Longer OAL and minimum charges

[COREY]

I am whipping up a load for my No1 in 37 H&H Mag; the throat is pretty deep on it and I can set the bullet out a bit more to get in nearer to the rifling. I am going to run a medium to heavy charge (not over book max) in it, but I was thinking about the minimum charge.

I read somewhere that one reason for the minimum charge data is because if the density is not high enough in the case that you can get an incosistant burn and actually cause a pressure spike (primer burns across a larger area). My question is what happens if you sit the bullet further out than what they spec for max OAL? Would you want to bump up the min charge to be safe?

 

[sunray]

"...sit the bullet further out..." You'll likely have chambering issues. If you get rifling marks on the bullet, back off the OAL a bit. Having the bullet just off the rifling doesn't work with all rifles either. There's a 'sweet spot' in all rifles. The problem is that finding it is a trial and error thing.

 

[Silverado]

IMO, you'll have no pressure problems seating to the lands with a minimum load.

From what I've read, and read and read, those scenarios are possible with REDUCED loads, (and then more to the point with slow burning powders) but not likely with minimum book loads. I believe the theory involves the primer flash bridging the top of the powder charge if it's sitting low and level from front to back of the case, with a big cavity all along the top.

The only thing that might keep you from seating to the lands is your magazine length if it's a mag fed rifle.

 

[The Baron]

From what I have read, reduced loads can be as dangerous as excessive loads, which is why the reloading manuals specify a minimum and a maximum charge. There is always a factor of safety in the loading manuals, so even with your bullet seated out quite far, I doubt you've have to worry about increasing the safe "minimum" load. If you're nervous though, go ahead and add a grain or two onto the minimum, which should still be well under max in that big case.

IMHO, there's usually not much to gain in shooting mimimum loads. The savings in powder is minimal, recoil (if a factor) is only slightly reduced (not like you're going to make a .375 feel like a .308) and accuracy is generally poor.

 

[303carbine]

I am whipping up a load for my No1 in 37 H&H Mag; the throat is pretty deep on it and I can set the bullet out a bit more to get in nearer to the rifling. I am going to run a medium to heavy charge (not over book max) in it, but I was thinking about the minimum charge.

I read somewhere that one reason for the minimum charge data is because if the density is not high enough in the case that you can get an incosistant burn and actually cause a pressure spike (primer burns across a larger area). My question is what happens if you sit the bullet further out than what they spec for max OAL? Would you want to bump up the min charge to be safe?

Buy a smaller gun if you want less velocity.

 

[Silverado]

IMHO, there's usually not much to gain in shooting mimimum loads. The savings in powder is minimal, recoil (if a factor) is only slightly reduced (not like you're going to make a .375 feel like a .308) and accuracy is generally poor.

There may be some worth in trying min loads. I had one particular 30-06 which shot amazing groups with a minimum load of IMR4350.

 

[Workin Man]

Corey, if I'm reading your post right, you are just starting to develop a load for this rifle. You definitely want to start with the minimum load listed in your manual and work up. Consider starting with the recommended COL as well, then play with seating depth after you find a decent load. You may need to do some additional tinkering with the charge wieght after seating the bullet out further, but it should be in the area of tenths of a grain.

 

[Silverado]

Workin Man has suggested the safest route certainly.

Personally, I gauge all my throats and load to the lands from the beginning, unless I'm going to feed from the mag. I've had rifles with long enough mags that it wasn't a problem. Others, not so much.

If you're unable to load to the lands for whatever reason, try a Lee factory crimp die. It makes the bullet pull very consistent on ignition, mimicking the effect of loading into the lands. Plus the FCD is cheap.