264 Win Mag Load Development

[Western Living]

I'm about to start developing a load for hunting with 264 Win Mag out of a 26" barrel with a 1:9 twist. Using Nosler factory ammo, the gun made about a three-quarter inch 3-shot group, so I determined it was worth the considerable expense to gear up to load for this rifle and cartridge. I'll be using Nosler brass and Redding dies.

I hunt mule deer and pronghorn in the mountains of the Great Basin area. A typical shot is not less than 200 yards. I've had good results using 6.5 Grendel and 6.5 Creedmoor and Barnes TTSX or LRX, 100 grain, 115 grain, and 127 grain. I will use copper monolithic bullets for the Magnum also. The 127 grain LRX is too long for the 1:9 twist according to Barnes, so I am thinking of the 100, 115, or 120 grain TTSX. The 100 will have the flattest trajectory, the longest MPBR, and it will almost certainly fully penetrate the largest mule deer. I'm not yet convinced the 115 or 120 grain bullets will have any advantage for me except perhaps on Elk, Moose or Brown Bear that I will not be hunting with this load.

The typical powders for 264 range from H4831SC, RL22, 7828SC, RL26, H1000, Ramshot Magnum, to Retumbo. Some less typical powders that may be good for this purpose nevertheless might be Accurate MagPro, or VV N170, RL33, StaBall HD, Ramshot LRT...

I've read in one of the Hodgdon Annual manuals that with lighter bullets, a faster powder is to be preferred. I'm not sure why and if it has to do with the mass of the bullet or the length and case capacity. Monos are longer for their weight than cup and core jacketed lead bullets. I also read that full cases of slightly compressed powder are to be preferred over cases with a bit of empty space in them. Those things were mentioned by John Barsness in an article on loading for the 6.5 PRC -- which has some similarities to the 264 Magnum. Understandably, Barsness used heavier bullets in the PRC than I'm intending for the old school magnum with monos, and the magnum's powder capacity is somewhat greater than the PRC, so I couldn't take his powder choices or the recommendations he received from Hodgdon.

I can hunt pronghorn when it's hot (100 deg. F) and muleys in cold temperatures. This last October it was -5 deg. F. I'm not hunting at distances that temperature stability is a major factor, but I'd better avoid the least stable powders.

The magnum is a "barrel burner" and I don't intend to ever replace the barrel on this original pre-64. I won't be experimenting with a lot of powders and bullets and so on. I'll pick a bullet, pick a powder, develop the load and hunt. I don't have the barrel life for a lot of second guessing. So I want to make intelligent first choices.

I tried some analysis in Quick Load. What I found was that something like 4831SC or RL22 allowed me to reach the MAP limit without quite filling the case. If I stepped up to some powders that would burn more progressively and should work better in this highly overbore case, like H1000, Magnum, or Retumbo, I would be overfilling the case before I could reach the MAP limit.

Of course, there are many threads where people recount what powders they've used with success. I've read a lot of those. However, much past experience with 264 can be characterized as:
1. 60+ years of tradition that didn't include more modern, slower, more progressive powders that didn't exist for most of the 264's history.
2. Heavy lead bullets rather than 100-120 grain monos.

I've read a lot of, "I did something different than what you're trying to do and as far as I can tell, it worked." I want to read more about some ideas concerning burn rate and progressivity and how they relate to bullet weight, bullet length, case capacity and bore.

Right now, I'm leaning toward the 120 grain and 4831SC as the traditional "safe bet." The 100 grain over Retumbo is appealing as a little more radical. The most radical experiment I might be willing to try would be Ramshot LRT -- it does very well in 257 Weatherby Magnum which has some similarities to the side of 264 Magnum I'm trying to load for.

I'm not chasing outright velocity per se. I believe accuracy and consistency is more important. On the other hand, the 264 is only distinct from just another Creedmoor, 270 or 308 because of velocity.

 

[AlabamaSlammer2]

I'm about to start developing a load for hunting with 264 Win Mag out of a 26" barrel with a 1:9 twist. Using Nosler factory ammo, the gun made about a three-quarter inch 3-shot group, so I determined it was worth the considerable expense to gear up to load for this rifle and cartridge. I'll be using Nosler brass and Redding dies.

I hunt mule deer and pronghorn in the mountains of the Great Basin area. A typical shot is not less than 200 yards. I've had good results using 6.5 Grendel and 6.5 Creedmoor and Barnes TTSX or LRX, 100 grain, 115 grain, and 127 grain. I will use copper monolithic bullets for the Magnum also. The 127 grain LRX is too long for the 1:9 twist according to Barnes, so I am thinking of the 100, 115, or 120 grain TTSX. The 100 will have the flattest trajectory, the longest MPBR, and it will almost certainly fully penetrate the largest mule deer. I'm not yet convinced the 115 or 120 grain bullets will have any advantage for me except perhaps on Elk, Moose or Brown Bear that I will not be hunting with this load.

