So this has been quite the journey trying to boil down months of telephone calls that resembled a classic "Walkabout" down-under! The first request is clear your heads and take this for what it is, just a concept.
Some time ago (April 2023) I started a thread on “Light fast and heavy fast” that was based upon there are several options to consider when shooting Hammers.
https://hammerbullets.com/hammertime/threads/light-fast-and-heavy-fast.296/
This thread percolated in back of my mind (dangerous place BTW) and brought the cartridge efficiency concept forward. This whole thought is driven by my archery experience. What? I have been a bow guy since we stopped using spears, there! I said it before @joe16 can jump in. Shooting lighter arrows for speed on 3D was the main culprit. However, when I switched to stiffer spine and heavier arrow for hunting, my bow speed did not drop off anywhere near expected! Why? The stiffer heavier arrow can absorb the bow energy more efficiently thus minimal drop in speed. This thought transformed into cartridge efficiency concept where a specific bullet dimension and ensuing weight can accomplish the same result. There is also a bullet weight and associated powder ignition efficiency that becomes part of the concept as well.
DISCLAIMER: this is ONLY a concept and does not state this is the ONLY load concept to shoot. Light laser fast, load manual velocities and heavy fast are still ALL viable loads. This is just an interesting thought “What if” and does it provide another load option to consider.
So about 6 months or so ago, Farleg and I started having conversations on this concept. You know they are great when your wife tells you to go into another room! Farleg also had similar concept bouncing around so it was “game on’!
The concept we fleshed out is for every cartridge there is an optimum bullet length and ensuing weight that allows the cartridge to maximize the case capacity to 100% thereby providing the most efficient performance for that bullet length and ensuing weight for that cartridge. What also led us down this path was my .270 Thors Hammer, a .270 Win in a 700LA with 3.67 maximum magazine COAL, 1:8 twist, 27” barrel, 0.290 freebore, 0.020 jump and 3.63 COAL. This rifle was built specifically to shoot the 156HH even though I had NEVER shot the bullet. I believed the build could wring out the max performance of this bullet upping the game for the .270 Win, excuse me, the infamous Skinny Ugly. The result was astounding. I never anticipated the performance that it delivered. The load topped out at close to 3300 and even then has room since I have not really kept looking for better loads. Nor have I changed primer to mag which may add? The rifle shoots exceptionally well so it was don’t screw up a good thing! The 3.63 COAL was selected to ensure the HP of the 156HH was not damaged in cycling from internal magazine. What’s the big deal? Well, it seems a blind pig can find an acorn with these build parameters. The added freebore allowed seating the heavier higher BC bullets out far enough such the bullet bases were at bottom of neck. What was interesting was the PDR bands aligned perfectly at case mouth so no loss of COAL. No, I did not have a clue this was happening other than velocities were way above expected even with cup and core bullets.
So, I backed the load down to 3205 as my hunting load. Accuracy is stellar and as luck would have it, I killed my biggest buck (161 7/8) in 2021 with it in Indiana on a private farm. Bullet performance was as expected and slosh factor was impressive. Even cup and core bullets were hitting velocities not normally associated with the .270 Win. Yes, the barrel length helped but the velocities were significantly higher than expected.
So @kneedeep: After reading @Farleg build up on this discussion, I’m excitedly waiting on your write up and findings @Muddyboots . I’m going to be highly disappointed if you’ve spent many hours discussing “getting the base of the bullet at the base of the neck.” We know how to turn cartridges into “skinny uglies” or creedmores.
Bullet at base of neck has been golden rule forever but is only one aspect of the total cartridge efficiency concept. So why does this rifle shoot so fast with a heavier bullet? We think it is because the 156HH meets a certain criterion that maximized the cartridge efficiency. The length of the 156HH is also coincidently 1.56” which allowed the COAL to max out to the 700LA magazine along with the added freebore. The magazine COAL and throat dimensions drive this number. In addition, @Steve Davis somehow knew I needed the PDR band placement EXACTLY where the case mouth and PDR bands intersected without requiring reducing the COAL. In this case, the bullet weight was already predetermined but we think this concept to be true for other cartridges and their actions as well. It doesn’t matter if a factory rifle or custom with freebore. The measurements for that cartridge will dictate the bullet length needed and ensuing weight once that bullet is made. We believe the velocity achieved under these parameters will be exceptional for the weight that is the end result of meeting the dimensional parameters.
The cartridge efficiency concept we came up with is:
Parameters:
Every action length and associated cartridge will be constricted by several factors:
So as you noticed, zero discussion on pressure and intended so. The pressure developed will be whatever the powder selected generates but recognize with 100% case capacity available this opens up a lot more powders to consider.
Again, we are NOT stating this is the ONLY means to load Hammers but an option to possible develop a load that probably the most efficient in design and powder ignition criteria. Will it be faster than a light laser? Heck no. We think this could be a very nice load that meets a lot of needs.
So what? You are right! It only provides another concept to chase in loading Hammers.
Some time ago (April 2023) I started a thread on “Light fast and heavy fast” that was based upon there are several options to consider when shooting Hammers.
https://hammerbullets.com/hammertime/threads/light-fast-and-heavy-fast.296/
This thread percolated in back of my mind (dangerous place BTW) and brought the cartridge efficiency concept forward. This whole thought is driven by my archery experience. What? I have been a bow guy since we stopped using spears, there! I said it before @joe16 can jump in. Shooting lighter arrows for speed on 3D was the main culprit. However, when I switched to stiffer spine and heavier arrow for hunting, my bow speed did not drop off anywhere near expected! Why? The stiffer heavier arrow can absorb the bow energy more efficiently thus minimal drop in speed. This thought transformed into cartridge efficiency concept where a specific bullet dimension and ensuing weight can accomplish the same result. There is also a bullet weight and associated powder ignition efficiency that becomes part of the concept as well.
