Help solve a mystery

[email protected] · December 10, 2009, 02:00 PM

I was shooting some reloads through a .357 S&W 686 with 6in. barrel and couldn’t figure this out.
My recipe:
Rainier 125g
Unique 6.3g
WSP
Col= 1.584
New Starline brass

Here’s the mystery.
Each time I would load 6 rds. the first round would sound like a squib and have very little recoil. I would stop, unload, check for a squib and continue. The subsequent rds. acted normal and maybe increased recoil as I went on but the difference between first and second was very noticeable. This happened EVERY time I loaded the gun over 100 rds. and only on the first rd. Other than that everything was normal and they were pretty consistent. The chances of it being a reduced charge on only the first rd. has to be close to zero, right? This recipe when I tested it and worked it up showed nothing like this. Is this more a gun issue than an ammo issue? Any ideas?

Doodlebugger45 · December 10, 2009, 02:19 PM

That appears to be a fairly mild load. I am wondering what kind of crimp you have on the bullets. Like maybe the first round is causing all the others to seat back a little bit further into the case, thus raising the pressure a bit? Just a guess though.

[email protected] · December 10, 2009, 03:30 PM

Sorry
Should have included that in the recipe. I was using a Redding taper crimp in a seperate step. I did have an issue at first, but it was bullet creep of .002-.004 and not setback and it was resolved with a tighter taper crimp.
You did get me thinking though. How much does "powder forward" or "powder back" affect this? Could it be that noticeable?

Doodlebugger45 · December 10, 2009, 05:04 PM

Hmmm... you might be onto something there. Some powders are more case-sensitive than others. I'm not sure about Unique. But 6.3 gr is an extremely light load. Looking back at my notes, I used to use about 9.0 gr of Unique when I used it at all. Even at that weight, there was a whole lot of space left in the case.

SL1 · December 10, 2009, 08:09 PM

How was the accuracy of your loads? The load seems light, so the first one may actually be the normal one. The later ones MIGHT be getting higher pressure from cylinder misalignment.

I had that happen to me with one revolver. The cylinder turning pawl was a little bit too thin, and it didn't turn the cylinder quite far enough for the cylinder bolt to go up into the slot to lock the cylinder in place for the shot. But ONLY when there was an empty chamber or two, so that the pawl was pushing "up-hill" to reach alignment. It could only succeed when the cylinder was not unbalanced by having bullets on one side and empty cases on the other. When I fired an unaligned round, it forced the cylinder into alignment, rather than blowing up the gun (fortunately), and the way I found out about it was (1) poor accuracy, and (2) bits of the bullet jacket stuck in the forcing cone. Once I started looking for the cause, it still took me a while to figure out why it was not happening with eveery shot.

Just a guess, your situation may differ.

SL1

[email protected] · December 11, 2009, 02:08 PM

Started working this load after advise here in regards to plated bullets i.e. using lead data or 10% under jacketed.Also, others recommended this range and as I worked up I found 6.3g gave good accuracy and felt like a good, and yes, fairly mild target load.
As far as cylinder alignment, I didn't notice the problems you mention and the load was fairly accurate and consistent, the only thing was these were "powder measured" rather than hand measured test loads. I guess I could check factory ammo($yuck!$) through it to see if it acts more normal or if it could be the gun.
I also just got a chrono so maybe I can get a better picture of what's happening.
Thanks for the help so far.

drail · December 11, 2009, 05:31 PM

Just a note here, if you're experiencing bullet pull you need more neck tension on your bullet. A crimp (any kind) will not hold a bullet against recoil forces. The case neck has to be 4 or 5 thous. under the bullet dia. Measure your expander plug and compare it to your bullet dia. If it's oversized turn it down in a drill until it is. You want the bullet to be held tightly enough that it won't move BEFORE you apply a crimp. The crimp only removes the flare you made when you expand the case. This applies to semi auto rounds as well.

**Bud Helms** · December 11, 2009, 05:37 PM

A taper crimp is a good way to apply neck tension. dmueller says he is doing that. If you need more neck tension, that Redding will do it.

Maybe time for a factory crimp die?

[email protected] · December 13, 2009, 10:15 AM

Yes, the creep I was getting disappeared after adding more taper crimp. Is it supposed to disappear? I don't know, but it did. Even if it was creep, shouldn't I get less recoil after the first few rounds because my col was increasing? I had the opposite happen. First round way light, 2nd thru 6th normal. If the recoil was increasing on the 2cd thru 6th it was very subtle.

10 Spot Terminator · December 13, 2009, 11:58 AM

Could this be in part to a freshly cleaned and lubed bore ??? I get this on rifles alot and the chrony shows the first round to be sustantially slower I have to figure due to reduced starting pressures . Heavier crimp reduces this phenomenon but doesnt eliminate it . As the lube disappears the accuracy of the rounds increases . I always fire a couple of fouling rounds through all of my hunting rifles before I pack them away to leave on a hunting trip and until now hadn't figured on doing the same for my hunting handguns . I have always used a stout crimp on all of my handloads for more uniform ignition of the powder from round to round and to eliminate the chance of bullet creep which can affect accuracy as well as create one hell of an aggrivation trying to get the cylinder to open on a revolver where one or more bullets crept out too far. 10 Spot

GP100man · December 13, 2009, 12:11 PM

when ya load the cyl try tilting the cyl up to position powder closer to the primer !!

This is why I use "CLAYS" position insensitive.

bfoosh006 · December 16, 2009, 12:37 AM

+1 with GP100man, if you have a chrono.. try an experiment..tilt the gun up, ( powder close to the primer) then slowly lower it to firing position. Fire over the chrono and try for accuracy. Then try it the other way, tilted down and then slowly up to fire. ( with the powder towards the front of the case) You will find that there is a big difference.

[email protected] · December 16, 2009, 04:37 PM

bfoosh006, I think this is the best explanation for what I was experiencing. I gotta go try it out when global warming returns. Never thought powder position would be that obvious. I'll let you know what happens.
Thanks to all for your help.

**Unclenick** · December 16, 2009, 06:27 PM

That's probably it. First round you bring the gun up from nose-down. Subsequent rounds have powder tossed to the rear by recoil and muzzle flip. I am surprised Unique is showing that much position sensitivity? With a heavier bullet it might not. With magnum primers it might not.

Go to 4.9 grains of Clays, 5.0 grains of Vihtavuori N310, or 5.1 grains of Red Dot for same-velocity loads with less position sensitivity.

Colorado Redneck · December 16, 2009, 11:11 PM

I have had experience with Unique producing significant variation in velocities. Glad this thread came along!

December 10, 2009, 02:00 PM	#1
[email protected] Member Join Date: November 27, 2007 Posts: 18	Help solve a mystery I was shooting some reloads through a .357 S&W 686 with 6in. barrel and couldn’t figure this out. My recipe: Rainier 125g Unique 6.3g WSP Col= 1.584 New Starline brass Here’s the mystery. Each time I would load 6 rds. the first round would sound like a squib and have very little recoil. I would stop, unload, check for a squib and continue. The subsequent rds. acted normal and maybe increased recoil as I went on but the difference between first and second was very noticeable. This happened EVERY time I loaded the gun over 100 rds. and only on the first rd. Other than that everything was normal and they were pretty consistent. The chances of it being a reduced charge on only the first rd. has to be close to zero, right? This recipe when I tested it and worked it up showed nothing like this. Is this more a gun issue than an ammo issue? Any ideas?

December 13, 2009, 12:11 PM	#11
GP100man Senior Member Join Date: August 1, 2007 Location: Tabor City , NC. Posts: 1,969	Powder position when ya load the cyl try tilting the cyl up to position powder closer to the primer !! This is why I use "CLAYS" position insensitive. __________________ GP100man

December 16, 2009, 06:27 PM	#14
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	That's probably it. First round you bring the gun up from nose-down. Subsequent rounds have powder tossed to the rear by recoil and muzzle flip. I am surprised Unique is showing that much position sensitivity? With a heavier bullet it might not. With magnum primers it might not. Go to 4.9 grains of Clays, 5.0 grains of Vihtavuori N310, or 5.1 grains of Red Dot for same-velocity loads with less position sensitivity. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

December 16, 2009, 11:11 PM	#15
Colorado Redneck Senior Member Join Date: January 6, 2008 Location: Northeast Colorado Posts: 1,993	This explains my experience I have had experience with Unique producing significant variation in velocities. Glad this thread came along!

December 10, 2009, 02:19 PM	#2
Doodlebugger45 Senior Member Join Date: April 15, 2009 Location: Wyoming Posts: 1,717	That appears to be a fairly mild load. I am wondering what kind of crimp you have on the bullets. Like maybe the first round is causing all the others to seat back a little bit further into the case, thus raising the pressure a bit? Just a guess though.

December 10, 2009, 03:30 PM	#3
[email protected] Member Join Date: November 27, 2007 Posts: 18	Sorry Should have included that in the recipe. I was using a Redding taper crimp in a seperate step. I did have an issue at first, but it was bullet creep of .002-.004 and not setback and it was resolved with a tighter taper crimp. You did get me thinking though. How much does "powder forward" or "powder back" affect this? Could it be that noticeable?

December 10, 2009, 05:04 PM	#4
Doodlebugger45 Senior Member Join Date: April 15, 2009 Location: Wyoming Posts: 1,717	Hmmm... you might be onto something there. Some powders are more case-sensitive than others. I'm not sure about Unique. But 6.3 gr is an extremely light load. Looking back at my notes, I used to use about 9.0 gr of Unique when I used it at all. Even at that weight, there was a whole lot of space left in the case.

December 10, 2009, 08:09 PM	#5
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	How was the accuracy of your loads? The load seems light, so the first one may actually be the normal one. The later ones MIGHT be getting higher pressure from cylinder misalignment. I had that happen to me with one revolver. The cylinder turning pawl was a little bit too thin, and it didn't turn the cylinder quite far enough for the cylinder bolt to go up into the slot to lock the cylinder in place for the shot. But ONLY when there was an empty chamber or two, so that the pawl was pushing "up-hill" to reach alignment. It could only succeed when the cylinder was not unbalanced by having bullets on one side and empty cases on the other. When I fired an unaligned round, it forced the cylinder into alignment, rather than blowing up the gun (fortunately), and the way I found out about it was (1) poor accuracy, and (2) bits of the bullet jacket stuck in the forcing cone. Once I started looking for the cause, it still took me a while to figure out why it was not happening with eveery shot. Just a guess, your situation may differ. SL1

December 11, 2009, 02:08 PM	#6
[email protected] Member Join Date: November 27, 2007 Posts: 18	Started working this load after advise here in regards to plated bullets i.e. using lead data or 10% under jacketed.Also, others recommended this range and as I worked up I found 6.3g gave good accuracy and felt like a good, and yes, fairly mild target load. As far as cylinder alignment, I didn't notice the problems you mention and the load was fairly accurate and consistent, the only thing was these were "powder measured" rather than hand measured test loads. I guess I could check factory ammo($yuck!$) through it to see if it acts more normal or if it could be the gun. I also just got a chrono so maybe I can get a better picture of what's happening. Thanks for the help so far.

December 11, 2009, 05:31 PM	#7
drail Junior member Join Date: February 2, 2008 Posts: 3,150	Just a note here, if you're experiencing bullet pull you need more neck tension on your bullet. A crimp (any kind) will not hold a bullet against recoil forces. The case neck has to be 4 or 5 thous. under the bullet dia. Measure your expander plug and compare it to your bullet dia. If it's oversized turn it down in a drill until it is. You want the bullet to be held tightly enough that it won't move BEFORE you apply a crimp. The crimp only removes the flare you made when you expand the case. This applies to semi auto rounds as well.

December 11, 2009, 05:37 PM	#8
Bud Helms Senior Member Join Date: December 31, 1999 Location: Middle Georgia, USA Posts: 13,198	A taper crimp is a good way to apply neck tension. dmueller says he is doing that. If you need more neck tension, that Redding will do it. Maybe time for a factory crimp die?

December 13, 2009, 10:15 AM	#9
[email protected] Member Join Date: November 27, 2007 Posts: 18	Yes, the creep I was getting disappeared after adding more taper crimp. Is it supposed to disappear? I don't know, but it did. Even if it was creep, shouldn't I get less recoil after the first few rounds because my col was increasing? I had the opposite happen. First round way light, 2nd thru 6th normal. If the recoil was increasing on the 2cd thru 6th it was very subtle.

December 13, 2009, 11:58 AM	#10
10 Spot Terminator Senior Member Join Date: January 3, 2008 Location: Central Oregon Posts: 348	Could this be in part to a freshly cleaned and lubed bore ??? I get this on rifles alot and the chrony shows the first round to be sustantially slower I have to figure due to reduced starting pressures . Heavier crimp reduces this phenomenon but doesnt eliminate it . As the lube disappears the accuracy of the rounds increases . I always fire a couple of fouling rounds through all of my hunting rifles before I pack them away to leave on a hunting trip and until now hadn't figured on doing the same for my hunting handguns . I have always used a stout crimp on all of my handloads for more uniform ignition of the powder from round to round and to eliminate the chance of bullet creep which can affect accuracy as well as create one hell of an aggrivation trying to get the cylinder to open on a revolver where one or more bullets crept out too far. 10 Spot

December 16, 2009, 12:37 AM	#12
bfoosh006 Senior Member Join Date: February 17, 2009 Posts: 1,089	+1 with GP100man, if you have a chrono.. try an experiment..tilt the gun up, ( powder close to the primer) then slowly lower it to firing position. Fire over the chrono and try for accuracy. Then try it the other way, tilted down and then slowly up to fire. ( with the powder towards the front of the case) You will find that there is a big difference.

December 16, 2009, 04:37 PM	#13
[email protected] Member Join Date: November 27, 2007 Posts: 18	bfoosh006, I think this is the best explanation for what I was experiencing. I gotta go try it out when global warming returns. Never thought powder position would be that obvious. I'll let you know what happens. Thanks to all for your help.