The typical powders for 264 range from H4831SC, RL22, 7828SC, RL26, H1000, Ramshot Magnum, to Retumbo. Some less typical powders that may be good for this purpose nevertheless might be Accurate MagPro, or VV N170, RL33, StaBall HD, Ramshot LRT...

I've read in one of the Hodgdon Annual manuals that with lighter bullets, a faster powder is to be preferred. I'm not sure why and if it has to do with the mass of the bullet or the length and case capacity. Monos are longer for their weight than cup and core jacketed lead bullets. I also read that full cases of slightly compressed powder are to be preferred over cases with a bit of empty space in them. Those things were mentioned by John Barsness in an article on loading for the 6.5 PRC -- which has some similarities to the 264 Magnum. Understandably, Barsness used heavier bullets in the PRC than I'm intending for the old school magnum with monos, and the magnum's powder capacity is somewhat greater than the PRC, so I couldn't take his powder choices or the recommendations he received from Hodgdon.

I can hunt pronghorn when it's hot (100 deg. F) and muleys in cold temperatures. This last October it was -5 deg. F. I'm not hunting at distances that temperature stability is a major factor, but I'd better avoid the least stable powders.

The magnum is a "barrel burner" and I don't intend to ever replace the barrel on this original pre-64. I won't be experimenting with a lot of powders and bullets and so on. I'll pick a bullet, pick a powder, develop the load and hunt. I don't have the barrel life for a lot of second guessing. So I want to make intelligent first choices.

I tried some analysis in Quick Load. What I found was that something like 4831SC or RL22 allowed me to reach the MAP limit without quite filling the case. If I stepped up to some powders that would burn more progressively and should work better in this highly overbore case, like H1000, Magnum, or Retumbo, I would be overfilling the case before I could reach the MAP limit.

Of course, there are many threads where people recount what powders they've used with success. I've read a lot of those. However, much past experience with 264 can be characterized as:
1. 60+ years of tradition that didn't include more modern, slower, more progressive powders that didn't exist for most of the 264's history.
2. Heavy lead bullets rather than 100-120 grain monos.

I've read a lot of, "I did something different than what you're trying to do and as far as I can tell, it worked." I want to read more about some ideas concerning burn rate and progressivity and how they relate to bullet weight, bullet length, case capacity and bore.

Right now, I'm leaning toward the 120 grain and 4831SC as the traditional "safe bet." The 100 grain over Retumbo is appealing as a little more radical. The most radical experiment I might be willing to try would be Ramshot LRT -- it does very well in 257 Weatherby Magnum which has some similarities to the side of 264 Magnum I'm trying to load for.

I'm not chasing outright velocity per se. I believe accuracy and consistency is more important. On the other hand, the 264 is only distinct from just another Creedmoor, 270 or 308 because of velocity.

I use Reloader 33 and 142 ABLRs.
Shoot great and good velocity - 3375 fps w 28” barrel. Shoots 1/4 to 1/2 MOA. They performed well on the deer I hunted.
Couldn’t get that velocity and accuracy with some of the other powders.

 

[AlabamaSlammer2]

I use Reloader 33 and 142 ABLRs.
Shoot great and good velocity - 3375 fps w 28” barrel. Shoots 1/4 to 1/2 MOA. They performed well on the deer I hunted.
Couldn’t get that velocity and accuracy with some of the other powders.

I have a 1 - 8 twist Bartlein

 

[Western Living]

I use Reloader 33 and 142 ABLRs.
Shoot great and good velocity - 3375 fps w 28” barrel. Shoots 1/4 to 1/2 MOA. They performed well on the deer I hunted.
Couldn’t get that velocity and accuracy with some of the other powders.

Why do you think that is?

 

[spife7980]

As to why a faster powder for lighter bullets: as the bullet moves down the barrel it is creating more volume behind it in the chamber plus the bore, as the bullet moves more and more volume is created. A powder when burned creates a certain amount of gas, the rate at which it converts to that gas is what we call the burn rate. A lighter bullet accelerates more quickly than a heavier bullet, f=ma and all that mass at rest stuff.

So a lighter bullet moves quicker making more volume behind it, to maximize that bullets time in the bore you want a faster powder to fill the volume behind the bullet in that limited time. A slow powder could still be burning when the light bullet is already gone from the barrel wasting energy and unrealized velocity.

 

[AlabamaSlammer2]

As to why a faster powder for lighter bullets: as the bullet moves down the barrel it is creating more volume behind it in the chamber plus the bore, as the bullet moves more and more volume is created. A powder when burned creates a certain amount of gas, the rate at which it converts to that gas is what we call the burn rate. A lighter bullet accelerates more quickly than a heavier bullet, f=ma and all that mass at rest stuff.

