ES13Raven Posted January 7, 2015 Share Posted January 7, 2015 Have you found too much crimp effects accuracy? I have been crimping to .377 - What measurement do you find gives the best accuracy in 9mm? Link to comment Share on other sites More sharing options...
redwoods Posted January 7, 2015 Share Posted January 7, 2015 I was shooting a CZ 75 SP01 using berrys plated bullets. The bullets were tumbling, a guy told me to put less crimp on them. I put less crimp on the new batch and they stopped tumbling. Crimp can effect accuracy. Not sure what my crimp measurement is now. Randy Link to comment Share on other sites More sharing options...
Sarge Posted January 7, 2015 Share Posted January 7, 2015 I think the 0ver crimping becomes a problem when it cut's plating or coating. Then it may effect accuracy. But I seen a shooters 9mm ammo that had a roll crimp on it. I mean these bad boys were all jacked up. the crimp was way into the lead on his bullets and he was still able to hit a target, although he was throwing a lot of C's & D's. It was hard to tell if his troubles were his ammo or him being a seemingly permanent d class shooter. i think all you can really do is make your own test rounds and see what happens with your gun. Put it on a rest on a bench and shoot some groups. My guess is you will find accuracy probably not as bad as you are envisioning. Us shooters, especially those of that reload, get fixated with 2" groups at 25 yards when in reality 90% of what we shoot are 10 yard targets with a huge A zone. .377 is about normal I would say. Many try for .376 but that's not always possible. It all depends on brass, bullets, etc. I'm loading RP brass and I'm only able to get .379 crimp. If you measure your case wall thickness and bullet diameter with calipers simple math will tell you what your crimp needs to be for that bullet and case. Link to comment Share on other sites More sharing options...
CZinZA Posted January 7, 2015 Share Posted January 7, 2015 Even crimping until the case mouth was buried in the lead bullet I have not seen a real change in accuracy. Provided your bullets aren't tumbling I suspect this is a bit of a red herring Link to comment Share on other sites More sharing options...
CoachLongShot Posted January 7, 2015 Share Posted January 7, 2015 Yes, definitely. I ruined a perfectly good box of Rainer bullets with too much crimp. Couldn't hit the side of a barn. They were all over the place. As for how much crimp, I put just enough to take the bell out of the brass. I'm not sure I have ever measured the crimp but will if you'd like. When I run my finger down the ammo from top to bottom you can feel the edge of the case under your finger tip. It's not smooth or rolled in towards the bullet. Coach. Link to comment Share on other sites More sharing options...
Kaskillo Posted January 9, 2015 Share Posted January 9, 2015 Xtreme 124gr plated dillon light crimp. You will see a "ring" on the coating but NEVER a cut thru it. Link to comment Share on other sites More sharing options...
ummm Posted January 9, 2015 Share Posted January 9, 2015 If you measure your case wall thickness and bullet diameter with calipers simple math will tell you what your crimp needs to be for that bullet and case. Can you go into more detail here, Sarge? I haven't heard this before. Thanks! Link to comment Share on other sites More sharing options...
ES13Raven Posted January 9, 2015 Author Share Posted January 9, 2015 It all depends on brass, bullets, etc. I'm loading RP brass and I'm only able to get .379 crimp. If you measure your case wall thickness and bullet diameter with calipers simple math will tell you what your crimp needs to be for that bullet and case. I'm getting .0135 for WIN brass and .012 for FC brass. I use Xtreme 147gr plated, which are .356 So WIN=.383 and FC=.380? Link to comment Share on other sites More sharing options...
razorfish Posted January 9, 2015 Share Posted January 9, 2015 The walls of the case in 9mm hold the bullet in 9mm Luger. If you're getting bullet setback (ie. not enough tension on the bullet) you simply lower your sizing die to create more tension on the bullet. The taper crimp die is basically used to remove any flare you added to aid in the seating of the bullet. Beyond that, the taper crimp has no effect on holding the bullet. I wish they would change the name of the "taper crimp die" in 9mm to "flare removal die". With mixed brass, I generally shoot for .380 of crimp with lead/coated lead bullets and .379 for FMJ bullets. Again, this is my rule of thumb and obviously if your using the same head stamp of brass you could fine tune your crimp. The best crimp in 9mm is NO crimp at all. Link to comment Share on other sites More sharing options...
