Working Up a load with a new powder

[pilgrim05]

When  I started reloading less than a year ago, it was very very difficult to find components, and you had to use whatever you were lucky enough to find.  I have a couple of pounds of IMR 4756 which I have successfully used with 115 FMJ.  Now I have some 124 FMJ and would like to load some but can't find a starting load.  Is there some rule of thumb you can apply to the published loads of 115 to find where you should start with the heavier 124?  With the 115's I have worked up to 5.5 grains with is accurate and comfortable with my CZ 75 long slide.

I really appreciate this forum and the advice I have been given in the past.

[chfields]

124 GR. BERB HBRN TP
Starting Loads
Maximum LoadsManufacturer   Powder   Bullet Diam.    C.O.L.       Grs.    Vel. (ft/s)     Pressure        Grs.     Vel. (ft/s)     Pressure
IMR    SR 4756    .356"    1.150"       4.9    967    27,100 PSI       5.4    1,066    30,800 PS


http://www.hodgdonreloading.com/data/pistol


Hope this helps...

[pilgrim05]

Thanks I'll give it a try .... Slowly and carefully!

[Radom]

Kind of an old thread now, but IMR SR 4756 is the absolute best powder I have found for 124 gr 9mm in CZ pistols in terms of accuracy.  I have been using it as my powder of choice for 124 gr since 2004.   

Powder: IMR SR 4756
Bullet: 124 gr FMJRN (mil spec)
Actual Load: 6.2 gr
OAL: 1.12"
Average Velocity (as chronographed): 1,186 fps
Case: Federal/Speer
Primer: Winchester

To the best of my knowledge, this load does not exceed SAAMI standards for 9mm Luger, but it is approaching the +P threshold. 

The published data has loads of 5.6 - 6.3 gr with a minimum OAL of 1.13" for this bullet.  I would start at 5.8 gr as a starting load, based on my experience with this powder.  IMR SR 4756 is very forgiving to changes in components.  You cannot double-charge with this powder; a full case of powder should not be a safety problem.  (In other words, a double -charge will overflow the case, and a full case is relatively safe.) 

I have written quite a bit on the merits of IMR SR 4756 over the years.  A google search for "IMR SR 4756 CZ" will find some of the better posts/articles, as well as other contributions/data from other CZ shooters.   

[chfields]

very interesting......I am awaiting the arrival of some 147gr HP from Xtreme bullets. I will be loading these for competition. This was recommended by another member of the forum and shooting team member. I have never shot 147's before and look forward to seeing how well I like them. The 124's shot very softly and I liked them. The 115's aren't bad, but I've only shot about 200rnds of them....I can't wait to try the 147's so I can compare and see what I like best....