Home Forums Reloading Big Game Rifles IMR7828 formulation changed?

So I had some really good groups in the past with IMR7828 powder and 160 Accubonds in my 7mm rem mag. Seems that I remember going all the way up to about 67 grains and didn't notice any pressure signs other than a little bit of primer cratering. I settled on 65.5 grains as it was most accurate. At the time it was also under the Max load recommended by Nosler for that powder and a 160 grain bullet.

Recently, I have found high pressure signs with that same powder charge. I also notice that the newer Nosler books suggest 64 grains as a Max charge. Unfortunately, I am only hitting 2900 fps at 64 grains, but no obvious pressure signs. This from the same rifle with a 26" shillen match grade barrel.

I did switch from regular IMR7828 to the ssc version due to availability, but the older style was still showing similar pressure issues.

Thoughts? I keep seeing where people are using 66-67 grains of this powder and getting over 3000 fps. I am definitely having pressure issues at 65.5 and wouldn't go over it.

FH

Have you switched anything else? Same brass? Primers? I've had great results from 7828 and ssc both.

Brass and primers can make a huge difference, especially if you are switching from something like a thin Winchester brass to a thick Nosler brass.

I would say you're seeing differences in lots. Not a formulation change.

Nosler or RP brass, two different loads with history, cci250 primers. Always kept the two loads with the two brands of brass separate.

Yup probably a different powder lot #.
My Nosler Fifth edition shows 60gr of imr 7828 for a 160 bullet ,I worked up loads for my 280ai for the 160 AB and 162 Amax both shot great at 60gr of imr7828ssc .
Ran out grabbed another can and backed off to 59gr from the new can of imr 7828ssc -same components -first shot seemed to have a bit of a "ring" to it -brass looked good mild bolt lift pressure -fired another round -locked the bolt closed.
Had to open it w/a mallet -believe it or not the nosler brass didn't look or measure any different than the other brass.
I pulled the bullets thinking I must have made a mistake with the charge --nope--- right on 59gr..
Hodgdon site shows 58gr max -the nosler fifth maual shows the highest charge I've seen anywhere.
In the mean time I found a great shooting load with 140gr NBT's and H-4831sc.
I'm waiting for imr 7828 ssc to get to the shelves in 8#rs then I'll start low again ---and stop buying 1# cans of powder.
Mike

I tried H4831SC but went to Reloader 22 with 140 BT and they shot great. I will need to verify these results but here is to hoping.

7828ssc is very accurate in my 7wsm, using 68.0 gr with WLRM, and WW brass produces consistent 3/4" groups with a 140 gr Nos E-tip.

7828ssc is friendly to alot of my guns....and I buy at least 3 one pounders at a time w/same lot number...usually plenty on the shelf around here.

The one consistent thing about reloading components is inconsistency.

5sdad,

Amen to that statement! Just really surprised at the very large change in "min and max" charges over the years. Dang that 65.5 grain charge was really accurate in her too.