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My Journey with the 38 Short Colt in 627


BallisticianX

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Well its been and experience but I got the 38 short colt dialed in with my 627. It started off with trying short colts with various bullet weights and powders with horrible results. 38 specials shot a bit better but not acceptable. That prompted closer inspections that found a tight cylinder gap with slight dragging from an out of spec barrel from the factory. Barrel got warrantied for a replacement that shot worse with anything I put down it. So I decided to get a custom barrel and be done with the problem. When I got it back it shot 38's fairly well but SC's were still horrible. As far as bullet weights while trying the new barrel the 160 bayous showed the most promise. But I noticed leading from firing minimal rounds. That prompted me too check some things and it dawned on me to measure the cylinder throats. Being an on and off project between other stuff I missed this early on. Plug gauges revealed the throats were between .356" and .3565". Considering the bore is at .357" I felt the swagging from the throats left the bullet undersize resulting in gas cutting etc causing the leading. I followed the old rule of throats should be .0005" to .001" larger than the bore diameter so I went ahead and honed the throats to .358". After this fix the short colts started to shoot well. Now it was onto load development. This is quite a discussed subject on here so I tried some powders favored on here as well as a few I had kicking around. Here is what I tried and my thoughts (for what its worth);

These are the loads that chrono'd to make ICORE pf or better with 160 gr Bayou at 1.200" OAL in custom 5" barreled 627 with 8 shot groups from a rest at 20 yards.

 

Red Dot: 2.8 gr, 121 pf, 1.6" group, found it to be very smokey, singed kernels with sooty residue, jumpy recoil, and extraction was smooth. This flake powder meters inconsistently of which correlates to the large velocity ES during chrono.  

Clays: 2.9 gr, 121 pf, 1.375" group, found it fairly clean with minimal singed kernels, recoil a bit softer than red dot, still a bit jumpy, and extraction was smooth.  This flake powder meters a bit better and posted a slight improvement in velocity ES than red dot but still inconstant but surprisingly it did not seem to bother the accuracy.  

Bullseye: 3.1 gr, 120 pf, .812" group (best group of all powders tested), no singed kernels but very sooty residue (dirtiest powder tested), recoil comparable to clays and extraction was smooth. This granular powder metered very well and velocity ES was better than clays but worse than WST.  

Titegroup: 3.0 gr, 122 pf, 1.375" group, no singed kernels with slight brownish residue, recoil was sharper and jumpier than any other powder used, and extraction was smooth. This granular powder meters well and had the lowest ES on velocities of any of the powders used.

WST: 3.1 gr, 123 pf, (haven't shot it for group yet), a couple singed kernels here and there and very little residue (cleanest of all powders tested), recoil was soft and least jumpy of any of the powders here, and extraction was smooth. This granular powder (that looks like course dessert sand) meters well and posted the 2nd best ES on velocity.

WW231/HP38: 3.3 gr 122 pf, 1.750" groups, some singed kernels and some soot, recoil was soft and not very jumpy, and extraction was smooth. This granular powder meters well and velocity ES was equal to Bullseye. 

WSF: 3.5 gr, 122 pf, 2" groups, abundance of singed kernels and some soot, recoil was slightly better than W231/HP38 , and extraction was smooth. This granular powder meters well and velocity ES was equal to W231/HP38 & bullseye. Interesting note on this powder; it produced consistent flyers, at least 1-2 in every 8 shot group. If not for the flyers it would have been more accurate than clays.

 

So in closing what I have found is faster powders are more consistent for the short colt when fired in the .357 mag cylinder. The faster powders are a bit snappier than the medium speed pistol powders though. Unfortunately the medium speed pistol powders do not perform consistently and are dirty. That being said it makes sense that a powder like WST thats in between the snappy fast and medium speed pistol powders would share the soft shooting and consistent velocity characteristics from both ends of the spectrum. I'm liking the feel of WST so far. I did not get to accuracy test it as it was the last powder I tested and ran out of time today working with it. 

 

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On 4/24/2017 at 11:56 PM, Kurusty said:

Just out of curiosity, why are you running them at 1.20"? Have you tried the same loads with different OAL?

