[Abby'sDad]

Loaded up 350 rounds of 38s using 4 different powders and 4 different bullets. Guns in question are my 66-2 I bought new ~1980, and my dad's NYPD M&P from 1950.
The issue was there were several (many overall) that would not chamber in the M&P but easily chambered - as in dropped right in - in the 66.

Were the older guns made with tighter chambers?

Also interesting was how the older M&P shot some loads MUCH better than the 66, even though velocities (over the chrono) were right about the same..........

Any insights?

 

[jonesy814]

Was there a specific headstamp of brass that did that?

 

[series guy]

A few years back I picked up a really sweet 1905 target model. I took it to our club pin shoot the next day knowing that someone would have some spare .38 Special rounds so that I could shoot my new to me gun. One shooter had a bunch of spare rounds but even though they dropped right in her Model 686 they wouldn't chamber in my 1905. Her father loads for her and doesn't roll crimp his loads. I have never had an issue with any of my loads but obviously the old gun had tighter chambers.

 

[59dexta]

I had that problem a few years ago. 38 special dropped into my model 10 and would not push into my Italian colt repo. Found the carbide sizing ring was no longer in the RCBS die. I bought it used so was it ever there? Now I make sure the due do not touch the shell holder so there is no chance to damage the carbide ring.

 

[jeepnut]

As far as accuracy were there some lead bullets and some coated/plated bullets. Found that a few years ago the forcing chamber was a little larger than guns made in 70s and later. Newer guns with the smaller forcing cones were made for the newer plated bullets. If memory serves, older guns were 13 degree and newer were 11 degrees (as a rule). My older revolvers all are more accurate with lead bullets. The chambers have been covered.

 

[Davwingman]

Model 66s are chambered in 357 Mag which means the chambers are about 1/10" inch longer than 38 Special chambers. I would be looking,checking your 38 rounds to see if perhaps they were slightly overcrimped thus creating a slightly bulged case just behind the crimp. Sometimes this is also the result if some slightly long cases being crimped too much. Because of the longer chambers in the 66 they will chamber with a slight bulge caused by overcrimping. You can check for this bulge with a measuring tool or just use a Magic Marked on the outside of the case & push the round into the 38 chamber. Where the Marker is rubbed of the case will tell you where the problem is.