copper after cleaning

[Rich Coyle]

Interesting observation: Cleaned my 6.5 Coyle rifle after firing seventy-one fireforming shots using Lapua 123 grainers. These were moderate loads. Lots of copper compared to the amount when I cleaned it after firing 116 shots with Hammer Bullets when there was almost no copper. These were full throttle loads.

Thanks Steve and Brian.

 

[RockyMtnMT]

We are seeing exactly the same results. Almost zero copper fouling even in new factory barrels. We just recently got a full custom rifle done. It had been test fired 3 times with jacketed bullets. Cleaned it before we started shooting it and pulled piles of copper out. Never saw a lick of copper after that with the Hammers. When we developed our copper alloy we requested a softer form to get the terminal performance that we were looking for. We were worried that the softer form would smear copper in the barrels. Thankfully it has worked perfectly. Min 2000 lb order for custom changes to an alloy makes your butt pucker when you are hoping the changes are going to produce what you are looking for.

Thanks for the report Rich.

Steve

 

[tim_w]

Steve,

Do you think the surface area of bearing surface in your bullet design is less than typical design such as the lapua's mentioned? I have seen less fouling like you have also when I have used GS bullets but as they have very small area with the engraving bands it stands to reason.

When considering effects of hardness you would think the harder the metal the less fouling but Lapua and most cup and core bullets use gilding metal i.e copper alloy with around 5% zinc and harder

After that I would think lathe turned pure copper bullets would be the softest as there is no work hardening when compared to swaged solid copper bullet thus harder than the turned bullet.

But as people are seeing less fouling with a soft pure copper bullet I have to think it has to do with the engraving/bearing surface.and/or possibly a design that decreases gas cutting spraying the bore with micro copper sputter. I recall early predecessor of the Barnes TSX the x-bullet had serious copper fouling effects because of the long bearing surface and had the pressure to go with it. When they went to the driving bands to address the issue it was around a 50% reduction which it seems with time has reduced further by changes in bearing surface vs neck length ratio.

 

[RockyMtnMT]

Yes it has everything to do with our patented baring surface, PDR. Before we made our own bullet we used the other premium bullets and had what we expected for copper fouling. Our PDR design was designed to give good rifling engagement but to minimize the hard contact in the grooves. Because our bands are a radius the amount of actual contact in the groove is very finite. The radius valleys are deeper than the bore dia so there is a place to deposit the engraved copper. Frankly we have far less copper fouling than was expected. I guess one of the several benefits from our design that we did not realize that we were going to get. The request for the softer than normal from the foundry that we get our copper from was a decision that it would be worth the extra copper fouling that would result for the improved terminal performance that we were looking for. We got the expected improvement on terminal performance with no increase in copper fouling. Life is good!!!

The driving purpose behind our design was to solve the problem that mono copper bullets have. What dia to make them to seal the bore on every rifle with out having pressure issues in some and poor accuracy in others. PDR does this with flying colors. They are highly accurate in every rifle that is properly functional. There are very few rifles that need any tweeking to seating depth to get sub moa. They are simply easier to load than any other bullet on the market.

Steve