Home Forums Reloading Big Game Rifles 7mm Mashburn and IMR7977

Have any of you tried this combo?
I just loaded up a couple starting with 7mm wby min of 72.5gr under a 160gr Nosler PT. 73grs. Pressure wise everything looks good and it gave me 3217fps. at 33 degrees.
I can't wait to load up some and see how it shoots.

As a reference, it takes me 75.5grs. of H1000 to push a 162gr. AMax to 3200fps.

I'll have to keep that powder in mind for my new mashburn that I'll have this spring. That powder suppose to be stabile in different temps?

Hodgdon has 7977 between H1000 and MagPro on their burn rate chart. Enduron powders are reportedly fairly temp stable, maybe not as good as Extreme Aussie powder.

7977 should work well in the Mashburn, H1000 and RL-25 are good in the 7RM with heavier bullets.

DF

Try RL-26.

How temp stable is RL-26 compared to 7977, Enduron Series?

DF

I'd like some info on that to.

My guestimate, based on what I've read, would be Extreme, then Enduron, then RL series. Just don't know the spread.

DF

Based on my 7-08 R15 sucks for temp changes. On the Mashburn R22 seamed erratic with high temp swings but not as bad as R15 in the 7-08. Considering I'm in Minnesota my range temps vary from -25 below zero to high 90's so temp insensitivity is very important. Even though the R powders are very accurate 15 is only used with junk bullets and offhand practice and R22 only sees fire forming loads in the Mashburn.

I have high hopes for the 7977. In the next 8 months I should be able to chrono every 10 degree change from -30 to 90+.

Look forward to your results, Les.

DF

Yes. Me too.


I have 7977 but have not tried it yet. Les thanks for the info.Sounds like another good Mashburn powder.

Hardest part is deciding on one...

Will the Mashburn outperform a 7mm ultra mag?

Hanco I sort of doubt it. The RUM has way more powder capacity, uses a longer barrel.I bet the biggest gains will come with the heaviest 7mm bullets.

But stick them both in a 24" barrel with 160-175 gr bullets and they might be close. I dunno.....never had a 7mm RUM.

There are faster 7mm's available than the Mashburn,especially today...but pure speed was not the only reason I built one...

Mule Deer posted a test today that shows RL-26 to not be temp sensative in his .270 at 0. Good news for the Mashburn world

The new RL series is reportedly an improvement over the older RL's. And why roll out a new series if it's not better...??

My question, how do the new RL's compare to Endurons and Extremes.

It's a competitive market and a race for the "perfect powder"...

All to our benefit.

DF

While we are on the subject of temp sensitively, how does Ramshot Hunter do?

IIRC, TAC and Big Game are reportedly better than Hunter and Magnum. How much better I don't know.

DF

I have had really good luck with 7977 in my 25-06 AI.

Going to try some in my .264 WM.

I think it is my new favorite magnum powder.

Good luck with your 7mm.

Some .264 fans swear by RL-33. I wonder how close 7977 burn rate is to RL-33.

DF

That's a great question! I would love to find some data on both.

Not even sure where to start with 7977 in the .264.