300 Weatherby QL Request and Node inquiry, Part 2

[Dr. Vette]

Part 1 was here:
https://forum.nosler.com/viewtopic.php?f=4&t=31582

Weatherby cases, capacity 103.9gr water
MRP powder
Fed 215M primers
Barnes 200 LRX bullet
3.665 COAL though I have them at 3.000 base to ogive when loading them.
Mark V, 26 inch barrel plus muzzle brake (Accubrake)

I chose MRP for this trial since I was not please with 7828SSC accuracy. And, RL-22 is listed as the "most accurate" powder for the 200gr/300Wby combination by Nosler. Since MRP is supposed to be "better" RL-22. I thought it was worth a try.

Some load data suggests I may be able to try a bit more powder. I'd love to know how close I might be to a node if QL suggests one with this combination.

Shooting Chrony at about 15 ft from the muzzle:

79.0: 2972, 2923, 2991
79.5: 3028, 3020, 3014
80.0: 3002, 3018, ?
80.5: 3070, 3060, 3063
81.0: 3057, 3085, 3056
81.5: 3081, 3085, 3077

Almost every group was a "two close and 1 far away" pattern, suggesting I may need to adjust COAL a bit shorter as well. Both Nosler and Barnes list 0.100 shorter for COAL with a 200 grain bullet.

All suggestions welcome.

 

[SJB358]

Just me, but I see spots that seem like its flattened.

79.5 and 80

Then 80.5 and 81

If it were me, I'd load the center of those two spots. Shorten the OAL to what Barnes suggests. Honestly from 79.5 to 81 isn't a large jump wither, so I'd probably load the center of that well. I'd bet in 9 rounds you'd see what you're going to get.

 

[Dwh7271]

I'd be surprised if you shorten them as Scotty mentioned and stuck 80.7 gr in there if you wouldn't find something pretty good. JMO though.

 

[Dr. Vette]

Thanks guys.
I'm trying to prepare for when the reloading room here in the new house is up-and-running. We have an elk hunt in early October, and I'm trying to press our builder to get my cabinets in. Perhaps tomorrow?

Anyone have a copy of QL by chance who can see if predicted and actual match enough to point out a node?

I need to buy my own copy, but no internet here (using phone as a hot spot) and, as noted, reloading room is not yet together.

Patrick

 

[Dwh7271]

I'll be glad to run it when I get home.
If I'm not mistaken, you have one at 80.7 or so which is why I suggested that. :grin:

 

[Dwh7271]

Cartridge          : .300 Weath. Mag.
Bullet             : .308, 200, Barnes 'LRX' BT 30374
Useable Case Capaci: 89.822 grain H2O = 5.832 cm³
Cartridge O.A.L. L6: 3.665 inch = 93.09 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : Norma MRP

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.629% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-06.3   86    74.50   2852    3613   50269  11966    100.0    1.415
-05.7   87    75.00   2870    3657   51244  12011    100.0    1.404
-05.0   87    75.50   2887    3702   52237  12054    100.0    1.392
-04.4   88    76.00   2905    3747   53250  12096    100.0    1.380
-03.8   89    76.50   2922    3791   54282  12136    100.0    1.367  ! Near Maximum !
-03.1   89    77.00   2939    3836   55335  12176    100.0    1.355  ! Near Maximum !
-02.5   90    77.50   2956    3881   56407  12215    100.0    1.343  ! Near Maximum !
-01.9   90    78.00   2973    3927   57501  12255    100.0    1.331  ! Near Maximum !
-01.3   91    78.50   2991    3972   58616  12294    100.0    1.319  ! Near Maximum !
-00.6   91    79.00   3008    4017   59753  12332    100.0    1.308  ! Near Maximum !
+00.0   92    79.50   3025    4063   60911  12371    100.0    1.296  ! Near Maximum !
+00.6   93    80.00   3042    4108   62093  12409    100.0    1.285  ! Near Maximum !
+01.3   93    80.50   3058    4154   63298  12447    100.0    1.273  !DANGEROUS LOAD-DO NOT USE!
+01.9   94    81.00   3075    4200   64527  12484    100.0    1.262  !DANGEROUS LOAD-DO NOT USE!
+02.5   94    81.50   3092    4246   65779  12521    100.0    1.251  !DANGEROUS LOAD-DO NOT USE!
+03.1   95    82.00   3109    4292   67057  12558    100.0    1.240  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba     92    79.50   3084    4225   66974  12140    100.0    1.245  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba     92    79.50   2950    3866   54893  12634     99.9    1.355  ! Near Maximum !

 

[Dwh7271]

OBT Nodes

	1			2		3			4			5
	0.882		0.966		1.106		1.191		1.329


                  6                      7
		1.415		1.553

 

[Dr. Vette]

OK, so if I'm reading it right that puts nodes at 74.5 and 78.0?

 

[SJB358]

OK, so if I'm reading it right that puts nodes at 74.5 and 78.0?

That's what I saw as well.

I'd try the 80.7 load though.

 

[Dr. Vette]

Hmm. Interesting.

I'm going to do some COAL tweaking first; might even do it at 80.7 just to see what happens.

 

[Dr. Vette]

Update:

Shorter COAL is not where it's at. I shortened down to 3.550 COAL as suggested by Barnes and Nosler, had speed bump by 40-50 fps and group size went to almost 5 inches for 3 shots at 100 yards. See attached target.

80.7gr of MRP, speeds were 3096, 3116, and 3107. Those are quite a jump from the 3060-3070 of 80.5 listed above.

I also tried 81.5gr of MRP since I had some good accuracy there last time. This too was at the shorter COAL. Speed was 3125 but VERY stiff bolt. Needless to say I didn't shoot the other 2 of this load I had made.

