case empty space, how much is too much?

[Motard]

Somtime I got concerned from action I perform routinary. This is the case for my 45-70 abitual reloads with Lyman's 457643 mould bullet. My all around charge is 37 gr Viht N130 x a 2.550 Coal wich, with the leverevelution brass, lets me with nearly 0.180 inch empty space in the case (4 mm). I have shooted plenty of this rounds with 1450-1520 average speed and very good consistency. But I also know that, in regards of the Case Capacty Rule, minimum loads should be 41,1 gr. Now I have absolved myself since now telling me that the 45-70 straight case and his wide load range, would admit this mistake. But really would like to ear from expert reloaders if I am not making some mess. Errare humanum est, perseverare est diabolicum

[paul h]

As with most things in reloading, there are no hard and fast rules. Some powders require a full or even compressed charge before they will burn consistently. Some powders will perform admirably with cases that have more air than powder in them and some powders will hangfire or have velocities all over the map with too much air space.

My rule of thumb is let the target and chrono tell me what the powder likes for a given chambering.

[fredj338]

There is really no rule as to load density. I have better results with 100% compressed loads but that isn't possible with faster powders. With really small charges of pistol powder in the 45-70, I used an over powder wad of Dacron for more uniform loads.

[Wayne Smith]

If you are getting a complete powder burn, i.e. no granuals left in the barrel, you have a fast enough powder to do this. One other trick is to hold the rifle vertically before each shot to settle the powder against the primer, then shoot a series holding the muzzle down settling the powder against the boolit. Do you have a difference in point of impact? Difference in velocity? If you do you have an issue with too much space. Especially if you use this rifle for hunting, how do you hold it when carrying it or in the stand? Yeah, muzzle down if you are like most of us!

[mongoose33]

PaulH and FredJ have nailed it.

If the load is working well for you, there is nothing left to be done--just shoot it!

If I were you, I'd do some checking as Wayne suggested with regard to powder position. My example isn't the same cartridge nor same powder, but I was experimenting with SR4756 with .38 special in my Rossi model 92--lots of empty case volume. Depending on whether the powder was against the primer or against the bullet, I'd have 100fps difference in the velocity.

Using Bullseye, by contrast, I don't have that effect. Bullseye is not so sensitive to position within the case; at least in this application, SR4756 clearly was.

[paul h]

Don't have my loading notes handy and it's been over 10 years, but as I recall when I was working up a plinking load for my 350 Rigby I found out that somewhere in the range of 20 grs of 2400 provided great accuracy with a 200 gr cast bullet. Now that load had about 2/3 of the case volume air and 1/3 powder and I didn't use any filler. I chronoed a 10 shot string and velocities varied all of 10 fps for a nominal 1400 fps and I didn't do any fancy tip the rifle up or down, just loaded it one at a time and shot.

Same rifle with a 280 gr cast bullet and ~44 gr of Varget (1/3 air space, 2/3 powder) shot my first five shot moa cast load. I was so happy I went back to the range with a box full of the same ammo. Ambient temperature had dropped from the 60's to the 40's and my magic load now had hang fires. So I tried the same powder charge but with different brands of primers and magnum primers. Only the CCI 200's would hang fire, but loads with the other primers shot 2 moa :(

Conversely with the same rifle in a former life as a 35 whelen ackley I used a mild charge of unique (don't recall what weight cast bullet) and velocities varied over 100 fps for a five shot string somewhere between 700 and 800 fps.

So no absolutes, let your gun tell you what it wants and stick with published data as it should keep you out of the hangfire or SEE dangers.

[Motard]

I was totally unaware about the up and down barrel trick. seems terribly effective as al the other great sugesstions I have had from you all. Thankyou si much. great fiid for mind

Sent from my C6903 using Forum Fiend v1.3.3.

[Yodogsandman]

Please read the following "Classic Sticky" before you use any fillers...

http://castboolits.gunloads.com/showthread.php?109280-The-proper-use-of-fillers

[Motard]

thankyou for the link Yodogsandman. Really i don't favor any filler. feel much confortable with some space in the brass. Considering the amount of space occupied by the powder and the bullet I assume tha if I am not aiming diretctly at my foots probably there is no space between primer and the powder. but still whant to investigate if that gap may be hatmfull in the long term. just wondering about making me a cleear plastic boolit that let me see throu once seated.

[swheeler]

There is really no rule as to load density. I have better results with 100% compressed loads but that isn't possible with faster powders. With really small charges of pistol powder in the 45-70, I used an over powder wad of Dacron for more uniform loads.

Sorry but I just don't like the over powder WAD idea. Instead I use enough fluffed and lightly compressed dacron filler to fill the entire space between the powder and bullet base, no wads.