Should COL change with shape of bullet?

Nate1778 · February 8, 2009, 09:58 AM

Sorry for the newb question, but should it. Meaning should a flat nosed bullet be seated further down than a round nosed bullet.

Further more, what is the best way to find the COL of my particular pistol. I know you can mic the chamber but it would seam to me the last rounds I have made to max COL are sticking in the barrel. Almost like the bullet is engaging the rifling as it is chambered. I looked at a factory hollow point round and it was .029 shorter then what I have been trying to make. It cycles fine without any sticking. The bullet I am loading is a flat top lead bullet. Any advice, I am thinking I do not want to fire a bullet that is in direct contact with the rifling.

As a side question to that is can I re-seat the bullets I have already made now that they have been seated and factory crimped? Meaning if they are too long can I push the bullet in further down without adverse affects?

IllinoisCoyoteHunter · February 8, 2009, 10:48 AM

Sounds like you need to shorten up your COL. Just don't be below the minimum COL for the given load. You do have a manual, right? Bullets seated to deep raise the pressure. COL should be measured from the tip of the bullet to the rim or base of the brass. stick your completed round in calipers and measure it, making sure it is somewhere between the min and max COL listed in the manuals. You may find that certain COL give you better accuracy. As far as pushing the already crimped lead bullet deeper....well, give it a shot. If you see the bullet being shaved by the brass case, then this is no good. If you put a fairly light crimp on it, you may find there is no problems. But if you heavily crimped the bullet and possible deformed the bullet through your crimping process, trying to seat it deeper may deform the bullet nose (by the seating die) or it may shave the lead bullet (from the brass case). Good luck.

Nate1778 · February 8, 2009, 11:01 AM

Yeah 2 manuals, neither meets my exact setup. .380, 100 grain lead bullet, I am using 3.9 grains Unique, and the manual is calling for accurate #2 (min COL .950) or accurate #5 (min COL .975). Am I stuck going and getting some different powder or is there a rule of thumb to live by in this situation.

kyle663 · February 8, 2009, 11:41 AM

chamber a loaded round , then eject it and check the bullet, that will tell you if its hitting the rifling. i couldnt find a loading for 100g lead with unique, but a 100g fmjrn min col is .975 with 4.3 gr max charge. go to alliants website and see if they have a loading for it. if it isnt touching the rifling, try increasing the crimp jus a little bit at a time and see if that helps.

FrankenMauser · February 8, 2009, 05:16 PM

Nate, I replied to the original post with the same information given here by other members.

But when it comes to Overall Length for bullets where you can't find data...
Don't trust what you see for similar bullets. No 2 bullets are alike. You need to find the OAL for yourself.

For the .380 it's best to start at .980" and reduce as needed.

**Unclenick** · February 8, 2009, 06:21 PM

Use the gun's barrel as the COL gauge. Example with 1911 barrel below. Third image (from left) shows what maximum COL looks like. This headspaces on the bullet, which is usually good for accuracy. What that COL is will vary with the bullet shape, as suggested by the OP. The reason military chambers for 5.56 and 7.62 NATO rounds have 0.030 longer freebore than commercial chambers is precisely because they have a range of bullet shapes to accommodate without running the bullet into the throat.

February 8, 2009, 09:58 AM	#1
Nate1778 Senior Member Join Date: January 21, 2009 Location: Louisville Ky Posts: 312	Should COL change with shape of bullet? Sorry for the newb question, but should it. Meaning should a flat nosed bullet be seated further down than a round nosed bullet. Further more, what is the best way to find the COL of my particular pistol. I know you can mic the chamber but it would seam to me the last rounds I have made to max COL are sticking in the barrel. Almost like the bullet is engaging the rifling as it is chambered. I looked at a factory hollow point round and it was .029 shorter then what I have been trying to make. It cycles fine without any sticking. The bullet I am loading is a flat top lead bullet. Any advice, I am thinking I do not want to fire a bullet that is in direct contact with the rifling. As a side question to that is can I re-seat the bullets I have already made now that they have been seated and factory crimped? Meaning if they are too long can I push the bullet in further down without adverse affects?

February 8, 2009, 11:41 AM	#4
kyle663 Senior Member Join Date: April 14, 2008 Location: IL Posts: 311	chamber a loaded round , then eject it and check the bullet, that will tell you if its hitting the rifling. i couldnt find a loading for 100g lead with unique, but a 100g fmjrn min col is .975 with 4.3 gr max charge. go to alliants website and see if they have a loading for it. if it isnt touching the rifling, try increasing the crimp jus a little bit at a time and see if that helps. __________________ NRA member 22LR,17hmr, 9mm, 9mm makarov, 38 S&W, 38/357, 41mag, 44mag, 45ACP, 7.62x39, 7.62x54, 222rem

February 8, 2009, 06:21 PM	#6
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,061	Use the gun's barrel as the COL gauge. Example with 1911 barrel below. Third image (from left) shows what maximum COL looks like. This headspaces on the bullet, which is usually good for accuracy. What that COL is will vary with the bullet shape, as suggested by the OP. The reason military chambers for 5.56 and 7.62 NATO rounds have 0.030 longer freebore than commercial chambers is precisely because they have a range of bullet shapes to accommodate without running the bullet into the throat. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

February 8, 2009, 10:48 AM	#2
IllinoisCoyoteHunter Senior Member Join Date: December 23, 2008 Location: Southern Illinois Posts: 1,527	Sounds like you need to shorten up your COL. Just don't be below the minimum COL for the given load. You do have a manual, right? Bullets seated to deep raise the pressure. COL should be measured from the tip of the bullet to the rim or base of the brass. stick your completed round in calipers and measure it, making sure it is somewhere between the min and max COL listed in the manuals. You may find that certain COL give you better accuracy. As far as pushing the already crimped lead bullet deeper....well, give it a shot. If you see the bullet being shaved by the brass case, then this is no good. If you put a fairly light crimp on it, you may find there is no problems. But if you heavily crimped the bullet and possible deformed the bullet through your crimping process, trying to seat it deeper may deform the bullet nose (by the seating die) or it may shave the lead bullet (from the brass case). Good luck. __________________ ~~IllinoisCoyoteHunter~~ ~NRA LIFE MEMBER~ ~NRA CERTIFIED INSTRUCTOR~

February 8, 2009, 11:01 AM	#3
Nate1778 Senior Member Join Date: January 21, 2009 Location: Louisville Ky Posts: 312	Yeah 2 manuals, neither meets my exact setup. .380, 100 grain lead bullet, I am using 3.9 grains Unique, and the manual is calling for accurate #2 (min COL .950) or accurate #5 (min COL .975). Am I stuck going and getting some different powder or is there a rule of thumb to live by in this situation.

February 8, 2009, 05:16 PM	#5
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,424	Nate, I replied to the original post with the same information given here by other members. But when it comes to Overall Length for bullets where you can't find data... Don't trust what you see for similar bullets. No 2 bullets are alike. You need to find the OAL for yourself. For the .380 it's best to start at .980" and reduce as needed.