| mrdinapoli New Member 
Posts: 25 | Jan 16, 2023 at 12:57pm harperc, riceman, and 10 more like this QuoteEdit  
Post by mrdinapoli on Jan 16, 2023 at 12:57pmI have been following and replying to a threat on the "Long Range Hunting" forum “WHY HAMMER BULLETS ARE ALWAYS FASTER." (https://www.longrangehunting.com/threads/why-hammer-bullets-are-always-faster.319315/), which contains some great discussions on Hammer bullets, pressure, and velocity. Some of the members asked that I upload some of my posts to the Hammer Time forum, so I am happy to do so and will include them below and in the next posts. I hope that they provide some good information and stimulate a great discussion.ORIGINAL POST 01/11/2023: The thread on LRH forum "Why Hammer Bullets are Always Faster" is very interesting, and contains much good info and theories, along with a lot of conflicting thoughts. I’ve started working up some loads for a 270 Wby with Absolute Hammer 116s and Hammer Hunters 117s this week (perfect timing), so I have been reviewing my reloading notes and giving this topic lots of thought lately. (By the way, I chose these bullet weights because they will stabilize in my 1:10” twist, and are similar in length to the 130 gr Nosler Ballistic Tips and HT bullets I have shot in the past.) I have not shot the Hammers yet and do not have the equipment to measure pressure. However, I have good experience with very similarly constructed HT bullets on medium game in the 1990s - 2000s. I also have 30+ yrs of reloading experience, so I do feel that much of this info will be pertinent and hopefully useful. Here are several thoughts and personal findings to consider as I read through this thread on Hammer Bullets. Some are repeats, some are new, but nice to have in one place. 1. The HT Bullets that is shot previously were solid copper lathe-turned bullets with the shank being land diameter and 11 driving bands being groove diameter. I worked up loads using IMR published load data for Nosler 130 gr Ballistic Tips with IMR-7828 for both the 130 gr HTs and 130 gr Noslers, slowly increasing charges from Minimum up to 1 gr under Maximum. In my Weatherby Mark V with a 24” barrel, I was able to drive the 130 gr HTs to 3408 fps (SD: 1.5), while I could only obtain 3301 fps (SD: 10.9) with the 130 gr Noslers using the same powder charge in each. I experienced some primer cratering with the Noslers, but had no pressure signs with the HT solids. The HT bullets shot very accurately and worked well, but, unfortunately, are no longer made. 2. While looking through various reloading manuals and online data, I almost never see published pressure data in new manuals any more that is original. Many of the published pressure data I found was copied from old information. I found 5 listed pressures for IMR 7828 with 130 gr bullets, and they all copied IMRs data from the 1980s. I could not find any current pressure data. This may be because the 270 Wby is a more obscure cartridge. However, I did find it interesting that members noted that some of the major manufacturers use QuickLoad to evaluate pressure (ie. Berger). With the explosion of new cartridges and components, it is likely that the majority of manufacturers now use modeling software to estimate safe pressure, then test loads in firearms to confirm safety and look for pressure signs. However, they don’t publish pressures either because it is modeled and not actually measured, or because they feel it may encourage users to push loads further. 3. It is true that reloading manuals and other published data is only a guide. Even if pressure data is supplied, it does not pertain to your rifle and components. That is why publishers always suggest starting about 10% low and working up. Due to differences in bore diameter, bore condition, bullet diameter, bullet composition, powder, bullet lots, chamber dimensions, case differences, etc, I’m surprised it’s not more than 10%. Bottom line: you have to be able to look for pressure signs in your system. They are not perfect, but will give you some guidance. 4. It has been stated multiple times in this thread that there is no such thing as a free lunch — more velocity = more pressure. This is a statement taken out of context. It is true that for a consistent system, including same bullet WEIGHTS and CONSTRUCTION, that it is not possible to get more velocity without more pressure. However, Hammer Bullets (and similarly constructed bullets) are different in design, material, and construction: 1) there are likely differences in the composition of the bullet material vs jacket material that will affect drag (lubricity); 2) the jacket and lead core of standard bullets will deform more easily, allowing obturation to the bore with less pressure than solid copper bullets; 3) there are clearly bearing surface differences between Hammers and other bullets with driving bands and standard bullets with a uniform bearing surface. 