624 accuracy issues?

[Daimler1989]

Hi,

I got a 624 4" six weeks ago and still am not sure, if it might have some accuracy issues or if I myself might be the problem (trigger pull).

I tried several handloads (7 grs VV N340 245 grs hard cast and Speer SWC soft point, 5,8 VV N320 200 grs hard cast, 8.5 grs VV N340 200 grs hard cast) and Winchester Cowboy ammo, all tested with great satisfaction in a 696 no dash even at 25 meters. The 624 is accurate until 15 meters (5 rounds group 2" or less), further away the groups open up significantly. No large difference between several loads, but jacketed bullets seem to bring sightly better accuracy. There is no significant difference in grouping between .429" to .431" bullets.

I checked the cylinder throats (can't mic them because I have no micrometer), and even the .431" Fiocchi SWCs can be pushed through with nearly no effort. The throats on the 696 are much tighter, a .429" bullet can't get pushed through even with effort. If the chamber throat makes the problem, can someone experienced please explain the process inside the gun to me? Do the bullets tumble when leaving the cylinder and thus have too much clearance when entering the barrel? Or do lead bullets expand in the wider throats and get "resized" or compressed again when entering the barrel? Leading is absolutely no issue, so I think the bullets go straight into the barrel without too much clearance.

Another theory of mine for the bad accuracy on greater distances is the trigger pull. The SA trigger has overtravel of 1 mm after releasing the hammer. I cross checked with my 27-3 at the range at 25 meters (this gun has no overtravel): groups with the 624 were about 5" to 6" with flyers included, the 27-3 groups 3"-4" and no flyers (both from a two hand hold, standing, no rest). So I think, the overtravel could affect my accurate shooting.

Sorry for my probably unprecise expressions, I'm not a native speaker.

best regards from Germany
Ulrich

 

[TSQUARED]

Ulrich,
I am puzzled by the results of your accuracy testing.

Since you have experienced the same results with 0.429" and 0.431" diameter bullets I believe that the chamber throats are not an issue.

I have a number of S&W revolvers with varying lengths of SA trigger overtravel and they have not adversely impacted my ability to shoot them. However that is subject to individual variation.

I use a 245 gr. LSWC 0.429" with 4.3 gr. Trail Boss powder in my S&W 696or 624 and have not expereinced any accuracy issues. My lead bullets are not ultra hard.
Tony

 

[cochise]

I have and shoot 4 different .44 specials. I found the lead SWC and type of powder does have an impact on accuracy of my revolvers. Ignoring the load used, I have found adjustment of the sights have the greatest effect on accuracy for me. All the trigger pulls are very similar in these guns.

My 4 inch model 24 was / is terrible compared to my 624 or 696. After shooting two boxes of ammo, I found the elevation adjustment on the model 24 could NOT be adjusted high enough. I bought a new elevation screw, "flat" nut, with locking "ring" spring and it did not help the grouping of my shots.

To raise my "point of impact", I had to cut a shim from an old credit card and wedge it under the rear sight. That DID cure my accuracy problem. The thing to remember each revolver has their own quirks and are prone to have different issues. The obvious is not always the answer. Enjoy "playing" with your handgun while you solve the problem.

 

[Daimler1989]

thank you both for your input.

The sights don't seem to cause any problems, as they are regulated perfectly for my preferred backup (hunting) load at 10 meters, POA and POI are the same. There is enough elevation space on the backsight left for correcting up and down. And as I wrote, grouping at 10 meters and even at 15 meters is no matter of concern.

regards
Ulrich

 

[cochise]

I guess the accuracy concerns you express requires experimenting with different bullets, different powders, and different loading of powders. It will take time from weeks to months, depending on your schedule and money at your disposal. I have found loading my bullets one to .5 grn below maxium, yeild the best accuracy. Unique and WW 231 has been good in my .44 specials. I would try 2400 too. Hard cast lead .431 bullets were good for me as well as Sierra JHC. Good luck!

 

[CWH44300]

If you can get unique powder try a charge of 6.5gr under a Keith style bullet that's not cast real hard, I'd try. 430" first and experiment with your charge as needed most 44 will like that bullet

 

[rockquarry]

I experienced a similar problem with Model 24-3s. I finally had a Lyman mould opened up to cast a .432" bullet. Also had to have my bullet sizing die opened up to accomodate the larger bullet, but the oversized bullet now fits the cylinder throat. Accuracy has improved and forcing cone leading was drastically reduced to almost nothing. Granted, it was a lot of trouble with some expense, but it cured the problem.

 

[Titegroups]

I don't buy into the idea of a gun being accurate at 10yds and not at 25yds unless the bullet is not being stabilized to begin with or is being destabilized crossing through the transonic zone. Poor accuracy(repeatability) shows up better at longer distances.