Heavy 357 Mag / CE Harris / IMR4198 / QL_Anomaly

[mehavey]

I've been playing with the RCBS 357-180 SIL in a 357 `94 Marlin 24" Cowboy, and ran into a Cast Bullet Association article citing a CE Harris load using IMR4198:

> ...a C.E. Harris load-- A 357 case full of 4198(17 gr) and a 190gr bullet.
> I shot 5 rounds into about 3". I didn't have any confidence this load would
> shoot particularly well, but I decided to bear down and try before I packed
> up to go home. I put the first of a five shot group exactly at point of aim,
> but at first I couldn't find the second shot on the paper until I saw that it
> had enlarged the first hole. the next three shots resulted in a clover leaf.
> A couple more 5 shot groups had 4 shots in a cloverleaf and a 5th opening
> the group up to less than 1-1/2". I loaded the other rounds 5 shots from
> the magazine but the 4198 loads were single loaded. I think this is the best
> shooting I ever did with a lever gun.
https://www.castbulletassoc.org/forum/thread/357-mag-marlin-rifle/

On whim I went to Quickload to see what a "357 case full of 4198(17 gr)" looked like in a 27.5gr (H2O) Starline case and got this:

QUICKLOAD Anecdotal display only -- NOT for use under any circumstance

OK... I've been using QL for 15 years and know most of its quirks & foibles, but this said such a load was absolutely, positively, YouGottaBeKidding, physically impossible.

So naturally I went down into the basement and put it to the test:

Any ideas . . . ?

 

[NoSecondBest]

I'm confused about your question. Yes, you can get 17.0g of powder in the case...we can see that. You've got 1/4" of space left to seat a bullet. OK, so what are you asking? It looks to me that even if you compress the charge you don't have enough room to seat a 180g bullet. Is that what you're asking?

 

[LeverGunFan]

He is saying that Quickload is calculating a 147% fill, or in other words the case would be full to the base of the bullet with only about 12 grains of 4198.

mehavey, what is Quickload using for the seating depth of the bullet you have used for this exercise?

 

[mehavey]

I'm running that RCBS 357-180_SIL (actually 186gr when GC'd) in a Marlin which limits OAL to 1.602" MAX
That means a shank depth (in the case) of 0.535".

I'm not worried about compressing what you see in the case -- no big deal at all.
But what you've said made me pause.

Normally I find compression just starts at an QL case fill of 104/5% (another one of those calibrated QL quirks)
If I pull the bullet out to a leave a shank depth of only 0.3" or so . . . . voila ! 105% fill.
Mystery solved. (Dumb... grashoppa)

Thanks


.

 

[LeverGunFan]

When I first started typing my reply I was thinking that the fill ratio was for an empty case... then I checked the Quickload documents and confirmed that it's to the base of the seated bullet. Good to know that Quickload is reasonably correct here. The Quickload calculated fill ratio depends on an observed powder density, but in practice you can pack the powder a little tighter in the case with a drop tube or by tapping the case to settle the powder.

 

[Unclenick]

Also, powder densities can vary by 6% from lot-to-lot, or, in the case of a stick powder, depending on how it vibrated down during transport. It also depends on the bullet design. If I take a 158-grain wadcutter and extend it about 0.1" I get to 186 grains. Pick the shortest 158-grain wadcutter and extend it .1 inch (assumes alloy density of about 11 grams/cc) and I can get the initial case fill down to 129%. Extending the bullet 0.15" gets it down to under 105%. Use a drop tube that is long enough or set the charged cases on a vibrating table and "voila!"