5. The difficult part to predict is how will all of these variables settle out. Will the decrease bearing surface and friction overcome any potential difference in lubricity and hardness in deforming the bullet to fit the lands and grooves (obturation). Only experimentation or actual pressure testing will be able to tell the difference in pressure and velocity for a standard bullet (ie. Nosler Accubond) vs a mono-core bullet with driving bands (Hammer). 6. Sometimes it helps to understand differences by looking at the extremes. Hammer (and similar) bullets use driving bands to reduce bore contact while maintaining an effective bore seal. These driving bands reduce the bearing surface and thus friction with the bore. This is akin to pushing a sled across the ground on a flat bottom (standard bullets) vs on skids or runners (Hammer bullets). For a given amount of work (in our case pressure), it is easier to move an object with less friction, both farther and faster. For example: If you could exert only 100 lbs of force on each of two sleds to move them down a road, one with skids (Hammer bullets) vs one with a flat bottom (standard bullets), which would be easier and faster — the skidded sled of course. 7. I have shown (above) that using the same powder and charge, other components, and rifle (Weatherby Mark V), that the HT bullets obtained faster velocity than the Noslers, while not showing the pressure signs seen with the Noslers. The bullet weights were measured and were the same. The only difference was bullet design and construction. 8. I have had great luck in the past using QuickLoad with standard bullets. However, I do not know if Hammer Bullets or similar bullets (ie. Barnes TSX and LRX) have been added to the bullet database. If not, QuickLoad may not be able to accurately account for the differences in land engraving resistance and bore contact / friction between standard core and cup bullets and solid copper bullets with driving bands. Therefore, QL may not be able to accurately predict pressure, velocity, and time data for these new bullets. I’m sure that updates will solve this problem, if not done so already. It is an incredible program. 9. Further, if engraving resistance and bore friction are reduced due to the design and construction of Hammer bullets, pressure will be reduced for the Hammers compared to standard bullets, regardless of velocity obtained. This would theoretically permit a larger charge of the same powder to be used to bring pressure up to “standard” pressure, while increasing velocities further. However, this reduced friction and pressure would also allow Hammer bullets to use (and possibly benefit from) faster burning powders, similar to how faster powders often show benefits for lighter bullets. Faster burning powders would allow higher pressure to be obtained in a shorter barrel time. This may allow higher velocities with the Hammers, especially in shorter barrels. 10. Finally, speed kills. Plain and simply. Roy Weatherby was correct — the hydrostatic shock created by a high velocity projectile will drop light and medium game much faster than a large slow moving projectile. The best measure of this effect is likely kinetic energy (KE = mass x velocity x velocity). I have shot whitetail deer with my 270 Wby at 3400 fps that dropped as if struck by lightning, while slower heavier bullets from a 45-70 passed through deer without the same dramatic effect. Both animals expired. However, the animals subjected to the shock of the hyper velocity bullet dropped immediately (likely due to nervous system shock), while the animals subjected to the slow, heavy bullet ran and eventually succumbed (likely due to blood loss). These slower and heavier bullets do not cause as much shock, but do penetrate deeply. The best measure of this effect is likely momentum (Momentum = mass x velocity). In KE, velocity is emphasized and is squared. However, for momentum, mass and velocity are treated equally. Momentum is great for large and dangerous game, where penetration is paramount, but speed kills in light and medium game. The benefits of Hammer and other mono-core bullets with driving bands is that you can use a lighter and longer bullet at much a higher velocities to gain a better trajectory and more shock because these solids will hold together, maintain their weight, and penetrate much deeper than cup and core bullets which will explode and /or shed significant weight at these high impact velocities. There is a trend toward heavier and longer bullets with a higher BC for long range shooting. However, I think this is moving too far along the pendulum, and many are sacrificing velocity for BC. This may be beneficial for long-range target shooting, but less so for hunting. I think that by taking advantage of lighter, higher velocity mono-core bullets with higher BCs that retain more weight, you can have the best of all worlds — high velocity, flat trajectory, reduced wind drift, high shock, and deep penetration. Best Wishes, Mike D. |
