HOGRIDER Posted December 10, 2014 Share Posted December 10, 2014 Specifically rfwobbly's post? Link to comment Share on other sites More sharing options...
johnsons1480 Posted December 10, 2014 Author Share Posted December 10, 2014 Specifically rfwobbly's post? Mr Heart - This is a common issue with the CZ 9mm chamber.... 1) The maximum COAL is not gotten from a book, it is a number that is derived from how your bullet interfaces with your barrel. In that sense, no one here can answer your question, because we simply don't have those items. So this is a measurement you have to make for yourself. 2) Guns from eastern Europe like the CZ and Springfield XD series are known to have very short freebores which compound this issue. Anytime I use a new bullet in one of my CZs I have to go through such a measurement exercise. The issue arises because in eastern Europe shooters can only buy RN bullets, everything else is illegal. Therefore CZ cambers are cut specifically for those ogive shapes to get the best accuracy. When you choose a different ogive shape bullet, you are then forced to start making allowances. Here's a cartoon of what's happening.... https://lh3.googleusercontent.com/-dScRenzwZzE/Tz3NEksXtcI/AAAAAAAADOU/_pS6NKuOtrU/s800/Bullet%20Shapes.jpg You can easily detect the issue by using a felt-tip marker to color the end of your cartridge and then rotating the round inside the chamber. This will show where your problem lies. It should then become obvious that each independent bullet will have its own specific maximum COAL, and that suggested lengths rarely have application when using the CZ chamber. Hope this helps. This one? With 124 grain bullets, I can pass the plunk test with 1.155" OAL. I chose 1.145" as the max to test because that is 0.01" shorter than something I could knowingly plunk test. At 1.100" with the 135 grain bullets, I chose this because the longest I could plunk and spin at was 1.110". I backed that off 0.01" to end up where I'm at. Different method than what Mr. RFWOBBLY laid out, but no I am not touching the rifling with either chosen load. Link to comment Share on other sites More sharing options...
HOGRIDER Posted December 11, 2014 Share Posted December 11, 2014 Hope you get to the bottom of this as there seems to be a lot of info here and on the CZ forum that's specifically devoted to the 75SP-01. Did you contact Cheely about checking the chamber? http://www.brianenos.com/forums/index.php?showtopic=205467 Also looking forward to your results from slugging the barrel. GOOD LUCK!! Link to comment Share on other sites More sharing options...
johnsons1480 Posted December 11, 2014 Author Share Posted December 11, 2014 Hope you get to the bottom of this as there seems to be a lot of info here and on the CZ forum that's specifically devoted to the 75SP-01. Did you contact Cheely about checking the chamber? http://www.brianenos.com/forums/index.php?showtopic=205467 Also looking forward to your results from slugging the barrel. GOOD LUCK!! I didn't contact Cheely. I decided to leave the barrel stock. I have observed myself being faster on the clock with 124 grain bullets, and I can load those as long as I want. I will certainly let you know tomorrow evening how the slugging goes. I have some Titegroup on hand, and I will very likely be trying that soon as well. Anyone have any thoughts on loads? I'm thinking FC Brass Federal SPP 3.5-3.9 gr Titegroup 1.135" OAL Bayou Bullets 124 gr RN I will, of course, fire these over a chronography checking for velocity and pressure starting at the bottom. Link to comment Share on other sites More sharing options...
robb315 Posted December 11, 2014 Share Posted December 11, 2014 How much crimp are you running? Just a thought but maybe you're swaging the bullet a little smaller with an excessive crimp causing the poor accuracy. I've loaded over two cases of the Bayou 135's with multiple powders for my Shadow and they'll all shoot into One of those 3" circle target stickers at 50'. I've used WST, 7625 and am currently using N320. Link to comment Share on other sites More sharing options...
johnsons1480 Posted December 11, 2014 Author Share Posted December 11, 2014 How much crimp are you running? Just a thought but maybe you're swaging the bullet a little smaller with an excessive crimp causing the poor accuracy. I've loaded over two cases of the Bayou 135's with multiple powders for my Shadow and they'll all shoot into One of those 3" circle target stickers at 50'. I've used WST, 7625 and am currently using N320. I'm crimping at .379. I am crimping just enough to remove the bell. I've pulled bullets, they aren't being swaged or marked. 3" at 50 feet is 16 1/3 yards right? I'm not sure how mine shoot at 50 feet, I've only shot at 75 feet for groups. Link to comment Share on other sites More sharing options...
robb315 Posted December 11, 2014 Share Posted December 11, 2014 I'm crimping at .376. About the only group shooting I do is when I'm chronoing my loads or checking my sight adjustment. I put one of those fluorescent orange 3" stickers on a blank piece of cardboard. I only have acces to a 50 foot indoor range to do all my load development. 16-2/3 yards. Link to comment Share on other sites More sharing options...
johnsons1480 Posted December 11, 2014 Author Share Posted December 11, 2014 I just got done slugging the barrel. The barrel slugged at 0.355". Bayou Bullets gauged at 0.365". It's now time to try Titegroup back to back with N320. I don't know when that will happen, but I'll update if I have any better results. Maybe I just suck at shooting groups? That would save me a lot of time lol Link to comment Share on other sites More sharing options...
