Variation in book loads

[caorach]

I am not really asking a question, or making a point, but just making a general observation that I'm sure is neither news to anyone nor especially useful but...

There is a considerable variation in the loads published in various books and manufacturer web sites (i'm not talking about random stuff on forums on the internet etc.but reliable published sources) to the degree that one starting load can be higher than the maximum load in another book.

Recently I worked up a 150 grain 308 load using Reloader 15 and stopped as I approached the maximum load in the book I was using. After some observations and shooting at 200 and 300 yards I concluded from the trajectory that my load wasn't going very fast so I referred to a range of other manuals and manufacturers to find that, in some cases, my load was below their starting load. I've since worked up another 4.5 grains, within book maximum, and am seeing no pressure signs but the recoil has increased somewhat and I suspect the velocity is now in the order of what I might expect for a 308 load. My barrel length is approaching 23 inches so it is not like I'm losing a lot of velocity for that reason.

I also worked up a 110 grain v-max load for the 308 some time back, again using published book loads. The first loads I used caused the whole case to be black and were clearly low pressure. I consulted several other books for loads and it wasn't until I got to the level of the max load in the first book that I lost the low pressure signs.

As a beginning reloader I like to be as conservative as possible and in the past I've tended to shy away from books with loads that looked higher than the average. However, experience seems to indicate that at least in the case of my rifle it is reasonable to work up towards the higher published loads as it may take these to give acceptable velocity and performance and, to date, I'm not seeing any pressure signs with them.

I find this a most interesting situation and would value any other opinions or views.

 

[stag1933]

Each rifle is an entity unto itself and what may appear to be a mild load in one rifle may be a maximum in another so it is prudent to approach each one with care.
Many years ago I had two 7mm Rem.Mags. at the same time, a Sako Finnbear and a Weatherby Mk.5 which had been re-barrelled with a Lother Walther barrel.
A moderate load for the Sako was a gross overcharge for the other yet with their own loads both shot better than one-inch groups and I won many stalkers shoots with them both on different days.

I recently purchased a 6.5X55 off this site and my first load attempt resulted in `sooted` cases, a couple of grains more sorted this and it immediately shot a group better than one inch which was satisfactory for starters.

HWH.

 

[enfieldspares]

The biggest single factor affecting your loads is one that you can do nothing about. The barrel the bullet passes along and the chamber the cartridge sits in.

Last year I had two identical BRNO ZKK 600 rifles in 270 Winchester calibre. One rifle identical in all respects to the other was 100 fps slower than the other. That was over a chronograph.

The next factor is the tightness of the case neck of your cartridge case and its grip on the bullet and how much your crimp - or not - varies from that used by the people who assembled the loads for the reloading book.

Everything else, powder, primer, bullet make, case make, you can select so as much as possible to copy exactly what was used to assemble the book load. But the neck tension and the chamber size and the friction in the barrel is as you find it.

 

[Muir]

Well put!
My 17 MachIV would blow primers with starting loads. My maximum loads were a full two grains lower than the listed starting loads. Turned out I had a barrel .0015" narrower than the standard 17 cal. It was all it took!~Muir

 

[8x57]

A fellow rifle club member has recently started to reload for his Manlicher SSG (.243w) using 80 grn Berger bullets and Vhitavouri N160 powder. Starting loads exhibited signs of extreme pressure. Load information was checked and re-checked and even the scales were checked but still extreme pressure was evident. The club has a chronograph and this showed that the bullets were travelling much faster than they should be. Powder charges were reduced further and further until all signs of pressure ceased and the velocity was back to what it should have been. The guy is now extremely pleased with his loads as they achieve good velocity with much lower powder charges than he was advised to use.
Is this typical of Berger bullets, I have no experience of them other than this?
Or does he have a very tight chamber in his rifle?

P.S. Factory ammo shoots and fits fine in the rifle. Reloaded cartridge dimensions have been checked and are fine.

 

[finnbear270]

Maybe there could be a frictional difference with their materials as opposed to other bullets makers?, just a guess on my part.

 

[Muir]

I would check case volume. Even between US makers, case volume differs enough to cause problems. This is why the old, almost patently ignored advice of again working up loads from scratch if you change a single component, still stands. Unless you are using the exact same brass and primers as the load developing entity you are entering relatively unknown waters. Ever notice that reloading manuals usually recommend starting at " five percent under minimum listed loads?" Good advice.~Muir

 

[jack]

Use a chrony to measure bullet speeds, you are guessing otherwise.
I use a Chrony F1, the basic model and thats all you need, it does not like sunshine but is fine otherwise.

 

[flytie]

I have been developing a load for my 6.5x55 and was baffled by the difference in powder maximum loads from my three manuals. So I did just what Muir said, 5% below minimum and worked up.

The 6.5 seems to be especially difficult because of the amount of old actions still being used which have very low pressure tolerances compared to newer actions. But i'm getting there slowly. I just need to use up all my old stock of RWS 140gn hollowpoints and I will be using my, very accurate, homeloads!

ft