I don't usually post much here as most that are into smokeless muzzle loading will log on to Hank's Message board for good solid information. http://hanksmessageboard.freeforums.net/board/3/modern-smokeless-muzzleloaders
Somehow, duplexing in smokeless muzzle loading seems to get avoided by most except for users that have found it to be a good way to go. NO, it is NOT dangerous! As with any loads, you have to be cautious as to the amount of powder(s). But mixing or loading backwards is NOT dangerous. In fact, doing any of those things mitigates the effects of duplexing whereby the velocity (and subsequent pressure) will be reduced. I have mixed and loaded backwards many times just to prove it.............always the same results----lower velocity! So then why duplex? Again, this is my personal opinion based on messing with these SML's for the past twelve years and probably 60% of all the loads I have shot (well over 20,000 shots-based on my precise record keeping) were duplexed. And, my most consistent in terms of ES in velocity and precision, have been with loads that were duplexed.
Although there are some good duplex loads that work with sabots, (10/50--4759/H-4198 and a 250 gr. bullet along with a smooth blue Harvester sabot), one has to be careful the barrel does not get so warm as to soften the sabot and then "blow it!" (the sabot that is). Duplexing really comes on stronger with sabot-less shooting. Here, we need to get the bullet to obturate quickly (this is with smooth sized bullets) in order for it to grab onto the rifling quickly and start spinning---------rather than "slip/sliding" down the barrel. The extra boost/spike in pressure will do that (IMO). Another advantage is that the faster/booster will more easily ignite under cold conditions or poor primer spark. I also feel that the booster powder will better ignite the main powder charge especially if it is a very slow powder.
Right now, I am working with IMR-8208 as my main charge and N-110 as the booster along with a 325 gr. Pittman AeroMax. My velocity is right around 2950 fps. If I call the total weight of the booster and the main charge as "X" to get this velocity, then I have to add two grains more of 8208 as a straight charge to get the same velocity. But, I believe I am getting a better powder burn, equal velocity, less powder, accuracy/precision on a par or usually better AND, lower ES (extreme spreads). When dealing with shots at longer range, particularly using bullets with a lower BC, ES can make a difference in vertical stringing.
Mind you, these differences do not occur EVERY time but over the long haul, with all the shots I have put down range, I would give the edge to duplexing..........and then maybe just with particular powders.
But then I hear people say: Too complicated for use when hunting?............NOT! Lets say that as I mentioned above, I have a duplex that shoots at 2950 and a single charge of 8208 that also shoots at the same velocity.................just not "bug hole" as good! So, I carry several vials of that charge for a follow up or finishing off shot! Although two vials taped together with the booster and main charge is just about as simple.
Anyway, just thought I would pass this on for shooters who are unaware or leary of duplexing.
Remember, barrels that have been bulged or blown have been the result of TWO bullets loaded----NOT from a hot charge.
Just a note: I am shooting a Remington CF short action with Hank's direct ignition. My barrel is 28" long (Brux 1-20) with the first five inches at 1.250" and a straight taper to .9" with Hank's adjustable tactical brake. My scope is a NF 12x42 BR. with fine (1/8) dot. Total weight is 17 lbs. The stock is a custom Wenig thumbhole and trigger is 6 oz. Shilen. BTW, the last groups shot with the above duplex components was .255" CTC for three shots at 100 yards with a ES of 9 fps. Three shot groups at 300 yards are generally under one inch with most closer to 1/2 to 3/4.
Somehow, duplexing in smokeless muzzle loading seems to get avoided by most except for users that have found it to be a good way to go. NO, it is NOT dangerous! As with any loads, you have to be cautious as to the amount of powder(s). But mixing or loading backwards is NOT dangerous. In fact, doing any of those things mitigates the effects of duplexing whereby the velocity (and subsequent pressure) will be reduced. I have mixed and loaded backwards many times just to prove it.............always the same results----lower velocity! So then why duplex? Again, this is my personal opinion based on messing with these SML's for the past twelve years and probably 60% of all the loads I have shot (well over 20,000 shots-based on my precise record keeping) were duplexed. And, my most consistent in terms of ES in velocity and precision, have been with loads that were duplexed.
Although there are some good duplex loads that work with sabots, (10/50--4759/H-4198 and a 250 gr. bullet along with a smooth blue Harvester sabot), one has to be careful the barrel does not get so warm as to soften the sabot and then "blow it!" (the sabot that is). Duplexing really comes on stronger with sabot-less shooting. Here, we need to get the bullet to obturate quickly (this is with smooth sized bullets) in order for it to grab onto the rifling quickly and start spinning---------rather than "slip/sliding" down the barrel. The extra boost/spike in pressure will do that (IMO). Another advantage is that the faster/booster will more easily ignite under cold conditions or poor primer spark. I also feel that the booster powder will better ignite the main powder charge especially if it is a very slow powder.
Right now, I am working with IMR-8208 as my main charge and N-110 as the booster along with a 325 gr. Pittman AeroMax. My velocity is right around 2950 fps. If I call the total weight of the booster and the main charge as "X" to get this velocity, then I have to add two grains more of 8208 as a straight charge to get the same velocity. But, I believe I am getting a better powder burn, equal velocity, less powder, accuracy/precision on a par or usually better AND, lower ES (extreme spreads). When dealing with shots at longer range, particularly using bullets with a lower BC, ES can make a difference in vertical stringing.
Mind you, these differences do not occur EVERY time but over the long haul, with all the shots I have put down range, I would give the edge to duplexing..........and then maybe just with particular powders.
But then I hear people say: Too complicated for use when hunting?............NOT! Lets say that as I mentioned above, I have a duplex that shoots at 2950 and a single charge of 8208 that also shoots at the same velocity.................just not "bug hole" as good! So, I carry several vials of that charge for a follow up or finishing off shot! Although two vials taped together with the booster and main charge is just about as simple.
Anyway, just thought I would pass this on for shooters who are unaware or leary of duplexing.
Remember, barrels that have been bulged or blown have been the result of TWO bullets loaded----NOT from a hot charge.
Just a note: I am shooting a Remington CF short action with Hank's direct ignition. My barrel is 28" long (Brux 1-20) with the first five inches at 1.250" and a straight taper to .9" with Hank's adjustable tactical brake. My scope is a NF 12x42 BR. with fine (1/8) dot. Total weight is 17 lbs. The stock is a custom Wenig thumbhole and trigger is 6 oz. Shilen. BTW, the last groups shot with the above duplex components was .255" CTC for three shots at 100 yards with a ES of 9 fps. Three shot groups at 300 yards are generally under one inch with most closer to 1/2 to 3/4.