CZ85Combat Posted December 12, 2014 Share Posted December 12, 2014 " The barrel slugged at 0.355". Bayou Bullets gauged at 0.365". ??????? Or did you mean 0.356? Link to comment Share on other sites More sharing options...
johnsons1480 Posted December 12, 2014 Author Share Posted December 12, 2014 " The barrel slugged at 0.355". Bayou Bullets gauged at 0.365". ??????? Or did you mean 0.356? Whoa there, definitely messed that up! Yes, I'm sorry. My barrel slugged at 0.3555", and the Bayou Bullets gauged at 0.3565". Link to comment Share on other sites More sharing options...
texasref Posted December 13, 2014 Share Posted December 13, 2014 I've been looking at this topic and I think you need to define what you want. From what I saw on the targets you posted your absolutely accuate enough for any USPSA/IDPA competition. If target shooting is the goal, you'll need to further refine your loading data. Your last post (barrel dia. of 0.3555") would suggest that you may be getting a little "blow-by" due to the bullet not being able to fill the barrel. This would cause some accuacy issues due to lost velocity. So.........with what you know I think I'd develop a load that shoots well and that you like and have plenty of powder for and use that. I believe its more important to practice/shoot and compete than to constantly develop loads for all the different powders out there. Altough it is interesting to do. And I'll admit to doing that too. Link to comment Share on other sites More sharing options...
johnsons1480 Posted December 13, 2014 Author Share Posted December 13, 2014 I've been looking at this topic and I think you need to define what you want. From what I saw on the targets you posted your absolutely accuate enough for any USPSA/IDPA competition. If target shooting is the goal, you'll need to further refine your loading data. Your last post (barrel dia. of 0.3555") would suggest that you may be getting a little "blow-by" due to the bullet not being able to fill the barrel. This would cause some accuacy issues due to lost velocity. So.........with what you know I think I'd develop a load that shoots well and that you like and have plenty of powder for and use that. I believe its more important to practice/shoot and compete than to constantly develop loads for all the different powders out there. Altough it is interesting to do. And I'll admit to doing that too. I totally agree. I re-read Ben Stoeger's live fire practice book on Friday, and realized I need to stop tinkering with this. I shot a match today, and my ammo was not an issue at all. I need to focus on practicing and not shooting over the chrono. This ammo is plenty good for USPSA, and I think I'm done. I have 6 more lbs of N320, so that's what I need to use. As far as blow by, my bullets are 0.001" larger in diameter than my barrel. How much bigger should they be? Link to comment Share on other sites More sharing options...
CZ85Combat Posted December 14, 2014 Share Posted December 14, 2014 You might want to try, N320 3.8-3.9gn at oal of 1.120 I get 2" or just under at 25yards with blue bullets. CZ75 SP01 Shadow Link to comment Share on other sites More sharing options...
johnsons1480 Posted December 14, 2014 Author Share Posted December 14, 2014 You might want to try, N320 3.8-3.9gn at oal of 1.120 I get 2" or just under at 25yards with blue bullets. CZ75 SP01 Shadow Based on the data I have, I don't think that would make power factor with enough cushion in my gun for me to be comfortable with it. I have tried 1.115 and 1.125 at 4.2 gr and was unhappy with the accuracy. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
9x45 Posted December 14, 2014 Share Posted December 14, 2014 9mm 125 TC Bayous on top of 4.0 grs TiteGroup at 1.080" OAL. Link to comment Share on other sites More sharing options...
ActionJackson Posted December 15, 2014 Share Posted December 15, 2014 I've had good luck with Alliant Promo / Red Dot in a G34. All groups are ten-shot strings and were tested from a Ransom Rest at 50 feet. SNS 147 1.155 3 grains 1.4'' TBB 147 1.13 2.8 grains 1.4'' Bayou 147 1.16 3 grains 1.5'' Link to comment Share on other sites More sharing options...
Buzzdraw Posted June 12, 2015 Share Posted June 12, 2015 Has anyone tried Alliant Extra-Lite powder in 9mm with a 125 gr coated lead bullet? I am look for results and data, if that exists. Its a fine powder that should meter well in measures. Link to comment Share on other sites More sharing options...
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