Rem Mag / RL33 / 180 Bergers

[c_bass16]

Alright guys, this is my first true LR caliber in a true LR rifle and since I was starting with a relatively "experimental" combo, I thought I would outsource some knowledge.

I'll give you the specs, and then some photos to see what you think.

Rifle
25" Rock Creek 1:8.5 M40 Contour
7mm Mag Match chamber
Win M70 CRF Classic, trued action and bolt

I'm testing RL33 simply because it was available when I was sourcing supplies and it was suggested as a good alternative for the 7mm Rem Mag with heavy bullets.

I've got 215 primers and 180 Target VLDs on hand and started with a ladder at 71 (way low I think) and went forward looking for case capacity, velocity, minimal horizontal stringing and of course, pressure issues.

I went up in .5gr increments at 475 yds and actually ran out of case capacity before I saw any pressure issues at all.

I've got a picture of two cases, my starting charge of 71, and my max as I believe case capacity was starting to reach the top. (bullet seating depth was .002 longer so it was just starting to push powder, but I could feel it shake so I just touched it down an extra .002 so all my loads were the same OAL to ogive)

Velocity over the last three .5gr loads finally stopped showing a velocity increase, and was hovering between 2945 and 2960, which also suggests approaching max efficiency if I've studied right.

It's really really really hard to see in the photos, but the lowest 71gr charge has a perfect looking primer with the exception of a very faint crater that you can barely feel with the finger nail.
The max charge was the same, not flat, but with the same faint crater that you can barely feel.
ZERO noticeable change in bolt lift, but with the CRF claw extractor, I can't exactly look for any marks on the case head.
I measured the cases looking for excessive expansion and the results were as follows.

Unfired
.489 at shoulder
.510 just in front of the belt

71gr
.492 at the shoulder
.511 just in front of the belt

Nearing full case
.492 at the shoulder
.512 just in front of the belt


With this info, (and I can try getting any other data that might be needed) would anyone suggest that this powder is not actually capable of reaching "legitimate MAX" with a heavy bullet IN MY RIFLE.

I still have plenty of room to seat the bullets OUT, and could even potentially seat them in a pinch, or even run a tighter bushing to increase pressure a little sooner, in hopes of squeezing velocity out of a slightly lighter load, but so far everything seems to be running safe.

I found two clusters on paper at 475yds that were promising.
One was a 3 shot, full grain, spread that settled at just over 1.1"
The other was a .5gr pair that were also at 1.2" apart.


Any thoughts or suggestions before I proceed?

 

[AZShooter]

I have used RL-33 quite a bit and it is slower than retumbo. RL-33 requires approx. at 7- 9% more powder to duplicate retumbo velocities. (that was the average amount of powder for a 7 rem mag, 6mm-284 and 257 weatherby I tested)

Alliant load data only has two loads listed for the 7 rem mag:

7MM rem mag 175 speer sp 75.2 gr RL 33 @ 2909 fps
7MM rem mag 175 speer deepcurl 73.8 gr RL-33 @ 2853
OAL for both is 3.290"

If you aren't getting any more velocity with more powder than there is no point in adding even more, you found the max in this case.

Quite frankly this powder is a bit too slow for your rifle BUT it will still work. If you cannot get other powders use it.

I tried it in my 24" 7 rem mag using a moly coated 162 a-max. I had a load with retumbo and wanted to compare them.

Retumbo 72 gr vel 2975
RL-33 worked up to 79 gr for vel of 3000 BUT the amount of compression caused the bullet to be seated out to the point it wouldn't fit the mag box!

It was easy to conclude that RL-33 wasn't to be used with that weight bullet.

I would just try to refine the load by tweaking seating depth and use it.

 

[c_bass16]

That was my conclusion as well...I built the rifle to shoot the 195's whenever they are released, and assume the powder would work better for those ultra heavy for cal bullets. I didn't expect someone like Nosler to release a lighter bullet with a (advertised) higher BC, so perhaps the 162 Amaxes and the new Nosler AB LR's will be a better option with a different powder.

I'll continue to use my supply and test some others till it's gone...UNLESS something outstanding happens.
If she shoots, I'll continue to use it.

So far, so good.
Thanks

 

[benchracer]

I have heard it said, while describing how RL-17 behaves, that velocity increases in a linear manner to a certain point, then the velocity actually falls off with the next step up in powder charge, followed by increased velocity with erratic ES and SD numbers and an eventual pressure spike. According to this description, the last powder charge before the velocity falls off is the max charge.

My understanding is that RL-33 is a slower powder with the same basic design properties as RL-17, so I am thinking that it may behave in a similar manner. I would, however, be surprised if you have enough case capacity to reach that point. For the time being, though, it looks like you have a load that will work just fine. You can always go a different direction when component availability returns to a more normal state.

I am interested in trying RL-33 in my .264WM at some point.

 

[c_bass16]

Finally got a load that should work out just fine. I think with some more time behind the rifle, it'll average a sub 1/2 group.
These were all on a perfectly clean, freshly scrubbed bore.
Shot #1 was right in the sweet spot...and I think I pulled shot #2 high at 12 o'clock.
Everything else felt good, but with some more trigger time...I'm confidant the rifle and I will get a little more "Zen"

1st 3 shot group

2nd 3 shot group

3rd 3 shot group

all three targets overlaid.

 

[highridge1]

I think the RL33 is going to do alot better in the bigger cases, like the Lapua, Ultra mags, 30-378,338-378 I think those are where it will really shine. I really don't think the RL33 will be any advantage in the smaller mag cases.

 

[c_bass16]

I agree. It might work well with the ultra heavy bullets, but for the 180s, I'm not seeing anything "outstanding".
I still need to do a drop test out to 1000 or 1200 to confirm everything, but it looks like I'm somewhere between 3020 and 3050 right now with a 25" barrel...and I'll accept that.

 

[Outlaw6.0]

I agree. It might work well with the ultra heavy bullets, but for the 180s, I'm not seeing anything "outstanding".
I still need to do a drop test out to 1000 or 1200 to confirm everything, but it looks like I'm somewhere between 3020 and 3050 right now with a 25" barrel...and I'll accept that.

I agree that you will probably see better results with heavies. How are you sitting, pressure wise, at your current velocity?



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[c_bass16]

I can feel a faint crater on the primers with my finger nail...but I could feel it at the very bottom of the ladder test as well, so I don't believe it's anything to be concerned about.
Primers aren't flat, no excessive case expansion, no sticky bolt and I can still chamber all my spent brass as if it were bran new.

I'm not sure where else to look for pressure.