Switching from copper to copper jacket and vise versa -- Causing Issues?

[Cholla]

I have heard from three talking heads that switching between copper monolithic and copper jacketed without scrubbing the barrel to bare metal can cause resistance issues and make accuracy suffer. In my quest to find the best load for my new 7 PRC I load up rounds during the week and shoot them before the wind picks up on the weekend. I have not been cleaning in between runs of bullets. Have you noticed an issue when switching back and forth? They claim the different alloys used cause an interaction between the metals.

I ask because I am about ready to send this rifle back as I can't find a consistently accurate load using handloads or factory.

 

[Rick Richard]

I have switched between Berger and Hammer within the same shooting session and individual sessions and…..noticed NO difference in accuracy.

 

[marc357]

I have found that if I start with a clean barrel and shoot Barnes, I'm good. If I switch to cup and core/ gilding metal jacketed bullets, it takes a couple shots to settle down/ stabilize, and I'm good. If I switch back to Barnes, it's shoots like crap, and continues to shoot like crap until I clean it.

 

[Phil Rizzo]

A tidbit to add. I shot about 35 apex afterburners starting with a perfectly clean bore scoped barrel. It has about 250 shots total now. Afterwards I expected to have a lot to remove before I tried another Berger. With n560 and n565 pushing them 3050 to about 3215 and there was zero, I repeat NO copper residue. I soaked and scrubbed and verified with my scope. 147gr AA/7prc

 

[dwightb]

With my 5R barrel I find that just switching cup and core bullet makers will throw off accuracy for a bit. After a few shots of the other it will come back. I have never shot cup and core then copper.

 

[Cholla]

I suspect it also depends on the powder used. The CFE line and others have copper removal agents.

 

[Namuh]

I have heard from three talking heads that switching between copper monolithic and copper jacketed without scrubbing the barrel to bare metal can cause resistance issues and make accuracy suffer. In my quest to find the best load for my new 7 PRC I load up rounds during the week and shoot them before the wind picks up on the weekend. I have not been cleaning in between runs of bullets. Have you noticed an issue when switching back and forth? They claim the different alloys used cause an interaction between the metals.

I ask because I am about ready to send this rifle back as I can't find a consistently accurate load using handloads or factory.

In my state I've had to hunt with non-lead bullets since 2019 so I've been shooting all copper since then, (since I don't have a choice). I personally haven't done much experimenting going back and forth between lead and copper but I watched this video a few weeks ago. I don't know if it will but it might help you out, take care and good luck.

 

[Tiny Tim]

While I don't have alot of experience changing back and forth, I would suspect some combinations and barrels may work better than others.......bullet materials, mono to C&C or visa-versa, powders used, factory or custom barrel........

Had a Remington 700 that wouldn't shoot Barnes after anything else. Had to clean it to bare metal fisrt. At its best was .625 MOA. .75-1 MOA was more typical.

 

[Chrsm]

seems very mysterious to me
Maybe through in some lead balls just for fun

 

[eric v.]

I have found that if I start with a clean barrel and shoot Barnes, I'm good. If I switch to cup and core/ gilding metal jacketed bullets, it takes a couple shots to settle down/ stabilize, and I'm good. If I switch back to Barnes, it's shoots like crap, and continues to shoot like crap until I clean it.

I have experienced the same exact same thing with my 6.5-300 Weatherby. I can shoot about anything that I want with, tight groups, as long as I start with a clean barrel.

 

[Shane Lindsey]

I have heard from three talking heads that switching between copper monolithic and copper jacketed without scrubbing the barrel to bare metal can cause resistance issues and make accuracy suffer. In my quest to find the best load for my new 7 PRC I load up rounds during the week and shoot them before the wind picks up on the weekend. I have not been cleaning in between runs of bullets. Have you noticed an issue when switching back and forth? They claim the different alloys used cause an interaction between the metals.

I ask because I am about ready to send this rifle back as I can't find a consistently accurate load using handloads or factory.

What rifle, factory or custom? What does it shoot like/accuracy? What factory ammo have you tried? What bullet/powder have you loaded for it already and are you starting on the low end of the charge weights (some guns don't like the higher ends)? How many rounds down the barrel? Heavy barrel, carbon fiber, thin pencil hunting barrel? How fast are you shooting between shots? I have CF barrels that will stack the cold bore and follow up and then walk after due to heat and heavy mirage coming off of it. Have you checked torque on all the action screws, scope base, scope rings, swapped to another scope. I would trouble shoot the rifle before switching up loads if nothing is shooting semi-accurately.

I have seen slight differences with a few, others, not so much.

Sounds like you need to work with one and stick with it until you find a load that works, then clean it and start over. BUT switching between the two while trying to find a load just adds another variable.

 

[lachoneus]

I have heard from three talking heads that switching between copper monolithic and copper jacketed without scrubbing the barrel to bare metal can cause resistance issues and make accuracy suffer. In my quest to find the best load for my new 7 PRC I load up rounds during the week and shoot them before the wind picks up on the weekend. I have not been cleaning in between runs of bullets. Have you noticed an issue when switching back and forth? They claim the different alloys used cause an interaction between the metals.

I ask because I am about ready to send this rifle back as I can't find a consistently accurate load using handloads or factory.

I primarily use Barnes bullets now, but noticed that if I shot a cup-and-core load and then followed up with the Barnes loads, the subsequent groups grew from sub-MOA to over 2 MOA in size and shots landed erratically. Cleaning the barrel solved the problem.

 

[littlebighorn]

I always clean my barrels between different brands of bullets because I have experienced "funky" groups if I don't.

 

[Varmint Hunter]

I switch back & forth on a regular basis without any noticeable issues. The Hammers that I'm using don't leave all that much copper in the bore so that may help.

Older Barnes bullets use to load barrels up terribly and they did not shoot well when interchanged with cup N core bullets. I think that is where the issue was first realized, but it may not be an issue with current monos that don't foul very much.