So, next question is -
Do I stay short COAL and re-shoot a ladder/OCW test at the new length? Or try and play with the longer COAL and original data?

Thanks for any suggestions.

 

[SJB358]

How did they shoot at Mag length?

 

[Nimrod84]

Dr. Vette,

I'm sure others much more knowledgeable then me will chime in.

Your higher velocity than anticipated with the 80.7 charge might be due to chronograph-itus - lighting conditions, low battery power or some other issue with the chronograph.

Personally I would retry the 80.7 MRP load at a little under your initial COAL like 3.66 and 3.655. I recently had some really good loads out my 280 Rem using 160 Accubonds with RL 22 which tightened right up with a small decrease in length. Additionally during testing there was a very noticeable 50 fps difference when the clouds & shadows showed up.

Good luck and shoot straight.

 

[FOTIS]

OBT Nodes

	1			2		3			4			5
	0.882		0.966		1.106		1.191		1.329


                  6                      7
		1.415		1.553

ok you lost me

where did you get this and what does it mean?

 

[Dwh7271]

It's from the OBT (Optimum Barrel Time) concept from Chris Long.
It's an excel spreadsheet, that didn't paste very well, that is linked to on his website.
Here's the info and the paper:
http://www.the-long-family.com/optimal barrel time.htm

FWIW, I like finding the flat spots with the MagnetoSpeed better. Faster and takes a bunch less shooting.

 

[FOTIS]

Thank you!

 

[Dr. Vette]

Dr. Vette,

I'm sure others much more knowledgeable then me will chime in.

Your higher velocity than anticipated with the 80.7 charge might be due to chronograph-itus - lighting conditions, low battery power or some other issue with the chronograph.

Personally I would retry the 80.7 MRP load at a little under your initial COAL like 3.66 and 3.655. I recently had some really good loads out my 280 Rem using 160 Accubonds with RL 22 which tightened right up with a small decrease in length. Additionally during testing there was a very noticeable 50 fps difference when the clouds & shadows showed up.

Good luck and shoot straight.

We started with a foggy morning. I know what you mean about speed, as I saw another rifle "gain" some speed once the fog burned off. 3006, 3009, 3007... then 3021, 3028. I knew what happened on that one.

I believe it was still foggy when checking the load. Does shorter COAL increase speed? Just might in this case...

I'm also going to recheck how long I can load them, but I think that I was initially as long as I could get and easily feed them through.

Hopefully Monday we can test again. I will also recheck targets from last year.

 

[Nimrod84]

Dr. Vette,

If I'm wrong some-one with more knowledge will be along to correct & educate me! Also the post grew on me and I really need to get some work done - so I apologize about not taking the time to trim the post.

I'm not sure on the shorter COAL increasing speed... I'm sure it could change the powder burn rate, increase pressure if the bullet was seated deep enough and gives a running start to the bullet so I would consider it a possibility.

The standard view with a large capacity rifle case is that you start close to lands - find your max powder charge - then you can safely work with shorter COAL's. Shorter COAL's mean the bullet has a longer free-bore to the lands, which means more time before the bullet and barrel seal (so you get gas blowing by the bullet) and thus additional time before the powder hits it optimal burn rate and the pressure increases. At some point bullets start going too deep into the case (pistol cases and small capacity rifle cartridges like the 5.56 / 223 are very susceptible to this) and the pressure increases & can spike to dangerous levels due to the powder burn rate changing, lack of airspace and other things I know little about.

I had missed this yesterday but your 81.5 grain load velocity increased by 40-50 fps as well and had a "VERY stiff bolt". So I think the loads did in fact have a higher velocity and pressure; I can't hazard a guess as to if it was from the weather, from the shorter COAL or something else that changed.

2nd post at viewtopic.php?f=4&t=35890 shows the grouping potential of small COAL adjustments which I what I recommended earlier.

However, as your velocity was increased (and you mentioned wanting a hotter load) I might look at splitting the COAL difference and try some loads at 3.63-3.62 COAL and 3.59-3.58 COAL to see if there are velocity differences along with any magical changes in groups per Barnes. viewtopic.php?f=4&t=20874 - TXbaldhunter posted the Barnes approach and DrMike of course has good insight into COAL and Monolithic bullets and starting them around 0.1 COAL off of the lands to start with.

I hope things are progressing smoothly with your housing project.

 

[kraky1]

Fwiw It's Not Unusual in my weatherby's to see the bullets gain velocity as they are seated deeper. I believe the difference is in the freebore throat of most weatherby's.... It's not the same situation as most throats in normal rifles. The Weatherby throat already gives you a run to the rifling with normal bullet length and by going shorter you are decreasing case capacity and not getting any help from the extra run at the rifling.
I played around a quite a bit with quick load and the OBT / barrel length idea and at first I thought it was valid and now I'm not so sure...actually doubt full.
Some of those lrx bullets need a tighter twist I'm not sure how you're twisted or what they recommend.
I have had excellent luck getting the 168 Barnes to shoot in almost every 308 caliber gun I have including the 300 weatherby..... it is all the bullet even the speed of a 300 Weatherby needs.

 

[kraky1]

And here's a crazy tip given to me by a guy that shoots alot of Barnes. Start load development by seating the bullet so that the top 1/3 of the top groove is exposed from the case mouth......this if it gives a reasonable jump to rifling...it has in most my rifles. Then work back or forward from there. I don't know why but I found good luck using the idea. My only guess is this would be very close to where factories would seat the bullet for factory ammo and perhaps Barnes knows where to put that Groove for the best overall accuracy?