I am going to try and keep this short as I am way behind on orders.
When it comes to our copper harperc is correct. It was not as simple as "Lets get some copper and make bullets". That is kinda what we thought when we started this journey. We were able to find one foundry that was willing to draw our copper to the specs that we want. We have tried the same alloy from a different foundry and it was not as good. It was stated that there is variation within a bar and I can not dispute this. Some of the pics that Yorke posted of his low vel impacts look to be from some of the stock that we are no longer using. That copper was a bit too hard and the petals did not come off square to the retained shank. What we are using now is more consistent with the low vel impacts and taking on the same form after impact at the high vel impacts.
When it comes to shedding the petals:
The problem with a bullet that deforms into a large frontal area, like the Barnes show in their deformed bullet pics, is they slow down inside the animal and do less and less damage as they slow down. Energy left in the animal is fireside folk lore and has nothing to do with science. There is no such thing as "knock down power". We have to interrupt the central nervous system. This is done in a couple of ways, most commonly by bleeding the animal out, or by impacting the brain. Sometimes we get the pure lung shot that results in drt. I believe this is done by hitting the animal in the perfect timing of the high point of the blood pressure in the heart rhythm, with the hit increasing the pressure due to the shock and causing the animal to stroke out. Thus directly effecting the brain.
We design our bullets to open as quickly as possible. Usually you will see that the bullet has done its expansion just under the hide as it enters the ribs. Often the entrance will look more like an exit. We want the petals off and the retained shank to have a flat square frontal area, kinda like a flat based bullet turned around backwards, or like a dangerous game bullet. The flat surface is key to making a large wound channel as it will displace soft tissue perpendicular to the direction of travel. vs a rounded mushroom that will more easily part its way through the soft tissue with less permanent wounding. The soft tissue is elastic and bullets do not cut they tear. Tearing is done by the vel that is travels through the soft vital tissue. As a bullet slows down after impact the amount of damage that it causes becomes proportionally less until it stops and no longer causes any damage. Conversely a bullet that deforms to a smaller but flat, square frontal area that will carry vel through the animal causing a larger permanent wound channel completely through the animal will result in a larger over all wound that will bleed faster.
The petals generally stay fairly large and do their own thing. We do not count on them like we count on the form of the retained shank, but the petals are a part of the equation and can not be discounted. Here is three pics of the same bullet during testing from 3400fps impact down to 1800fps impact. This is what we expect. This was testing a line of bullets that we call the DeadBlow. These bullets are designed to retain 50% or a little less depending on the size of the bullet. We can produce these in any of the Hammer Hunter line. We have not had the time to load them all on the website but they are able to be ordered if some one wants them. I personally use the higher weight retention but the DeadBlows have proven very effective with no ore meat damage than our Hammer Hunter line. This test was a 150g 30cal. The Hammer Hunter line will look exactly the same with a larger retained shank at 70% retention.
Steve
