Until recently I only used JHP in revolvers and pistols and never gave thought to seating depth in relation to distance from the rifling as I did with rifles. The distance from the cylinder to the rifling in a revolver prevented any attempt at such measurements.
My guide to seating depths was the manuals from various manufacturers, even though the bullet I was using may not have been the same as that in the reference. I never experienced any problems, so never gave it another thought.
But recently I began to use cast bullets, and when an order of coated bullets from Missouri Bullet Company arrived, I wondered how I should decide on seating depth.
I dismantled my 9mm Walther to get the barrel alone. I dropped a bullet into the barrel, tapped it lightly in place, then inserted a cleaning rod into the muzzle until it gently touched the bullet, and marked a half-circle on the rod at the muzzle. Then I inserted a dummy round of the same bullet I had been using, and made a full circle on the rod. I carefully measured the distance between the marks to obtain the distance of the ogive of that bullet from the rifling.
Here’s what I found with the various 115gr 9mm bullets I have available:
Hornady XTP 115gr JHP: COL= 1.050 Distance from rifling= 0.09”
Precision Delta 115gr JHP: COL=1.055” Distance from rifling = 0.09”
Remington 115gr JHP COL: 1.125” Distance from rifling= 0.066”
Missouri Bullet Co. 115gr Coated “spire”: COL 1.060” Distance = 0.080”
Great. But so what? What SHOULD the distance be in a handgun cartridge?
I then measured each bullet. I can’t make a table here as it never comes out as such, so I’ll have to give you this info per line:
Hornady 115gr XTP JHP .355” diameter; OAL= 0.541” Base to ogive= 0.288”
Precision Delta 115gr JHP .355” diam; OAL 0.551” Base to ogive = 0.273”
Remington 115gr JHP .354” diam; OAL 0.530” Base to ogive= 0.272”
Missouri Bullet Co 115gr coated .356” diam; OAL 0.550” Base to ogive= 0.288”
What have I learned? Even though their base to ogive distance differs by 0.015” I accidently have the distance from the ogive to the rifling the same, at 0.09” for both the Hornady XTP and Precision Delta.
Since the Missouri Bullet has the same base to ogive length as the Hornady XTP (0.288”), it makes sense that I should change the COL to from 1.060” to 1.050.”
I’ll take any recommendations you have to offer regarding the Remington bullet.
Now, having gone through all this, I’m left with a question as to how the various reloading manuals derive their COL data. I’ll just use the 115gr information.
LYMAN- “Universal Receiver”
115gr Hornady XTP COL: 1.090”
115gr Barnes TACXP COL: 1.100”
HODGDON –no gun listed, just barrel length and twist
With Hodgdon powder - 115gr Speer Gold Dot HP COL 1.125”
With IMR Powder- 115gr Rem JHP COL 1.110”
With Alliant powder- 115gr FMJ (No manufacturer) COL: 1.120”
With Winchester powder: ALL BULLET WEIGHTS= COL: “1.169 MAX”
SPEER – Smith & Wesson model 5906
115gr GDHP: COL 1.125”
115gr TMJ: COL 1.135”
115gr JHP: COL 1.125”
So- how do you guys/gals (if any) decide what your COL should be for your revolvers and pistols?
My guide to seating depths was the manuals from various manufacturers, even though the bullet I was using may not have been the same as that in the reference. I never experienced any problems, so never gave it another thought.
But recently I began to use cast bullets, and when an order of coated bullets from Missouri Bullet Company arrived, I wondered how I should decide on seating depth.
I dismantled my 9mm Walther to get the barrel alone. I dropped a bullet into the barrel, tapped it lightly in place, then inserted a cleaning rod into the muzzle until it gently touched the bullet, and marked a half-circle on the rod at the muzzle. Then I inserted a dummy round of the same bullet I had been using, and made a full circle on the rod. I carefully measured the distance between the marks to obtain the distance of the ogive of that bullet from the rifling.
Here’s what I found with the various 115gr 9mm bullets I have available:
Hornady XTP 115gr JHP: COL= 1.050 Distance from rifling= 0.09”
Precision Delta 115gr JHP: COL=1.055” Distance from rifling = 0.09”
Remington 115gr JHP COL: 1.125” Distance from rifling= 0.066”
Missouri Bullet Co. 115gr Coated “spire”: COL 1.060” Distance = 0.080”
Great. But so what? What SHOULD the distance be in a handgun cartridge?
I then measured each bullet. I can’t make a table here as it never comes out as such, so I’ll have to give you this info per line:
Hornady 115gr XTP JHP .355” diameter; OAL= 0.541” Base to ogive= 0.288”
Precision Delta 115gr JHP .355” diam; OAL 0.551” Base to ogive = 0.273”
Remington 115gr JHP .354” diam; OAL 0.530” Base to ogive= 0.272”
Missouri Bullet Co 115gr coated .356” diam; OAL 0.550” Base to ogive= 0.288”
What have I learned? Even though their base to ogive distance differs by 0.015” I accidently have the distance from the ogive to the rifling the same, at 0.09” for both the Hornady XTP and Precision Delta.
Since the Missouri Bullet has the same base to ogive length as the Hornady XTP (0.288”), it makes sense that I should change the COL to from 1.060” to 1.050.”
I’ll take any recommendations you have to offer regarding the Remington bullet.
Now, having gone through all this, I’m left with a question as to how the various reloading manuals derive their COL data. I’ll just use the 115gr information.
LYMAN- “Universal Receiver”
115gr Hornady XTP COL: 1.090”
115gr Barnes TACXP COL: 1.100”
HODGDON –no gun listed, just barrel length and twist
With Hodgdon powder - 115gr Speer Gold Dot HP COL 1.125”
With IMR Powder- 115gr Rem JHP COL 1.110”
With Alliant powder- 115gr FMJ (No manufacturer) COL: 1.120”
With Winchester powder: ALL BULLET WEIGHTS= COL: “1.169 MAX”
SPEER – Smith & Wesson model 5906
115gr GDHP: COL 1.125”
115gr TMJ: COL 1.135”
115gr JHP: COL 1.125”
So- how do you guys/gals (if any) decide what your COL should be for your revolvers and pistols?