Ontarget Posted October 10, 2021 Share Posted October 10, 2021 (edited) With some recent 9mm reloads, I noticed minor keyholing on the target. The bullets were RN Blue bullets 125g. What causes bullets to keyhole? Is it a problem with the bullets or with the reloading process? Thanks. Edited October 10, 2021 by Ontarget Link to comment Share on other sites More sharing options...
Sarge Posted October 10, 2021 Share Posted October 10, 2021 9minor or 9MAJOR? Minor loads it’s generally weak loads or possibly an over crimping issue or simply the gun doesn’t like those bullets. What is FPS? MAJOR loads can be same thing but typically it’s comp strikes Link to comment Share on other sites More sharing options...
Guy Neill Posted October 10, 2021 Share Posted October 10, 2021 Likely the most common cause is low velocity, but over driving the bullet. bullet damage, wrong rifling twistor no (or too little rifling) can all be factors. Link to comment Share on other sites More sharing options...
Ontarget Posted October 10, 2021 Author Share Posted October 10, 2021 These are minor loads at about 1000-1050 fps. 127K power factor. Link to comment Share on other sites More sharing options...
Guy Neill Posted October 10, 2021 Share Posted October 10, 2021 What is the bullet diameter? Do you know the bore diameter.\? Is that an expected velocity or a measured velocity? How much crimp? Link to comment Share on other sites More sharing options...
OnePivot Posted October 10, 2021 Share Posted October 10, 2021 Your velocity is sufficient to not keyhole. It's usually the 147+ grain bullets that have issues. How's your barrel? Clean with a good crown? Weird buildup or damage can keyhole. Or crimping/shaving issues. Link to comment Share on other sites More sharing options...
Ontarget Posted October 10, 2021 Author Share Posted October 10, 2021 .355 diameter bullets shooting an M&P Pro. I don't see any problems with the barrel. That was measured velocity. 4.0g Win 231 15 shots Hi= 1047 Lo= 985 Av=1016 ES= 62 SD=18 PF= 127,000 Link to comment Share on other sites More sharing options...
AHI Posted October 10, 2021 Share Posted October 10, 2021 Do you use a Lee factory crimp die? Link to comment Share on other sites More sharing options...
stick Posted October 10, 2021 Share Posted October 10, 2021 Usually too much crimp will make the bullets keyhole. Do you know what your crimp is? Here's how to measure crimp. "With a caliper measure the thickness of the brass at the case mouth, multiply times two and add the bullet diameter. That's your zero. After running your rounds through the crimp die, measure the loaded round at the case mouth and the difference from your zero is your crimp". Link to comment Share on other sites More sharing options...
Sarge Posted October 11, 2021 Share Posted October 11, 2021 5 hours ago, Ontarget said: These are minor loads at about 1000-1050 fps. 127K power factor. If it were me I would bump the load .2-.4 and make sure crimp is ballpark .378 and rechrono and look for keyholing Link to comment Share on other sites More sharing options...
Ontarget Posted October 11, 2021 Author Share Posted October 11, 2021 (edited) Thanks, Gentlemen, for your replies. I have been using the Dillon crimp die. I'll check my measurements on the crimp. I'm not expert at how much crimp is enough, so I will try to understand this better. Usually, if the rounds fit the Dillon 9mm case gauge, I assumed the crimp was correct. Do you recommend I change to the Lee FCD? Edited October 11, 2021 by Ontarget Link to comment Share on other sites More sharing options...
Absocold Posted October 11, 2021 Share Posted October 11, 2021 Poor bullet design. Bullet damaged. Bullet damaged during firing (many causes). Improper bullet ogive. Bullet too small or too big for barrel. Bullet losing jacket (various causes). Wrong bullet weight/shape/design/velocity for rifling twist rate. Worn rifling. Damaged or off center crown. Bullet striking muzzle device. Too much bullet crimp. Barrel fouled. There's more but I got bored. Link to comment Share on other sites More sharing options...
