My Pietta 58' w/ 5.5" barrel
When I bought my Pietta 58' NMA w/ a 5.5" barrel from Cabelas in November I was impressed with it's fit & finish & how handy it seemed since it has a shorter barrel than my 23 year old Remington copy but when I took it out I found that it's grouping capability was not what I was hoping for, no matter what powder charge I used it was a so so performer.
Well after running 100 rounds through it & smoothing up the internals it still was a mediocre shooter & after reading a few posts on The High Road, & here I found what may have been my achilles heel.
One was that 2 of the cylinders were just slightly off in alignment "not much but I could see just a slight touch of the chamber in the bore as looking through the barrel.
& then there is the chamber to barrel dimentions.
Grove diameter: .4495
Lands diameter: .4400
Chamber diameter: .4460 - .4465 in the 3 cylinders I have for it.
Curious I talked to Rifle "on THR" & he pointed me twords Manson Reamers to acquire a reamer to increase the chamber diameter to .4500 or maybe .4510.
Well Friday my .4460/4510 reamer was home & I reamed the first cylinder & checked the alignemnt.
Nearly perfect, I had to try to look for the chamber while looking through the barrel & yesterday after running 3 full cylinders of .457 144gr. Ball with 40gr. FFFG Goex I see that I did not take too much metal off & seems to Proof good & will hold up to my normal load of 35gr. FFFG Goex or less with no ill effects & even with 40Gr. my last full cylinder "where I tried to aim my shots" it showed very good promise of accuracy where I was able to achieve a very respectable 4" group at 20 yards "compared to a before best group of 4" with just 30gr. @ 15 yards."
Next weekend will give me time to run some aimed shots through it but already I see that this decision was well worth the effort.
I'll post pictures later today.