Did Copper Fouling Cause My Pressure? 25 Mega Bore Scope + Ladder
Rifle Accuracy and Reloading
3,995 views
Before heading to the range I bore scoped the barrel from the muzzle in — checking the chamber walls, the freebore/leade area, and looking for a carbon ring. Several of you commented that the cartridge case might be too long and running into the leade, so I checked that too. Full look inside the barrel at 200 rounds.
Then back to the bench at 100 yards, starting at 66 grains of Retumbo and working up.
Results: no pressure signs at 66 grains — no sticky bolt lift, clean primers, nothing on the case head, and consistent velocity (3131, 3120, 3125). I continued the ladder up to 68 grains, where the primer edges started to flatten, and that's where I stopped. Those rounds weren't filmed, but there's a target photo at the end.
The takeaway: cleaning down to bare metal eliminated the pressure signs. The last time I'd done that was around 100 rounds. Since then I've cleaned thoroughly every time I changed a component, but never all the way back to bare metal — and in that stretch I've run hammer bullets, Barnes solid copper, and various cup and core bullets. My best guess is that mixing those bullet types built something up that caused the erratic pressure.
Have you ever run into this? I'd like to hear your thoughts in the comments.
⏱️ Chapters
0:00 The pressure problem recap
0:41 Checking case length vs. the leade
1:16 Two hours of cleaning — first bore scope look
1:50 Chamber walls and freebore
2:35 Carbon ring check
2:56 Lands at 200 rounds
3:16 Back at the bench — 66 grains
4:16 First shots and velocity
5:35 Results and takeaway
#Reloading #PrecisionRifle #ShermanWildcat #LoadDevelopment #RifleAccuracy #PrecisionRifle #Handloading #PressureSigns #BergerBullets #Retumbo #25Mega
12 Comments
Seated like 90 thou off.
Bigger jumps make your ammo more field reliable. Plus TMKs prefer it.
If your ammo is loaded correctly then it doesn't matter how dirty your barrel is. Also your zero doesn't change.
Did Copper Fouling Cause My Pressure? 25 Mega Bore Scope + Ladder
Rifle Accuracy and Reloading
3,995 views
Before heading to the range I bore scoped the barrel from the muzzle in — checking the chamber walls, the freebore/leade area, and looking for a carbon ring. Several of you commented that the cartridge case might be too long and running into the leade, so I checked that too. Full look inside the barrel at 200 rounds.
Then back to the bench at 100 yards, starting at 66 grains of Retumbo and working up.
Results: no pressure signs at 66 grains — no sticky bolt lift, clean primers, nothing on the case head, and consistent velocity (3131, 3120, 3125). I continued the ladder up to 68 grains, where the primer edges started to flatten, and that's where I stopped. Those rounds weren't filmed, but there's a target photo at the end.
The takeaway: cleaning down to bare metal eliminated the pressure signs. The last time I'd done that was around 100 rounds. Since then I've cleaned thoroughly every time I changed a component, but never all the way back to bare metal — and in that stretch I've run hammer bullets, Barnes solid copper, and various cup and core bullets. My best guess is that mixing those bullet types built something up that caused the erratic pressure.
Have you ever run into this? I'd like to hear your thoughts in the comments.
⏱️ Chapters
0:00 The pressure problem recap
0:41 Checking case length vs. the leade
1:16 Two hours of cleaning — first bore scope look
1:50 Chamber walls and freebore
2:35 Carbon ring check
2:56 Lands at 200 rounds
3:16 Back at the bench — 66 grains
4:16 First shots and velocity
5:35 Results and takeaway
#Reloading #PrecisionRifle #ShermanWildcat #LoadDevelopment #RifleAccuracy #PrecisionRifle #Handloading #PressureSigns #BergerBullets #Retumbo #25Mega