7 rum, RL33 and the 190 matrix Load Development

[Doublezranch]

Today Zayne and I took advantage of the WAY above average weather and headed to the range. Our goal was to see how the 7 rum works with 33 and the 190 matrix. Needless to say the results were interesting. We loaded 6 groups of 3 starting with 90 grains and working to 96 grains respectively. Since there is no data for this combo we made a educated guess at 90 grains for a starting point.
After Zayne settled in, the first 90 grain rocket was placed in the chamber and BOOM! Easy bolt lift, soot everywhere and dimpled case. Too light. Ok...let's try 91. Settled in...BOOM! Easy bolt lift..soot everywhere and dimpled case. Too light. Ok..let's try 92. The dimpled cases stopped at 95 grains with soot on every single case. Even the 96 grain cases. Every charge was too light. The awesome thing of the whole day were the groups. They were amazing. Even though the charges were light, they shot well better than I could have ever dreamed. Zayne and I plan on loading another ladder starting at 97 grains and head to 102 grains. These bullets are seated 30 thou off the lands and loving it!! Once we get settled on a load, we will throw a chrono out and get some speeds. Here is a picture of Zayne's 96 grain group at 100.

 

[Deleted member 46119]

Give us a COAL for a QL sanity check.

 

[bigngreen]

Yeahhhhh, giver the onion man!!gun)I'm going to bring my 7 RUM back into action when I get a box of 195 Bergers should be something to behold!

 

[Doublezranch]

You made me spit out my coffee Rhian!!

The COAL is incredibly long. Total overall length is 3.98. The picture tells the rest of the story. It's almost silly...

 

[Deleted member 46119]

I love the look of it......

More data will make this all more accurate. Fired case capicity, barrel length and velocity but:

Assuming R-P brass and a 26" Barrel, a fired case capacity close to what QL has and the weighting factor that I believe is correct (lots of assumptions)

RL-33 is a great powder for it.

Your starting load is appropriate.

Your 96 grain load is close to a OBT node at ~3200fps with ~60k psi. With those shots. The OBT and velocity might be close to reality but the psi could be as far away as the next planet.

What will hold is that 1 grain steps is about 2k psi increase. You should be very close to 100% case capacity at 98 grains. AFAIK RL-33 can be compressed.

IIWM: I'd make some 96 grain loads and chron them when I make the next steps in the ladder.

 

[Deleted member 46119]

The 28-Nosler is throwing the 190 Matrix about 200fps slower at the same "indicated" pressures with a load thats 10 grains less.

I believe the 190 Matrix and some day the 195 Berger will make the 7RUM come alive.

 

[Deleted member 46119]

I love the look of it......

More data will make this all more accurate. Fired case capicity, barrel length and velocity but:

Assuming R-P brass and a 26" Barrel, a fired case capacity close to what QL has and the weighting factor that I believe is correct (lots of assumptions)

RL-33 is a great powder for it.

Your starting load is appropriate.

Your 96 grain load is close to a OBT node at ~3200fps with ~60k psi. With those shots. The OBT and velocity might be close to reality but the psi could be as far away as the next planet.

What will hold is that 1 grain steps is about 2k psi increase. You should be very close to 100% case capacity at 98 grains. AFAIK RL-33 can be compressed.

IIWM: I'd make some 96 grain loads and chron them when I make the next steps in the ladder.

Marshal pointed out that my QL length on the 190 is too long. I fixed it.

Your 96 grains is closer to 3100fps at 56k psi. Matches your no pressure signs better.

 

[MontanaRifleman]

What will hold is that 1 grain steps is about 2k psi increase. You should be very close to 100% case capacity at 98 grains. AFAIK RL-33 can be compressed.

I can easily get 102 gr of 33 in my 300 RUM with RP brass.

Looking forward to the results of next go around DZ

 

[Doublezranch]

I shoot 102.7 grains out my 300 rum as well. Both are very similar in length. My 230 bergers are just shy of 4 inches. Looking very forward to the next round. The chrono is making the trip this time. No matter what, when that bullet hits, should be very devistating.

 

[Lefty7mmstw]

holey Hanna ZZ, that's a lot of rl33 for a 7rum... I need to pull a few of my 168 bergers and run them up with rl33; I had been pushing them with 95gr rl50 for a nice, mild load. I think rl33 may get them singing a bit faster and stay accurate. I still think the 175gr and above pills are the way with the 7rum though...