While loading up ammo for next weekend's expansion test, I thought a few people may be interested in how I come up with my reduced velocity loads to simulate LR impacts. I've seen more than a few very sketchy reduced loads posted that simply reduced the powder charge listed in a book or using pistol powder. There's an easier and safer way if you have the right tools available.
Right off the bat I'll say that Quickload is a great tool if you know how to use it properly. It can also get people into a whole lot of trouble if they aren't careful. The basic rule of "garbage in, garbage out" applies here! This is the basic process I used to come up with reduced velocity load for a 300gr bullet in the 338/375 Ruger Striker.
The first step is to select the projectile and chambering that I'm working with. This is also where I enter all the specifics such as COAL and barrel length. Here I've chosen the Berger 300gr OTM to be loaded in the 338/375 Ruger as well as entering in the 18" barrel length of the pistol.
The next step is to figure out what powders will give a low muzzle velocity while providing a good case fill. This is important; just reducing a powder charge from a load manual can result in squib loads or possible powder detonation cause by improper ignition from the primer. The general rule that I follow is to use a powder that would normally be considered too slow for this application. The slower powder will typically take up more space in the case and give a good case fill. I like to keep fill levels above 80%. Here I've selected the burn rate range as well as target velocity and fill ratios.
Now Quickload has generated a list of potential powders that fall within the parameters I've selected. This list will show expected fill ratios, pressures and velocities at a specific powder charge. Here I'll review the list and see what powders I have on hand that will work. I'm going to go with H-1000 for this application.
The next step is to take the powder that I want to use and select a charge weight. I can either let Quickload generate a chart of predicted charges with my selected powder or I can choose the charge myself. I already had a pretty good idea what charge weight I'd use so I just entered 70.0gr of H-1000 for a fill ratio of about 93%.
The last step is to review the predicted results from my powder charge selection. Here I'm looking for a specific velocity while staying within a safe pressure range. If the predicted velocity isn't what I want, I'll adjust the powder charge while still watching both pressure and fill ratio. If I can't get the numbers I want I'll just move on to a new powder.
The last step is to load up a few test rounds and give it a go. It's important to understand that Quickload gives predictions, not load data. Once you get a feel for how to properly apply the info you get though, it's a great tool. My results are typically within about 50fps of the predictions. Since every barrel is a little different though the results always vary a bit. I will usually take the data I get from Quickload and then cross reference it with other data from either past loads or from load manuals just to get addition info.
