20 GA Ultra Slug mis-fires

[student]

In trying my roundball loads in my new Ultra Slug barrel, I have been getting frequent misfires (about 40% of the time) where the firing pin has only made a small dent in the primer.  Sometimes I can recock the hammer and it will fire, but many times it won't.  It seemed to be related to how firmly I close the action, but I still have cases where the firing pin won't dent the primer deeply.  I also thought it might be related to the transfer bar, but even with very careful conscious trigger hold back it misfires.

I have never had a misfire with any of my rifle barrels.

Do you have any ideas beyond back to the factory?

Student

[044]

Student,did you do a trigger job on this gun?Did you try factory slugs before you tried your round ball loads?What kind of a press or hand primer did you use?Another possibility could be the brand of primers,some fit tighter than others and seat differently.I have noticed the difference in my sporting clay loads.

[student]

Griz -

I have not fired any factory ammo in it.  My gunsmith did a trigger job on it, but I have fired many rifle rounds (factory and reloaded) with nary a mis-fire  I used a Lee Load-All press, the shells are Win AA (the new type).  When I examine the seated primers, they seem just like anything else.

I guess I can try some factory ammo, and maybe some different hulls for reloads.

Thanks for your ideas.

Student

[scruffy]

Could you just have a set of hard primer???  Maybe a new batch of primers will fix you problem.

I'd also clean the dickens out of that thing.  There are others here that can give advice on what to spray down in it to clean it out (I'd use break cleaner and then spray a small shot of remoil but I doubt that's what your supposed to do).

If it's clean, different primers still fail to fire, I'd have the head space checked.  Maybe the chamber is cut wrong (rim too deep).

later,
scruffy

[student]

Scruffy, I followed your advice and cleaned the trigger/hammer assembly real well with brake cleaner, and was able to get reliable ignition with primed (but  not loaded) hulls in my backyard.  I loaded some more rounds, but with my new lot of primers, and went to the range.  

The new loads did pretty well, not 100%, but about 90%.  I think I have a number of factors coming together here, but I think I can solve all these problems by using Remington Peters SP  hulls instead of the new AA.  That seems to be the most important factor.

Thanks for your help.

Student