Over crimping 38 special

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  • Last Post 16 June 2024
2frogs posted this 10 June 2024

Smith 686 38/357 I am getting some really poor 25 yard accuracy with coated cast bullets in about 15 bhn. These are .358. 160 grain commercial bullet. Tried several different powders. They shoot all over. I'm wondering if I am using to much crimp.. Going to load some of the more accurate loads and use a lighter crimp.. any thoughts or this ?? Thank you

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RicinYakima posted this 11 June 2024

You have to provide "normal" and "Over" in thousandths of an inch measurements. I have no idea what you are talking about. 

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Aaron posted this 11 June 2024

It's probably bullet sizing relative to the cylinder mouths although over-crimping coated bullets may induce issues. All the more reason to stick with regular lubed bullets aka greasers.

 

With rifle in hand, I confidently go forth into the darkness.

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9.3X62AL posted this 14 June 2024

Pandora's Box just blew open.  

Short version......Loading cast bullets in revolvers has very different rules than assembling j-words into cases and sallying forth.  Generally--you want just enough crimp to retain bullets against recoil impulses, and jsut enough case neck tension and bullet pull to enable progressive ignition of the given powder.  I stopped using heavily-deterrent-coated powders like H-100 and WW-296 3 decades ago with my castings, because the heavy bullet pull and crimp required to make the fuel work also distorted castings (reduced their diameter during seating).  Most die sets are 'Biased' toward jacketed bullets.  First clue.  

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2frogs posted this 14 June 2024

I greatly appreciate your reply. It's something to consider. I think I had to much crimp. I read where a heavy crimp was needed. At 25 yards my so called groups looked more like a shot gun pattern. And of course it could very well be the powder I used. These are T B bullets lead round nose flat point. The 180 gr if have shot great, maybe the revolver just doesn't like the 158 gr. Thanks for your reply.. john

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Eutectic posted this 14 June 2024

Make sure you are not distorting the bullet. Pull some and mike the diameters.

Always seat and crimp in a separate step! After seating the case mouth bell should still be open.

Then apply the crimp if desired. A dedicated crimp die like the Redding Profile Crimp has much to recommend it.

My experience is the least crimp is best.

Steve

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2frogs posted this 14 June 2024

I don't think the bullet is getting distorted. Maybe the gun just doesn't like that bullet.. no sure .. I might just remove the flair from the case. Going to try 4227 powder next..thanks for the reply.. john

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Ken Campbell Iowa posted this 14 June 2024

you could load just one cartridge no-crimp at a time and shoot for accuracy ... to test ...  then it doesn't need a crimp at all to avoid cyclinder jamming.  

then try Bullseye powder, usually best ignition.

might sort out some parameters.

if you find accuracy then you could start adding crimp to see how far you can go.  let us know ....   not enough has been reported on this exact topic, that is not just speculation.

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2frogs posted this 14 June 2024

Think I will try that possibly tomorrow. That's a damn good idea.. thanks. But I have no bullseye powder. Haven't seen any in a long time. I hate that hazmat fee..

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Aaron posted this 15 June 2024

Here is, in my humble opinion, a "normal" crimp that I use on my 357 cartridges. When I began reloading, I would seat and crimp on the same stroke but later learned it is much better (more consistent) to seat and crimp on separate strokes. Others may disagree with my evaluation of a "normal" crimp but I feel most will agree. When loading for a 454 Casull with a SSK bullet, I use a heavy crimp. Believe me when I tell you it is different than that shown here.

All of my revolver crimps look like this. I do not load powder coated slicks in a revolver or powder coated anything for that matter in a revolver. I have used some Blue Bullets in the 45 ACP with a taper crimp and those work just fine. I am afraid a normal crimp on a powder coated revolver bullet, even with a crimp groove, will penetrate the super thin coating of the bullet and either affect accuracy or induce leading, or both. Hence, I avoid it entirely.

Ken makes a great suggestion above and I see that you may try that. Please let us know how that works out for you.

 

With rifle in hand, I confidently go forth into the darkness.

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2frogs posted this 15 June 2024

To ken I tried your idea today six different loads five shots each no crimp group size in was about the same as with the crimp so I'm starting to think the 686 does not like that bullet I think I'm going to load some and try them in my Rossi that has that weird 30 twist nothing to lose might just as well try it thank you very much for your advice but I'm not going to give up yet okay later

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Duane Mellenbruch posted this 16 June 2024

I have not seen any comment that you have tried the bullet fit in the cylinder throat.  Does there seem to be a slight resistance as the bullet alone is passed through the cylinder throats?  Slightly undersized bullets are not helpful in finding accuracy.  Just because they are marked at .358" does not mean that is accurate. 

The image of the cartridge in the above post by Aaron is a bit more crimp than I use. May as well ask if you are using matching HS 357 cases or 38 special cases.

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2frogs posted this 16 June 2024

I measured the bullets. All 358. What I can't figure is the 180 grain swc shoot fantastic. It's the 160 gr round nose flat point that are giving me fits..lol. so I guess the cramp wasn't the issue.. I think the gun just doesn't like that damn bullet. I'm going to try a few in my Rossi just to see how they function in it with the 30 twist.. all cases are the same brand,I even trimmed to the same length.

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