19-4 - 1st firing of 158gr LSWC - horrible groups

KeithNyst

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I have a S&W 19-4 357 I recently purchased. I get good groups with Remington and Winchester 38 special 130grs. Today I loaded up some 38 specials with 158gr LSWCs with Unique (4.2, 4.4 and 4.6 grain) to try them out. Roll crimped at the crimp groove. .... horrible groups, at 25 yards bullets were all over the paper.

I measured the cylinder throats with my Brown & Sharpe caliper … all are in the .354 to .357” range. I’m thinking the throats are too small, resulting in swaging of the bullets to a diameter too small for the barrel lands to engage the LSWCs. This is my first revolver, so I’ve never encounter this before. I never had a problem reloading LSWCs for my .45 1911s. Feedback/guidance would be appreciated.
 
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My M19 6" with 4.4grs of Unique was a light load that did not do well either.
5.0grs of Unique at 909 fps was a lot better in accuracy.

I got the 158gr LSWC up to 1014 fps with a heavy load of Unique in the 38 special loading.

I got my best accuracy in the 357 case with Unique kicking out a medium load at 1133 fps.

Lots of powders will work with the lead 158gr bullet............
Good luck.
 
What does the barrel slug out to be? Also, did you run the mike on a few of the SWC's?

I have not slugged the barrel. That is on my list to do ... will pick up a few 1/4oz bell sinkers next time I'm in town. I did mike a few bullets; they run a tad over .358, a few ran .359.

FWIW ... firing from 19-4 6", I chrono'd 7 rounds of each Unique load. The 4.2s averaged 820fps with SD of 18; the 4.4s averaged 870fps with SD of 16; the 4.6s averaged 903fps with SD of 12. I know the 903fps sounds high for 4.6grains; but I used check weights on the balance and went from the balance to a digital on every round ... perhaps an indication that the lands are not digging into these bullets.
 
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You cannot accurately measure the inside diameter of a cylindrical hole using a dial caliper, simply cannot be done! Second, you cannot accurately measure the diameter of a barrel slug from a barrel with an odd number of grooves! This requires either a "V Anvil" micrometer with the legs of the anvil having the correct included angle for the number of grooves. For 5 grooves that is 108 degrees. You can also use the appropriate gauge block, a standard micrometer and the correct formula for the gauge block you have. The "V anvil" micrometer will run $400-600 or more. A gauge block probably less than $50, but I know of no current source.

Contrary to popular myth you don't have to know the groove diameter of your barrel, only that it is no larger than the cylinder throats! Slug the barrel and try the slug in the cylinder. Ideally the slug will pass through the throats with very slight resistance, but not fall freely through. If the slug does fall freely all is not lost as cast bullets should be .001-.002" larger in diameter than the groove diameter anyway. Simply slug the cylinder throats and size (or order) your bullets accordingly.

BTW, did you even measure the bullets you bought, or just take the makers word for diameter? That may be the problem! For .38/.357 buy bullets .359-/359"! Most cast bullet sellers size their bullets to .357", too small for good accuracy. They also cast them 18-22+ BHN, this is far harder than needed for revolver bullets and can cause leading. .38 Spl. will do far better with 10-12 BHN, and .357 no harder than 15 BHN! They cast them hard because most consumers have bought into the "The harder the better" BS because they really aren't cast bullet savvy!
 
Alk8944, I did mike about a dozen of the bullets. Most were just a tad over .358" (none under .358) and one was .359". They are BH 18.

I'll pick up some lead bell sinkers and slug the barrel and then drop into the cylinder. Thanks for this info. Keith
 
I assume that you're shooting your 19 from a solid rest to check group
size at 25 yds to test the gun and not yourself? I agree with the above
statement that you can't measure cyl throats with calipers. But I doubt
that undersize throats are your problem. I would try a different powder
if I were you, something faster burning that works better at std 38 spl
pressures like 231 or 700X or Bullseye. Some dedicated cast bullet
shooters think that it's necessary to clean all copper fouling from a
bore before shooting lead through it to get accuracy. Since you're
using 38 spl brass in 357 chambers make sure your chambers don't
have leading in front of your brass.
 
