Reloading and chronograph question

Just started reloading about a month ago. I handloaded 20 cartridges each consisting of a Federal 210 large rifle primer, 44.8 gr. of IMR 4064 powder, 180 gr pointed soft point bullet by PMC in a Winchester 30.06 Springfield case. This is an initial load according to Lee Reloading manual with a maximum charge of 49.5 gr. of IMR 4064 powder not to be exceeded.

At the range I sighted in my new Ruger MkII 77 with a Leupold Vari-X II at its highest power (9x) two inches above the bulls eye with factory ammo - Winchester Classic 180 gr PSP. With the reloaded ammunition, the same rifle shoots 3.5 inches lower, i.e, 1.5 inches below the bulls eye. Can I assume the the reason for this is a decrease in muzzle velocity from the initial reloads?

Is it then safe to assume that I may increase the charge from 90.5% of maximum (44.8gr) to perhaps 97, 98 or 99% or even 100% of the maximum 49.5 gr? Assuming the firearm can handle the increase pressures. BTW, what are the signs of increasing pressures?

Also, can using a chronograph help in determining a safe and accurate load? I was looking at an entry level F-1 Chrony chronograph. Is this any good or should I spend a little more for features I may or may not need in any of the higher line chronograph by Chrony Inc.

Any information, opinions and advice will be greatly appreciated.

Thanks in advance, Jim

p.s. I find reloading to be quite fascinating and rewarding. Always wanted to do it but never had the time until now.

#Is it then safe to assume that I may increase the charge from 90.5% of #maximum (44.8gr) to perhaps 97, 98 or 99% or even 100% of the maximum #49.5 gr? Assuming the firearm can handle the increase pressures. BTW, #what are the signs of increasing pressures?

In the loading manual, MODERN RELOADING by Richard Lee, (which is the manual I believe you are using) you can look at Chapter 9 which is titled 'All About Pressure'. There is one page in that chapter which lists many of the signs of excessive pressure.

You might want to consider adding another reloading manual to your library. The current Speer manual has some photographs of rifle cartridges that have been loaded with overpressure loadings. The current Lyman manual has some simple drawings which are very easy to use to see signs of excessive pressure in a cartridge.

I rarely reload for rifle as most of my efforts are towards handgun handloading efforts but I did check a couple of other manuals and the load you are using is somewhat on the light side. This could, and I repeat the 'could', cause the deviation in your point of impact.

******** Those who beat their swords into plowshares will plow for those who don't. ********

Jim - the different impact could be pressure, velocity or performace of the bullet (ballistic coefficient).

Pressure is indicated by several observations - flattening of the primer, et.al.

My approach to reloading - I will start at about a 90 percent of max load - loading 3 to 5 rounds 'batches' each with a 1 to 2 grain increase in powder. I will shoot those loads, measuring the velocity and group size. The group size will typically decrease and then increase with increasing load. I continue this process - decreasing the load increment - all the time striving for the best accuracy. I will typically 'tune' loads to a tenth of a grain. What I have found is that when the accuracy is good, the velocity doesn't change much with increased load. As an engineer, I find this interesting and have always intended to study this observation further.

Get at least two different loading manuals - say Sierra and Hornady. They both have good information about the reloading process, pressure, and many other items. Be careful and have fun.

To tell you the truth, except with really fast burning powders, I've not found that tenth grain changes make a noticable change. Either in group measure- ment or velocity. However, I measure each charge to within tenth grain before pouring into the case. 'To each his own'

My theory is that when you reach that point of 'diminishing returns' you have approached 'bore capacity' for that particular burning rate of powder. Adding more powder raises pressure more than added velocity is worth.

About the time you have found your 'sweet spot' with powder charge try varying the seating depth of your bullets. In every case I've run across the accurate OAL for a rifle is longer than the max. book OAL. Just this last weekend I was testing a few loads for a 7x57 Mauser and 154gr Hornady Interlocks. By going from 3.035 to 3.060 OAL the group size (5 shots) would go from 1.5-2.0' to an inch plus/minus. With the longer OAL I did notice an average velocity drop of 20 fps.

Bill Van Houten (USA Ret) 'No matter how hard you try, you can't throw a potato chip very far.'

#To tell you the truth, except with really fast burning powders, I've not found #that tenth grain changes make a noticable change. Either in group measure- #ment or velocity. However, I measure each charge to within tenth grain before #pouring into the case. 'To each his own'

Current theory seems to be that the variance in powder charge is the least important part of a handload. In other words, being off even 2/tenths of a grain does little to affect an already accurate load. But a bullet that is heavier or lighter than the average can easily be a flier.

#My theory is that when you reach that point of 'diminishing returns' you have #approached 'bore capacity' for that particular burning rate of powder. Adding #more powder raises pressure more than added velocity is worth.

I am interested in this idea of 'bore capacity'. What do you mean by this?

******** Those who beat their swords into plowshares will plow for those who don't. ********

Let's see if I can put it in words that I can understand. 8>

How about 'the amount of gas you can force through the bore in a given time'. The time being how long the bullet is in the barrel of course. As velocity increases it takes more gas at more pressure to push the bullet faster. But we are restricted by the bore diameter as to how much of that pressure can be applied base of the bullet. A large part of the added pressure (or added powder) is wasted. There comes a time when little velocity is added from a large increase in pressure. The effective 'bore capacity'.

Using IMR 4895 powder in a *modern* 7x57 Mauser at very moderate loads a 1gr. change of powder gives ~ 100fps change. However with a Hornady 154gr bullet going from 42.0 to 43.0 grs of IMR 4895 increases from 2726 to 2758 fps.(32fps)

As a side note: At 42.0 grs increasing the OAL by .025' reduced mv by 29fps At 43 grs the reduction was 20fps.

All MVs given are average for 5 shot strings. Bill Van Houten (USA Ret) 'No matter how hard you try, you can't throw a potato chip very far.'

#Let's see if I can put it in words that I can understand. 8> # #How about 'the amount of gas you can force through the bore in a given #time'. The time being how long the bullet is in the barrel of course.

I don't know how to say this but I think that you are on the right track, but....not exactly.

Your mention in an earler msg of 'diminishing returns' just jumped out at me. As a handgun reloader I really understand that term, especially when working towards a hunting load.

So far this week I have kicked around your idea of 'bore capacity' and I think that it really should be: 'the amount of bullet you can force through the bore in a given time' or in other words the 'amount of bullet obturation that can take place in a given time'.

Pressure in the bore would be caused by the amount of resistence from the bullet trying to make its way to the end. Put to much pressure behind that bullet and it will be squeezed up against the lands and grooves creating friction. The more powder you put in a cartridge the more hot gases that are generated therefore the more pressure against the bullet and the greater the obturation and so the greater the resistance going down the bore.

The reloading law of 'diminishing returns'. No way around it.

All we really need is enough pressure to cause the base of the bullet to obturate and press up against the rifleing. This will cause the bullet to pick up the spin caused by the twist, stabilize itself, and steer the bullet downrange.

******** Those who beat their swords into plowshares will plow for those who don't. ********

there is a good description of load development called the 'ladder test' it is in german but GOOGLE will translate.

Go to GOOGLE.COM search for this exact set of words: carl cranz load development ladder test

you should only get 2 hits

click on translate page....read...go to range. good luck.