IMR 7977 in 240WBY

[Bfh_auto]

I'm wanting to try a 100 interlock or 95sst with IMR7977 this fall. I've been unable to find any data for it.
I am not looking for someone's load, just a recommended starting point.

 

[243winxb]

No data for 240 wby. https://imrpowder.com/imr-enduron-7977/

Contact Hodgdon. https://imrpowder.com/company/contact-us/

IMR 7828 has data at Nosler & Hodgdon. "C" = Compressed Loads.

The burn rate chart lists 7977 as slower then 7828. May not be able to get enought 7977 into the case for top velocity.

I would look for IMR 7828 SSC .

 

[243winxb]

https://www.shootingtimes.com/editorial/ammunition_st_mamotaip_200909/100079

We tested loads at both maximum normal pressures and at the starting loads (some labs calculate start loads — we shot them). Standard primers caused no ignition issues at the max load but posted higher extreme variations in pressure and velocity in the lower pressure regimes of the start loads. In extreme cases, the start loads produced short delayed firings — probably in the range of 20 to 40 milliseconds but detectible to an experienced ballistician. Switching that propellant to a Magnum primer smoothed out the performance across the useful range of charge weights and completely eliminated the delays.
If I've recommended a Magnum primer in reloading data I've developed, it's because my lab results show it's needed.

A mag prime will help problems like this.

 

[Bfh_auto]

Latest range results using IMR7828...
95gr B-Tip 53.0grs IMR7828 Ave(3) 3282 fps Es 65 Stdev 35 65 Degrees
100gr Partition 54.0grs IMR7828 Ave(3) 3145 fps Es49 STdev 25
86gr F-Tip 54.0grs IMR7828 Ave(3) 3286 Es52 Stdev 26
All the loads are running 100-150 fps under Quickload predictions even after I updated the actual case capacities. I've been using CCI 200 primers. Seeing the large deviations I am suspecting that moving to a Magnum primer might improve velocities and lower variations. I am also noticing some smoke left over in the barrel and chamber. Although it doesn't seem like you would need a Magnum primer to light-off powder charges less than 60 grains.

I'm getting similar velocities with a case full of H1000. I used LR primers without issues.
I just wanted to try something different.

 

[Bfh_auto]

No data for 240 wby. https://imrpowder.com/imr-enduron-7977/

Contact Hodgdon. https://imrpowder.com/company/contact-us/

IMR 7828 has data at Nosler & Hodgdon. "C" = Compressed Loads.

The burn rate chart lists 7977 as slower then 7828. May not be able to get enought 7977 into the case for top velocity.

I would look for IMR 7828 SSC .

Thanks.
7977 allowed for a little more velocity than h1000 in 280AI. I figured it would do the same in the 240.
240wby isn't a common cartridge so it doesn't get all the love from powder testers.

 

[Bfh_auto]

Here is the reply I got from Hogdon.


About the lack of recent data for the 240 WBY MAG cartridges, we do not have many inquiries about the 240 WBY MAG. I cannot say when we might have updated info as our lab is backlogged and they are not sure when there will be time to get to the lower priority cartridges for updating.

 

[243winxb]

The 7977 is a double based powder containing nitroglycerin. The nitroglycerin should produce more energy per grain. May require less powder & fit in the case, providing maximum velocity?

The 7828 is single base powder. So it may benefit from a magnum powder?

https://imrpowder.com/resources/safety-data-sheets/

 

[Bfh_auto]

The 7977 is a double based powder containing nitroglycerin. The nitroglycerin should produce more energy per grain. May require less powder & fit in the case, providing maximum velocity?

The 7828 is single base powder. So it may benefit from a magnum powder?

https://imrpowder.com/resources/safety-data-sheets/

That's what I was hoping for. I don't have quick load and the powder suppliers don't care about it because it's an uncommon cartridge.

 

[GooseGestapo]

Contact Hodgdon. They might can help.

You could start with starting load for H4831, and work up one grain at a time watching velocities and measuring case head expansion.
Old school way...

 

[Bfh_auto]

Contact Hodgdon. They might can help.

You could start with starting load for H4831, and work up one grain at a time watching velocities and measuring case head expansion.
Old school way...

I posted Hogdon's reply. It was basically you shoot an uncommon cartridge so tuff luck.
I was thinking about finding several cartridges that use 4831, 7977 and h1000 and seeing what I can extrapolate.
I have a newborn and a 1 1/2 year old so possibly being my face off is no longer a valid option.

 

[GooseGestapo]

Approach conservatively and you’ll be fine.
I still have all my fingers and both eyes and started reloading 50yrs ago.
No internet, or much good advice back then. Just random publications, and a healthy rumor mill.

You wouldn’t believe how many arguments I used to have over folks using IMR 3031 (supposedly) in a .38Spl. , or folks insisting they were using a full case of Unique in a .30/06.
ie: they didn’t know what they were talking about and wanted others to think they did...

Turned out, it was Win231 in .38 and H4831 that had been transferred to a relabeled Unique container.

 

[Bfh_auto]

I finally got some time to look up charge weights of cartridges that use both imr7977 and h1000. The charge weight of 7977 varies between 102% and 104%.
I used data for a 100 gr bullet with the 95 SST and got 3500 fps. I didn't have pressure signs, but I'm going to use what was supposed to be a starting charge as the maximum one and work down for best accuracy.