Fasthenk65 Posted December 27, 2018 Share Posted December 27, 2018 Since I changed bullets from 147gn to 124gn my COL is not consistent. Changes are up to 0,2 mm / 0.008 inch per round. Any advise? Link to comment Share on other sites More sharing options...
Sarge Posted December 27, 2018 Share Posted December 27, 2018 My adviCe is not to worry too much about it and do a forum search for the subject. Bullet profiles, lubing cases, sorting brass all has an effect on oal Link to comment Share on other sites More sharing options...
IGOTGLOCKED Posted December 27, 2018 Share Posted December 27, 2018 (edited) 5 hours ago, Fasthenk65 said: Since I changed bullets from 147gn to 124gn my COL is not consistent. Changes are up to 0,2 mm / 0.008 inch per round. Any advise? I'm quite OCD regarding my reloading... I agree with Sarge, and I will tell you the one step I implemented which made the biggest difference in reducing coal variance was sorting brass by headstamp... Edited December 27, 2018 by IGOTGLOCKED Link to comment Share on other sites More sharing options...
Fasthenk65 Posted December 28, 2018 Author Share Posted December 28, 2018 Tnx guys, I'll check tomorrow if that solves the issue Link to comment Share on other sites More sharing options...
ChuckS Posted December 28, 2018 Share Posted December 28, 2018 Take some of the shortest rounds and the longest rounds to the range and test for accuracy. If you can't tell the difference, move on to other issues Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted December 28, 2018 Share Posted December 28, 2018 6 hours ago, Fasthenk65 said: my COL is not consistent. Changes are up to 0.008 inch per round. That's not bad - doubt there's any problem with that. Link to comment Share on other sites More sharing options...
Fasthenk65 Posted December 28, 2018 Author Share Posted December 28, 2018 Ok, picked up some new S&B brass. Tested again. Main differences gone Amazing how different brass makes can make a difference in COL but it does! Tnx guys. Link to comment Share on other sites More sharing options...
MemphisMechanic Posted December 28, 2018 Share Posted December 28, 2018 (edited) Yep. But if you get the accuracy you want out of mixed brass with a .008” OAL variation? Skip sorting by headstamp and run it. I’ve always gotten the accuracy I needed out of such setups - whatever my production guns are capable of. Don’t load for minimum OAL variance. Don’t load for softest possible recoil. Get the ammo tuned to shoot as straight as possible. Grouping well is all that matters.. and sometimes I’ve had pretty large OAL variations, and a large SD, but the gun printed that load 2-2.5” at 25yd. That means I’m done and happy, no matter what my chrono and calipers are telling me. Edited December 28, 2018 by MemphisMechanic Link to comment Share on other sites More sharing options...
Railroadie Posted January 3, 2019 Share Posted January 3, 2019 I don't see how different brass would make a difference? Maybe someone can explain. What type of bullet are you using? RN, HP. FP? I know on FP and HP I get about a .002 variation but with RN, the oglive of the bullet isn't always the same and COAL will vary. Link to comment Share on other sites More sharing options...
MemphisMechanic Posted January 3, 2019 Share Posted January 3, 2019 7 minutes ago, Railroadie said: I don't see how different brass would make a difference? Maybe someone can explain. What type of bullet are you using? RN, HP. FP? I know on FP and HP I get about a .002 variation but with RN, the oglive of the bullet isn't always the same and COAL will vary. It does. It’s a big factor in “widely varying” OALs coming off of your progresive press. If you don’t beleive us, pick out 30 of the same headstamp and load them in sucession with mixed brass. Link to comment Share on other sites More sharing options...
Railroadie Posted January 3, 2019 Share Posted January 3, 2019 Are you also saying this large variance will happen when seating FP bullets with the FP seating stem? Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted January 3, 2019 Share Posted January 3, 2019 2 hours ago, Railroadie said: I don't see how different brass would make a difference? Each brass type has different dimensions - slightly different, but that makes for slight differences in OAL. Link to comment Share on other sites More sharing options...
