confused need input

[remmag]

hey everyone
i will apologize in advance , this will be long
i loaded and shot my first rounds last week, 45 apc with 200 grain rnfp led bullets. all went well except 5 out of 10 rounds woulld stovepipe , like the loads were too weak for my smith's spring . but they all fired fine

loaded the rounds per the lee loading manual 5.1 grains of unique with 1.190 oal, that is per the book the starting load and the max load . i do not know if this is right or a misprint because the recoil and the action of the gun seemed weak

i got another manual (lyman) and it has 2 loads for 200 grain led bullets. on the upper right hand corner of eack load table there are 2#s that i cant find the meaning of
first load
2 unknown #s bc;.063 and sd;140
starting load unique 6.0 grains max load 7.5 grains with a oal of 1.235 (which by the way my chamber does not seem to like

second load they show for 200 grain led bullet
bc;.076 sd ; 140
starting grains 5.0 and max 7.5 oal 1.161

my questions are which manual to safely go by, why are they different and what are the 2 (unknown #s for )

i appreciate all of the help you guys have been

 

[Paints]

Unfortunately, there are no good answers. Yes, all my manuals disagree In the Lyman manual, it has a max load for one SWC that is the same as the starting load for another SWC.

Some of the variations are because of a different bullet size. A different taper can mean a different bullet height. I usually check a half dozen different references....and walk away unsure

Of course, a different seating depth will change the pressure.

Unique is a fairly forgiving powder. I would kind of pick an average between your references. FWIW, I have the same problem with 200 grn RNFP bullets.

Compare the rounds you've shot to some known commercial loads. If your failure to eject rounds seem weak compared to the commercial rounds, it likely means that you can increase the powder charge a bit.

BTW, you can't always trust a single manual. That's why we say to have several. I have some .357 rounds here loaded according to the '98 Hodgdon manual that are far above what Hodgdon recommends today.

Ken

 

[243winxb]

bc = ballistic coefficient sd=Standard Deviation As posted below

SD=sectional density

 

[rfwobbly]

Some things to remember...

The Alliant Powder book shows MAX of 5.4gr Unique at OAL 1.190 or greater for 200gr lead. That would put the starting load at 4.9gr.


The amount of powder and the space inside the case under the bullet are the 2 main contributors to pressure. The longer the OAL, the greater the volume under the bullet. So you have to use more powder to get back up to the same pressure as found in a short OAL. If you'll look at the 3 loads, the ones with more powder simply have a longer physical length. So "length" and "powder" measurements go hand-in-hand. (See graphic)

The second thing is the bullet shape. As the bullet shape changes, the height of the bullet changes. Again, it's not the OAL that's really important. It's the OAL minus the bullet height, because that's what determines the volume inside the cartridge case.

Remember too, the testing is not done in a pistol, but a test barrel. So the powder load and the OAL are simply "guestimates" even if you are using the exact bullet in the reloading manual. And even then, your gun's spring weights and slide lubrication can play a significant part in FTF's.

All these reasons are why we ALWAYS start at the minimum and work up. We can get close, but we really DON'T know until we shoot the "starting load".

Now in a 45ACP, especially if it's not a RN bullet, sometimes you have only one OAL that will feed. In that case you take your "magic" OAL, find a load close to that length, and let the OAL dictate the load. Follow?


If you were thinking this was hard science, it ain't.

 

[243winxb]

stovepipe- The fired case must stay on the bolt face till its hit by the ejector. If the next round in the magazine hits the recoiling case, its knocked off the bolt face and is caught by the slide. Sometime the lips of the magazine can also hit the recoiling empty fired case. Make dummy rounds and work the action slowly, see what takes place. COL is not in a book, it has to be learned. A small amount of lead should be just above the case mouth using a lswc.

 

[243winxb]

Seat your bullet till it measures .450" on the bullet, right in front of the case mouth. Seems we went over this before, but missed a few things like stove pipes. http://www.thehighroad.org/showthread.php?p=6240275#post6240275

 

[remmag]

243
i am sorry but i did not see your last post on my prior thread, the picture you have given on the bolt is a big help. i did check my rounds in the chamber ,when i went with the load at 1.235 oal it was like the one on the far right (bullet seated out too far) with an oal of 1.190 i am at headspace ok
rfwobbly that was big help, i will be ohnest i aam going to have to think it through to say i 100%follow, i am a little lost on the oal minus the bullet height
thanks all for the responces and i will load some at 5.2 5.3 and 5.4 grains tomorrow and test

 

[jr_roosa]

SD does not mean standard deviation in this context. It stands for sectional density.

 

[243winxb]

i will load some at 5.2 5.3 and 5.4 grains tomorrow and test

Start with 5.4gr as this is a light load for a cast bullet. Then go up by .3 gr. at a time, is what i would do. Jr Rossa, thank you, SD=sectional density. Goes with the BC i knew that, just didnt think of it.

 

[remmag]

will do
thanks