Ruger 4 5/8 3 screw w/45 ACP Cyl


Well-Known Member
Looking at Creeker's post the other day inspired me to try the 45 ACP cyl that came with my gun years ago. Went out to the range today and not a single round would fully seat in any chamber - bummer. Shot other guns tho. To make a long story short, I discovered that no sized case (no bullet involved) longer than .889" would seat in the chambers. According to Hornady, .898" is the spec length for 45 ACP cases and the cases I measured were more like .891-.898 and would not fully seat. So, I watched Lynn shoot his 45 ACP cyl so I know his works, how about others ? BTW, even some factory jacketed ammo would not fully seat.


Well-Known Member
my Ruger conv cylinder (New Model Flattop) will pass the plunk test with a 1.225" coal H&G #68. And shoot it very well.

PS: Posted and then saw where you said factory won't plunk test. Send it back!
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Well-Known Member
It's an unconverted 3 screw from Dec 1970, no way is it going back. It shots 45 Colt (w/the Colt cyl) very well and many of my 45 Colt loads are 45 ACP level, so I don't really mind that it doesn't work, I was just surprised and wanted to know if it was a wide spread problem or not.


Staff member
Make a pound cast of the front of the chamber and start of the throat. Is it just a tight chamber?

Don't blame you at all for not wanting to send it back. Too good a gun for that.


High Steppes of Eastern Washington
You realize that the case does not fully seat? It only goes into the top of the extractor groove? At least on two of the early ones I owned. Not trying to be a smartaxx, but did you try and rotate the cylinder? Ric


Well-Known Member
Keep working with it Cherokee,I think you're gonna get it straightened out. Don't blame you for not wanting to send it back either.Good luck.


Active Member
My Blackhawk conv. had to go back because the ACP cylinder looked like they reamed it with a cement block. They did replace the cylinder and it does shoot fine now but anything over .451 must be seated to the case mouth.
On another note, I put a Power half cock trigger kit in it and it would only cock sometimes. Most of the time it would not stay cocked and fall to half cock. I checked trigger pull weight and with the 17 lb. mainspring it has 24 oz. Removed the kit called Brownells and sent it back.


Well-Known Member
In almost 60 years, I have never trimmed 45 ACP cases and don't plan on trimming them either. As to fully seating, if the case seats enough to rotate past the loading gate (most don't), they hang up on the recoil shield (a hard stop, can't force it) and I have to remove the cylinder, then the case drops out of the chamber. DougGuy can fix it for me if I want to spend the money.


High Steppes of Eastern Washington
OK, Cherokee, that is probably the right solution. There was a problem with early .45 ACP cylinders have headspace issues and chamber tolerance problems also. Sent one back to Ruger and fixed the other one myself.


Well-Known Member
Sounds like you need to determine minimum protrusion necessary to clear the recoil shield, then add enough to that to make .898" and have all the holes touched up to that depth. DougGuy will need some measurement to work. I have a .45 ACP standard reamer you could borrow but it has the wrong pilot for revolver throats.