Sight Correction for 8-3/8" 27-2

TAROMAN

TAROMAN

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Just purchased a nice 27-2.
Checking it out today and it shoots 6-8" high at 25 yards with the rear sight fully depressed.
Same result with everything from light to heavy and slow to fast.
Front is a .248 Patridge rear is a .160 blade.
All I have in the parts box is a .146 rear blade.
Sight calculations make my head hurt, so asking for help if a .014 change will get me into the ballpark?
Or, is it parts ordering time - again.
Next step would be a .278 front, I guess?
 
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Thanks for that.
Always wondered if there was a chart.
Odd as my 28-2 easily shoots to the sights with any load.
The 27 must be regulated for the real screamer loads.
 
TAROMAN said:
Just purchased a nice 27-2.
Checking it out today and it shoots 6-8" high at 25 yards with the rear sight fully depressed.
Same result with everything from light to heavy and slow to fast.
Front is a .248 Patridge rear is a .160 blade.
All I have in the parts box is a .146 rear blade.
Sight calculations make my head hurt, so asking for help if a .014 change will get me into the ballpark?
Or, is it parts ordering time - again.
Next step would be a .278 front, I guess?
Click to expand...

Changing from a .160 blade to a .146 on an 8-3/8" gun (ten inch sight radius) will change point of impact 1.26" at 25 yards.

To change point of impact by 8" at that distance, you'll need a total sight height change of around .09". Changing out both front and rear sights as you described above only nets you .044.

I'm a little puzzled by the statement that POI is the same regardless of ammo. Usually slow, heavy bullets strike higher and light, fast bullets lower.
 
Hornady 158 FTX at 1280 FPS
158 LSWC at 1129 FPS
158 LSWC at 900 FPS
148 LHBWC at 788 FPS
All chronographed
All easily shoot to POA (w/adjustment) in my 28-2
Never shot 125s in 357. Seems as if this is what this one needs.
 
POI varies with load, but is always high. 6" to 8" depending on the load.
Removed the rear sight to ensure there wasn't some junk under it that would prevent fully depressing it.
 
DWalt said:
Could your barrel be slightly bent?
Click to expand...
Thought of that. If it is, its certainly not visible with close visual inspection.
The gun appears to have been fired very little as evidenced by the recoil shield.
Just amazed that loads that shoot to the sights on my 66-1, 627, 681 and 65-5 are so far off on this one.
There's no evidence that the front sight pin was ever touched, its basically so well blended in that its invisible.
 
357 full-house loads in 27-2

I had the same problem. I recall a member instructing me to try 158 grain full-house loads. His belief was that the 27-2 had sights installed for this load. I learned this after I sent the gun back to SW and they hand made a front sight for me on my 27-2. Try the full loads first--that should be about 1500 fps.
 
What you really need is not a sight change, but a really old-time S&W gunsmith to give it a couple or three whacks with a lead babbitt.

This is not a process you want to watch with your own revolver. :)
 

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Just went back to my Hornady book, the 158 at 1280 is right at maximum.
I'm thinking something is amiss here. Any adjustable sighted S&W should be able to be adjusted to hit with any reasonable load.
I'm convinced that something is amiss.
S&W service is totally slammed these days, so I'll start searching for a 'smith with a babbitt. Around here, if it isn't a black rifle, the so-called gunsmiths are lost.
 
TAROMAN said:
Just went back to my Hornady book, the 158 at 1280 is right at maximum.
I'm thinking something is amiss here. Any adjustable sighted S&W should be able to be adjusted to hit with any reasonable load.
I'm convinced that something is amiss.
S&W service is totally slammed these days, so I'll start searching for a 'smith with a babbitt. Around here, if it isn't a black rifle, the so-called gunsmiths are lost.
Click to expand...

For a more gentle approach, there is an article in the 2000 Gun Digest (starting at page 71) titled "Sighting in Single-Actions", by Todd G. Lofgren. In the article he uses a hydraulic 12-ton arbor press to bend barrels of his fixed-sight single actions to shoot to point of aim. He did it all by trial and error, but it might be possible to make some calculations and use a dial indicator to minimize the amount of tweaking needed.

Used copies of the 2000 Gun Digest are available on Amazon for about $4.00.
 
moosedog said:
I think Shawn NcCarver's post is probably it. That's what they would do at the factory.
Click to expand...

In fairness, I am not sure what they might do at the factory, but I agree with the conclusion mentioned - that the revolver SHOULD be able to be sighted in for the load in question with the standard sight set-up.

Despite the current service situation at the factory, I would still send it to S&W. One of their experienced gunsmiths is the only way to go here. And the answer may NOT be a babbitt bar, but something else.

Were it my revolver, I would want the factory to decide the cause and figure out the best fix to make it shoot right.
 
A couple of old gunsmiths have described bending the frame with a babbitt bar to correct windage but I’ve not been told how or where you’d whack the frame to correct elevation. Are any of you sure elevation can be corrected with babbitt?
 
Talk about SCREAMING loads. l have an old S&W ammo brochure that quotes 2001 FPS for their 90gr load in 357 Mag
 
Move the target!

Try moving the target out to a more reasonable distance for the 8 3/8" barrel. Try 100yds! Your problem is the heavy bullets are in the longer barrel for more time. This means the gun is in the recoil arch higher when the bullet exits the barrel! My 10 5/8" barrel Silhouette hits the target at 200yds, if I do my part right!
jcelect SWCA#LM723
 
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