So a lighter bullet moves quicker making more volume behind it, to maximize that bullets time in the bore you want a faster powder to fill the volume behind the bullet in that limited time. A slow powder could still be burning when the light bullet is already gone from the barrel wasting energy and unrealized velocity.

Agree. There was a point with Retumbo that no matter how much I increased the powder charge - it would finish combustion out past the barrel and you could see the fireball grow. Velocity maxed out around 3100.

 

[Western Living]

I understand that powders don't have a fixed burn rate, but they burn at different rates depending on the pressure and time.

A large charge of powder like Retumbo can complete 100% combustion in an 18" barrel if the pressure is high enough. If the powder charge is too small because the case does not have enough capacity, the burn rate will be lower and combustion slower. For example, if I put a charge of 71 grains of Retumbo in a 264 case behind a 100 grain TTSX, the case will be 100% full, but combustion will only reach 48,000 psi and it will take 32 inches of barrel to complete the combustion. With a 26" barrel, combustion will only be 97% complete -- which is in itself fine. Some of the highest velocity results come from an even smaller portion of the total charge being burned before the bullet exits. On the other hand, the low pressure in this case is resulting in poor combustion.

If the charge mass is increased to 74 grains, we can reach 55,000 psi and complete 100% combustion in 26 inches of barrel. That 74 grains will be a compressed charge.

If we could increase the charge mass to 77 grains, we could reach the 62,000 psi maximum peak pressure for the cartridge and burn the entire charge in only 20 inches of barrel. The problem is we probably cannot fit the bullet in a case with 77 grains of Retumbo. They just don't fit.

Pressure is not the only thing that changes the burn rate of a powder, but it can also change with the combustion time. I understand that combustion deterrents in the powder can make it burn slower and the more deterrent, the slower the burn. The burn rate of the powder/deterrent mixture doesn't stay constant throughout the burn time. The rate is a function of the surface area of the granules that are burning. With an extruded powder, the granules are cylindrical and in some designs like H1000, they can have a hole through the axis of the cylinder. Combustion begins on the surface of the granule. Because of the hole through the cylinder, as combustion continues, the surface area increases as the granule burns from both the outside in and the inside out. Hollow cylinders are one way to make a progressive burn rate, but there are other ways such as donut-shaped flakes, multiple holes through extruded powders, and variations in the porosity of the grains. Ball powders with their spherical shape would tend to be digressive in burn rate, but there may be ways to manipulate that also.

So now I want to consider the bullet moving along the bore to make more room behind it to allow for more expanding gas. First, let me put a couple powders and the distances the bullet moves into perspective. A full charge of H4831SC will reach peak MAP when the bullet has moved about 2.5 inches. A full charge of Retumbo will reach peak MAP when the bullet has moved about 3.5 inches. The bore size matters here. Two and a half inches of travel can create a lot of volume in a 45 caliber bore, but not so much in a smallbore. The 264 is a highly overbore cartridge. Traditionally, the 257 Wby. was the only one more overbore. So it has a high volume of powder to create pressure to be relieved through a relatively small hole.

It makes sense that a lighter bullet would accelerate and therefore relieve pressure faster. The smaller bore diminishes this effect. What I'm actually seeing in the model is that a faster powder like H4831SC is that peak pressure is reached at 2.5" of travel and after that the pressure falls off more rapidly than with Retumbo. So what would "fill in" the volume of space created behind the bullet moving down the bore would be a slower burning powder with a more progressive burn rate -- one that doesn't reach peak MAP too soon but which progressively increases the burn rate in consideration of the expanding volume behind the bullet as it moves down the bore. The limitation seems to be the case capacity and how progressive we can make a powder. Ideally, we would keep 60,000 psi behind the bullet all the way down the bore. Realistically, we make that much pressure for a quarter of an inch of the bullet's travel, before and after which the pressure is building up or falling off rather dramatically. Slow, progressive powders make this tapering more gradual and allow a larger overall charge mass which can deliver more energy under the pressure/time curve. At some point, we can't fit enough of the powder base and deterrent into the case for it to develop enough pressure for good combustion. That's why we have the Jeffery-based Nosler 26 and the 6.5-300 Weatherby and we could make other ultra-magnums or a STW-based 264.

 

[FLIGHT762]

If you already have the H-4831 SC, I would go with it and the Barnes 120 TTSX. See if you can get to 3200 + FPS safely & accurately. If so, you're good. Should work in your Rifle.

H-4831 is a good temp stable powder and will work for your hunting conditions. That bullet will work for what you're going after.

 

[Dead Eye Dick]

Watch your OAL. I understand that Winchester used a bore rider bullet when they designed the .264. (Part of the reason the 7mm Remington overtook it so easily). Anyway, the throating might be very tight.