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During my lengthy experimentation I found 1.200" OAL was beneficial vs shorter OAL I tried with the Bayou 160. Lighter bullets did not show as much improvement when varying the OAL. (The amount of taper crimp applied regardless of type and weight of bullet remained constant with no change after initial adjustment to .358" diam pills to just put a noticable but shallow depression on the bullet. I did try a couple .357" diam bullets that would have had a smidge less on it.) 

Anyway the 160 gr produced noticeably better accuracy and felt less snappy with the 1.200" OAL. The accuracy I attribute to shortening the distance of bullet jump to the throat with the longer OAL. The reduction of recoil with heavier bullets I attribute to the larger void left between the powder and bullet reducing initial pressure spikes with the longer OAL. Lighter bullets wont benefit from longer OAL in the bullet jump reduction as the bullet itself is shorter to begin when considering the needed bullet engagement in the case. But the bullet profile itself of course can change that. But pressure reduction with any bullet should be considered carefully when choosing the OAL & seating depth. Yes lighter bullets are more forgiving as less mass requires less energy to move (theoretically less pressure/energy gets them moving and out of the case) than compared to a heavier bullet.  But it still can get you into trouble if care is not taken to stay on the longer end of allowable OAL. Now add the faster flavors of powder and the OAL gets even more critical with heavier pills. Then to add one more thought to the think tank is the crimp and that is critical for any weight bullet. (A heavy crimp on a lighter bullet can equal required energy to move as a heavier bullet with a lighter crimp.) Thats why I consider a taper crimp is required on short colts as it is more forgiving with variations in amount of crimp for release than a roll crimp. With all that considered that how I arrived to the 1.200" OAL....it is safe and produces best results!  

Edited by BallisticianX
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Thank you. I was just curious because I use the same bayou bullet with 4.2 grains of Power Pistol @ 1.180" OAL and I have had good results. I've also tried 142 and 147 FP projectiles with 4.8 grains of PP @ 1.16" OAL and didn't notice any difference in recoil. The Montana Gold 142's did group the best of all them though. The jiheads did very well also.

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17 hours ago, AzShooter said:

Keep you OAL at 1.20 and try Vhitavhori N 320.  I was shooting 3.4 grains and making power factor plus getting groups of 1 inch and a half at 25 yards from a rest.

I got some great groups with Bullseye. I just thought it was quite snappy, jumpy and of course very filthy. VV powders are not common place in most gun shops here so Id have to order it. I usually dont order up large quantities of powder before I know its what I settled on committing to. Of course its not cost effective to order a pound of anything either.  So with that said I picked up what was on the shelves in conjunction with what I already had in my supply. So far the best feeling and clean burning powder I have tried is WST. Of course its the only one I did not spend time with shooting test groups as I ran out of time during my bench session. I did bump my initial WST load from 3.1 gr to 3.2 gr to chrono closer to 125 pf I like for ICORE. It made exactly a 125.1 pf  and it did not get any snappier and still no jumpy feel. I have high hopes it will shoot well, If it keeps it within 1.25" at 20 yards its going to be my Short colt load. 

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I would like to know what custom barrel you have and the rifle twist?

This is some great research Thanks.

You probably know this but I think it should be said. Kernels of unburnt powder are the death of keeping a good trigger during a match. The kernels lodge under the extractor and creat a stif trigger. Powders that seem sooty type of dirty don't cause this problem over the course of a day at a match.

JA

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1 hour ago, JAustin said:

I would like to know what custom barrel you have and the rifle twist?

This is some great research Thanks.

You probably know this but I think it should be said. Kernels of unburnt powder are the death of keeping a good trigger during a match. The kernels lodge under the extractor and creat a stif trigger. Powders that seem sooty type of dirty don't cause this problem over the course of a day at a match.

JA

The barrel was made by Pinnacle High Performance out of Quakertown, PA. I am not privy to what brand of blanks he uses but he contours and works them to perfection. It is super accurate. The twist is 1 in 14. I chose that twist as its a good all around twist for good results with both light and heavy bullets. 

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50 minutes ago, Alaskan454 said:

I thought you finally started drinking the kool aid?  Back to LC already?

 

nope - never switched to shorts, bought 500 shorts to test around with last year I think it was, after some comparative testing between long colt and short colt I decided short colt wasn't worth it at all. 

Edited by alecmc
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