338 Allen Xpress, RL33 load development

[Fiftydriver]

Mark,

My OAL is 3.9" right now with .008" jump. Close to what you are asking. In about three more days I should have more data. 100gr is no problem with pressure signs and will be working up from here.

Just about what we were estimating it would be. Thanks for the information. One less thing I have to try to remember to do today!!!

 

[Fiftydriver]

Played a bit more with some experimenting with RL33 again today at lunch. Its been pretty well estabilished that this powder wants heavy bullets seated close to the lands for best consistency.

Today I wanted to play with neck tension to see if it had any effect on velocity results. For a standard velocity, I took five rounds of my regular 300 AX ammo loaded with the 200 gr Accubond and chronoed them. They averaged 3421 fps and had an ES of 22 fps.

Next I took some of my 7mm AM brass, necked it up to 30 cal and bumped the shoulder slightly to fit in my 300 AX chamber. Loaded 5 rounds. I did this because when you take the 338 Lapua down to 7mm, fireform it and then neck it back up to 30 cal, the necks get quite hard and neck tension increases dramatically. These five rounds average 3428 fps with an extreme spread of 26 fps. No real measureable change.....

Next up I took five rounds of the same brass and annealed it so the case necks were very soft. So soft in fact that when I seated a bullet, I could move that bullet with decent finger pressure so the case was JUST offering enough neck tension to hold the bullet in place. These five averaged 3430 fps and has an ES of 18 fps.

In all honesty, I do not see where neck tension has any real effect on velocity consistency with this powder. Should be noted that all loads were seated to 3.635" which is JUST kissing the lands.

I then repeated the same test above but seated the bullet 100 thou off the lands. Here are the results:

Standard 300 AX brass.............3378 fps............78 fps ES
High neck tension brass............3393 fps............83 fps ES
VERY light neck tension brass....3353 fps............105 fps ES

Again, this basically is saying that distance off the lands is the main factor in velocity consistency with RL33.

As mentioned barrel heat has also shown some effect on velocity spreads so I wanted to test this a bit as well. Let the barrel cool all afternoon and then just when I was leaving the shop, I took 10 rounds and shot them through the chrono with roughly 60 seconds between each shot. Here are the results of velocity as the barrel heat increased.

1. 3436 fps
2. 3418 fps
3. 3419 fps
4. 3434 fps
5. 3438 fps
6. 3408 fps
7. 3455 fps
8. 3428 fps
9. 3411 fps
10.3458 fps

As you can see, from a cold and cool barrel, shots 1 through 4 were quite tight with an 18 fps spread. Shots 4 through 8 had a 47 fps spread and shots 9 and 10 were also 47 fps spread. Total extreme spread was 50 fps.

Now, to confirm test, I let the barrel cool outside until it was barely warm to the touch, in the mean time I took cases from shots 6, 7, 9 and 10. These were the two lowest and two highest velocities. I did this just to see if the velocity spreads were a result of these cases and not the barrel heat. Same exact load, shot these four again with 60 seconds between each firing. here are those results

Case 6. 3428 fps
Case 7. 3421 fps
Case 9. 3438 fps
Case 10.3423 fps

Extreme spread for these four cases was a very nice 17 fps, these cases were the widest spread in the previous test but also 4 of the last 5 rounds fired in the hot barrel.

Its looking like barrel heat is certainly causing some effect on extreme spread. Luckily for us big game hunters, this really does not mean anything. In cool or cold barrels it appears that the first 4-5 shots are quite consistant which is far more then we will generally need. Interesting results so far.

Again, appears that RL33 has some unique personality traits but do not think they are bad enough to cause any real problems once we get them figured out and learn how to load for this new powder.

 

[Kiwi Greg]

Thanks again Kirby for the work you are doing & sharing

 

[MMERSS]

Thanks AZShooter and Tumbleweed for a starting point for the 230s.

Results from today's range day.

100gr RL-33 loaded to 3.9 OAL with .008" jump.

3240 fps ES 7

I was seeing extractor marks with this short of a jump compared to .038" and no pressure signs. However, the ES was great. Kirby you nailed it. Big bullets close to the lands for pressure consistency.

Tomorrow I will back off in .5gr increments and see what I can come up with.

Does anyone have temperature regression data for RL-33?

 

[MontanaRifleman]

Thanks AZShooter and Tumbleweed for a starting point for the 230s.

Results from today's range day.

100gr RL-33 loaded to 3.9 OAL with .008" jump.

3240 fps ES 7

I was seeing extractor marks with this short of a jump compared to .038" and no pressure signs. However, the ES was great. Kirby you nailed it. Big bullets close to the lands for pressure consistency.

Tomorrow I will back off in .5gr increments and see what I can come up with.

Does anyone have temperature regression data for RL-33?

Nice velocity.... what length barrel?

