New 645 jam

[HarryH]

Hi, I was shooting my Model 645 today and had 2 jams that I have never seen before. They were a failure to chamber. The new cartridge had started up into the chamber and was caught with the bullet of the cartridge at the top of the chamber, just inside the chamber, and wouldn't go in. I have used this bullet successfully many thousands of times in this gun, Lyman's 200 grain semiwadcutter.

I have 2 loads that I use with this bullet, a starting load of 3.5 grains of Bullseye, and a heavy load of 6.9 grains of Unique. Today's malfunctions were with the light load.

The gun went to Smith in about 1999 and they put several new parts in, likely including a new recoil spring. But the recoil spring has not been replaced since then.

It is very important to me to be able to shoot my light load and my heavy load with the same recoil spring.

What should I do to be sure to prevent today's failure to chamber in the future?

 

[stansdds]

Shooting a light load and a full power load with the same recoil spring is a very tall order. With the 645/4506, a full power load will typically function best with a 16 pound recoil spring, but a light, target load may not have enough power to fully cycle the slide, which can result in a failure to feed and even a failure to fully eject. Using a lighter, 14 pound spring is likely best for target loads, but will result in the slide cycling faster than designed with full power loads, which can lead to failure to feed as well as battering the impact points between the slide and receiver.

 

[davew357]

Hi, I was shooting my Model 645 today and had 2 jams that I have never seen before. They were a failure to chamber. The new cartridge had started up into the chamber and was caught with the bullet of the cartridge at the top of the chamber, just inside the chamber, and wouldn't go in. I have used this bullet successfully many thousands of times in this gun, Lyman's 200 grain semiwadcutter.

I have 2 loads that I use with this bullet, a starting load of 3.5 grains of Bullseye, and a heavy load of 6.9 grains of Unique. Today's malfunctions were with the light load.

The gun went to Smith in about 1999 and they put several new parts in, likely including a new recoil spring. But the recoil spring has not been replaced since then.

It is very important to me to be able to shoot my light load and my heavy load with the same recoil spring.

What should I do to be sure to prevent today's failure to chamber in the future?

You can try increasing the powder charge from 3.5 grains to maybe 3.8 grains and give that a try.

 

[Rick H.]

26 years is a LONG time for a recoil spring to operate especially if you are shooting regularly with it. My "initial" course of action would be to really do a go clean and polish of the chamber and ramp and replace the recoil spring with one similar to what you have been running. The recommended replacement of a recoil spring is 2 to 3 years of regular shooting or 2,500 to 3,000 expended rounds. This is just common sense with an auto-loader. If you still have problems you may have to dig deeper into it, such as different weight springs for light and heavy loads, but take the best course of action first and easiest.

Rick H.

 

[mscampbell2734]

The later 4506s came from the factory with 2 recoil springs, a 14 lb target spring and a 20 lb duty spring. I agree trying to use one spring for two signicantly different loads is asking a lot.

I'd go to Wolff and order some new springs. Just be aware for whatever reason the Wolff 4506 duty spring is actually the target spring. The full power duty ammo spring is the 20 lb spring they list for the 1006.

 

[stansdds]

Yes, somewhere along the line the recoil spring for the 645/4506 and the 10mm 1006 became the same. Personally, I feel that an 18 or 20 pound recoil spring in a 5 inch 45 ACP pistol is too heavy unless you are shooting 45 Super. I expect the use of a common spring was more for reducing logistics and less about pistol reliability.

 

[HarryH]

Thank you for all of your responses, It's great to have so many people who are knowledgable about Model 645. I have ordered from Wolff a 14 pound factory equiv spring and we'll see how it handles my starting loads. Thanks again.

 

[mscampbell2734]

Yes, somewhere along the line the recoil spring for the 645/4506 and the 10mm 1006 became the same. Personally, I feel that an 18 or 20 pound recoil spring in a 5 inch 45 ACP pistol is too heavy unless you are shooting 45 Super. I expect the use of a common spring was more for reducing logistics and less about pistol reliability.

I agree the 20lb spring IS excessive. But the more I teach and shoot the more I'm convinced Smith did it because a lot of shooters are lazy SOBs who think a spring should last the lifetime of the gun. By starting with an extra heavy spring by the time 25k rounds have been fired that extra heavy spring is down to what it should be and still functional

 

[Frank Black]

My 645 has never hiccuped whatsoever with my handloads. When I got it, I replaced the recoil spring (obviously being of unknown round-count to me) with a Wolff 17lb spring.

My handload runs a 230grn coated hardcast RN slug (H&G #34 profile) over 4.8-5.0grns of Bullseye. That’s not a max load either, more like mid-range. Very accurate and no jam-skis.

 

[Fastbolt]

This what S&W offered as a recoil spring kit for the full-size .45's in the 90's.



These were the part numbers for the set of springs and the separate springs.
193020000 RECOIL SPRING SET (20071 & 20161) $2.50
200710000 RECOIL SPRING - WADCUTTER $1.45
201610000 RECOIL SPRING - STANDARD

Hmmm, dunno why the linked pic isn't appearing ... (Okay, now it is )