for him to mention so it is going to be rare.
What I did with 243 cast was count clicks. My cast load was 43 clicks different than my jacketed one. No left-right regulation was needed. Keep a piece of paper under the cap stating which it is set for.

[dverna]

It can be a challenge finding an accurate cast bullet load.....well at least it is for me. Trying to find one that shoots to the same POI as jacketed will make it even more frustrating.

Some scopes have a resettable zero so that makes it easy to dial in your setting for different loads. But most scopes do not. You might get lucky but the chances are not great.

One option is to buy another set of rings and an inexpensive scope for your 50 yard shooting and swap scopes as desired. I always check zero before a hunt so if the scope was off by a few clicks it would not matter.

[charlie b]

If you have a good scope just record the zero for both loads. When done with practice reset the scope. I do that between my plinking loads, 'full power' cast loads and jacketed loads in the same rifle.

[JonB_in_Glencoe]

I got three words for you, "Mil dot reticle"

[1006]

Out to 150 yards, if you can make them the same velocity, they will both land on the same target. It might not be the same exact poi, but close. I did it for my Grandsons and Son In-law with a 243 load of 100 grains for the Son, and a 75 grain load for the kids. Load data was used to approximate the same muzzle velocity. 150 yards is not far enough out to see a dramatic difference in trajectory. However, they may may not shoot with the same level of accuracy with each load.The 243 is so accurate that no differences were noted. I was using jacketed ammo in both loads. They both ran around 2900fps.

[hoodat]

What slays me is the freakin windage variance that I often encounter with different bullet weights, or even different powder charges.

It's not uncommon for a different bullet brand of the same weight to group 1" left or right from the one I've tuned my rifle to. One inch is a lot when I'm trying to pop a ground squirrel at a couple hundred yards. jd

[cwtebay]

You can likely get on paper using a ballistic calculator by plugging in your velocities and bullet - then ladder load from there for fine tuning.

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[Goofy]

What Slobalt asked about ain't that tuff to do. 1) Cast bullets can be quite precise if one does the homework. The gun/load combo that fired the target below has the same zero at 20 & 50 yards
https://i.imgur.com/0LR49yA.jpg

2) he was asking about a hunting load zeroed at 150 and a plinker that would shoot to the same POI at 50. I take that to mean he wants two different loads zeroed at two different ranges. Zero the hunting load, then start working on the cast load. Guess on my part but a check of the hunting load at 50 would give a fella a fair idea of what charge would be needed to accomplish that. Thinking that something in the 1,000 fps range with cast might do the deed.

Another cast load I shoot is black powder propelled and I've not seen the need to mount a scope on the old cannon yet. Target below shot with a tang sight, elbow rest at 100. The difference in POI at 100 and 50 is quite small.
https://i.imgur.com/8kja5Q1.jpg

[gwpercle]

Ken Waters in Pet loads claimed that the 280 Remington had the unique ability to group accurate loads of different weight bullets very close at 100 yards. I have seen that with 175 and 140 gr bullets. It was unique enough for him to mention so it is going to be rare.
What I did with 243 cast was count clicks. My cast load was 43 clicks different than my jacketed one. No left-right regulation was needed. Keep a piece of paper under the cap stating which it is set for.

The 41 magnum does the same thing ... Elmer Keith even noticed it and I thought the fixed sights on my model 58 S&W 41 magnum ( my avatar) would be a problem ... they aren't .. Cast Boolits from 195 gr. , 210 gr. 215 gr. 220 gr. & 240 gr. all group close enough to each other that it's easy to remember to hold a little high or a little low for the lighter / heaver boolits . The revolver is regulated for the 215 grain load .

For your load #2 , try a 170 or 180 grain cast lead boolit and 13.0 grs Red Dot or 12.0 grains Unique and @ 50 yds. use the Troy Landry Testing Method.... Choot Em' !
The above advice is simply from experience ...no formula no APP that I know of .
Gary

[1006]

My apologies, I did not read the initial post correctly. I obviously thought the objective was to get the same POI at the same range of 150.

[Markopolo]

Some scopes have a resettable zero so that makes it easy to dial in your setting for different loads. But most scopes do not. You might get lucky but the chances are not great. .

this is what I do... i have that on my 308 and it works pretty nicely

[robertbank]

What I would do is first sight in your load for 150 yards. Once done, set a target at 50 yards and without adjusting your scope see where your bullets are hitting at 50 yards. From there try some cast loads you have and adjust them to hit where the 150 yard POA hit.

Take Care
Bob

[Wilderness]

What I would do is first sight in your load for 150 yards. Once done, set a target at 50 yards and without adjusting your scope see where your bullets are hitting at 50 yards. From there try some cast loads you have and adjust them to hit where the 150 yard POA hit.

