CVA Scout – 4198 vs 4227

I bought a pound of 4227 and decided to do some comparison tests today between 4198 and 4227 out of my CVA Scout.  I am shooting the 278g Accumax bullet.  I've shot a little over 200 rounds out of my gun over the past 4 months and up to this point my best groups were with 61-62g of 4198 and a wool wad (consistently grouped 1" or better at 100 yards).  Today I was pleasantly surprised to find that 4227 performed even better.  I started with 53g (minimum load for my powder chamber) and once I hit 54g there was no need to go any further.  It was obvious I had found my load.  I attached a picture below of my best group.  This load shoots 2575 FPS out of my gun.  

Here are the reasons I like 4227 better than 4198:
1. Lower ES and better groups out of my gun
2. It is a faster burning powder and should swell the bullet faster
3. My groups were actually better without a wad
4. I get the same velocity as 4198 with 5-6 grains less powder


View Attachment

Steve and Kyle both did a QL calculation for me using 54g 4227 and a 278g Accumax bullet. The calculated pressure was around 50,000 psi, so for a CVA Scout I think this is probably about the max load you would want to shoot. Buckeye also commented in another post that he would not recommend using over 55g of 4227 in a break action gun.

Quick Load is a centerfire program. In a conventional cartridge rifle, the bullet is jammed into the throat of the barrel. There is a very fast pressure rise that engraves the rifling into the bullet. The pressure spikes very quickly and then decreases quickly as the bullet goes down the barrel.

Quite a different scenario occurs in a smokeless powder MLer. The bullet is only held by the lands with appx 0.0035” of space to the bore. When the powder ignites, the pressure swells the bullet AS IT IS STARTING TO MOVE DOWN THE BARREL , so unlike the cartridge rifle where all this engraving occurs at a finite place, this land engraving/obturation over a much greater distance. How far down the barrel this takes? I have no idea. A smooth sized bullet would go farther than a full sized bullet (452 or 402) and surely farther than a full sized, bore size bullet (458 or 408).

FWIW, with my comparatively low to moderate loads, I full size in order to shorten the obturation distance and hopefully to increase the consistency of the obturation distance. I anneal monolithic bullets for the same reason.

Many early PT calculations verses QL estimates were fairly close, but most were done with saboted loads (which obturate quicker than bore sized bullets) and with comparatively fast powders. I believe that the differences between PT and QL calculations would be much greater with smooth sized bullets and our slower powders. However, the elongated burn causes the calculated speeds to be uncannily close. Actually, with a high percentage burn, virtually the same total energy is obtained- just over a longer distance, which results in about the same energy imparted to the bullet. So, virtually the same speed results. 

In summary, I believe that there is a much longer sustained pressure in a smokeless MLer resulting in close to the same velocity as a CF would have with the same bullet wt and powder but with a significantly lower peak pressure(in the MLer). 

If you were to take a 8-9# total weight rifle (like my ultralite 40, or a light break open) and shoot it, say with a 250g bullet @ 2,800’/sec and then the same wt CF rifle with the same wt bullet/velocity, the perceived recoil would be radically different. The CF would seem much more brutal as it is a virtually an instantaneous jerk whereas the MLer would feel much gentler. The difference is - the obturation distance which greatly lowers the peak pressure.