With 'sd' of only 12-20' l would say the accuracy problems are not in the loads. Undersized bullets cause very high variations in velocity due to gas leakage. Maybe check the barrel muzzle crown for nicks and burrs
 
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Jes my suggestions for beginning lead shooters. Slug the barrel. Slug the cylinder throats. Measure with Micrometers. Unless made by a drunken monkey, I doubt if any S&W cylinder throats run .354". Forget the "slight pressure to push a bullet through the throats" method and measure the bullets and throats. 95% of the time this will eliminate/reduce leading and give good accuracy (but you may need to "tweek" the loads and bullet diameters). I have used wheel weight alloy and range lead (11-13 BHN) for my .357 Mag. and .44 mag. bullets and have driven them to Magnum velocities without leading mainly because they fit the guns...
 
BHN 18 lead bullets do their best at the top velocity in the
38 and 357 weapons, do to their hardness.

Target loads should have a 12 BHN if possible....... even lower
since most are under 900 fps.

You might try 7.0 grs of Unique in the 357 magnum case and see if that 18 BHN bullet will settle down at 25 yards, with a 88% loading.

Good shooting.
 
Look at the rear of your bullets. If they are bevel & not round that could be a problem. I shoot all flat based lead in my wheel guns. My 19-5 2 1/2 does not like bevel base lead. Your 4.6 of unique should be dead on. I shoot 4.7 @ 50 yards with a round nose bullet 6 inch barrel k frame 38 special. Let us know what the fix is.
 
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Before you go beating you head against the wall and slugging , micro metering ,measuring etc.
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Perhaps get some softer bullets like 12 BHN and try those,? As Nevada posted above.

You shooting single or double action, Shooting a revolver as why mo different than a semi auto.:)
 
Pin gauges for measuring cylinder throats, and slug the barrel, but you cannot direct micrometer or caliper read the slug from an ODD NUMBER rifling (S&W), as mentioned in post #5 above.
 
Almost impossible to accurately measure throats with caliper. Pin gages or an ID micrometer. Too small of throats, even 0.001" can ruin lead bullet accuracy. No such problem on a single chamber semi. Hard bullets won't help either if they are undersized. They won't bump up to fill the rifling & they will skid & lead badly.
 
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I would suspect it's the bullets and not the gun due to the factory jacketed loads shooting well.
What brand bullets are they? What distance are you shooting at?
I would try others and step them up a bit in velocity to at least 850-900 FPS.
 
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BHN 18 lead bullets do their best at the top velocity in the
38 and 357 weapons, do to their hardness.

Target loads should have a 12 BHN if possible....... even lower
since most are under 900 fps.

You might try 7.0 grs of Unique in the 357 magnum case and see if that 18 BHN bullet will settle down at 25 yards, with a 88% loading.

Good shooting.
What is the 88% you reference? Thank you.
 
I would suspect it's the bullets and not the gun due to the factory jacketed loads shooting well.
What brand bullets are they? What distance are you shooting at?
I would try others and step them up a bit in velocity to at least 850-900 FPS.

Well it is the gun or bullet, depends on how you look at it. Small cyl throats & jacketed are far less a problem than lead bullets. There is a reason everyone that shoots lead bullets says 0.001" larger than bore dia minimum. You need that for the bullets to grip the rifling. If you swage the bullet to 0.356" & the bore is 0.357", your bullet isn't stabilizing, it's 0.002" undersized & skidding in the bored not twisting. If your throats are 0357" & under, you aren't going to get a lead bullet to shoot well. Open the cyl to a uniform dia of 0358" or stick with jacketed. You might get useful accuracy going to a soft lead bullet under 900fps, it may bump up enough to grip the rifling, but 0.354", not likely.
 
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If you are really interested in slugging your barrel, Dardas bullets has slugs available for a buck each. After slugging your barrel, send it back to them with contact info and they will measure your slug at no charge.

FWIW, I have used Dardas cast bullets in the past, and been very happy with them.
 
I wouldn't be so upset with the first attempt at an accurate load. I would try some different test lots with different powder charges. I always shoot hot loads in my .357, save the mild stuff for .38 spec. My revolvers always are more accurate than me.
 
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