Question about load data... newbie...


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Afy
April 9, 2007, 03:45 PM
I have only very recently begun experimenting with hand loading.

Have a question, say the load for a caliber states to use a 100 Gr Bullet with 60 grains of H-4831.

What will happen if you use 50 grains? Or 55 grains?

I am currently shooting out to 100 meters and max of 200 meters normally. Bench rest groups only.

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308win
April 9, 2007, 04:15 PM
If the reloading data say to not reduce load you shouldn't. Otherwise, prudent reloading practice is to, as a starting point, reduce recommended load by up to 10% of published data to allow for variations in the firearm, case capacity, etc., especially if you are starting with or close to the maximum published load. If you are not using the same bullet as the loading data you should reduce your starting charge weight to allow for the difference in bearing surface of the bullet profile. Some powders are position sensitive or develop different pressure profiles with reduced loads therefore reduced loads should be avoided (the data will usually so indicate).

Jim Watson
April 9, 2007, 04:36 PM
If a single load is published for a calibre, powder, and bullet weight, then it is a maximum and should not be loaded to start. Read the fine print in your manual about "starting loads" and "working up" to at or near the maximum.

The usual starting load is 90 percent of the maximum, 54 grains in your example. A slow burning powder like 4831 should be reduced that much to start, but no more. There have been reported some dangerous aspects to loading greatly reduced charges of slow burning powder. If you don't like the velocity you get from 54 grains of 4831, pick up a load for, say 4895. It is a medium burning rate powder of great flexibility and can be loaded over a very wide range from 60 percent of maximum on up.

Shoney
April 9, 2007, 04:42 PM
Since you do not list the cartridge your hypothetical question refers to, it is hard to give an accurate answer.

Any time you reduce loads well below the minimum load, you are in danger of SEE (Secondary Explosive Effect) or more commonly referred to as detonation rather than burning of the powder. The greater the reduction, the greater the chance of catastrophic problems. Going a good deal below minimum load is a dangerous and unwise practice

Afy
April 10, 2007, 12:01 PM
Pick any rifle cartridge from the Lyman Reloading guide.

They Give a Minimum load based on bullet type and weight and a max load.
The question was what if you go below minimum load.

In my case the cartridge I am interested in is the 300 Win Mag with H4831 powder...

hankpac
April 10, 2007, 02:01 PM
If you load a round to less than what is listed, (and that is after checking more than one manual to compare) then by definition you are loading a squib round.
Experimenting with loads is part and parcel of the reloader's world, but within published parameters. Sometimes very experienced loader/shooters adjust above or below the documented loads, but it is often under controlled conditions, with a strain guage, proofing barrel, etc.
Inexperienced shooters do this too....I call them idiots. Wait till you have some real experience, and can describe yourself as a scientist before you go jacking around with loads.
To address your question: the least that could happen is that you would have an innaccurate round: not enough velocity to stabilize the bullet in flight, short trajectory, poor terminal performance (either on a target or inhumane kill on a game animal) Worst is a true squib that lodges unnoticed in the barrel and causes unrepairable damage when a second shot is fired. Poor burn rates is also a problem, with "hang fires", and other problems.
Stick to published data, and be very, very careful when loading.

Shoney
April 10, 2007, 02:09 PM
Afy:
I cannot find a recipe for IMR4831 and 100gr bullets. I have found one for 110gr bullets of max 83 gr, min 75.5 gr.

A 60 gr charge is 28.8% below max with a load density of around 65%; while the 50 gr charge is a 40% reduction below max and has a load density of around 54%. Does anyone else hear the "Red Phart Alarm" going off??????

Please do not attempt this unless you are in a protected area, using a string to pull the trigger. (Muttering depressedly to self,:barf: :cuss: "Must be nice to throw away good money on a good rifle, using a bad idea.:banghead: :cuss: )

You would be much better served to use loads of Unique or BlueDot for your reduced loads. Do a search for that topic.

Afy
April 11, 2007, 11:04 AM
OK.. will stay within published parameters... and stick to what the manual descrbes as a minumum for a given bullet and powder combo. :)

Thank you all...

Jim Watson
April 11, 2007, 11:41 AM
If you want to load your .300 Win Mag more lightly, check out the Hodgdon Youth Load section. They use H4895 which is a very flexible powder so you can have tested loads that don't kick. Much safer than underloading a slow powder like H4831.

http://www.hodgdon.com/data/youth/300winmag_y.php

Shoney
April 12, 2007, 01:08 AM
Afy: It is probably better for you to understand "the WHY" reduced loads are dangerous with slower extruded powder. Several years ago I read an article in the American Rifleman about the hazards of reduced charges. They put forth a very plausable theory, and I repeat theory, because there are others:

At primer ignition the flash strikes and ignites the powder close to the flash hole, deflects up and skips over the middle powder, igniting the powder at a point near the shoulder-neck junction. The powder then burns simultaneously toward the middle, causing a spike in pressure. Under normal conditions it would burn from rear to to some point in the barrel.

When powder/case densities are reduced (not nearly as low as you are looking at), you will see some experienced shooters raise the rifle to 12 O'clock, then slowly lower it to the shooting position, then fire. This gives a more even burn and less chance of the pressure spike.

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