POI and POA issues in Ruger SP-101

[Special_K]

I just started reloading for .357. I am having some issues with POI and POA though. When my POA is center mass the POI lands about 4" low even at close distances of 21 yards.

The load I'm using is various .357 brass with:
3.2 grains of Hodgon Clays
158 grain Semi-wadcutter by Missouri Bullet.

I just currently got in some 148 grain wadcutters as well and I have loads ranging from 2.3-2.5 grains of Clays in a .38 special case. (These have not been tested yet)


So, How do I adjust my POI to match my POA with the rugers combat sights? It hits center but just to low. For social purposes it would be just fine but the OCD is coming out in me.

-K

 

[jbrown13]

To raise your point of impact with fixed sights you will have to shorten (grind down) the front sight. Once ground down it is difficult to add height later, so be certain you need to do it before putting the grinder to it.

 

[Special_K]

From what I understood one could change the bullet weight and the POA would change considerably, is this true? Should I go out and try a range of bullets from 110 up to 200 and see what happens?

 

[jbrown13]

From what I understood one could change the bullet weight and the POA would change considerably, is this true? Should I go out and try a range of bullets from 110 up to 200 and see what happens?

That's what I have heard also. However, I don't have enough knowledge to give give you any specific data about this. Maybe RCModel or Walkalong will come along and can answer that question. I do know that with my Ruger Vaquero I did not see much difference in POI with 125 gr. HPs, 148 gr. HBWCs or 158 gr. FPs. It shot low and I did grind the front sight down to get POI near POA, and it now shoots more accurately than I can hold it with all 3 bullet styes and weights.

 

[GooseGestapo]

Within published loadings, you can increase the powder charge to increase the recoil, which raises the muzzle relative to the point at which the bullet exits the muzzle. (the gun starts recoiling before the bullet exits the barrel).

You need to check the POA/POI with 158gr factory Magnum ammo to determine if it is still below POA. If so, then I'd start to consider shortening the front sight.

There is a formula for determining how much, but with a 2.5-4" bbl it's going to be on the order of .05-.1". Or, not very much!

I'd try upping the powder charge on the 158gr load slightly (but don't exceed published max) and see if that helps.

Back in the '70's and '80's when I carried an issue S&W mod65, It was customary to file a small amount off the front sight to raise the impact with the 125gr JHP ammo that was the prefered duty load. However, if you cut too much, you had to have a gunsmith re-install a front sight at your expense. This could run upwards of $100 if the front ramp had to be milled due to a forged/machined on front sight.

The S&W's were regulated with a 158gr load at ~1,200fps with the SMALL grips. If you installed the large "Magna style target grips" which most did, and shot the 125gr loads, you would shoot ~6-8" low at 25yds.

Not sure what load Ruger regulates it's guns with, but my (wife's) SP101(2") shoots POA with Winchester 125gr +P at 7yds. She didn't like the .357's due to recoil, noise, and muzzle flash. Can't blame her, either.....

 

[Kernel]

Different weight bullets can have a HUGE effect on the POI vs. POA. Keep in mind though, that bullets don’t travel in straight lines. They travel in an arc. The POA and POI will only coincide at two spots. The near zero and the far zero. Grinding on, or adding to, the front sight won’t change that fact. All it does is move the zero closer or farther away. If your dead on at 20 yds, you’ll be off at 30. Dead on at 30, you’ll be off at 20. And so on.

A lot of guys want a perfect zero at 20 yds, (or 25 yds, 50 feet, or how ever their range is set up). That’s understandable, it makes for neat targets, but it’s also purely arbitrary and of little practical value IMO.

Before you do anything, maybe you should find out where it does zero. Say it’s 40 yds. Is a 40 yd zero unreasonable in .357 Mag? It certainly has the energy to be effective at that range. And you’d be surprised, with a little practice, how easy it is to hit targets at 100 yds with a handgun. Could you live with it being 4” low at 21 yds? Why does it even matter? Group size is what counts. Everything else is just a sight adjustment.

 

[rcmodel]

The problem is, you are shooting very light .38 Spl level loads in a revolver sighted at the factory for a heavy bullet .357 load.

Up the powder charge, increase the bullet weight, or file off the front sight.
Your choice.

But if you file the front sight, you are ruining the gun forever for use with full power .357 ammo.

rc

 

[jbrown13]

The problem is, you are shooting very light .38 Spl level loads in a revolver sighted at the factory for a heavy bullet .357 load.

Up the powder charge, increase the bullet weight, or file off the front sight.
Your choice.

But if you file the front sight, you are ruining the gun forever for use with full power .357 ammo.

rc

That's the reason I chose to shorten the front sight. I'm an old fart with a bad shoulder and only shoot light 38 special loads out of my Vaquero. I also only shoot at an indoor range with a max. distance of 25 yds. If you intend to shoot full power 357 loads follow RCModel's advice.