6.5 Creedmoor/RPR Load questions

[PatMiles]

Bought a Ruger Precision Rifle in 6.5 Creedmoor to shoot longer distances for fun. Shot it for a while and then put a 26" PVA barrel on it, can't leave well enough alone. The barrel was chambered to SAMMI specs per Josh. I started load development with Berger 140 Hybrids and the gun likes having the bullets .040" off the lands @ 2.1750" CBTO. Using Lapua brass with Federal 205M primers I loaded a half dozen of the following with Hodgdon H-4350. All loads weighed on a A&D FX120i scale.
40.3 gr
40.5 gr
40.7 gr
40.9 gr
41.1 gr
I wanted to find a load that would give me a velocity of 2750 fps or close to it.
I fired one of the 41.1 BB's which read 2750 on my MagnetoSpeed chrono...COOL! Then I tried to open the bolt, NOT! Had to use a plastic mallet and whack it HARD 2 or 3 times. I immediately dialed it back to the 40.5 gr load (2673 fps) which also needed a bit of persuasion by the aforementioned mallet. Needless to say, the day ended after only two rounds going down range.
Later that night I loaded some once fired Hornady large primer (Fed 210M) brass. One each with 40.3, 40.5, 40.7, 40.9 & 41.1 grains of H-4350. Neck tension was set at .002", bullets seated @ 2.1750". Only difference was brass and primers. The results are as follows,
40.3 gr chrono error, easy, smooth bolt lift and opening.
40.5 gr, 2710 fps, easy, smooth bolt lift and opening.
40.7 gr, 2743 fps, easy, smooth bolt lift and opening.
40.9 gr, 2758 fps, easy bolt lift with just a hint of hesitation on opening
41.1 gr, 2769 fps, easy bolt lift with a hint of hesitation on opening.

I realize there will be some difference in case capacity between the Lapua and Hornady brass but what might be the reason for extremes in bolt opening?
Thoughts?

 

[MSS]

Pressure? I noticed this recently as well and plugged them both into quickload. The higher case volume of the hornady equates to lower pressure. The lapua runs about 3000 psi higher for like charge weights according to QL. This is like running the lapua with a .7 or so higher charge. All this is from 4451 as powder but I imagine it’s similar for all powders.

 

[PatMiles]

Pressure? I noticed this recently as well and plugged them both into quickload. The higher case volume of the hornady equates to lower pressure. The lapua runs about 3000 psi higher for like charge weights according to QL. This is like running the lapua with a .7 or so higher charge. All this is from 4451 as powder but I imagine it’s similar for all powders.

I figured pressure was involved given the over expansion of the Lapua brass. I also thought that pressure and velocity were related but I guess not. Needless to say, I have a lot to learn. I'll check H2O case capacity on both the Lapua and Hornady brass.

 

[Zero333]

Check neck diameter of fired brass to make sure you have more than 0.0015" clearance all around, aka 0.003" difference from loaded to fired brass.

Polish the chamber a little. I polished the chamber of a Savage rifle years ago and it did the trick.

 

[MSS]

My Hornady is 53.27. Lapua 52.23. This was an average of 10 cases each. The Hornady cases had more weight variation swings so I culled out any wild ones to use later as foulers. Pressure and velocity have a relation but keep in mind this is not a like to like comparison. All things being equal pressure should track with charge weight and in turn, velocity. Every time I think finally get it, I learn something new. Guess that’s part of the fun.

 

[MSS]

As usual use at your own risk. Start 10% lower and work up. I set OAL to SAAMI so your results will be slightly different. You also have a hotter lot than the default so I adjusted the burn rate a bit.

Hornady Brass

Cartridge : 6.5 Creedmoor Hornady
Bullet : .264, 140, Berger VLD Hy Tgt #26414
Useable Case Capaci: 46.875 grain H2O = 3.044 cm³
Cartridge O.A.L. L6: 2.825 inch = 71.76 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : Hodgdon H4350 ?

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.723% 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

-07.2 91 38.50 2586 2079 43831 8036 98.9 1.448
-06.5 92 38.80 2604 2108 44803 8083 99.0 1.434
-05.8 92 39.10 2622 2138 45795 8129 99.2 1.420
-05.1 93 39.40 2641 2167 46809 8173 99.3 1.406
-04.3 94 39.70 2659 2197 47847 8216 99.4 1.393
-03.6 95 40.00 2677 2227 48907 8258 99.5 1.379
-02.9 95 40.30 2695 2257 49991 8297 99.6 1.366
-02.2 96 40.60 2712 2287 51101 8335 99.7 1.353
-01.4 97 40.90 2730 2317 52235 8371 99.8 1.340
-00.7 97 41.20 2748 2348 53395 8405 99.9 1.327
+00.0 98 41.50 2766 2378 54581 8438 99.9 1.314 ! Near Maximum !
+00.7 99 41.80 2783 2408 55794 8469 100.0 1.302 ! Near Maximum !
+01.4 100 42.10 2801 2439 57036 8498 100.0 1.289 ! Near Maximum !
+02.2 100 42.40 2819 2470 58302 8525 100.0 1.277 ! Near Maximum !
+02.9 101 42.70 2836 2500 59605 8551 100.0 1.265 ! Near Maximum !
+03.6 102 43.00 2853 2531 60938 8575 100.0 1.253 ! Near Maximum !