Sarge Posted January 9, 2015 Share Posted January 9, 2015 If you measure your case wall thickness and bullet diameter with calipers simple math will tell you what your crimp needs to be for that bullet and case.Can you go into more detail here, Sarge? I haven't heard this before. Thanks!ES13 got it. Measure case wall thickness and multiply by 2. Add the bullet diameter and this should be the number for removal of all flare. Example Montana gold bullets usually measure at .3545. Case wall is .012 x 2=.024. So crimp should be around .3785 Link to comment Share on other sites More sharing options...
ES13Raven Posted January 9, 2015 Author Share Posted January 9, 2015 So WIN=.383 and FC=.380? Would .383 pass the case gauge? Link to comment Share on other sites More sharing options...
RDA Posted January 9, 2015 Share Posted January 9, 2015 So WIN=.383 and FC=.380? Would .383 pass the case gauge? Which case gauge? Seriously, if you are using properly dimensioned 9mm bullets and proper 9mm brass, removing the flare should allow them to gauge/chamber (assuming you don't have another dimensional issue). Link to comment Share on other sites More sharing options...
ES13Raven Posted January 9, 2015 Author Share Posted January 9, 2015 (edited) Saami specs are .380 to .381 for 9mm Edited January 9, 2015 by ES13Raven Link to comment Share on other sites More sharing options...
Sandbagger123 Posted January 9, 2015 Share Posted January 9, 2015 unless you use the same head stamp brass of the same length the crimp will vary due to the length of the case. i have seen more of a accuracy issue with power more than crimp. Link to comment Share on other sites More sharing options...
Sarge Posted January 9, 2015 Share Posted January 9, 2015 unless you use the same head stamp brass of the same length the crimp will vary due to the length of the case. But it will still be much closer than using mixed headstamp Link to comment Share on other sites More sharing options...
R.Elliott Posted January 9, 2015 Share Posted January 9, 2015 I field a lot of customer questions for a cast/plated bullet manufacturer outside of Toronto. The single biggest issue I've run into with customers who are experiencing accuracy problems (that are not skill related) with plated bullets is over-crimping. I don't think I've had a single instance were backing off on the taper crimp didn't fix the problem. Link to comment Share on other sites More sharing options...
GJGary Posted January 10, 2015 Share Posted January 10, 2015 I head stamp my 9mm brass and adjust crimp accordingly with no problems. I see more crimp issues in 45 where I don't head stamp my brass but am seriously thinking about it. Link to comment Share on other sites More sharing options...
Khaot1c Posted January 12, 2015 Share Posted January 12, 2015 (edited) I seem to have gotten wrapped around the axle regarding crimp. A lot of my searches have simply ended with "apply a light taper crimp" but the word LIGHT is very subjective. I was of the mindset that the headspace gauge and the plunk test are pretty much the ultimate go/no-go for finding crimp. That was until I started loading the 200gr SWC for my Kimber Eclipse 1911. Even though cartridges I reloaded would pass the headspace and the plunk test, I could not get through an entire 7 round magazine without a Fail to Feed. In going back to the 1911 forums I was given a formula to make crimping a measureable standard and not a qualitative guess. TaperCrimp = (( Case Wall Thickness x 2 ) + Bullet Diamater) - .003 I tried that, and it worked. My FTF issues were gone! So, naturally I thought it would be a GREAT idea to apply that across the board in all of my reloading. Now I'm wondering if that is in fact too much crimp on a plated bullet. I'll add that I pretty much use plated bullets from Xtreme almost exclusively. I do have that "ring" in the plating that was mentioned earlier, and the plating is not "CUT". I've recently tried doing some workup loads with the 124gr Round Nose and the 124gr Flat Point. No matter what I’ve tried thus far, the accuracy is not what I was hoping for at 25 yards. I have to believe there is another force at play here. This thread almost confirms that, but I still don’t know what to do about it….. Edited January 12, 2015 by Khaot1c Link to comment Share on other sites More sharing options...
