Marvel conversion with Federal HV Match Gold Medal

I recently switched from Eley Sport to Federal Premium HV Match Gold Medal and on a couple occasions I've experienced two shots for one trigger pull.  I tracked down the cases from those shots and this is how they look:




Obviously the rounds were fired before the case was fully into battery, hence the bulge at the bottom, and the strikes on the rim seem to be a bit lighter than normal.  I'm using the same lower for my service pistol, and the half-cock notch is good so the hammer isn't following.  I still have the stock recoil and firing pin springs installed that came with the Marvel conversion.  

I'm thinking that the HV ammo with the stock recoil and firing pin springs are causing the firing pin to rebound and hit the rim as the round is on the way to be chambered, causing the firing before it is fully into battery.  Perhaps I need a bit stronger recoil and/or firing pin springs with the HV ammo?

Has anyone seen anything like this when firing HV ammo out of the Marvel conversions?

Every Marvel I've seen to some degree or another bulges the cases even with SV ammunition. My older Marvel longslide will shoot 9/16" at 50 yards, so even though I don't like the bulges, it doesn't seem to effect accuracy. From what I was told it has something to do with how chambers were cut. The Nelson doesn't seem to do it as badly. 
Jon

These bulges occur when fully in battery as well. If pistol wasn't in battery the disconnecter would prevent firing. 
Jon

I have never seen bulges like that out of my Marvel.
But have seen that in a 10/22 on occasion but not the topic here.
If I did, I would stop shooting that ammo and find out why it is happening.
The hammer should not follow if the slide is out of battery.
There is a tolerance of what is out of battery and have seen some that would do it.
Some shooters would put a piece of credit card to slightly hold open the slide to dry fire a Marvel and the hammer would drop.
My Marvel will not.
I am no gunsmith but someone will come along.

Clarence

I had that happen with my first Marvel when using Federal 711b, only ammo it happened with. Federal 711 also went full auto in my IZH-35, only ammo to do that. There might be a tolerance stacking problem with your Marvel and that one brand of ammo? Fat case heads and minimum headspace on the unit can cause a slam fire.

Every other case looks normal and doesn't bulge, only the two that resulted in the double fire had the bulge.  I'm wondering if the firing pin is rebounding on its own due to the HV causing more violent movement of the slide than the SV I was shooting before?  Could also add to it that I've heard the Federal is more sensitive and strikes that weren't setting the other stuff off are setting this off.

I'd really like to get this ammo to work as I had a pretty decent stash of it fall into my lap...

When I built the homemade IZH, I had something similar happen when testing is with some cheap HV 22. Lightning I think it was called. I too fell into a pile of it at almost no cost to me. In my gun it was partially opening too soon. I'm not sure how a HV .22 is made but it may use a slower burning powder. (my guess with no facts to support it) It may begin to push the slide back until the pressure rises enough to swell the case and hold it in the chamber until the pressure drops allowing the case to push the slide back since a .22 is simply blow back with no locking lugs. My cure was to increase recoil spring compression weight.

I tried the heavier spring on my Marvel but it wouldn't cycle.  So I stuck with the 8# spring. I haven't been shooting my Marvel, so next week I'll try it with Lapua, CCI SV, Aguila and RWS R50 and see what results I get.
Jon

Jon Eulette wrote:I tried the heavier spring on my Marvel but it wouldn't cycle.  So I stuck with the 8# spring. I haven't been shooting my Marvel, so next week I'll try it with Lapua, CCI SV, Aguila and RWS R50 and see what results I get.
Jon

 Were you using HV ammo?

Frank

No. All SV match.
Jon

Just a theory but if you have ever watched a slow motion video of a 22 bolt going into battery well they bounce. It happens so fast the odds you would be pulling the trigger at the same time would be near impossible BUT if the rim of the round is too thick (out of spec) I could see them going off as they are slammed into battery. They would possibly go off as the bolt bounced causing the bulge, again just a theory. The firing pin strike may have come after the round went off.

- Dave

You do change out you recoil spring every 5,000 rounds (case).

Gus

I'm assuming that with the Eley the gun worked OK. Seems that the cause is the HV ammo. If it were me I would attempt to determine if the bulged case round is the cause of the double or the result. Not knowing the Marvel well I don't know if the slide stop can be inserted so the the stop is not in the hole so that it will not hold the slide back after the last shot in the magazine is fired. I do it sometimes on my 1911. I would then load one round in the magazine and fire a number of rounds looking for a double (hammer down on empty chamber) I would capture each empty case and inspect it.

I just remembered working on Marvel with dirty chamber before that wouldn't completely seat rounds into chamber and bulged cases like that. Most Marvel's will fire with slide out of b a there considerably more than other pistols. My bulged cases from my pistol are barely bulged in comparison to your photos. So I would double check chamber for build up preventing complete chambering. 
Jon

My marvel would double due to slam fire from the extractor.  The roll pin would not be centered in its hole and that would cause the extractor to bind.

Rob i don't think the extractor could cause a slam fire. The Marvel slides are extremely light and cycle at a very high velocity in comparison to steel .45 slide. Most common reason for slam fires is short sear and probably a less than ideal half cock notch. The lighter slide causes a bounce when going into battery. The bounce will cause hammer to follow. I work on many pistols that the half cock doesn't work properly.  It's easy to get a 2.5# trigger job on a Marvel,  but 2# needs more expertise. I spoke to Larry Nelson about the chamber issue of bulging before and he said it's the way Marvel Precision was cutting their chambers. The Nelsons I've shot don't seem to bulge the cases like the Marvels.
Jon

All of my triggers have mile long hammer hooks and 4lb triggers.  There was no hammer follow.

The doubling only occurred when the extractor roll pin backed out causing an immovable extractor.

How would that cause a double? Immovable extractor only relates to feeding of next round (I would think extraction wouldn't be an issue). Next round from magazine would probably slide under extractor during feeding similar to feeding .45 round. You know another thing that is common is if the trigger stop isn't working as a stop, they can allow too much trigger travel which will allow pistol to double. Recently saw that with 2 low end .45's.
Jon

I don't know Jon. I can send you the old slide if you want to figure it out.

If it was the lower, wouldn't it double with the new slide or the Advantage Arms conversion that I use now?  Wouldn't it double as a .45?

Jon Eulette wrote:How would that cause a double? Immovable extractor only relates to feeding of next round (I would think extraction wouldn't be an issue). Next round from magazine would probably slide under extractor during feeding similar to feeding .45 round. You know another thing that is common is if the trigger stop isn't working as a stop, they can allow too much trigger travel which will allow pistol to double. Recently saw that with 2 low end .45's.
Jon

Depends on how it feeds.  If the round just bounces around and the extractor pops over the rim when it closes then it can slamfire if the extractor is frozen.

I would think that if extractor had to snap over the rim that it would slow the slide velocity and not slam fire? Gonna have to give this some more thought. 
Jon

For clarification are we talking slam fire from firing pin inertia or hammer follow down? Thanks
Jon

I'm thinking slam fire from firing pin inertia due to the HV ammo. I'm using my service pistol lower and can't get the hammer to follow and the half cock notch is good.

Been giving some thought to Rob's post. I never considered the possibility that the extractor could act as a firing pin if it became rigid. I feel enlightened :p)
Jon

you might want to check the federal rounds. I had several cases that had larger rounds in them than my aw93 would chamber. I had to switch to eley or aguila to get rid of the problem, mine didn't bulge the case cause the rounds would no chamber far enough to fire.