Technical Newsletter From Your Ballistic TechniciansVolume 2, Issue 1
|Flash Hole Deburring and
Primer Pocket Uniforming (cont.)
by Dave Brown
| Q. Some of my friends are avid varmint shooters, and have told me that I need to uniform and deburr my flash holes for best accuracy. What are they talking about?
A. Flash Hole Deburring and Primer Pocket Uniforming are two separate, simple, and permanent case preparation steps towards better ignition. We'll take a look at each, and explain the differences between them.
Here in the U.S., the standard flash hole is normally about .080" in diameter. PPC cases and some European cases are smaller, so if you need to deburr any of these you'll need to contact Sinclair International for a slightly modified tool. It's important to understand that we're going to leave the flash hole's diameter alone. Most flash holes are punched rather than drilled, so there is often a burr left on the inside. It's beneficial to both ignition and accuracy to remove this burr.
| To do this, we place the deburring tool into the case from the mouth, so that it centers its tip in the flash hole. Giving a quick twist, you'll feel the cutter hang up momentarily on the burr(s). When the burr has been removed, the tool will turn freely and the task is accomplished. Tap the case mouth on the bench to remove any debris from the case, and we're done.
A primer pocket uniformer is a tool made to uniform the depth of the pocket and square the radiused bottom edge of the pocket. Normally, these tools consist of a small carbide cutter of the same dimensions as the pocket to be cut, usually either Large Rifle, Small Rifle. Inserted into the primer pocket, a shoulder on the tool will come to rest on the head of the case to prevent it from cutting too deeply.
Remember, we don't want to alter the dimensions of the primer pockets, we just want to make sure they are all uniform and within specs. Giving the tool a few twists, we will feel the cutter removing any high spots, radiused corners within the pocket, etc.. After this is done, our primers may be seated with less variation in depth and seating pressure. As you can see this will aid in consistent, uniform ignition, and better accuracy.
|Thank You For Your Support
Adam Braverman, Vice President, Sales and Marketing
I know that it sounds like an old Bartles and James wine cooler commercial, but Sierra Bullets is very sincere. When I arrived at Sierra, we had three technicians answering your phone calls from 8:00 am to 6:00 pm central time. In that year, 1992, we took over 31,000 calls from reloaders like you.
Two years later, we have six technicians and we accept calls from 8:00 am to 10:00 pm, Monday-Friday. During 1994 we answered 43,554 calls, produced the first two issues of the X-Ring, continued to work feverishly on our 4th edition Rifle and Handgun Reloading Manuals (for introduction in January 1996), gave 181 plant tours and sent out tens of thousands of pieces of information requested by our callers.
At present, we are 2.6% ahead of our 1994 pace in calls received. Please be patient with the techs when you call as we handle each call in the order it was received, and remember, some questions can be answered in two minutes, while other concerns require much more attention. I welcome you comments and suggestions. Thank you and good shooting!!
By Tommy Todd
Q. Primers have been in pretty short supply lately. Can I substitute Large Rifle primers in my .44 Magnum revolver, since I have some of them on hand?
A. We don't recommend it. Dimensionally, Large Rifle and Large Pistol primers will interchange. However, there is a world of difference in how the two are constructed, due to the difference in operating pressures they are intended for. As a general rule, rifle primers are constructed with much thicker cups, to withstand the higher pressures at which rifles operate.
In many instances pistols and revolvers will not give reliable ignition with rifle primers, due to the thicker cup. Conversely, the thinner cups of pistol primers may pierce if they are used in a rifle, allowing gas to escape back into the action . This results in an obviously dangerous situation. Remember, too, that not all primers give the same results when switching from one brand to another. Just changing brands of primers calls for a load reduction, and working the load back up again for both safety and accuracy. Switching types is just asking for a large economy sized box of trouble. Stick to the correct primers for the application you are loading for.
| .223 Remington For Dogs!!
By Robert Treece
Q. What bullets should I use for an upcoming prairie dog hunt? I'll be using a .223 Remington and am confused by the wide variety of bullets offered in the .22 bore size.
A. Sierra's 50 or 55 grain Blitz bullets are probably going to be your best choices if you're using a conventional (1x10" thru 1x14") twist barrel. These thinly jacketed bullets give explosive expansion, making them ideal choices for instant, humane kills on small varmints such as prairie dogs. The Blitz bullets were designed specifically for the medium capacity cases, such as the .222 Remington, your .223 Remington, and the .222 Remington Magnum. The flat base offers no real disadvantage in these cartridges, since they are generally used at ranges of 250 yards or less. You may want to avoid the Blitz bullets for the larger cases like the .22-250 and the .220 Swift, or fast (1x7" thru 1x9") twist barrels. Either of these may cause the Blitz's thin jacket to disintegrate in flight
| 22-250 For Dogs!!
By Paul Box
Q. This summer I'm planning on doing some prairie dog hunting with my 22-250. I'm undecided on which bullet to use, the Sierra 55 gr. HPBT or the 55 gr. SBT. Which one will make the best choice for me?
A. In towns where shots are often 300 yards and closer, the 55 gr. HPBT makes a fine choice because of it's inherent accuracy and quick, positive expansion. In towns where shots may come at the extreme ranges of the 22-250's limits, the 55 gr. SBT will make a better choice due to its higher ballistic coefficient. This holds especially true when shooting across wind swept prairies. The higher B.C. of this bullet will help it buck the wind better and arrive on target with less drop, higher velocity, and greater energy.