Help! A Uberti 73 .357/38 accuracy problem

[Lefty Dude]

A shooting Pard of mine that shoots SASS has a new 73 short rifle. He is shooting 38's, the piece is tuned action very smooth. His problem is, the piece will not shoot accurate at 25 yards. No group every shot is a flyer and they are 8" and more. Loads are his hand loads which he also shoots is his Ruger OMV's. He also shoots this same load in his Marlin 94/.357/.38/. He has been shooting this rifle at standard SASS rifle distances. However this last match there was a bonus target at 30-35 yards, he missed. This past week we benched the rifle at the range and found the grouping problem. I suggested he clean the barrel well and then we would slug the bore. To day he brought the rifle over to my place and we slugged the bore.
Here is were it gets interesting; The first measurement I did with my Micrometer I got .355" groove to groove, the second set of grooves I measured .357".

This is a new one on me, I have never had this happen before.
Has anyone experienced this before ?
Is this the cause of the accuracy & grouping problem ?
What size bullets could he use to be of benefit for accuracy ? .356, .357., .358 ?
What can we do to get this piece to group ?

The load he is using now is a 125 gr. RNFP, sized .357" and he is using Trail Boss powder.

We need some advice from the Choir.
Help! Help! Help!



LEFTYDUDE... I'M NOT SURE THIS WILL HELP BUT WHEN I SHOOT 38 AMMO OUT OF MY '73 I HAVE TO SEAT THE BULLET OUT AT LEAST AN 1/8 OF AN INCH FURTHER.. I THINK THE JUMP TO THE BORE IS TOO LONG FOR THE 38s NORMAL LENGTH AND THE BULLET WHILE SILL IN THE 357 MAG FRONTAL POTION OF THE CARTRIDGE CHAMBER DOESN'T STAY COAXIAL IT TIPS.... LOOK AT A FIRED BULLET AND SEE IF THE RIFLING IS HEAVIER ON ONE SIDE THAN THE OTHER NOSE TO BASE... IF SO THAT'S THE PROBLEM......PACO

[Ben_Rumson]

I've seen two different groove diameters on a slugged bullet.. I'm not positive but I think it was on my Uberti 73 SRC 44-40 ..But I've only shot jacketed through that one so far & it's a great shooter. See how your pard's rifle shoots after the good cleaning...Using .357s seems like a happy medium..What size is he shooting now?

[J Miller]

The proper way to slug a barrel is to push (tap) a dead soft lead slug through the barrel, then measure it with a micrometer. That will give you a much better reading than using calipers at the muzzle.

Personally, I'd up the bullet diameter to .358" and raise the weight to 158grs. I know the cas game is all about speed, but the gun manufacturers still build them to use the most common ammo. In the 38 Spcl and .357 that is a 158gr bullet.

Joe

[PawPaw]

Every firearm is an individual unto itself. What works in one doesn't necessarily work in another.

Something is different with your friend's gun. Maybe the bullets are slightly undersize for that particular barrel. Maybe the twist is different. Maybe the throat is longer or shorter. All rifles are different.

[Lefty Dude]

The proper way to slug a barrel is to push (tap) a dead soft lead slug through the barrel, then measure it with a micrometer. That will give you a much better reading than using calipers at the muzzle.

Personally, I'd up the bullet diameter to .358" and raise the weight to 158grs. I know the cas game is all about speed, but the gun manufacturers still build them to use the most common ammo. In the 38 Spcl and .357 that is a 158gr bullet.

Joe

Joe;

The barrel was slugged properly, and a Micrometer was used for the measurement. The measurments were taken from the Slug not the muzzle with a calipers.
I have loads of 125 gr. that will shoot very tight groups at 50 yards with my marlin 94CBC.
The Slug from this Rifle is giving non-conforming measurements which I have never experienced before. And I have been slugging barrels for 30 years.

[Gun Smith]

Not knowing how the rifle receives the rifling, it seems to me that the bore either is oval ?, or the grooves were cut different side to side ? A bore in this configuration will shoot an oval bullet. I don't think your going to get any accuracy from an oval bullet. I'd slug it again and verify the out of roundness. I believe that this rifle may also want a diet of heavier bullets. I always try to use a cast bullet at least .002" larger than the groove measurement.

[J Miller]

The proper way to slug a barrel is to push (tap) a dead soft lead slug through the barrel, then measure it with a micrometer. That will give you a much better reading than using calipers at the muzzle.

Personally, I'd up the bullet diameter to .358" and raise the weight to 158grs. I know the cas game is all about speed, but the gun manufacturers still build them to use the most common ammo. In the 38 Spcl and .357 that is a 158gr bullet.

Joe

Joe;

The barrel was slugged properly, and a Micrometer was used for the measurement. The measurments were taken from the Slug not the muzzle with a calipers.
I have loads of 125 gr. that will shoot very tight groups at 50 yards with my marlin 94CBC.
The Slug from this Rifle is giving non-conforming measurements which I have never experienced before. And I have been slugging barrels for 30 years.