Boomstick303 Posted October 11, 2021 Share Posted October 11, 2021 (edited) If you have any, maybe try some factory ammo to rule out the gun/barrel. If you don’t keyhole with the factory ammo then most likely it’s your load. If you key hole with the factory ammo then it’s most likely the barrel and/or gun. That way you identify the issue quicker, saving ammo and time. Edited October 11, 2021 by Boomstick303 Link to comment Share on other sites More sharing options...
AHI Posted October 11, 2021 Share Posted October 11, 2021 21 hours ago, Ontarget said: Do you recommend I change to the Lee FCD? NO It has been known to cause your issue! Next question: How are you determining that the bullets are tumbling? "Bad" cardboard has been known to cause some to believe they have issues .They do not. Unsupported paper taires like tumbling. Etc. Link to comment Share on other sites More sharing options...
Cuz Posted October 12, 2021 Share Posted October 12, 2021 The Lee factory crimp die is only not recommended for coated bullets, right? I’ve used it for years with copper plated, and now jacketed bullets with great results. I have read in multiple places that you shouldn’t use it with coated bullets. Also, regarding crimp, is it true that over crimping is only an issue if it breaks through the coating or plating which could cause the bullet to separate? Are there any known drawbacks to a slightly tighter crimp with jacketed bullets like Precision Delta or Montana Gold? I thought they both had pretty hard jackets. Link to comment Share on other sites More sharing options...
AHI Posted October 12, 2021 Share Posted October 12, 2021 (edited) 2 hours ago, Cuz said: The Lee factory crimp die is only not recommended for coated bullets, right? I’ve used it for years with copper plated, and now jacketed bullets with great results. I have read in multiple places that you shouldn’t use it with coated bullets. Correct 2 hours ago, Cuz said: Also, regarding crimp, is it true that over crimping is only an issue if it breaks through the coating or plating which could cause the bullet to separate? Are there any known drawbacks to a slightly tighter crimp with jacketed bullets like Precision Delta or Montana Gold? I thought they both had pretty hard jackets. There could be accuracy issues. These issues may not show up at normal uspsa distances.otherwise Correct. Edited October 12, 2021 by AHI Link to comment Share on other sites More sharing options...
Farmer Posted October 13, 2021 Share Posted October 13, 2021 (edited) 20 hours ago, Cuz said: The Lee factory crimp die is only not recommended for coated bullets, right? I’ve used it for years with copper plated, and now jacketed bullets with great results. I have read in multiple places that you shouldn’t use it with coated bullets. Also, regarding crimp, is it true that over crimping is only an issue if it breaks through the coating or plating which could cause the bullet to separate? Are there any known drawbacks to a slightly tighter crimp with jacketed bullets like Precision Delta or Montana Gold? I thought they both had pretty hard jackets. The Lee die has more affect on cast and coated bullets because generally they are larger diameter, ie .356”. This bulges the case slightly more than a .355 bullet. The whole theory behind the die is that it resizes the loaded rounds to make sure they will function in any gun. The problem with this is the carbide ring at the base of the die also squeezes the bullet down inside the case making it smaller too. If you have thick brass it’s even worse. I have pulled and measured some that after using the die on them were squeezed down to .353. With jacketed and some plated they are small enough and hard enough to resist the swaging and most of the time don’t even touch the bottom ring. Some of the plated bullets will swage down but they tolerate it better because of the plating being harder than a poly coating. Hope this helps. Edited October 13, 2021 by Farmer Sp Link to comment Share on other sites More sharing options...
Cuz Posted October 13, 2021 Share Posted October 13, 2021 Yes, thanks, the last 3 replies confirm what I’ve always believed. Basically, the U die is best only used with jacketed bullets. And, sorry for the thread hijack, but I thought it had some pertinence to the topic. Link to comment Share on other sites More sharing options...
AHI Posted October 13, 2021 Share Posted October 13, 2021 45 minutes ago, Cuz said: Yes, thanks, the last 3 replies confirm what I’ve always believed. Basically, the U die is best only used with jacketed bullets. And, sorry for the thread hijack, but I thought it had some pertinence to the topic. U die is not the same die as the Factory crimp die. two different dies. Link to comment Share on other sites More sharing options...
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