Help! - Long slide short cycling

[Rod4277]

I’m looking for some guidance. I didn’t put the detailed firearm description in the title because I’m looking for some more generic trouble shooting information.

I’m having a short cycling issue with a semi-automatic pistol.

Here are the details:
Firearm: AMT Automag III – 30 Carbine
See the attached document with pictures, parts diagram and picture of new and “original” recoil rod spring.

Firing sequence: Manual cycle slide for first shot > Fire > spent shell ejects > next shell in magazine chambers with proper lock-up > attempt to fire second or subsequent round does not fire > pull back hammer about 1/8 inch it clicks 9short cycle) > attempt to fire successful without any jams and it fires every time as long as you pull hammer completely back.

I have tried different ammo including Federal 110 gr. SPRN. The gun is accurate and fun to shoot except for the short cycle issue.

History - The gun is recently purchased with original box and paperwork. It appears to be in very good condition and not fired very much. It was very dry so we gave it a good cleaning and lubricated it generously. We have put 60 rounds through it.

I had a gunsmith recommendation to shorten the Recoil, Rod spring. The plan is to shorten the spring to decrease the tension and increase the travel of the slide. I purchased 2 brand new springs. I was surprised to find that the new spring were about 1 inch longer that the original spring. See the attached picture. I wonder if the springs are cut during factory assembly or someone else was experimenting too. I’m looking for a reality check here. I hope someone out there has some expert advice.

Have a great day!

 

[rcmodel]

It's normal for a brand new spring to be longer then a used spring that has taken a set.

As for shortening the spring?
I suppose you can try it, since you have two back-up springs.

rc

 

[Walt Sherrill]

As mentioned, new springs will always be longer than springs that have been used. (Coil spring will take a "set" with time/usage and then not become a lot shorter.)

It could be that the recoil spring is TOO STRONG for the ammo you're using. You could try cutting a coil off the existing (old) recoil spring -- since you have a replacement spring on hand. Or try hotter ammo.

Before you cut anything see what happens with the new recoil spring installed and some also try some hotter ammo.

 

[Rod4277]

rcmodel: Thanks for your reply and info.

I read a thread on another forum that supports what you said about the spring taking a "set". In this case the thread was refering to a 1911. But this thread indicted the spring fatigues over time and use. It also indicated to replace the spring when it was about and inch shorter than a new one. So I guess I should at lease give the new spring a try first. Then I can try trimming it. I just don't know how much and the Automag isn't as easy to disassemble as my 1911A1. The barrel bushing is a tight fit and you can't use a bushing wrench like you can on the 1911. If the issue was on my 1911 I would prepare a couple springs and change them out in the field.

Thanks again for your input.

Rod

 

[Walt Sherrill]

The "inch shorter" rule isn't a good one... (That rule assumes a standard spring length, and there isn't one... It would depend entirely on the specific model (barrel length, the weight of the spring, and how it is made -- there are more variable than just length).

There are a lot of variables, here...

You can try shortening the OLD recoil spring by a coil, and see how it does. If that doesn't work, try the new spring. It may be that the old spring was just too stout (or the ammo you were using was weaker than needed to work with that spring.)

You may have just gotten hold of some underpowered ammo, too -- unless you're hand loading. Try other ammo before doing anything more drastic.

(The other option is that you're accidentally "limp wristing" -- something that's possible with a new/different gun. This is less likely, but a slim possibility.)

.

 

[VAPOPO]

My thoughts would go toward the ammo, Reloads? Wolf? Bullet weight? etc try using only full power ammo from Winchester, Remington or maybe some hotter reloads with heavier than normal bullets. Standard for the .30 carbine is 110 grains right? As a side note a lot of AMT designs were notoriously finiky on what they would feed and were very sensitive to bullet profile so I would focus on FMJ rounds and make sure they feed first.

 

[Rod4277]

Thanks fot all the replies. I live in a very small town here and 30 Carbine Ammo is scarce here. I have only been able to try two typws so far. I was lucky to find Federal 110 gr. SPRN ammo and that's really all I have right now. I tryed on other brand that was steel cases the first shot fired but the shell would not extract. I had to drive it out with a cleaning rod. I should have known better then to buy steel case ammo. I'll get some Winchester or Remington 110 gr. FMJ's on order as VAPOPO recommended.

Also, I do reload but don't have 30 Carbine dies yet.

This gun is a "blast" to shoot and I'm able to shoot 2 1/2 - 3 inch groups at 25 yds which isn't bad for an oldtimer with old eyes. It will be even more fun when I solve the short cycling.

Thanks again for the advice!

Stay tuned!