I'm the proud owner of a new 625-8, 4" barrel that may well become my favorite S&W! I'm a long time reloader but not alot of cast bullet experience. Got some hardcast 200gr swc and loaded up 25 with 7.5 gr Herco.

At the range the new 625 gave shotgun type patterns (6-8") at 20 yds with this load. Several shots out of each cylinder appeared to be keyholed. Commercial and reloaded jacketed stuff shot fine in the new revolver(2"). The 200 gr SWC load seemed to shoot OK with 2-3" groups in my 5" Kimber Gold Match. The load felt a little hotter than the commercial stuff based on recoil but should'nt be faster than 900-1000 fps

I miked the cast bullets at .452. I also miked the chamber throats at .450 maximum. Bullets would not pass through the chamber with several fairly heavy taps with a rod and the started end of the bullet miked .450. I bought 500 of these bullets and would like to get them to shoot. Any suggestions would be greatly appreciated.

Welcome to the forum!

The throats are too tight! You can have them reamed to .452" for about $50. The undersized throats are squeezing your bullets down, causing a loose fit in you bore. I gaurantee you that correcting the throats will make a HUGE difference.
It's been my experience that beveled based bullets exaggerate this problem.

For best performance the cast bullet must fit the bore properly. As pointed out above, it appears that your revolver's forcing cones are reducing bullet diameter (which will also deform the cast bullet to some degree) thus the bullets are not being fully engaged by the rifling. Recovered bullets may show considerable gas-cutting around the bullet bases.

I would recommend having the chamber mouths reamed. Even with the stronger jacketed bullets your revolver is probably generating an undesirable spike in chamber pressures as the jacketed bullet is swaged through the undersized chamber mouths. Althought the stronger jacket material is accepting rifling engagement better, accuracy is being affected to some degree.

If you are the original purchaser of this revolver S&W might very well correct this as a warranty issue.

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To this I will add, the undersized bullets do allow gas to get up alongside of the bullet, which cancause leading issues, and a loss in velocity as the high pressure gas blows by the bullet.

This guy can get your cylinder mouths squared away:

Cylindersmith.com Hand reamed cylinder throats

As long as those are too tight, that gun will not shoot cast bullets well.

Has anybody here used this place to have cylinders reamed ? How was the work ?

I have used cylindersmith for a Ruger .45 Colt. It shot pretty well before. After reaming and a new patridge sight and trigger job by Alan Harton, it is a real shooter. Turnaround time on the reaming was fast and the work was good.

I have two 625's - one is a 625-8 JM Special. I have three friends with 625-8's. All of the cylinder throats are right at .452" and they shoot EXTREMELY well (well under 1" at 25 yards). If yours are indeed .450" then they do need reamed to correct specs (.452"). As I see it, you have two options. Call Smith & Wesson and see if they'll send you a mailing label. The other is to send the cylinder only to Cylinder Smith for proper reaming. Cylinder Smith will probably give you better turn around but it will be on your nickel...

Choices, choices, choices...

Dale53