Lefty Dude,

My bad. I've been reading for almost 50 years and sometimes my brain just don't comprehend what my eyes see.


Joe

[Lefty Dude]

Not knowing how the rifle receives the rifling, it seems to me that the bore either is oval ?, or the grooves were cut different side to side ? A bore in this configuration will shoot an oval bullet. I don't think your going to get any accuracy from an oval bullet. I'd slug it again and verify the out of roundness. I believe that this rifle may also want a diet of heavier bullets. I always try to use a cast bullet at least .002" larger than the groove measurement.

Agreed;
We are going to re-slug the piece tomorrow at the range. The barrel is clean & no lead or fouling. I checked it with my bore light before we lubed the bore prior to the slug procedure . I did notice the slug drove in extremely harder than usual. I always put hoppes bore grease on the slug before I start it in the muzzel. The slug showed a very fine imprint, with no deformities of any type. I did remark that it seemed to have a deep rifling and very sharp and defined grooves as I mic'ed the slug.

Tomorrow when I re-slug the bore I will measure the depth of each groove with my calipers, which I did not do today. This was a surprise and thru us both for a loop so to speak. This is something we did not expect.

If it is an oval bore, I guess he will just have to live with it. It will limit the usefullness of the piece.

[Tycer]

If the larger side is .357" I'd go .358" and then try .359".

[Nate Kiowa Jones]

Hi lefty,
Here's how I like to slug a bore. I like to use a slug of soft lead that is at least 1 1/2 times long than the bore that's being slugged. This extra length assure that the slug doesn't wobble or try to turn in the bore as it's hammered through. This can be verified with short slugs. Measurements will vary depending on where you measure it. The longer slug yields more consistent results. Make sure the bore is clean lead free and lightly oiled, as in an oiled patch pushed though it.
You can drive the slug in from the muzzle if you use a leather or rubber mallet so as not to damage the crown. I like to drive it all the way through to feel and high spots or bulges. I like to use a brass or hardwood dowel that is close to bore size. A rod that is too small can deform the soft lead. Next if it's a levergun I use two wooden dowels just smaller than the bore and cut to the cartridge OAL. These are inserted into the chamber end and the action closed. Next the slug is re inserted in the muzzle end and driven to the wood dowel then bumped up so it's now tight. Now, open the action, remove the dowels and gently tap the slug on out. This will give you a really true picture of the bore just in front of the chamber or farther out depending on how many dowels are used.
To measure I like to use a zero-ed Starret micrometer. I don't think most dial calipers are accurate enough.

Is you slug soft lead and is it long enough not to wobble

[Terry Murbach]

I WOULD TAKE A LONG LONG LOOK AT THE LOAD ITSELF. THE BULLET WEIGHT IS WRONG FOR SUCH THINGS, THE PROPELLENT IS REALLY--REALLY!!-- WRONG FOR SUCH THINGS.
BUT THEN AGAIN MOSTLY ALL THE LOADS USED IN THE SILLY-SASS ARE WRONG FROM EVERY POINT OF VIEW LET ALONE THEIR APPROPRIATENESS DUPLICATING WHAT WAS AVAILABLE IN THE " OLD WEST."
I WILL BET YOU STANDARD CORRECTLY THOUGHT OUT AND CORRECTLY DEVELOPED LOADS WILL SHOOT JUST FINE IN THAT UBERTI.

[Griff]

Can't really add more than what Paco, Terry and Nate said. May be a load issue, but it may also be a bullet issue. Are they swaged or cast? I can't imagine the twist rate in a .357 rifle would be anything but standard, but...? Also, I'd also recommend that bullets be sized at least .358. Have you done a chamber cast to see if it's oversize? If so, it might exacerbate the problems with bullet jump when using .38Special cases.

[Nate Kiowa Jones]

I WOULD TAKE A LONG LONG LOOK AT THE LOAD ITSELF. THE BULLET WEIGHT IS WRONG FOR SUCH THINGS, THE PROPELLENT IS REALLY--REALLY!!-- WRONG FOR SUCH THINGS.
BUT THEN AGAIN MOSTLY ALL THE LOADS USED IN THE SILLY-SASS ARE WRONG FROM EVERY POINT OF VIEW LET ALONE THEIR APPROPRIATENESS DUPLICATING WHAT WAS AVAILABLE IN THE " OLD WEST."
I WILL BET YOU STANDARD CORRECTLY THOUGHT OUT AND CORRECTLY DEVELOPED LOADS WILL SHOOT JUST FINE IN THAT UBERTI.

You sound like one of those AR 15 shooting Tactical Timmy's that thumb their nose at leverguners. The SASS game is not about period correct old west and never was. It's a fantasy game, part history, part Hollywood. The majority of the folks that have come to the game were never gun people. Some come for the history, but some come just for the dressup fantasy B-Western appeal from their childhood. Many of the lady's and youth play the game because those wimpy loads you dislike are easy for them to handle. The SASS game has done more to convert non gun owners into gunrights supporters than any other gun game every before. All gun owners deserve respect.