ES13Raven Posted January 12, 2015 Author Share Posted January 12, 2015 TaperCrimp = (( Case Wall Thickness x 2 ) + Bullet Diamater) - .003No matter what I’ve tried thus far, the accuracy is not what I was hoping for at 25 yards. I have to believe there is another force at play here. This thread almost confirms that, but I still don’t know what to do about it….. Interesting formula. Anyone have a ransom rest and some free time to test different crimp measurements? Link to comment Share on other sites More sharing options...
Khaot1c Posted January 12, 2015 Share Posted January 12, 2015 I can find the time (still on "terminal leave" following my retirement) but I don't have a rest. I've been shooting supported from a bag. But I drink a little too much coffee to trust that..... Link to comment Share on other sites More sharing options...
vinceislander Posted January 12, 2015 Share Posted January 12, 2015 I tried that, and it worked. My FTF issues were gone! So, naturally I thought it would be a GREAT idea to apply that across the board in all of my reloading. Now I'm wondering if that is in fact too much crimp on a plated bullet. I'll add that I pretty much use plated bullets from Xtreme almost exclusively. I do have that "ring" in the plating that was mentioned earlier, and the plating is not "CUT". I've recently tried doing some workup loads with the 124gr Round Nose and the 124gr Flat Point. No matter what I’ve tried thus far, the accuracy is not what I was hoping for at 25 yards. I have to believe there is another force at play here. This thread almost confirms that, but I still don’t know what to do about it….. I'm currently loading Xtreme 124gr RN and previous to that 124GR FP. My bullets do have a "ring" when pulled with or without crimp and from various 9mm brass, but mostly Win. I bell the cases just enough where the bullet sits upright for seating and "crimp" to undo most of the belling. Measurements are between 0.379-0.380in. In my setup, crimp has a significantly less impact on accuracy compared to bullet type, OAL and powder. Later three variable are currently being "fiddle" with in my attempt to find an accurate load. Link to comment Share on other sites More sharing options...
Khaot1c Posted January 12, 2015 Share Posted January 12, 2015 (edited) It seems to me pistol would follow rifle with "cause and efffect". If I remember correctly, a string of shots that has a vertical tendancy is a result of varying neck tension. Something tells me it's probably not that easy.... I understand we aren't applying a crimp to increase neck tension but rather to remove the flare from bullet seating. It just seems to me that any working of the case mouth will increase neck tension. So the goal is to standardize a crimp the removes the flare AND will still allow proper headspacing. Edited January 12, 2015 by Khaot1c Link to comment Share on other sites More sharing options...
ES13Raven Posted January 12, 2015 Author Share Posted January 12, 2015 Some interesting data: AAA 147gr crimp = .376 (measured different head-stamps) Win White Box 115gr crimp = .375 Fed Champion 115gr crimp = .375 Link to comment Share on other sites More sharing options...
JMike Posted January 15, 2015 Share Posted January 15, 2015 If you measure your case wall thickness and bullet diameter with calipers simple math will tell you what your crimp needs to be for that bullet and case.Can you go into more detail here, Sarge? I haven't heard this before. Thanks!ES13 got it. Measure case wall thickness and multiply by 2. Add the bullet diameter and this should be the number for removal of all flare. Example Montana gold bullets usually measure at .3545. Case wall is .012 x 2=.024. So crimp should be around .3785 Thank you Sarge! That is the most complete explanation I have read here or anywhere else. Link to comment Share on other sites More sharing options...
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