Sighted my Colts this weekend - bad ammo?

JonnyP · May 10, 2010, 11:37 AM

Took my King Cobra and Anaconda to the range this weekend with a little sight vice. Got to work.

Both required a little tweaking, but they're both "spot on" now at 75 feet. Used SD ammo for this purpose. I think it was 200 gr JHP for the .44 Magnum and 170 gr FMJ for the .357 Magnum.

Then something strange happened.

Started using up some .38 spl rounds I bought when I purchased a snubby for my wife (eventually sold it, but that's another thread). The shots were, for the most part, significantly lower than the ammo I used to sight the gun (King Cobra). My target was only about 15 feet away. Didn't have any more of the SD ammo and didn't want to buy another box just to recheck my work, so I just left and thought I'd try again another day.

Did I just get some bad ammo, or is this to be expected?

girvin02 · May 10, 2010, 12:15 PM

Heavier bullets will impact higher than lighter bullets.

briandg · May 10, 2010, 01:22 PM

your handguns, when fired with lighter loads will be in a much lower state of recoil when the bullet leaves the barrel. The line that you sight in on is not remotely on the point of impact, it will always be above the actual point of impact,so that when recoil forces the barrel upward, it will leave the barrel when it is on the proper line.

SVO · May 11, 2010, 02:13 AM

Could be that the .357, depending on loading, could have had a higher velocity with a flatter trajactory than the .38 specials.

velocette · May 11, 2010, 08:32 AM

Any handgun when fired has recoil. The gun will be moving in recoil while the bullet is still in the barrel. With heavier & lighter bullets, the heavier slower bullet will hit higher as it is in the bore, recoiling longer. Conversely, the lighter, faster bullet will hit lower.
It is a common task to regulate a fixed sight handgun's vertical point of impact with the same weight bullet by varying the powder charge, larger charge, (higher velocity, less barrel time), lower impact; lighter charge = higher. Or bullet weight, lighter bullet, lower impact; heavier bullet, higher impact.
When you think about it, one would wonder how anyone could hit anything with a handgun with all the things going on at the same time.

Roger

Kreyzhorse · May 11, 2010, 11:19 AM

Quote:

Could be that the .357, depending on loading, could have had a higher velocity with a flatter trajactory than the .38 specials.

+1

The difference in bullet weight and loadings (.357 vs .38) would cause a difference in point of impact. Couple that with the fact that you went from 75 feet to 15 feet and I think that would likely explain your results

May 10, 2010, 11:37 AM	#1
JonnyP Senior Member Join Date: October 16, 2009 Posts: 195	Sighted my Colts this weekend - bad ammo? Took my King Cobra and Anaconda to the range this weekend with a little sight vice. Got to work. Both required a little tweaking, but they're both "spot on" now at 75 feet. Used SD ammo for this purpose. I think it was 200 gr JHP for the .44 Magnum and 170 gr FMJ for the .357 Magnum. Then something strange happened. Started using up some .38 spl rounds I bought when I purchased a snubby for my wife (eventually sold it, but that's another thread). The shots were, for the most part, significantly lower than the ammo I used to sight the gun (King Cobra). My target was only about 15 feet away. Didn't have any more of the SD ammo and didn't want to buy another box just to recheck my work, so I just left and thought I'd try again another day. Did I just get some bad ammo, or is this to be expected?

May 10, 2010, 12:15 PM	#2
girvin02 Member Join Date: November 25, 2009 Posts: 32	Perfectly Normal Heavier bullets will impact higher than lighter bullets.

May 11, 2010, 08:32 AM	#5
velocette Senior Member Join Date: May 25, 2007 Location: South Florida Posts: 786	Any handgun when fired has recoil. The gun will be moving in recoil while the bullet is still in the barrel. With heavier & lighter bullets, the heavier slower bullet will hit higher as it is in the bore, recoiling longer. Conversely, the lighter, faster bullet will hit lower. It is a common task to regulate a fixed sight handgun's vertical point of impact with the same weight bullet by varying the powder charge, larger charge, (higher velocity, less barrel time), lower impact; lighter charge = higher. Or bullet weight, lighter bullet, lower impact; heavier bullet, higher impact. When you think about it, one would wonder how anyone could hit anything with a handgun with all the things going on at the same time. Roger __________________ Trigger control + Breath control + Sight alignment = Gun Control. http://www.hrpclub.info/

May 10, 2010, 01:22 PM	#3
briandg Senior Member Join Date: May 4, 2010 Posts: 1,701	your handguns, when fired with lighter loads will be in a much lower state of recoil when the bullet leaves the barrel. The line that you sight in on is not remotely on the point of impact, it will always be above the actual point of impact,so that when recoil forces the barrel upward, it will leave the barrel when it is on the proper line.

May 11, 2010, 02:13 AM	#4
SVO Senior Member Join Date: December 21, 2009 Location: Texas Gulf Coast Posts: 585	Could be that the .357, depending on loading, could have had a higher velocity with a flatter trajactory than the .38 specials.