.357/.38 different POI???


PDA






BoneDigger
April 24, 2007, 03:02 PM
I took the 686 to the range today and tried some .357 and some .38. Both were WWB, but the .357 was JHP, and the .38 was solid points.

I noticed that the gun, wich has a 2.5 inch barrel, shot much better with the .357 than the .38. Any reasons why this would be the case?

Todd

If you enjoyed reading about ".357/.38 different POI???" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
jbauch357
April 24, 2007, 03:37 PM
It may all be in my head, but I notice considerably better accuracy with .357 mag rounds compared to the .38 special rounds when shot out of my 4" GP100.

Also even given the substantially lower recoil (i.e. easier shooting) of the .38 special rounds compared to .357 mag I don't see any difference in grouping when shot out of my 2 1/4" SP101.

raghorn
April 24, 2007, 03:39 PM
Higher velocity rounds will tend to hit lower than slower ones. The bullet leaves the barrel quicker, so is less affected by recoil.

harbinger_j
April 24, 2007, 05:41 PM
I always thought it was because I tried harder with the .357s
I go through .38s like nothing, but if I am going to shoot a .357 I make it count.

I am also shooting a GP100 4"

Sniper X
April 24, 2007, 06:30 PM
Sounds backwards to me, my Python, Tarus 88, TC, and GP100 ali shoot way more accurate to about 50 yards with .38spl SWC match rounds than with .357 mag anything. In .357 they are accruate, but not as accurate as with the .38spl swc's. Shoot, the Python (6in) makes a raggad hole at 25 yards off the rest! So does the (6in) GP100! The TC is super accurate with both, and is scoped so it is like cheating.

tasco 74
April 26, 2007, 03:01 AM
yep my n frame smith shoots .38 spl wcs more accuratly than .357 magnum swcs too..... i've heard it's because of more bearing surface on a full wc bullet.............

_N4Z_
April 26, 2007, 07:19 PM
Difference in POI also could be the result of different bullet weights being fired.

You said they were both WWB brand, but you did not say what grain was listed on box.

Were they all 110, 125, 158, or 180gr.? Usually I shoot 158gr everything. I have found though that many times the .38's (around here anyway) can only be had in 130gr. fmj, which is almost 30gr lighter than the .357's I normally practice with. That difference does produce a different POI for my Rugers.

FXWG
April 26, 2007, 10:04 PM
Difference in POI also could be the result of different bullet weights being fired.

Muzzle velocity of the .38 vs .357 should make a diference as well.

tasco 74
April 26, 2007, 10:12 PM
i think fxwg is right.. muzzle velocity has more to do with it than weight of bullet...... as gravity is constant and equal of both weights of bullets.....ie if you were to drop a 125 gr bullet and a 180 gr bullet from a 50 story building at the same exact time they would travel the 500 ft and strike the ground at the same time.............

_N4Z_
April 26, 2007, 11:48 PM
ie if you were to drop a 125 gr bullet and a 180 gr bullet from a 50 story building at the same exact time they would travel the 500 ft and strike the ground at the same time.............

ummmm ? :scrutiny: .... if they were falling in a vacuum maybe.

texas bulldog
April 27, 2007, 12:00 AM
ummmm ? .... if they were falling in a vacuum maybe.

nope...shouldn't make any difference. unless we're talking about something that is literally feather-weight, they should drop at exactly the same rate save only any potential difference in terminal velocity. terminal velocity is caused by drag and varies with surface area, not mass. since the two bullets weights have nearly the same surface area, this effect would be minimal if observable at all.

gallileo proved this [and many other things] long ago and was put through the inquisition for suggesting such heresy. don't believe him? drop a golf ball and a bowling ball off your roof simultaneously. you will notice that they strike the ground simultaneously.

_N4Z_
April 27, 2007, 08:07 AM
Here's a good explanation and somewhat applicable.



One surprising characteristic of the force of gravity is that the acceleration it causes in falling bodies is independent of the mass of the object. This is provided there is no air or other resistance to the motion.

In other words, a 5-pound weight would fall at the same rate as a 10-pound weight. If dropped from the same height, they would take the same time to hit the ground. Of course, in dropping a lightweight object, air resistance often will slow the lighter object down more than a heavier object.

