Light firing pin strike problem - 20 gauge ultra slug hunter

[lost.in.indiana]

Hey there-

Got a question that I hope someone can help me with.  I have a 20 gauge ultra slug hunter that I've had for 3 years now.  I have exclusively used Lightfields for the past 3 years with no problems whatsoever (misfire, or anything else).  I tried several different brands when I found that the Lightfields grouped the best.

So here's my issue:  I came across some Winchester Partition Gold slugs (2-3/4", 1900fps, 260 grain) really cheap a while back at Meijer so I bought 7 boxes.  I went to the range to see how they would shoot, and the first round didn't fire.  I tried firing it twice, and no luck.  The primer had an indentation on it, but compared to the Lightfields, the indentation wasn't nearly as pronounced.  I did nothing to change how I was shooting (same rest, same squeeze, etc).

The next 4 Winchesters fired just fine - and they grouped extremely well, with their POI being just about an inch right of the Lightfields at 50 yards.

I went to the range yesterday to see how they would perform at 100 yards, and the first two went into the same hole.  The third - didn't fire the first time.  The second time I pulled the hammer back, got a good sight picture and squeezed the trigger - boom - it fired.  I fired a fourth round with no problems.  They grouped exceptionally well (<2" at 100 yards).

This makes me a bit nervous to hunt with this round as 2 out of 10 rounds have failed to fire on the first time. 

Is it how I am pulling the trigger that is causing this?  Any ideas why these rounds are being finicky in my gun when no other round has ever caused a FTF?  Is there anything I can have done to the gun to make the pin strike "harder?"  I really love this gun, and like the ballistics of the Winchester rounds.

Thanks for your help / thoughts.

[quickdtoo]

Weak hammer springs are a known issue, you can get replacements from Brownell's, Numrich or Wolff, trigger work is covered in the FAQs. Since it only happens with one type of ammo, I'd suspect a headspace issue caused by thinner rims on that ammo. If you're pulling the trigger all the way to the rear instead of releasing it as it breaks can cause the transfer bar to fall before the hammer can strike it, it will cause problems. The easiest way to fix the problem if it's a headspace issue is to remove a few thousandths from the face of the hammer where it stops against the frame, this will allow a little deeper pin strike.

Tim

[lost.in.indiana]

This is really helpful - thanks.

Is there any way to polish the hammer enough while it is mounted to improve the pin strike?  I don't know if I want to go and disassemble it tonight... and hunt tomorrow with it, if you know what I mean.  I have a dremel tool with the standard set of attachments.

Thanks again Tim.

[quickdtoo]

I use a dremel cutoff tool to trim mine, just cock the hammer and touch it with the tool, I just walked Pete thru this same thing on a Sportster. 

Tim

http://www.gboreloaded.com/forums/index.php/topic,188998.msg1098941981.html#msg1098941981

[lost.in.indiana]

Awesome - thanks so much for your help Tim.  I'll give this a go tomorrow after the morning hunt.

John