IMR 4756 ?

[NJM15]

Due to the shortage of powder I bought 2 lbs of IMR 4756 powder locally loaded 20 9MM rounds with the recommended starting load of 4.5 gr and 20 with 4.8 gr max is 5.2 well the problem is there's not enough energy to eject spent shells I can manually eject so I know the gun seems to be functioning ok they fire off ok although seems kind of weak. As soon as I get the bullets ordered from Extreme (thank for the tip) I will try the max load. All I have ever used is American Select and HS6 with no problems what so ever after loading about 2k rds.
I am firing a Sig 226
Any suggestions?

 

[Peter M. Eick]

That is normal. 4756 has been really wimped out with recent data. Find some older data and it should work just fine. I have shot probably 70 lbs of 4756 over the last few years and have 5 8 lb jugs of it in the queue to use up.

4756 is great in the 38 Super and 38 Special by the way.

I work up my 4756 loads over a chrono and just load them until I get the velocities I desire or I get the older book max loads. In most cases my desired velocity comes first. Older data can be hot so work up carefully.

 

[Nevada Ed]

IMR....SR4756 powder is a high energy powder that has been
reduced to where it is of almost not worth loading.

When it first came on to the scene it was a high velocity powder
in the 38 special...........now it is down to target load speeds.

It works great for me in 4" or longer barrels in 38 and 357 magnum loads but I also have the help from a chrony to get factory loads.

We will not have to worry much longer, with it being discontinued...........................

 

[pbcaster45]

I worked up a load in my 9mm using my chronograph to keep an eye on things. My Bar-Sto barrel has a short throat so I have to seat deep.

Starting load.

Bullet: Montana Gold 124 gr. JHP
Powder: IMR SR-4756 5.0 grs.
Primer: Federal 100
Case: Federal
LOAL: 1.075 (.812 with Stoney Point)
Avg. Vel.: 1010.35 fps
ES: 42.57
SD: 18.45

Final load. Powder is compressed but it shoots great! I'm making it my standard practice load.

Bullet: Montana Gold 124 gr. JHP
Powder: IMR SR-4756 5.7 grs.
Primer: Federal 100
Case: Federal
LOAL: 1.090 (.825 with Stoney Point)
Avg. Vel.: 1149.34 fps
ES: 31.54
SD: 9.05

 

[Treeman]

4756 is a very good 9mm powder.....but data in most handgun cartridges varies all over the place. !980's data from IMR was very accurate compared to actual performance in my guns and never has given any surprises regarding pressures. Speer 8 is pretty accurate regarding velocities but SOME of it is "high pressure". Some current data seems utterly disconnected from any practical application (but by golly it was mild, safe, and the bullet made it out of the end of a 10 inch test barrel!)
I have found 5.7 gr of 4756 115gr, RemHP at 1.075 OAL to be good standard pressure load in my guns.
6.2 grains under a 124gr RemHP at 1.140 OAL is a top load but not excessive in my guns that can tolerate greater OAL. Use caution. double check my data. Hope this helps.

 

[NJM15]

Checked with IMR via email they said try 5.0 gr to see if that might help. Funny thing is all the loads that didn't eject from the handgun worked great in my cheapo Hi point 9mm carbine. Right now the only 9mm bullets I have are flat point that I use to load my 357Sig ammo don't know if I can use them in 9mm loads

 

[oldman10mm]

I use SR4756 for 9mm,38sp,357M,40S&W,10mm,44M.

my standardized loads for 9mm
-88-90 jhp- 7.0 for 1350fps 8.0 for 1500fps
-115jhp 6.0 for 1100fps 6.75 for 1200fps
-120lead 5.5 for 1230fps

 

[NJM15]

Thanks OLDMAN I will wait for the answer from IMR
I shoot 115 gr plated round nose lead I know IMR wont recommend anything over max but as long as it don't pack the case its ok with me

 

[Rule3]

Checked with IMR via email they said try 5.0 gr to see if that might help. Funny thing is all the loads that didn't eject from the handgun worked great in my cheapo Hi point 9mm carbine. Right now the only 9mm bullets I have are flat point that I use to load my 357Sig ammo don't know if I can use them in 9mm loads

Blow back VS locked breach

The Sig has a pretty heavy recoil spring So you will either go with a higher charge. change the recoil spring or use a better powder.


4756 is more of a big caliber powder per the description. Not much data for 9mm for it so there must be a reason.

Perhaps delete your other post on this.

 

[Alk8944]

NJM15,

All you are going to get from IMR is referred to Hodgdon's which is now the distributor for the IMR brand. One clarification to what has been said before. SR-4756 was not developed as a handgun propellant, although it works very well for this purpose. The SR designates Sporting Rifle, should be obvious.

Loads. I assume you got the starting load from Hodgdon's web site. Hodgdon's has become extremely conservative in the past few years, possibly as a result of issues where they continued to insist there was no problem with reduced loads with H-110 for years, in spite of Winchester cautioning against reducing loads more than 3% with their brand 296, which is the same propellant manufactured by St. Marks in Florida. The problem was real! 'Nuf said.

When in doubt my habit is to go directly to the source for loading data. In this case it is to the last IMR "Handloader's Guide". Remember that pressures in the manual are listed in CUP and not PSIG as is frequently used today, but not always! SAAMI still lists CUP information for some cartridges.

