My Pietta 58' w/ 5.5" barrel


August 10, 2008, 10:52 AM
Hello all.

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 here, & Firing Line 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 here" & 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 some picture later today.

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Bad Flynch
August 10, 2008, 12:55 PM
Try lowering your powder charge to around 22 grains of FFFg and using a filler wad to make up the difference in volume. Most target shooters shoot loads in that range.

August 10, 2008, 02:31 PM
I've tried from 20 - 40gr. charges & it wasn't any real improvement.

I've tried my hand at benching this piece & even single chamber shots to see if it'd show improvement but not really, think that the blowby was effecting the shot just enough to make the shots inconsistent.

August 10, 2008, 10:18 PM
Here is a few pictures of it & it's rig.
Not only did I Ream the chambers to be slightly larger than the Grove diameter of the Barrel but I also modded the rear of the cylinders to allow the use of the snail capper, & while I was waiting on the reamer I smoothed all the edges & lightly blued them to give that worn but not worn out look.

Oh and please forgive the fact that she's loaded, but I've gotten her ready for her next outing.

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