Well, I was able to get a small supply of RL33 from a very gracious fellow member of LRH.com that live near Bozeman. To him I say thank you very much for your help with this testing.
I wanted to see what the 338 Raptor would do with RL33. In my gut I felt this powder was to fast in burn rate but sometimes you get surprised so wanted to prove it to myself before I made any opinions. While I felt RL33 may be magical in my 338 Allen Xpress and other 338 Lapua Improved designs, the Raptor has a 10-15 grain larger usible powder charge range so felt it may be just a bit to large to be right for RL33. Only one way to find out though, get some bullets in the air.
Using the 300 gr Berger Hybid seated to 4.320" OAL and lit off with a Fed-215 primer. I started at 106.0 gr which was a very low starting point but wanted to make sure I was safe as I have had NO experience with this powder. This was in fact a very mild powder charge producing only 2789 fps. I say only but we were already at 338 Lapua performance levels!!!
Seeing this, I jumped up 4 grains to 110.0 gr charge and this time only got 2812 fps, when you go up 4 grains and only increase 23 fps, you know your running VERY low pressures in a large capacity case!!!
Increased another 4 grains to 114.0 gr and it was obvious that finally the pressures were starting to build getting some work done with a velocity of 2904 fps. From here out, I increased two grains at a time until I got the first hint of an ejector ring on the case head.
114.0 gr.............................2904 fps
116.0 gr.............................2956 fps
118.0 gr.............................3016 fps
120.0 gr.............................3065 fps
122.0 gr.............................3129 fps
124.0 gr.............................3182 fps Slight hint of ejector ring on case head
I could have increased powder charge more but in working with this new case, once you get to the level that you start to see a very faint ejector ring, your at the max working load. Another grain of powder may have been just fine, another two grains would have started to noticeably loosen the primer pocket so why waste brass. For RL33, in this 29" barreled 338 Raptor, 3182 fps is my max working load. Not 3200 fps but for all intent and purpose, same thing.
After this test, I set back and reviewed all the velocity test data and tried to determine what I felt was the best all around load that I wanted to test at long range for an accuracy test of the rifle. The criteria for the best all around load must have the following:
1. Pressures comfortable enough to allow +8 firings per case
2. Consistent velocities
3. High load density
In looking over all the load data from the tests using WC860, US869, H-50BMG, RL50 and RL33, I came to the conclusion that the load using 127.0 gr of RL50 was the best all around load. In early testing, it showed very comfortable pressures an average velocity roughly 3150 fps. This was 50 fps off the max load using this powder and had a load density of roughly 98%.
The RL33 loads were quite good but the load densities were a bit lower then I like.
The US869 loads produced significantly more velocity well over 3200 fps but velocity spreads were a bit higher then the RL50 loads and there is no meaningful difference at long range between 3150 fps and 3200 fps so I went with the tighter velocity spreads.
I did however want to prove the +8 firings per case requirement so to do so, I picked out the case from this batch of test cases that had the highest pressure test load from the RL33 test loads, this was basically a 3200 fps level load. This case had a slight ejector head on the case. Why not start with a virgin case, could have and would have been a more accurate indicator of the brass life using my chosen load but I figured I would pick a case that had already had a high pressure loading on it and if that case could still get me 8 firings, I would know that all the virgin cases would easily make it past 8 firings per case.
So, I FL sized this one case, trimmed it to length and deburred it. Seated a Fed-215 primer, threw in 127.0 gr of RL50, seated the berger 300 gr to 4.320" and shot it over the chrono.
The first firing on this case had produced 3182 fps, that was using RL33.
The second firing with the RL50 load clocked 3148 fps. After each firing, I would FL resize the case, reprime, repowder, seat bullet and fire again. I would repeat this until I either found the primer pocket was to loose to hold a primer without gas leaking or I reached the acceptable number of firings.
Firing #3...........3151 fps Primer pocket tightness unchanged
Firing #4...........3152 fps Primer pocket very slightly looser
Firing #5...........3183 fps Primer pocket remained similar to previous.
-Case length had increase slightly and needed to be trimmed which I am sure was the result of the increase in pressure as it had slightly contacted the end of the chamber neck.
-Trimmed case back to original length
Firing #6............3159 fps Primer pocket slightly looser but still plenty of resistance when seating primer.
** Case neck no longer expanding to allow bullet to freely pass through fired case neck. ANNEALED CASE NECK after 6th firing.
Firing #7............3173 fps Primer pocket remained similar to #6 firing
Firing #8............3167 fps Primer pocket slightly looser but still solidly holding primer. No gas leakage of any kind.
-Trimmed case to original length
-Needed to bump shoulder an additional 3 thou for proper chambering with no resistance, important for a case of this diameter and especially length.
Firing #9............3167 fps Primer pocket pretty loose but still solidly holding primer and no gas leakage of any kind
Firing #10..........3159 fps Primer pocket loose but again, no gas leakage of any kind.
Full Length sized the case, reprimed it and trimmed it. Put it back in the ammo box and have no worries about getting at least 1-2 more firings off this case.
The average velocity for all 9 firings with this powder charge was 3162 fps with an extreme spread of 35 fps. That was including the high velocity reading of 3183 fps which I am sure was caused by the case mouth contacting the end of the chamber. If you take that one high firing out of the string, the ES was 25 fps. Not to bad for basically a 10 shot string and plenty consistant for anything I will ever do with the rifle, including 2000 yard class shooting.
Every firing on this case left a faint ejector ring. No shiny ring, just a faint compression ring similar to what you see on factory 300 RUM brass. This brass is not as strong as Lapua brand 338 Lapua brass, not nearly as hard in the case head. It seems to be very similar to Remington RUM brass or Norma brand 338 Lapua brass with a faint ejector ring showing up at between 65,000 and 68,000 psi.
So, with this load which averaged 3162 fps and allowed +10 firings per case, it easily covers my criteria for an all around great load. Had I started from a virgin case, I am sure that this case would have held TIGHT primer pockets for several more firings. By the end of this case life test, the primer pocket was very loose but again, there as no gas leakage of any kind and I could not push out the seated primer using hand pressure and a small diameter steel punch pushed through the case mouth. Using this load, 100 round of brass would likely offer at least 1200 rounds down the barrel, possibly more.
I do not what anyone reading this to think that these primer pockets are holding virgin tight for +10 firings, that is certainly not the case, what I am saying is that the primer pocket is staying plenty tight to securely hold a primer for +10 firings with no gas leakage of any kind. That is 100% acceptable for me and showed no sign of any dangerous situation.
Once the case reached the 6th firing, the primer pocket tightness seemed to pretty much stabilize and remain very similar through out the rest of the test. While the primer pocket continued to loosen as more shots were fired on the case, the difference from firing to firing were very slight and again, when the case was done with this torture test, it was reprepped and the entire batch of 50 rounds of brass were loaded up with this load and I have no worries about getting at least 1-2 more firings on this case.
Next up is accuracy testing.
One thing I did notice was that with the virgin brass, neck run outs were a bit larger then I like to see. On once fired cases, the neck run out really tightened up well and as such bullet run out also improved dramatically so we will see how this shows up down range. The throat on my Raptor chamber is very tight, only 1/2 thou over nominal bullet diameter so that will correct some of this bullet run out on virgin cases but I am sure accuracy will improve notically on the second firing on these cases but that is not unusual for any brass.
We will see how the bullets fly and how close they land!!!