 

[MMERSS]

Nice velocity.... what length barrel?

30"

 

[Fiftydriver]

Thanks AZShooter and Tumbleweed for a starting point for the 230s.

Results from today's range day.

100gr RL-33 loaded to 3.9 OAL with .008" jump.

3240 fps ES 7

I was seeing extractor marks with this short of a jump compared to .038" and no pressure signs. However, the ES was great. Kirby you nailed it. Big bullets close to the lands for pressure consistency.

Tomorrow I will back off in .5gr increments and see what I can come up with.

Does anyone have temperature regression data for RL-33?

I have only done a very limited amount of testing in different temps and that was with my 7mm Allen Magnum with the 180 gr Berger VLD. This was before I had figured out that velocity consistency was dramatically effected by jump to the lands and in my old 7mm AM barrel, these bullets were making quite a jump to the lands so my information is likely not all that solid.

Still, I had loaded the 180 gr berger up to around 3330 fps in 60 degree temps. Tested them on different mornings, at 30, 40 and one afternoon at 75 degrees.

On the low end, five shots averaged 3308 fps. On the top end, the average velocity was 3356 fps. So in my mind with a 45 degree temp change with the same load, there was a 48 fps velocity spread. If you had developed your load and drops for around 50 degree, there would only be a +/- 24 fps variation for a temp range from 30 to 75 degrees at least for temp change alone.

Now, keep in mind, these results were average velocity levels but the extreme spread of these 5 shot groups ranged from 45 to 80 fps so how much stock I would put on these results is not a great amount but it did show a trend.

Need to test now that I know better how to load this powder and should be able to get more accurate and usible test numbers.

 

[MMERSS]

Need to test now that I know better how to load this powder and should be able to get more accurate and usible test numbers.

Thanks Kirby for your tests. They are full of great info. I believe I am close with the RUM for final load development and at a respectable MV increase over Retumbo. Sub 1/2 MOA precision as with Retumbo TBD.The next few days will tell.

Temperature regression will be on the radar after final tune. If your initial data holds correct, an increase of approximately 1 fps/deg is worth taking note.

 

[MMERSS]

Conducted RL-33 tests today with jump to lands of .008" and .016".

.008"
99gr MV 3215 ES 10
99.5gr MV 3236 ES 11

.016"
99gr MV 3199 ES 25
99.5gr MV 3230 ES 36

Grouping was best with the .008" jump. My next load will be 99.2gr at .007" for MV and group comparison.

Kirby pointed out a pattern with the AX and RL-33. This same pattern seems to be holding for the 300 RUM. The closer the bullet is loaded to the lands the lower the ES.

 

[Fiftydriver]

Conducted RL-33 tests today with jump to lands of .008" and .016".

.008"
99gr MV 3215 ES 10
99.5gr MV 3236 ES 11

.016"
99gr MV 3199 ES 25
99.5gr MV 3230 ES 36

Grouping was best with the .008" jump. My next load will be 99.2gr at .007" for MV and group comparison.

Kirby pointed out a pattern with the AX and RL-33. This same pattern seems to be holding for the 300 RUM. The closer the bullet is loaded to the lands the lower the ES.

Have you tried just kissing the lands yet? If you do, drop your load a couple grains and work back up. Seems to produce the sharpest pressure spike seated just to kiss the lands. With the load developed for this seating position, perfectly safe but can jump pressures noticeably if you do not reduce loads and work back up.

The sharper pressure curve seems to be what RL33 really likes and the more data we are getting seems to be supporting this more and more. I think we are starting to figure this powder out guys, great testing and good data!!

 

[MMERSS]

Have you tried just kissing the lands yet?

I will throw in 3 rounds at 97.5 with no jump.

 

[MT4XFore]

I went out yesterday to test my AX as well. The first load I tested was with the 300 Berger OTM. I used 106gr. of RL33 as that load showed 3006fps out at Kirbys. Now my AX has a 27" barrel and a standard chamber. My first shot yesterday clocked at 3040fps. Difference is his velocity and mine probably due to different chronys. Temp yesterday was 47*. I shot a five shot group, but when I went to retrieve the info to put down in my log book, I accidentally hit the "forget" button rather than the "fv" button. I am such a dummy sometimes!! I think I remember a 3017 and a 3063 as well, but I'm not sure. What I am sure about is the 200yd. group it shot. Four of the shots had two touching and two right beside them inside 3/4". The "flier" opened up the group to 1". No signs of pressure whatsoever!

Next I shot 5 shots with the 250gr. Berger OTM and 114.5gr. of RL33 using Lapau brass.. I made sure NOT to press the forget button this time and my results were:
Av Vel = 3342
Hi Vel = 3363
Lo Vel = 3331
es = 31.47
sd = 12.20
No pressure signs here either. Primers still nice and rounded with no sharp protrusions and easy extraction.