Take Care
Bob

I can give you a start with .30-30 and .308. My Savage 99 .30-30 is zeroed for 150 m and the Ruger 77V .308 for 200 m with the good stuff. Then I go looking for a 50 m dead on zero for the cast loads. For both I use the Lyman bullet #311576HP (115 gns) and Unique. A few shots will get you there, at one grain increments, and watch the POI move up the target (and sometimes laterally as well).

My 50 m zero load for both rifles is now 12 gns Unique. This is quite sharp in .30-30 (1945 fps, groups each side of 2") but modest in .308 (1875 fps , group < 1"). Other rifles might require less or more velocity to find the 50 m zero.

Why do it? For finishing off, or for a quieter shot when less is enough, or for decapitating rabbits (.308). When you need a light load, you may not have time to fiddle with sight settings.

[facetious]

I have done it with .38 and .357 .

I worked up a load for the.357 and sited in first then worked up the .38 , upping the charge from a starting load till the POI was the same.

This was at 25 yards, past that and POI start to spread. Inside 25 yards thy were the same. Also the .38's were not hotloads more upper end of standard pressure.

[robertbank]

I have done it with .38 and .357 .

I worked up a load for the.357 and sited in first then worked up the .38 , upping the charge from a starting load till the POI was the same.

This was at 25 yards, past that and POI start to spread. Inside 25 yards thy were the same. Also the .38's were not hotloads more upper end of standard pressure.

My work in this area involved the .45acp & 45 Colt using 200 Gr LSWC in my Ruger Convertible. Started with the 45 Colt. I used my Chrony to match velocities. This made the job easier.

Take Care

Bob

[358429]

I found it very interesting, that in two revolvers (60-9 j frame magnum 2 inch snub, and SP101 4 inch), 148 grain button nose wadcutters over 3 grains winchester 231 in special brass shot to the same point centered on the target as 110-125 grain jacketed hollow point over 20 grains of winchester 296 magnum brass, at 25 yards, in my hands.
Could they be further apart on the load data??
[emoji1787][emoji1787]trial and error haha.

I have noticed a trend with the pistols and revolvers, that increasing bullet weight usually rises point of impact compared to point of aim, at standard loadings for a specific chambering at between 20-50 yards (example 9x19, 38 special, 357 magnum).

Specifically in 308 winchester, I have found that factory 147 grain pmc ball shoots almost exactly 4 inches higher at 50 yards compared against my self cast 308 loads (170 grain lee with out gc installed over Imr4227/Imr3031)

Slowbalt, I don't have enough data specifically with rifle, to quote numbers offhand, but I would expect there may be a similar trend, between velocity/bullet weight/recoil/sight height over bore centerline, that you may be able to exploit multiple zeros for different loadings. Good luck for this project of yours! I think robertbank has the right idea. (Post number 17).

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[Wolfdog91]

https://youtu.be/H9J3PVcbr30

https://youtu.be/3xHpxSm2beE

https://youtu.be/BCWHyU5pOik

[robertbank]

I found it very interesting, that in two revolvers (60-9 j frame magnum 2 inch snub, and SP101 4 inch), 148 grain button nose wadcutters over 3 grains winchester 231 in special brass shot to the same point centered on the target as 110-125 grain jacketed hollow point over 20 grains of winchester 296 magnum brass, at 25 yards, in my hands.
Could they be further apart on the load data??
[emoji1787][emoji1787]trial and error haha.

I have noticed a trend with the pistols and revolvers, that increasing bullet weight usually rises point of impact compared to point of aim, at standard loadings for a specific chambering at between 20-50 yards (example 9x19, 38 special, 357 magnum).

Specifically in 308 winchester, I have found that factory 147 grain pmc ball shoots almost exactly 4 inches higher at 50 yards compared against my self cast 308 loads (170 grain lee with out gc installed over Imr4227/Imr3031)

Slowbalt, I don't have enough data specifically with rifle, to quote numbers offhand, but I would expect there may be a similar trend, between velocity/bullet weight/recoil/sight height over bore centerline, that you may be able to exploit multiple zeros for different loadings. Good luck for this project of yours! I think robertbank has the right idea. (Post number 17).

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A heavier bullet travelling slower than a lighter bullet will spend more time in the barrel. As the barrel rises under recoil the bullet exits the barrel at a higher level and hits the target higher as a result. Simple physics. That is what you are observing.

Take Care

Bob

[charlie b]

Pistols do have more changes due to recoil than rifles. Also why a pistol fired from a rest will frequently have a different POI than one fired free standing and another POI if fired with one hand.

[robertbank]

Pistols do have more changes due to recoil than rifles. Also why a pistol fired from a rest will frequently have a different POI than one fired free standing and another POI if fired with one hand.


That observation may be true but likely has nothing to do with the gun, just saying.

Take Care

Bob