Load development for point of aim

[awaveritt]

I have shot a thousand or so 158gr. lead boolits over 3.5 gr. of Bullseye thru my S&W 638 and have become used to the point of aim relative to my sighting hold. Now I'm casting some 125 gr. RN and am wondering what kind of change in point of aim I can expect. I plan to also use 3.5 grs of Bullseye to start out, but will this raise or lower the expected point of aim? I'm assuming an increased charge will be needed to return to my original point of impact with the 125 grain boolits. Anyone already invented this wheel?

[bobthenailer]

i beleive the 124 grain bullet with the same powder charge will shoot slightly lower because of less recoil and higher velocity. at what distance will you be shooting ? the farther the distance the more impact change but for short distances the change will be less

[canyon-ghost]

I believe he's right, without increasing the powder charge, the lighter bullet will be lower in poa.

Using a 115 grain bullet in 32-20 and a 98 grain bullet left me a one tenth grain of powder increase to push the lighter bullet the same 100 meters. The lighter bullet was necessary for the 10" TC barrels. They just naturally like lighter bullets that run faster. Accuracy was a somewhat smaller group but, either would do the job.

I, too, like to have 2 or 3 molds that fit the same caliber, makes for some interesting shooting.

[waco]

less boolit weight, less gravity, higher velocity, HIGHER impact

[2ndAmendmentNut]

In my 357mag loads I can get 125gr~160gr boolits to pattern in the same spot. However shooting 170gr~215gr the boolits do definitely pattern higher, by 3 to 6 inches depending on powder charge.

[bgokk]

Pushing a lighter boollit faster from the same handgun as a slower heavier boolit will result in the faster boolit having less time in the barrel thus it will exit while while the handgun is lower in it's recoil. This results in it striking LOWER in relation to the sight setting and sight picture of the heavier boolit.

[MT Gianni]

There are a ton of good 150-159 SWC molds. I would look to duplicate my known trajectory with one unless you want to relearn a curve with a lighter bullet.

[freedom475]

Pushing a lighter boollit faster from the same handgun as a slower heavier boolit will result in the faster boolit having less time in the barrel thus it will exit while while the handgun is lower in it's recoil. This results in it striking LOWER in relation to the sight setting and sight picture of the heavier boolit.


This is GREATLY increased with a big handgun like the 475... If I slow down the 430Gr. LBT's they will hit Very High, even out over 100yrds. And they start walking left (I'm right handed).. I hit almost 2ft left and about dead on for elevation at 200yrds with the slow-heavy's running about 950fps...if I bring these up to 1250-1350fps things start to return to my aiming point and I have to hold high at 200yrds.

[stubshaft]

I would drop the charge down to 2.5 - 2.7 BE and check the POI. I agree with the majority of comments here, but if shooting at known distances 25 or 50 yards than relearning the trajectory is not too difficult.

[smith52]

Pushing a lighter boollit faster from the same handgun as a slower heavier boolit will result in the faster boolit having less time in the barrel thus it will exit while while the handgun is lower in it's recoil. This results in it striking LOWER in relation to the sight setting and sight picture of the heavier boolit.

I agree, the lighter bullet will strike lower than the heavier bullet in the same gun. bgokk explained it well.