Next I shot 5 more shots with the 250, this time using HSM(Bertram) brass and the same powder charge:
Av. Vel = 3346
Hi Vel = 3365
Lo Vel = 3331
es = 34.26
sd = 12.44
As you can see, they were almost identical. However where the difference showed up was in the pressure signs. The HSM brass had flattened primers and were extremely hard to extract. I didn't need a mallet to open the bolt, but the heel of my hand was sore. LOL A perfect example of the quality of Lapua brass, as if ya already didn't know.

The groups with these two loads were not good. It's obvious to me that I am going to need to seat to the lands and reduce my loads a bit. So, more testing to come. I will tell y'all more as it happens.

Jim

 

[MMERSS]

I shot three loads at 300 today.

.010" 98.5gr 3189 ES 36
.010" 97.5gr 3169 ES 23
.000" 97.5gr 3180 ES 15

97.5gr groups showed most promise just at 1.7" each with some changing winds. Both these groups showed approximately 1" vertical.

Again ES showed lowest values with seating closest and in this case on the lands.

RL-33 is showing an estimated velocity increase of 170 fps over Retumbo with the same MOA potential.

 

[Fiftydriver]

I shot three loads at 300 today.

.010" 98.5gr 3189 ES 36
.010" 97.5gr 3169 ES 23
.000" 97.5gr 3180 ES 15

97.5gr groups showed most promise just at 1.7" each with some changing winds. Both these groups showed approximately 1" vertical.

Again ES showed lowest values with seating closest and in this case on the lands.

RL-33 is showing an estimated velocity increase of 170 fps over Retumbo with the same MOA potential.

We are really developing a personality for RL33 and so far it seems to be very predictable with the results.

As with all powders, it may come down to a compromise with seating depth off the lands for velocity spread control but also finding the right spot for best accuracy. In my experience and I am sure in pretty much everyone elses as well, that often times, the very lowest ES numbers does not nessesarily mean that that load will be the most accurate. Often they are but just as often they are not.

This next comment is not directed toward your rifle or tests in any way, just a general comment for other members. Sometimes, especially in factory rifles chambered in large magnums, if you seat the bullets to contact the lands, you will get some group stringing. In my testing, this has been a result of bolt preload.

Bolt preload, especially in an out of box factory rifle can cause noticeable and measureable stringing in groups. This is generally a result of inconsistent bolt lug contact to the receiver bolt lugs support or simply an unsquare situation as a result of machining in the total receiver. GENERALLY, uneven bolt lug contact will result in vertical stringing. Unsquare condition in the receiver can result instringing in pretty much any direction.

Anyway, back to what can cause bolt preload. There are three major things that cause this.

1. Bullet contacting the lands of the rifling which puts pressure against the bolt head when the bolt is closed causing bolt preload.

2. Cases that are tight in the chamber, when the bolt is closed on a case that contacts the should or the chamber solidly, again, there is pressure on the bolt head when the bolt is closed.

3. Foreign matter between the bolt nose and the barrel breach can also cause bolt preload and serious accuracy issues.

Again, these three issues are seen mostly with factory rifles. WITH custom receivers and rifles, generally things are much more finely machined so bolt load does not cause as much of an issue.

Now why does bolt preload cause stringing, well, simply put, it will create inconsistent vibration patterns in the bolt, receiver and often barrel, the larger the diameter of the case head, the more dramatic it can be as seen on target.

This is why I have always said to build a rifle in a 223 that shoots well under 1/2 moa is EASY, to do the same thing in a 338 Lapua is MUCH more challenging. Not hard, anyone can do it, just more attention to detail is needed whereas with the small diameter 223, you can get away with ALOT more because the bolt thrust generated by the very small case head is extremely small and often times, even a bolt with only one bolt lug supporting the case will still shoot very well because the 223 does not have enough bolt thrust to compress the bolt to the point where it flexes enough that the floating lug I forced to contact its support surface.

In a 300 RUM however, or example, again, not referring to your rifle, just in general, if there is a floating bolt lug, even moderate pressure loads will produce enough bolt thrust to flex the bolt head until it contacts the bolt lug supports. This will result in inconsistent vibration patterns in the rifle system and as a result, generally stringing on target.

Again, its often a compromise and balance to find the best seating positon for lowest extreme spreads possible yet also the best accuracy and consistency on target with the best shaped groups.

I have said it a million times, any ES under 30 fps will be extremely useful for long range hunting even out to 1000 yards and beyond as long as the load shoots consistently and accurately in the rifle used. Obviously if you can get the accuracy with very low extreme spreads, best of both worlds but sometimes we get caught up in that magical single digit ES load but forget to pay more attention to the groups we are seeing downrange.

Again, just general comments, not directed toward anyone or anything in this thread, just spewing what I have seen in my playing with different loads and rifles.