Not only does is the acceleration of gravity independent of the mass of an object, but it is also independent of the velocity of the object parallel to the ground.

In other words, it an object is traveling at some velocity parallel to the ground, it will fall at the same rate as a stationary object. Thus a bullet shot from a gun will hit the ground at the same time as one that was simply dropped from the same height.


That last line is somewhat interesting when thinking about the POI, which is what the poster originally inquired about.

tipoc
April 27, 2007, 08:31 AM
A lighter bullet will tend to impact lower than a heavier bullet. Most fixed sight 38/.357 guns have sights which are regulated for a 158 grain bullet. A lighter load will have a lower POI. There are exceptions to this but those have more to do with the particulars of the individual gun and the load.

tipoc

TYY
April 27, 2007, 02:15 PM
You have to separate the issues of BULLET DROP and MUZZLE RISE. Of course a faster projectile will drop less, but a heavier one may recoil more causes more muzzle rise and hit higher (assuming range/drop is not an issue).

Vern Humphrey
April 27, 2007, 02:58 PM
.357/.38 different POI???

--------------------------------------------------------------------------------

I took the 686 to the range today and tried some .357 and some .38. Both were WWB, but the .357 was JHP, and the .38 was solid points.

I noticed that the gun, wich has a 2.5 inch barrel, shot much better with the .357 than the .38. Any reasons why this would be the case?

I'm not sure I understand this thread -- the title talks about Point of Impact, but the text talks about accuracy.

Do you mean different loads shot to a different POI? That's not at all uncommon. Or do you mean your .38 Specials shot into larger groups than your .357s?

ZeSpectre
April 27, 2007, 03:05 PM
When shooting my SAA revolvers I'm consistantly a bit low with the light "cowboy" .38 special loads, and much closer to POA when I put full power .357 Magnum

BoneDigger
April 27, 2007, 04:50 PM
Vern,
Actually, you are correct, the title and thread are a little misleading. The .38 caliber rounds were less accurate than the .357, but there was ALSO a different POI. The grouping of the .357 from the same distance, was much better than the .38. Also, the .38 was hitting low and left (different POI) where the .357 was dead center.

In fact, I shot the .38 ammo first and was about to adjust my sights, but then I tried the .357 and it was right on.

Todd

Vern Humphrey
April 27, 2007, 04:55 PM
Chantges in POI are to be expected when going from one cartridge to another -- especially in a small revolver. You can even get significant POI changes from one load of the same cartridge to the next. In fact, I know people who have "zeroed" a fixed sight revolver by experimenting with different loads and finding one that shoots to POI.

Most .357s will shoot .38 Specials with good accuracy, in my experience. Your problem may be the load or lot, rather than a generic problem with .38 Specials in general.

Risasi
April 27, 2007, 04:58 PM
Same here, pretty much every six gun I've ever owned has a different POI when shooting .357 vs .38spl. My favorite right now is a 3" SP-101. I usually shoot the 158gr in .357, 125gr in .38spl. At ten yards I believe .38 is about a 1.5" low, and a little less accurate. For carry I generally stick to .38 125gr Gold Dots. Fast to action, great followup shots.

The only wheelguns I own any more are all snub nose for close in defensive work. All I concentrate on are quick vertical strings COM. If I can put two into the pelvis and one in the neck/head I'm happy.

When shooting for points I prefer a slide action.

tipoc
April 28, 2007, 11:50 AM
Vern is right.

Most all guns show some preference for one load (meaning a certain type bullet at a certain weight and velocity) over another or one brand of ammo over another. This is usually the result of the production tolerences built into the gun coupled with the shooters skills of course.

Most .357s shoot .38 very well. But that doesn't mean that they shoot all .38 well. The gun and shooter will have their preferences. Being more accurate with one load than another. A big part of the challenge of handgunning is finding out which your gun prefers. This involves a good deal of shooting and keeping track.

Most .38 caliber fixed sight wheel guns are set at the factory for POA-POI with a 158 gr. bullet for either 15 or 25 yards.

That bullet weight and velocity effect POI is why they make adjustable sights. For fixed sights you experiment till you find the load that your gun likes best and stick with that one.

tipoc

If you enjoyed reading about ".357/.38 different POI???" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!