Hornady COL gauge

Bucky said:

In my never ending search to improve my overall shooting, I have purchased a Hornady COL gauge

MMmmmmmmmmmmmm

OK so I watch you tube video's on how to do it, and then think to myself, "hey this is easy enough", so I grab the .222 and its out into the shed.

MMmmmmmmmmmmmmmmm, ( a bit more !)

I am just touching the lands, with the slightest of pressure, and with my cleaning rod am tapping the projectile back off the lands, and then reseating the projectile back onto the lands again.

Reading 2.192", and am very proud of myself.

I do a 2nd, 3rd, 4th, and 5th reading, only to discover that everyone is different, ranging from 2.192"-2.255"

Now I am confused, and left wondering if I have wasted my money.
MMmmmmmmmmmm (No.3)
Is it me that has not got the feeling ?
Have I got a slight ridge in the chamber, that might be tricking me ?
Has my Irish herritage really kicked in ?

Any help would be appreciated

Cheers Bucky

Click to expand...

Using one of these is really an inexact science and mostly "feel" in seating the bullet onto the lands at the same pressure everytime. This is VERY hard to do. Agreed by most all, not possible and will give different readings most all the time. As you become more atune to doing it the deviation will lessen. Your readings you gave had a deviation of .063 over just 5 times. This is not very many times to get used to doing it. Probley getting it down to a deviation of .02X - .03X and then taking the average over a number of readings is the best one can do. Also the accuracy of the gauge must be considered also. PRACTICE, PRACTICE, PRACTICE.

I assume you are doing this to increase or lessen the JUMP of the bullet onto the lands. Playing with OAL to find the right formula for ONE HOLE GROUPS culminates with with the OAL. Weather the jump is .01 or .025 or "0" when you find the magic OAL the jump (whatever it may be) will be what it is.

Bucky

You are doing the correct thing in shooting in small batches and seeing what the results are. Picking a number (.01) off the lands does not guarantee good results. Some guns shoot better with a short jump, some with a longer jump. You never know till you try some.

The important thing is to keep your brass the same length, and keep the same brand, type, bullets. Changing one or both of those variables will change the jump and your formula goes to He**.

Every brand/type bullet will have a different length Bearing Body ( the part that contacts the lands). For More accurate OAL measurement a COMPERATOR should be used along with your micromenter. Measuring to the tip (Miplant) of the bullet will not give as accurate a measurement. Not every bullet, even of the same brand/type will have the same Bearing Body and length of Ogive. Comperators are made for caliber specific bullets and measure from the start of the bearing body and eliminate the varring length of the ogive from the measurement. Also competition grade micromenters are made for more exact measurements. I know, more gadgets, more money.....never ending.

As for the .270 yes, the throat of the chamber is deep. In comparison to the .222 a lot. Just look at the length difference of the two bullets. Also the .270 has to accomidate for a wider variety of bullet types. Go to a 30-06 and they are even deeper. Also in some rifles the makers have what is called more pronounced (Guiding Lands) STARTING LANDS in their standard hunting barrels than say Match barrels. The lands start off wider and tapered down as opposed to starting sharp and pronounced. These make it really hard to adjust bullet jump....matter of fact almost impossible without just plain trial and error loading. Make a round to long (no primer of course) to chamber and start backing it off till it does.

I don't want to come off as a smart allek...but lengthing OAL with bullets that already have a long Ogive and Bearing body, espically ones with poly tips MAY NOT feed out of a magazine any longer or chamber reliably. Match shooters don't worry about this as rounds are inserted One at a time or shot in a single shot rifle.