Wobbling bullets.

[Black Jaque Janaviac]

I posted this on the SASS wire a few day ago then it got buried rather quickly.

My first handloads for my .357 Rossi seemed to be wobbly.  The holes in the paper are ever-so-slightly keyholed.  The groups are so-so.  The direction of the keyhole is never consistant, although the amount of the keyhole is.

I suspect the bullet is just wobbling, not tumbling.  

How do you correct this?  

With 5.0 grains of Unique in a .357 case, I wouldn't think they're fast enough to lead the barrel excessively.

I'm using home-cast 158 grain RNFP.  Tumble lubed with Liquid Alox.

[John Traveler]

Hi, Black jack!

When the ,357 Rossi carbines first came out several years ago, some gunwriter described what you noticed, namely possible bullet tumbling with factory lead WC loads.

That 5.0 grains of Unique in a .357 case sounds pretty mild.  Have you tried anything with higher velocity?  I like Unique too, but only in full-charge lead bullet or hot .38 special jacketed bullet loads.

Tumbling of lead bullets generally indicates poor bullet- to-bore fit, or understabilization from low velocity or slow rifling twist.  Have you slugged the bore to determine bore diameter?  What weight and profile are your bullets?  RN?  SWC?

Let us know how it works out.

[Black Jaque Janaviac]

Thanks John.

158 grain RNFP from Lee dbl cavity mold (358-158-RF).   Cast with wheel weights.

No I never slugged the bore.

As-cast, they mic out at 0.360" if I just touch the caliper to the bullet surface.  If I put a little pressure on it, they mic 0.358".  The bullets look a little frosty which may explain the difference when pressure applied.  Some of them look exactly like galvanized sheet metal with the little "flakes".  They drop out of the mold shiny, but cool frosty.

I considered the fact that the charge was light.   But people shoot .38 spls in these guns with little complaint.  Perhaps Unique is not the powder to try with these reduced charges.

Here's what I'm thinking of trying:

In addition to tumble lubing, I might try pan-lubing also.   Just in case it's leading.

Or, I'll try increasing the powder charge a bit.  5.0 grains is under the normal minimum in the Lee manual.  But it's above the maximum for Unique's "Cowboy load".

I also might try loading these in .38 spl cases.  5.0 grains is over the Lee Manual's max for .38spl.  I suppose I'd have to drop back down and work up to that point - unless someone advises me otherwise.

[HWooldridge]

You can test your wobble theory by shooting into a good sized phone book a few times at the same range and examine the bullets to see if they are tipping.  You could also shoot a round or two into a deep water trough and inspect the slugs for barrel fit and whether you are getting some skidding across the rifling.  Most modern carbines have a very mild twist so won't stabilize a long bullet without some decent velocity but 158 gr is a standard weight and you would hope the maker designed it correctly.  If you have a variety of bullets, try a 148gr or lighter with the same charge - it should be a clean hole.  Conversely, anything over 158 gr with the same charge will be worse.

The galvanized look is the W/W alloy - pure lead doesn't look like that.  A hot spot will be frosty with a small, tight grainy look and the area is usually sunken, which is cause for rejecting it.  If you push a clean, dry, tight patch thru the barrel, you should know quickly if it's leading.  Good luck...Hollis

[John Traveler]

One last thing I forgot to mention:

I've examined several Rossi rifle barrels that a Rossi repair dealer had at one time, and was astonished to find many rifling defects including ragged grooves, rough reamer marks on lands, uneven grooves, chatter marks, and marks by obviously chipped cutters, etc.  

These were all .22 rimfire barrels, and the gunsmith said that he saw a RATION of them back in the 1980's.  He had a warranty repair station and did a lot of fixing of new rifles.

Dunno if your model rifle was affected, but maybe slugging the barrel is in order?

[Black Jaque Janaviac]

John,

It shoots factory ammo fine.  So I would think the rifling is OK and it's more something to do with the load.  

I recovered some bullets from the melting snow and they look OK.  Rifling marks are clear.

Would slugging the barrel make rifling defects obvious?  What would I look for?  Can I look for that in the recovered bullets?

The gun isn't particulary old.  It's in excellent shape.  Has the safety on the top of the bolt.  And is imported by LSI, if that helps give an indication of the date.

Also, the accuracy isn't horrible.  Not at 42 yards anyway.  It's certainly within minute-of-pop-can.  I wonder if it could be a crimping thing too.  Not enough and the Unique doesn't get going fast enough?

[John Traveler]

OOPS!

Your mention of the word "snow" tipped me off on this one.

What are your ambient temperatures?

Some powders do not function well in extreme cold.  Try a different powder, and hotter primers.

Yes, examining recovered slugs can clue you as to whether the bullets are skidding through the rifling.  But you indicated that the rifling marks are clear.  "Slugging" the bore will determine if groove diameter/bullet diameter are compatible.  It will also reveal tight and loose spots in the bore.

You say that it shoots factory ammo okay, and you get tin can accuracy from your loads?  that sounds normal enough.

Let us know how you make out!

[Black Jaque Janaviac]

John,

Hey thanks for the tips.

I reloaded some with 5.6 grains Unique and there seemed to be some improvement - so I think I'm getting somewhere.

THEN, I tried warming a few cartridges in my front pocket.  I don't know if it cured the wobble completely but it sure as hell tightened the group!  Put 4 out of 5 in a 1 1/4" black dot at 42 yards.  Thanks to the black dot, I can't really make out whether there's much wobble or not.  But the one that flew wide seemed to hit straight on.

So, this load is finicky with the outside temp.   :noway: