125 gr SWC not plunking

[1SOW]

What does your load data say for max. Load and with what specific bullet?
If the seating depth isn't excessively deeper,  using ratios can do a "rough" estimate for your max load with your bullet.

[IDescribe]

I measured (Dummy cartridge tests) that an OAL of 1.05 would fully pass the plunk/turn test

Okay, before we go any further, saying that an OAL of 1.05 would fully pass the plunk test isn't the same as saying what your max is.

Did you determine the max OAL for that bullet in your chamber?  Or did you look at the published Ramshot data, see that the closest bullet in the published data is a 124gr Lead RN at OAL 1.05, then load that SWC to 1.05 and verify that it would pass the plunk and spin test?

[charlus]

Thanks guys for offering help.
The max load for the 124gr RN lead (not SWC) is 5.0 gr of BS Silhouette (quite a slow burning one) and I intend to test with a load slightly under the 4.5 starting load and look for any over pressure signs. Minimum OAL is 1.05 (for the 124gr RN) but at that length the SWC seats deeper in the case and the shoulder protrudes 1mm off the mouth and barely enters the leade.
As I do target practice only (ISSF style) I am looking for the lowest load that will cycle the slide OK and give good accuracy.
Maybe some of you have tested different powders/loads in the same configuration. The S2 doesn't give much leeway with this type of bullet. Much more picky than my good old P38 that gobbles anything that fits inside the magazine.

[Wobbly]

Welcome Aboard !

So the downloadable Ramshot load data for SILHOUETTE has a 124gr lead bullet listed that we can use to get started. Yes, it's a RN bullet, but it's, as we say, "close enough for government work"...

124 (Lead) LC RN 5.0gr 1,091 5.3gr 1,149 38,330psi 1.050" OAL

First thing we notice is that 1.050" is VERY short for a RN anything, so this puppy is deeply seated. That's perfect for us, becasue your SWC is also 124gr and it's going to end up fairly deeply seated. So we can use this data directly.

Having looked at everything, I'd start at 5.0gr. If you want to start at 4.5gr that's OK, especially since most target shooters want a bullet down closer to maybe 1045fps. I believe it's OK to go below the Starting Load, I simply think you might get incomplete burns with smutty cases or some un-burned powder around the chamber, but no show stoppers.

? Having said all that, SILHOUETTE probably delivers excellent accuracy, but really is more for faster loads. You might be happier with a slightly faster powder, that woun't have near the case fill, and which will be able to generate slightly lower velocities. You decide.

? If you like the accuracy and the cleanliness at 5.0gr, then you might consider re-springing the gun. Springs are probably available by now.

All the best.   

[charlus]

Thanks Wobby. Your conclusions comfort me. Why don't you write a book you could title "paralleling published loading data" ? It would be a blockbuster!
When I'm done with my tests, I'll post them.

[Wobbly]

When I'm done with my [Silhouette] tests, I'll post them.

http://www.czfirearms.us/index.php?topic=73822.0

Check out this testing done a while back. It never went forward becasue Painter shot my chrono that day.    But now I have a new chrono (which I keep hidden) and can replicate loads and test here if you like.

We really do need a new powder thread on Silhouette powder testing. It's great stuff. So when you get ready we can publish that together.

 

[IDescribe]

Charlus, you still haven't told us what your MAX OAL is or how you determined it -- your actualy MAX OAL without rifling engagement, just a hair, a thousandth or two out of rifling engagement.

I ask because my ShadowLine is short-throated, even for a CZ, and I can seat that exact bullet at 1.065.  At that OAL, I have a seating depth of .310.  At 1.05, your seating depth is .325, which is REALLY deep.  The inner diameter of a 9mm case starts to shrink dramatically at .300 from the case mouth, and at 1.05, which is .325 into the case, I'd be afraid of damaging the bullet base, which is HORRIBLE for accuracy.

So again, have you determined a TRUE max for that bullet in that chamber?  It matters.

As to Silhouette, it's great powder, and it's slow-burning, so you're not going to have to worry about over-pressure because of deep seating, especially given the nature of the bullet in the load data, as Wobbly pointed out.    Let us know.

[painter]

When I'm done with my [Silhouette] tests, I'll post them.

http://www.czfirearms.us/index.php?topic=73822.0

Check out this testing done a while back. It never went forward becasue Painter shot my chrono that day.    But now I have a new chrono (which I keep hidden) and can replicate loads and test here if you like.

We really do need a new powder thread on Silhouette powder testing. It's great stuff. So when you get ready we can publish that together.

 

I shoot everyone's chrono except mine. Brand new in the box...where it will stay.

[charlus]

Perfect. I'll start some trials next week and if still alive will post the first results. No speed data as the indoor range I use next to my home can't accommodate the chrono. Have to go far West in the pampa to set it up.

[Wobbly]

Charlus, you still haven't told us what your MAX OAL is or how you determined it -- your actualy MAX OAL without rifling engagement, just a hair, a thousandth or two out of rifling engagement.

I ask because my ShadowLine is short-throated, even for a CZ, and I can seat that exact bullet at 1.065.  At that OAL, I have a seating depth of .310.  At 1.05, your seating depth is .325, which is REALLY deep.  The inner diameter of a 9mm case starts to shrink dramatically at .300 from the case mouth, and at 1.05, which is .325 into the case, I'd be afraid of damaging the bullet base, which is HORRIBLE for accuracy.

So again, have you determined a TRUE max for that bullet in that chamber?  It matters.

In my SP01 Tac, that bullet pushed consistently between 1.100 and 1.090", so I ended up with an OAL of 1.075". I know that defies all the seating info given above, but that's what I recorded back several years ago. That OAL leaves a consistent shoulder exposure of 0.025 to 0.030", and I've never had a feeding issue.

Hope this helps. 

[IDescribe]

No, no, Wobbly, I get that. 

It's just that the OP initially posted an OAL that coincidentally matched the OAL (1.05) for the load data he was using, which was for a 124gr RN.  I was trying to discern whether or not he had actually taken any steps to determine a good working OAL for that bullet in his chamber, or if he simply took the OAL from a load for an RN bullet and loaded his SWC bullet to that OAL, then confirmed that it plunked and spun. 

It just wasn't clear from his post or his (absence of) answers to questions about it whether or not he went through any steps other than just taking the published OAL for an RN and running with it. 

[Wobbly]

My Bad !

I was trying to prod the OP to answer your question by showing him my answer. I'm well aware it's not the answer you wanted. I should have worded it differently to make it clear.

Or clearer.

Or mo' clear.

 

[painter]

My Bad !

I was trying to prod the OP to answer your question by showing him my answer. I'm well aware it's not the answer you wanted. I should have worded it differently to make it clear.

Or clearer.

Or mo' clear.

 

Let's be clear...

as much as I'd like to shoot every chronograph in existence...

I'm weak. Can't do it.

[charlus]

No, the 1.05 figure didn't come from the load data. Pure coincidence. Comes from measuring chamber length, leade length and rifling length and bringing the shoulder to just barely enter the leade by 1/10 th of a millimeter. The bullet diameter is a bit too much to rotate freely in the leade (maybe due to the coating) and I don't want to build too much pressure.
By trials, I will increase very slowly the OAL and check for signs of over pressure (Gosh, I wish they could make an affordable pressure gauge)
I have ordered some Starline brass as I don't feel comfortable using the Freedom brass I have from my ammos. They seem to have had problems with theirs when reused.

[IDescribe]

Charles, you might be a bit Too concerned about overpressure for the powder you're using.  People use that powder to drive 124gr bullets 1350-1400 feet/sec for 9mm major competition shooting.

NOW, you are using a lead bullet seated quite a bit deeper than what those guys are doing, so I'm not saying you could go to 1350 without issue - - I am sure you WOULD have issue - - but at the velocities you're targeting, you're not going to have a problem.  You can load that bullet right into the lands, and with that powder, as long as you start low and work up, you won't have any issues.