Rebarreling and Home-Shop Machining

Pacific Tool and Gauge Reamer

I received the Reamer that I specified in the Winchester Short Magnum (WSM) Rifle Project that is described in a topic below. It’s a really beautiful tool. I have placed a 30/06 reamer with a standard leade (British spelling to avoid confusion) length just above the WSM reamer so that you can see visually the long leade. I ordered an extra long leade to use the cartridge in a long action with heavy bullets without intruding into the case capacity so much. The reamer is from Dave Kiff at Pacific Tool and Gauge 1-541-826-5808. Also pictured is a floating pilot range rod in .30 caliber and a Go-Gauge in .300 WSM from the same source. Photo 2 shows the Reamer Blue Print.

Leupold Long Range Scope

The scope in photo 3 which I plan to use with this new rifle is a 8.5 x 25 x 50 Leopold Mark IV Long Range MI. This particular scope has the mil dot reticle with 5 spaces (four dots) above and below center and also to the left and right. See photo 4. The spacing of the dots are normally 1 milliradian at 10 power. On this scope it is at maximum power although there is no indication on the scope. The dots can be used with a mil dot master or the mil dot formula to range objects of known dimensions as well as to provide quick windage correction points. See the ranging example below.

Ranging With the Mil Dot Reticle and the Mil Dot Formula

Photo 4 shows what my mil dot reticle looks like (without the red markings). The mil dot formula is fairly easy to use with a calculator. If you are in the field, it would be better to have a table. The calculations are easier if the target is 1 yard 2 yards or ½ yard tall. A deer from shoulder to brisket is about 18 inches or ½ yard. I did not have a deer handy so my target was 16 inches tall or .44 yards tall. I ranged it with the scope set at maximum power which seems to be the correct setting to get mils (Milliradians). The target spanned the distance from the center of the cross-hair to the top of the second dot below center. Study Photo 4. Since the dot is .2 mils in diameter, I subtracted half a dot (.1 mil) from 2 mils getting 1.9 mils. Once you know these two figures you can use a table, Mil Dot Master, or the following formula to calculate the distance.

Range to Target in yards = (Height of Target in yards x 1000)/(Height of Target in mils)

Range to Target in yards = (.44 yards x 1000)/ 1.9 Mil

Range to Target in yards = (440)/1.9 Mil

Range to Target in yards = 230 yards

I ranged the distance with a laser range finder and it was 240 yards. That’s pretty good agreement. More to come on drop compensation by using a power that makes the dots 4 MOA.

For a deer at ½ a yard from shoulder to brisket the math is somewhat easier. The formula becomes

Range to Target in Yards = (500)/ Target Height in mils

if the deer covers 2.5 mil from shoulder to brisket the range is 500/2.5 = 200 yards

Holdover with a 4 MOA dot 

             If You like to holdover for wind and elevation you can convert the 1 milliradian dot spacing (3.45 MOA per milliradian) to a 4 Minute of Angle (4MOA) dot spacing. Here is the procedure. Mark out 21 inches (20.94 inches = 20 Minutes of Angle) on a large target at 100 yards. Adjust the power until the top of the lower post and the cross hair just bracket the marked area. Use a white out pen to put an indicator line on the power ring. (It ends up between 20x and 25 X). Now each dot is worth 4 MOA. It is much easier to divide a 4 MOA space in your head than it is to divide and calculate with 3.4 MOA (1 milliradian) space between the dots. It is more accurate to shoot by using the elevation turret, but if you are in a hurry this might help. If your comeup is 8 MOA at 400 yards, then you would hold the second dot below center on the target if your power ring is lined up with the whiteout mark.

Nosler 200 grain Accubond in .30 Caliber

I have some of this new offering from Nosler in hand now. The 200 grain Accubond is .12 inch longer at .765 inch, on the cylindrical portion of the bullet, than the 180 grain Nosler Ballistic Tip bullet. The overall length of the bullet is 1.489 with a very good ballistic coefficient of .588.

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