point of aim vs. impact, 125gr vs.158gr.

T

trigger45

New member
In my ruger sp101 .357 mag. with 3" barrel , 125gr hits about 4-5 inches low. if i were to file the front site down by half it would be dead on. I f i were to were to use 158gr. ammo would the impact be higher or lower? what are the experiances with your gun? If I cant get the 158gr. ammo to work ill just stick with the 125gr. ammo and file down the frount site. :cool:
 
The 158 grain bullet will be moving slower than the 125 grain bullet, exiting the barrel later, thus allowing the barrel to rise slightly more due to recoil. The strike on target, given the same point of aim, will be higher on the target.
 
Poi

In my 3" S&W M65 at 50ft, the 158gr loads impact 2.5-3" higher than Federal 125gr Classic JHP's.
 
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The 158 grain bullet will be moving slower than the 125 grain bullet, exiting the barrel later, thus allowing the barrel to rise slightly more due to recoil. The strike on target, given the same point of aim, will be higher on the target.
Click to expand...

Wow... That's really interesting that that is the reason why the heavier grains hit higher.

In my 686, the heavier grains definitely hit a few inches higher, but I didn't know why. I thought they just "flew straighter" or some such thing, because they are heavier. It's interesting that it actually takes into account the muzzle rise of the gun. :eek:

Learn something new every day... I love these forums...
 
I noticed a large difference between POI and POA also. My solution was to add "Crimson trace" grips to my SP. By doing this I effectively added "adjustable sites" without permanently modifying the gun.
 
At close ranges trajectories are pretty flat, the exit time/muzzle rise determines, for the most part, POA/POI. Because of this, barrel length becomes an important variable. If you want to play with different loads adjustable sights are a blessing. You can compenate with the elevation setting.

Lots of luck and good shooting.
 
Just make sure you are using correct follow through when shooting before you file those sights down. It's a common problem. If you are not sure, shoot a couple of cylinders, then have someone load for you including a couple of empties in there. Lack of follow through (dropping the muzzle on firing) will be readily apparent when you snap on an empty. Some other problems can be diagnosed this way too.
 
The "dwell time" in the barrel has less to do with the higher POI for 158gr bullets than the higher momemtum those bullets have. Many 158gr and 125gr bullets fired from 1 7/8" barrels have fairly similar velocities, in the 700-800fps range, but the 158gr bullets always hit higher since the greater momentum causes more muzzle lift.
 
I have a sp101 2 1/4 .357 mag. i use a jacketed hollow point 125 gr I've used the 158 gr. and 180 gr. but 125 seems the best for me. :)
 
FWIW, I just acquired some of the new Gold Dot 135gr+P JHP rounds, reportedly specifically designed for "snubby" revolvers, that is, designed to shoot to POA in 1 7/8" barreled S&W J-frames and the like, including Taurus Model 85 and others.

My experience with snubbies over a period of two decades has shown me that they seem to come from the factory made to have POI and POA coincide for 158gr+P LSWCHP, especially for the vertical dimension, and at least approximately in the horizontal (windage is never exactly right, but we're talking about altogether-non-adjustable sights here, after all).

To date, I've found that the various lighter .38 Special rounds, such as the 125gr+Ps, while espoused by some, never shoot to POA for me, but always shoot considerably lower than POA.
I've always favored the 158gr loads, accordingly.

I was pleasantly surprised today to find that the new 135gr+P JHP Gold Dots shoot right to POA in my 340PD.
Spot on.
Felt recoil is trivial, and certainly less than with any of the 158gr loads, which are minimal in recoil, yet the new round has less yet.
The new round has a very large hollow point, and I suspect it may well yield 9mm-style performance out of these little pocket guns.

I can't say anything about velocities, as I don't own a chronograph, and don't have access to one. Maybe someone else can report on this.

A friend of mine had some samples of the new round, in the 50 round boxes apparently initially intended for police sales, which is how I came by it.
I don't know if it's readily available in stores yet, but it's supposedly to be marketed to civilians in twenty round boxes.
 
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My experience with snubbies over a period of two decades has shown me that they seem to come from the factory made to have POI and POA coincide for 158gr+P LSWCHP, especially for the vertical dimension, and at least approximately in the horizontal (windage is never exactly right, but we're talking about altogether-non-adjustable sights here, after all).

From what I've read on the S&W Forum, that's correct. S&W revolvers chambered for .38 or .357 are dialed in vertically for 158gr loads.

Here's a pic of the difference in my 3" M65.
 

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I would assume that a .357 mag would be sighted in for a .357 mag, not another caliber, although it can be shot with it.

Just a guess, though.
 
I just returned from my second range visit with my new 637 today. I shot 130gr FMJ the first visit and accuracy was right on at 10 yards. Today I tried 158gr LRN and was always 3in high at 10 yards.
 
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