Railroadie Posted January 3, 2019 Share Posted January 3, 2019 You guys are stating that it happens and different sizes etc. But you aren't telling me why. COAL is from the bottom of the case to the top of the bullet. The bottom of the case is always touching the bottom of the plate, whichever type plate that is. And then the bullet is pressed in the casing to an adjusted stop position. Even though case sizes have different thicknesses they are all expanded by the same expander. To me the only thing that effects COAL is bullet shape or inconsistent press stroke Link to comment Share on other sites More sharing options...
ddc Posted January 3, 2019 Share Posted January 3, 2019 24 minutes ago, Railroadie said: To me the only thing that effects COAL is bullet shape or inconsistent press stroke... And to some of use there is more going on than those two concerns. Yes, bullet shape has a big impact. However if you discount the effect that brass has on COL then you are missing something. Way too many people to disregard have observed that brass has an effect on COL. Not all brass is created equal. Some cases are more "stiff" than others. More resistant to belling and more resistant to bullet insertion. Some brass is "softer". CBC brass is known for being "stiff". Blazer is known to be "softer". Try an experiment: 1. Sort out a bunch of brass by headstamp and keep the CBC brass in one pile and Blazer brass in another. I'd suggest at least 20 cases of each. 2. Load 'em up. 3. Measure the COL of each run. Link to comment Share on other sites More sharing options...
Railroadie Posted January 3, 2019 Share Posted January 3, 2019 Okay, I will be loading some once fired soon and will do that. Are you saying that the brass can basically spring back on certain brands and cause this difference in COAL? Just a thought Link to comment Share on other sites More sharing options...
Sarge Posted January 3, 2019 Share Posted January 3, 2019 39 minutes ago, Railroadie said: Okay, I will be loading some once fired soon and will do that. Are you saying that the brass can basically spring back on certain brands and cause this difference in COAL? Just a thought I think it’s likely that thinner case walls allow bullets to seat easier and hence possibly deeper for a given stroke. But regardless of the reason oals vary by headstamp. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted January 3, 2019 Share Posted January 3, 2019 7 hours ago, Railroadie said: To me the only thing that effects COAL is bullet shape or inconsistent press stroke We are dealing in thousandths of an inch. If I get a primer that is just barely too high, it affects the OAL, big time. Just a burr on the nose of the JHP bullet will swing the dial. That's how small a difference we're talking about. Almost anything can affect the OAL by 1/1,000th of an inch. Link to comment Share on other sites More sharing options...
BentAero Posted January 4, 2019 Share Posted January 4, 2019 On 1/2/2019 at 11:33 PM, ddc said: And to some of use there is more going on than those two concerns. Yes, bullet shape has a big impact. However if you discount the effect that brass has on COL then you are missing something. Way too many people to disregard have observed that brass has an effect on COL. Not all brass is created equal. Some cases are more "stiff" than others. More resistant to belling and more resistant to bullet insertion. Some brass is "softer". CBC brass is known for being "stiff". Blazer is known to be "softer". Try an experiment: 1. Sort out a bunch of brass by headstamp and keep the CBC brass in one pile and Blazer brass in another. I'd suggest at least 20 cases of each. 2. Load 'em up. 3. Measure the COL of each run. Truer words were never spoken. Those fric*^#@kin CBC brass are of the devil. Almost every time I get a 'flier', sure enough, it's a CBC or CFL. I've learned they aren't worth the hassle and they go straight into the junk brass bin. Link to comment Share on other sites More sharing options...
George16 Posted January 4, 2019 Share Posted January 4, 2019 On 1/2/2019 at 11:37 PM, Railroadie said: Okay, I will be loading some once fired soon and will do that. Are you saying that the brass can basically spring back on certain brands and cause this difference in COAL? Just a thought Yes they do. It’s ability to deformed/stretch under pressure due to outside forces differs on the brass’ elasticity or ductility. Thinner metals can be stretched/deformed easier and can also spring back faster than a thicker piece of brass. Federal, blazer and win brass are thinner compared to CBC, GFL, Xtreme and other headstamps. I sort my brass and even with the same headstamps, there is still variation in COA but it’s very minimal. The different length of the brass also affects the seating of the brass itself especially on progressive presses. Even Dillon’s instructions tell us to make sure all the different stations (sizing and powder) has brass in them to get consistent COL. There’s a big difference in COL if you seat a bullet with the other two stations empty compared to when there is brass in them. Link to comment Share on other sites More sharing options...
IGOTGLOCKED Posted January 5, 2019 Share Posted January 5, 2019 Railroadie, All which has been said is spot on. I would however suggest making one change at a time and taking note of your results. I am quite particular regarding the results of my reloads and can tell you with all certainty the single biggest difference in reducing the oal for me was sorting by headstamp. And I take the time as I switch headstamps to tweak the dies that are required to do so to maintain my intended oal. My oal is now kept to under 5/1000ths Happy New Year from IGG! Link to comment Share on other sites More sharing options...
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