You didn't list bullet weight, but the charges in Hodgdon match their data for the 115. Curiously, if you had looked at 124 gr. data you would see the charges are higher! For some reason they show a LRN for the only 115 gr. bullet, go figure! Here is the data from the IMR manual.**

115 gr. JHP, LOA 1.110"
SR 4756, 6.3 gr. compressed, 1175 fps, 30,600 CUP

124 gr. FMJ, LOA 1.135"
SR 4756, 6.3 gr. compressed, 1160 fps, 32,400 CUP

**(This data is with Rem 1 1/2 primers, and, probably, Remington bullets)

Yes, the charge weight is the same! That is all the powder the case will hold, even compressed, and stay within the pressure limitations of the cartridge which is 35,000 PSI.

If you compare starting to maximum loads in many manuals you will see that generally the "starting load" is simply the "maximum" reduced by 10%. Using this standard the starting load for this powder/cartridge combination would be 5.6-5.7 gr. And Hodgdon shows 5.2 as a Maximum load??? That's barely a starting load based on original IMR published data! And you wonder why your pistol won't function with a load (4.5 gr.) almost 30% (weight, not pressure!) lighter? Interpolated that's not even a good .38 Spl. load based on pressure. The 4.5 gr. is only developing something like 15-18,000 PSI.

Bottom line? There is absolutely nothing wrong with SR 4756! The problem you are having is that the Hodgdon data is so deficient as to produce completely useless ammunition!

This is an excellent example of the admonition to always cross-check as many references as possible! It isn't always to avoid high pressures. I hope you learned something.

 

[NJM15]

Thanks

NJM15,

All you are going to get from IMR is referred to Hodgdon's which is now the distributor for the IMR brand. One clarification to what has been said before. SR-4756 was not developed as a handgun propellant, although it works very well for this purpose. The SR designates Sporting Rifle, should be obvious.

Loads. I assume you got the starting load from Hodgdon's web site. Hodgdon's has become extremely conservative in the past few years, possibly as a result of issues where they continued to insist there was no problem with reduced loads with H-110 for years, in spite of Winchester cautioning against reducing loads more than 3% with their brand 296, which is the same propellant manufactured by St. Marks in Florida. The problem was real! 'Nuf said.

When in doubt my habit is to go directly to the source for loading data. In this case it is to the last IMR "Handloader's Guide". Remember that pressures in the manual are listed in CUP and not PSIG as is frequently used today, but not always! SAAMI still lists CUP information for some cartridges.

You didn't list bullet weight, but the charges in Hodgdon match their data for the 115. Curiously, if you had looked at 124 gr. data you would see the charges are higher! For some reason they show a LRN for the only 115 gr. bullet, go figure! Here is the data from the IMR manual.**

115 gr. JHP, LOA 1.110"
SR 4756, 6.3 gr. compressed, 1175 fps, 30,600 CUP

124 gr. FMJ, LOA 1.135"
SR 4756, 6.3 gr. compressed, 1160 fps, 32,400 CUP

**(This data is with Rem 1 1/2 primers, and, probably, Remington bullets)

Yes, the charge weight is the same! That is all the powder the case will hold, even compressed, and stay within the pressure limitations of the cartridge which is 35,000 PSI.

If you compare starting to maximum loads in many manuals you will see that generally the "starting load" is simply the "maximum" reduced by 10%. Using this standard the starting load for this powder/cartridge combination would be 5.6-5.7 gr. And Hodgdon shows 5.2 as a Maximum load??? That's barely a starting load based on original IMR published data! And you wonder why your pistol won't function with a load (4.5 gr.) almost 30% (weight, not pressure!) lighter? Interpolated that's not even a good .38 Spl. load based on pressure. The 4.5 gr. is only developing something like 15-18,000 PSI.

Bottom line? There is absolutely nothing wrong with SR 4756! The problem you are having is that the Hodgdon data is so deficient as to produce completely useless ammunition!

This is an excellent example of the admonition to always cross-check as many references as possible! It isn't always to avoid high pressures. I hope you learned something.

With the new info I have received on this forum I will use it and reload accordingly .
I always go by Manufacturers recommendations if they are not right I have no other way of knowing.
S AND W forum, A wealth of information

 

[peterthefish]

I'll mimic what others have said but add a cautionary note. I started loading SR-4756 based on some recipes from my Lyman manual. No problems, although it seemed to behave better for light loads than heavier. I was working up some loads for 147 9mms and looked at the website data. It seemed light but I used it as my starting point and was rewarded with my first squib ever - that too in my 986 where I could have easily pulled the trigger again.

All I can think is 4756 is much more erratic at high pressure than old data indicated - perhaps a characteristic picked up by newer equipment? Maybe this is why it's out of production? The given load data on the Hodgdon website is just crazy low - using identical components I get loads 100 FPS slower in .45 - that's a big difference.

 

[boatbum101]

It gets hinky when crowded & varies ( sometimes a good bit ) from lot to lot . Personally if I have a good load that's hot , when I get a new lot I work back up to velocity of the original load not the charge weight .

 

[rwsmith]

I wonder......

IMR....SR4756 powder is a high energy powder that has been
reduced to where it is of almost not worth loading.


We will not have to worry much longer, with it being discontinued...........................

Discontinued? With that kind of watering down why would anyone expect different? Gosh, the powder we are marketing as being for really wimpy loads isn't selling? I guess it will have to be discontinued....... duh.