Gas Checked vs. Non-Gas Checked

[Old Grumpy]

I have some bullets I wish to load for my .500 S&W Mag. They are cast 440gr FP and are not gas checked. I normally use Lyman's 49th for my starting data or possibly information from powder manufacturers. The problem I have is what data I am finding is for gas checked 440gr bullets. (Lyman's 49th only shows one cast load and it's for a 375gr GC bullet)

Since my bullets are un checked and my intended use is "plinking" I would like to develop a load using Unique. I've found some data for a "mild" load, again using a gas checked bullet of the same weight, that lists 10.0gr running about 970 fps.

I believe gas checks help protect the base of the cast bullet from the hot gas. They are normally found in bullets intended for much higher velocities than I intend to use. Given the case volume of the .500 S&W, the lower pressures I will be having are gas checks required? As far as bullet resistance going down the bore are gas checked bullets measurably different than non gas checked bullets?

Does anyone have any experience loading for the .500 S&W Mag with non gas checked lead bullets?

I would like to use Unique (I've got a bunch) but in a pinch I also have 2400, AA #9, IMR 4756, Blue Dot, Lil'Gun, Titegroup, and W231.

Again my intended use is mild target/plinking loads.

Thanks for any insight you have to offer.
Grumpy

 

[rcmodel]

lower pressures I will be having are gas checks required?

No.

rc

 

[osteodoc08]

I don't have any suggested loads for unique, but Trail Boss would be right up your alley with your intended purpose.

 

[Old Grumpy]

I do have some data for "cowboy" loads using 440gr non gas checked bullets, but no Trail Boss.

Grumpy

 

[rcmodel]

Trail Boss data =

Fill the case to the base of the seated bullet and don't compress it.
Then gofer it!

That's all you need for data.

rc

 

[Old Grumpy]

Thanks RC, I meant I don't have any Trail Boss powder.

Grumpy

 

[Shrinkmd]

There is data on using Unique and Trail Boss with the 330 gr plain base bullets. I think I have posted these already. For stronger stuff, I've been using 34 gr of 2400, which go about 1580 fps. Now that I have a micrometer, I've been meaning to try making up some 300MP loads and try to squeeze a little more oomph out.

I've read that you can measure with a real micrometer the unfired brass and then measure after firing to see how much the loads are expanding the area around the case head. I need to read up own this some more. I want to stay safe, and now that I have a new tool to use I'd like to explore a bit.

Is it true that accurately measuring this expansion (and hopefully avoiding any) is the safest way to know if your loads are safe? I was going to guesstimate some startling loads based on alliants data for 49 gr of 300MP with a 350 Speer jsp.

 

[bluetopper]

There ought to be some 500 data with Unique powder on the Hodgdon reloading data site.
Plain base bullets will be fine if you keep them a bit under max loadings.

The only 500 I have is a Handi-Rifle. Gas check bullets are all I ever shoot in it, all at full charge loads.

 

[Kp321]

Unique is made by Alliant, not Hodgdon, so take a look on their web site too.
An old rule of thumb was gas checks were not needed below 1000 to 1200 fps.

 

[jaysouth]

According to internet lore, the velocity range at which leading will occur is 1,400 - 1,500 fps. If you are shooting bullets in the sub-1,000 fps range, you should not need a gas check to prevent leading.

Have you slugged your bore?

Micrometer and a chronograpy are a handloader's friends.

 

[ArchAngelCD]

I don't load for the 500 Magnum but I do load plain base cast bullets for the 30-30 and 45-70. I have shot a plain base 165gr .309" 18 BHN bullet in the 30-30 @ just under 1800 fps without leading the barrel. I forget the exact numbers but I think the 405gr plain base bullets I shoot in my 45-70 are traveling ~1500 fps and no leading there either.

The Lyman 4th Edition Cast Handbook as data for the 500 Magnum and a 440gr Cast bullet using Unique. The data is for a 10" universal receiver.
Unique 12.0gr 1026 fps 20,600 PSI (starting load)
Unique 17.5gr 1297 fps 44,100 PSI (Max listed)

You said you also have 2400, AA #9, IMR 4756, Blue Dot, Lil'Gun, Titegroup, and W231.
Of those powders Lyman's data includes AA#9 and Lil'Gun if the loads using Unique don't work out well for you. They also list Enforcer, 4100, H110 and IMR4227 but you don't have those powders on your list.