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 98 41.50 2821 2473 59791 8254 100.0 1.268 ! Near Maximum !
Data for burning rate decreased by 5% relative to nominal value:
-Ba 98 41.50 2699 2264 49568 8532 98.9 1.367


Lapua Brass

Cartridge : 6.5 Creedmoor Hornady
Bullet : .264, 140, Berger VLD Hy Tgt #26414
Useable Case Capaci: 45.835 grain H2O = 2.976 cm³
Cartridge O.A.L. L6: 2.825 inch = 71.76 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : Hodgdon H4350 ?

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.723% 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

-07.2 93 38.50 2609 2116 45641 8004 99.1 1.421
-06.5 94 38.80 2627 2146 46672 8049 99.2 1.407
-05.8 95 39.10 2646 2176 47726 8093 99.3 1.393
-05.1 95 39.40 2664 2206 48804 8135 99.4 1.379
-04.3 96 39.70 2682 2236 49908 8175 99.6 1.365
-03.6 97 40.00 2700 2267 51037 8214 99.7 1.352
-02.9 97 40.30 2718 2297 52192 8251 99.7 1.339
-02.2 98 40.60 2737 2328 53375 8286 99.8 1.326
-01.4 99 40.90 2755 2359 54586 8319 99.9 1.313 ! Near Maximum !
-00.7 100 41.20 2773 2390 55825 8351 99.9 1.300 ! Near Maximum !
+00.0 100 41.50 2791 2421 57091 8381 100.0 1.288 ! Near Maximum !
+00.7 101 41.80 2808 2452 58392 8409 100.0 1.275 ! Near Maximum !
+01.4 102 42.10 2826 2483 59721 8435 100.0 1.263 ! Near Maximum !
+02.2 103 42.40 2844 2514 61082 8459 100.0 1.251 ! Near Maximum !
+02.9 103 42.70 2862 2546 62477 8483 100.0 1.239 !DANGEROUS LOAD-DO NOT USE!
+03.6 104 43.00 2879 2577 63906 8506 100.0 1.227 !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 100 41.50 2845 2515 62570 8192 100.0 1.243 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba 100 41.50 2724 2307 51829 8492 99.0 1.339

 

[dsinfour]

When I was using Hornady brass with 140 grain pills I was using 42.0 grains of H4350 and when I went to laupla brass I had to cut the charge back by one whole grain to 41.0 grain that was in a 30 inch tube.. Don't try the same load in different brass.. You know the drill start low and watch for pressure and keep them all in the center..

 

[PatMiles]

MSS,
Thank you for the work up sir! Great information.

 

[PatMiles]

dsinfour,
Yes sir, I know the drill.
According to Berger's book the minimum powder charge is 36.5 grains of H-4350 while the max is 40.7. I started at 40.5 and ran into HARD bolt opening, mallet, immediately. Berger tested with a 24" barrel while mine is a 26". Berger calls out a 2.800" OAL while mine is 2.875". I didn't think I was that far out of line but it is what it is.
Thanks for the reply!

 

[Jackal2016]

dsinfour,
Yes sir, I know the drill.
According to Berger's book the minimum powder charge is 36.5 grains of H-4350 while the max is 40.7. I started at 40.5 and ran into HARD bolt opening, mallet, immediately. Berger tested with a 24" barrel while mine is a 26". Berger calls out a 2.800" OAL while mine is 2.875". I didn't think I was that far out of line but it is what it is.
Thanks for the reply!

Keep in mind that the Berger book doesn't include which brand of brass it used to develop those charts. With your results with the Lapua brass, I think it's a safe bet that it wasn't done with the Lapua brass. I'd hazard a guess that it was done with Hornady brass.

 

[PatMiles]

Jackal,
That's the missing link in the Berger book.

 

[MSS]

MSS,
Thank you for the work up sir! Great information.

Anytime. Enjoy!

 

[PatMiles]

Anytime. Enjoy!

Was the above info worked up with Quickload?

 

[MSS]

Yes.

 

[PatMiles]

Ordering Quickload, where to find useable case capacity for various brands of brass?
TIA

 

[MSS]

You will want to fill them with water and test yourself because it can vary slightly based on your chamber. I followed this guide:

http://www.the-long-family.com/Tuning QL to achieve best results.pdf

 

[PatMiles]

Thank you sir.

 

[MSS]

I really like Quickload. I just got it myself and it has really helped me dial in loads.

 

[PatMiles]

Check neck diameter of fired brass to make sure you have more than 0.0015" clearance all around, aka 0.003" difference from loaded to fired brass.

Polish the chamber a little. I polished the chamber of a Savage rifle years ago and it did the trick.

Zero,
Polishing the chamber did the trick! I shot the rounds that I didn't shoot when I ran into the HARD bolt opening which were 40.7, 40.9 & 41.1 grains of H-4350. The bolt opened and extracted the brass easily, no hesitation at all.
Only four rounds of each chronographed but the ES results were:
40.7 gr ES=4
40.9 gr ES=7
41.1 gr ES=6

 

[Zero333]

Zero,
Polishing the chamber did the trick! I shot the rounds that I didn't shoot when I ran into the HARD bolt opening which were 40.7, 40.9 & 41.1 grains of H-4350. The bolt opened and extracted the brass easily, no hesitation at all.
Only four rounds of each chronographed but the ES results were:
40.7 gr ES=4
40.9 gr ES=7
41.1 gr ES=6

I'm happy things worked out. It kinda hard to explain how to polish a chamber, so I thought if you can figure out how then you'll be fine.
I used a piece of felt (1/4" diameter) screwed the felt on a screw and the screw was welded to a rod and the rod was on a cordless. Then I put polishing compound on the felt.
I can imagine many other ways of doing this.