DISCLAIMER: this is ONLY a concept and does not state this is the ONLY load concept to shoot. Light laser fast, load manual velocities and heavy fast are still ALL viable loads. This is just an interesting thought “What if” and does it provide another load option to consider.
So about 6 months or so ago, Farleg and I started having conversations on this concept. You know they are great when your wife tells you to go into another room! Farleg also had similar concept bouncing around so it was “game on’!
The concept we fleshed out is for every cartridge there is an optimum bullet length and ensuing weight that allows the cartridge to maximize the case capacity to 100% thereby providing the most efficient performance for that bullet length and ensuing weight for that cartridge. What also led us down this path was my .270 Thors Hammer, a .270 Win in a 700LA with 3.67 maximum magazine COAL, 1:8 twist, 27” barrel, 0.290 freebore, 0.020 jump and 3.63 COAL. This rifle was built specifically to shoot the 156HH even though I had NEVER shot the bullet. I believed the build could wring out the max performance of this bullet upping the game for the .270 Win, excuse me, the infamous Skinny Ugly. The result was astounding. I never anticipated the performance that it delivered. The load topped out at close to 3300 and even then has room since I have not really kept looking for better loads. Nor have I changed primer to mag which may add? The rifle shoots exceptionally well so it was don’t screw up a good thing! The 3.63 COAL was selected to ensure the HP of the 156HH was not damaged in cycling from internal magazine. What’s the big deal? Well, it seems a blind pig can find an acorn with these build parameters. The added freebore allowed seating the heavier higher BC bullets out far enough such the bullet bases were at bottom of neck. What was interesting was the PDR bands aligned perfectly at case mouth so no loss of COAL. No, I did not have a clue this was happening other than velocities were way above expected even with cup and core bullets.
So, I backed the load down to 3205 as my hunting load. Accuracy is stellar and as luck would have it, I killed my biggest buck (161 7/8) in 2021 with it in Indiana on a private farm. Bullet performance was as expected and slosh factor was impressive. Even cup and core bullets were hitting velocities not normally associated with the .270 Win. Yes, the barrel length helped but the velocities were significantly higher than expected.
So @kneedeep: After reading @Farleg build up on this discussion, I’m excitedly waiting on your write up and findings @Muddyboots . I’m going to be highly disappointed if you’ve spent many hours discussing “getting the base of the bullet at the base of the neck.” We know how to turn cartridges into “skinny uglies” or creedmores.
Bullet at base of neck has been golden rule forever but is only one aspect of the total cartridge efficiency concept. So why does this rifle shoot so fast with a heavier bullet? We think it is because the 156HH meets a certain criterion that maximized the cartridge efficiency. The length of the 156HH is also coincidently 1.56” which allowed the COAL to max out to the 700LA magazine along with the added freebore. The magazine COAL and throat dimensions drive this number. In addition, @Steve Davis somehow knew I needed the PDR band placement EXACTLY where the case mouth and PDR bands intersected without requiring reducing the COAL. In this case, the bullet weight was already predetermined but we think this concept to be true for other cartridges and their actions as well. It doesn’t matter if a factory rifle or custom with freebore. The measurements for that cartridge will dictate the bullet length needed and ensuing weight once that bullet is made. We believe the velocity achieved under these parameters will be exceptional for the weight that is the end result of meeting the dimensional parameters.
The cartridge efficiency concept we came up with is:
Parameters:
Every action length and associated cartridge will be constricted by several factors:
- The Action maximum COAL for its magazine in conjunction to the throat dimensions.
- The bullet length dependent upon base of bullet located at bottom of the neck of the cartridge brass and still meet the magazine COAL and throat requirements. Notice ZERO reference to bullet weight. Since this is likely a new bullet, these dimensions will drive what the end weight of the bullet will become.
- The brass capacity regardless of the brass manufacturer will be at 100% for that specific brass since the bullet will not occupy the potential case capacity by residing within the neck of the brass. This allows for maximum powder for the cartridge and opens up the potential for additional powders that may hit pressure prematurely due to bullet intrusion into case volume or allow more space for powders that may run of room but not hit pressure.
- We also think a flat base bullet will do better in this approach to maximize bullet weight to length ratio. This also brings in the caliber to shank ratio, and terminal performance that might see improvement with flat base improving shank penetration. The flat base does not give up anything to a boattail in average hunting distances to 500 yards. We think there is likely to be better powder efficiency on flat base for this purposes. I’ll ask @Farleg to jump in here.
- PDR band placement on bullet becomes critical such the PDR bands align with case mouth so you do not have to seat deeper to find crimping point. This is same for HH and HHT which are the primary bullets we discussed. However, the AHT may be a much better selection due to the nose design for factory throats. More to come about this bullet.
- A scalloped shank was one of the first thoughts @Farleg suggested. We are not sure if practicable. The clean shank is likely still best option.
- The PDR band placement design needs to take into account brass trim length as well to ensure consistent PDR crimping location without losing COAL.
- The type of Hammer bullet is also irrelevant since we are strictly discussing a specific bullet length to meet an efficiency based upon certain dimensions. Though we both believe this will be a HHT or an AHT decision.
So as you noticed, zero discussion on pressure and intended so. The pressure developed will be whatever the powder selected generates but recognize with 100% case capacity available this opens up a lot more powders to consider.
Again, we are NOT stating this is the ONLY means to load Hammers but an option to possible develop a load that probably the most efficient in design and powder ignition criteria. Will it be faster than a light laser? Heck no. We think this could be a very nice load that meets a lot of needs.
So what? You are right! It only provides another concept to chase in loading Hammers.
