Got a 3” Ruger GP100 in 357mag (model 1715-fixed sights), secondhand but it still had the factory grease (dried) in it and didn’t appeared to have been shot.

Went to the range today and fixed that. So I’m shooting at 10 yards and my rounds are printing 2” below the target. I’m using the golfball on a tee hold on a target. 158grain factory ammo. The sight is 0.200” tall. (Benched shooting)

Can anyone measure their GP100 front sight and lemme know if this is just a standard height or should I file some off to get a POA=POI?

Or should I be using 125 grain ammo?

Or does anyone know if the factory sights are regulated at a different distance like 15 yds (and would that make a difference)?

I’ve emailed Ruger a while ago and they haven’t reposnded, re: what the ammo and sight regulation for the SP101 with trench rear sights.

My 4" GP 100 is 0.268" from top of barrel to top of sight. so, taller than yours.

I'd guess it's setup for 125gr loads, that's what nearly every fixed sight .357 is going to be designed around.

quote:

Originally posted by guido_sst:
I'd guess it's setup for 125gr loads, that's what nearly every fixed sight .357 is going to be designed around.

The 357 magnum was first introduced with the 158 just like the 38Special at the time.

It could be they opted for a different front sight for use of the 125.

I have a SP101 and it shoots POA with 158s at 10yds. And a Model 65 that shoots 158s POA.

I’m gonna go back out tomorrow and try some 125s. But if that’s the deal I’m gonna get a different sight so all my 357s can use the same ammo,

quote:

Originally posted by MikeinNC:

quote:

Originally posted by guido_sst:
I'd guess it's setup for 125gr loads, that's what nearly every fixed sight .357 is going to be designed around.

The 357 magnum was first introduced with the 158 just like the 38Special at the time.

It could be they opted for a different front sight for use of the 125.

I have a SP101 and it shoots POA with 158s at 10yds. And a Model 65 that shoots 158s POA.

I’m gonna go back out tomorrow and try some 125s. But if that’s the deal I’m gonna get a different sight so all my 357s can use the same ammo,

You're absolutely right and I've got a .38/44 Heavy Duty that loves 158s, but 125s have been more popular for the last 40 years.

Went back to the range today, at 15 yds (benched) it’s still low.

I measured the SP101 and its front sight is 0.173.

I shot some 125s and they were 8” low.

I’m gonna go back tomorrow and bring a file. Just swipe then shoot a 10 rnd group. Then do it again. Till I get it close.

Ruger hasn’t returned my inquiry online.

ChatGPT search compiled that the 158 grain load is correct for sight regulation.

A second search stated that the proper sight picture is one where the front sight covers the desired point of impact.

"Regulation" of a fixed sight revolver was long ago and they have been cranking them out to that nominal height ever since. Guns, ammo, sight picture, and grip all vary. I thhink you are expecting too much of them.

The sight blotting out the desired POI is sometimes called the "combat" sight picture, more often seen with three dot sights. I consider it quick and nasty and not something I want to do on purpose.

There is the 6 o'clock sight picture with the front sight at the bottom of a a bullseye target. Best for a standard target at a standard distance.

And finally we have the center hold. The top of the front sight is in the middle of a bullseye or at the desired point of impact of a silhouette. Once called the "Marine" sight picture. I think it is the most versatile and would alter or replace a sight to get there.

The 125-grain being much lower than the 158-grain matches my experience. The time in barrel coupled with the recoil-induced weapon rotation changes the POI.

Heavier and slower 40 S&W has a higher POI than the lighter and faster 357 Sig, in the same pistol, for me.

I have a Smith 65 (fixed sight) and I ran the barrels muzzle to muzzle with a brass rod to line the bores up and the GP100 is much taller. The Smith prints POA with 158 ammo.

I also went to Dawson Precisions website where they have an easy front sight equation. You plug in the sight radius, the distance and how low/high your group is and they tell you what sight height to get. Turns out I need a .179 sight.

Went to the range, benched the gun and shot a group. About 2” low. I then began filing the top of the sight down a little at a time, using my digital caliper. Shot a group, did some trial and error and got the group to cutting the bull just where the POA is.

Took a measurement and it’s .179 (close enough)

Just finished cold bluing the bare sight.


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BTW Ruger online customer service is none existent.

It sounds like your Ruger's factory sights were set up for Center Hold sighting at between 15 and 25 yards. Using 6:00 sighting (guessing that's what "golfball on a tee" refers to), you would definitely print low.

At 15 yards POI would not be as low as 10, but it would still be low using that sight pic.

Switching to a lighter bullet will actually pull your groups down, as you found out. A lighter bullet will exit the barrel faster, i.e. earlier in the recoil cycle when the muzzle has not jumped as high.

Sounds like you fixed the problem by filing down the front sight, so good deal. Been there myself.


Sight Pics_Von Stavenhagen by kpkina, on Flickr

quote:

And finally we have the center hold. The top of the front sight is in the middle of a bullseye or at the desired point of impact of a silhouette. Once called the "Marine" sight picture. I think it is the most versatile and would alter or replace a sight to get there.

Totally agree. I replaced the factory "combat sights" on my P229 with simple blade-in-notch sights (from Dawson Precision), and couldn't be happier. Sometimes old school is the best.

For clarity when I said goofball on a tee, I was referring to the center black ball of the target displayed, being just atop the front sight post. Much like your left picture if the whole of that target was black.



Kkina you may be right WRT the original sight settings. If Ruger had ever answered my inquiry I could ask them.

And now that you mention the “combat sighting” on your Sig, my duty gun(P226) was set up that way, wherever you blocked the front sight with the tritium vial(white dot) that was the impact. I hadnt thought of that until just now. It didn’t make much of a matter whe the B27 target has such a large “center” area to qual on

quote:

For clarity when I said goofball on a tee, I was referring to the center black ball of the target displayed, being just atop the front sight post. Much like your left picture if the whole of that target was black.

That's fine, same concept. Actually it makes sense, since I would have normally expected a larger offset at 10 yards, at least 3" worth.

Call Ruger and tell them. Modern day Ruger kind of sucks as a company compared to the old days, but they'll probably still help you out with another height blade.