260 Rem, R17, 142gr. ABLR

[Leslil]

Cartridge : .260 Rem
Bullet : .264, 142, Nosler AccuBond LR 58922
Useable Case Capaci: 46.178 grain H2O = 2.998 cm³
Cartridge O.A.L. L6: 2.910 inch = 73.91 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : Alliant Reloder-17

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% 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

-20.0 75 33.60 2219 1553 30167 9034 96.3 1.553
-18.0 77 34.44 2273 1629 32141 9277 97.2 1.512
-16.0 79 35.28 2326 1706 34240 9504 98.0 1.472
-14.0 81 36.12 2380 1786 36483 9714 98.6 1.433
-12.0 83 36.96 2433 1866 38870 9906 99.1 1.392
-10.0 85 37.80 2486 1948 41416 10078 99.5 1.350
-08.0 87 38.64 2538 2031 44135 10231 99.8 1.310
-06.0 88 39.48 2590 2115 47036 10363 100.0 1.272
-04.0 90 40.32 2641 2200 50136 10474 100.0 1.236
-02.0 92 41.16 2692 2285 53448 10578 100.0 1.200 ! Near Maximum !
+00.0 94 42.00 2743 2372 56993 10678 100.0 1.166 ! Near Maximum !
+02.0 96 42.84 2793 2459 60791 10776 100.0 1.134 !DANGEROUS LOAD-DO NOT USE!
+04.0 98 43.68 2842 2547 64859 10871 100.0 1.102 !DANGEROUS LOAD-DO NOT USE!
+06.0 100 44.52 2891 2636 69227 10963 100.0 1.072 !DANGEROUS LOAD-DO NOT USE!
+08.0 102 45.36 2940 2725 73912 11051 100.0 1.042 !DANGEROUS LOAD-DO NOT USE!
+10.0 103 46.20 2989 2816 78957 11136 100.0 1.014 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 94 42.00 2842 2547 69461 10272 100.0 1.082 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 94 42.00 2590 2115 46011 11021 98.4 1.278


What do you all think? Extraction is effortless, primers look good and no ejector marks. Is 2900 safety doable with R17 and the 142's?

 

[Dwh7271]

It's your rifle and your call.
I think you'll find you're already at higher pressure than QL shows if the numbers to the left of your charge weights are chrono speeds. If you calibrate QL to what you're actually seeing you're probably in the 66-67k range with your top charge already.
Can you reach 2900? Certainly. Should you? That's up to you. Just realize you'll be over 70k when you get there. Although it's done at those levels by others there is a toll on rifle and brass up there. Fwiw, I have no issue with good brass and a good modern action pushing into the 63-64k range above that I try not to go. My solution is another powder /bullet combination or a bigger cartridge.
Again, can you reach 2900 w that combo; yes. Would I do it? Assuredly not.
YMMV.

 

[jimbires]

did you correct your case capacity in quickload ?

 

[Leslil]

I'm not interested in running anywhere near 70k. Period.
I wasn't sure how much being able to seat the bullet out to 2.92 oal would help with speed and pressure. I know there is no free lunch, you can't have one without the other. If I want to go fast I'll grab my Mashburn RIPBob.

Someone on here ran the QL for me so case capacity is probably the default.

 

[Dwh7271]

If you know capacity stick it up here and one of us can fix it up for you.
Good call on the Mashburn. :grin:

 

[jimbires]

I'm not interested in running anywhere near 70k. Period.
I wasn't sure how much being able to seat the bullet out to 2.92 oal would help with speed and pressure. I know there is no free lunch, you can't have one without the other. If I want to go fast I'll grab my Mashburn RIPBob.

Someone on here ran the QL for me so case capacity is probably the default.

the longer COAL will help some . I've found a few default water capacties that were off a bunch, compared to mine . could be different makers brass , chamber size , what ever , but these little differences do add up . bigger water capacity = lower pressure , then we add more powder to get the pressure back up = more velocity .

I like to use 5 pieces of brass . fire them a couple times by necksizing only until they start to get tight in the gun . do not resize or deprime , do nothing . weigh the empty brass , then fill it to the top with water and weigh it again . do not over fill , the water should be level with the brass . the difference is your water capacity .

 

[Leslil]

I'm getting 55.3grs level with the top of the brass.
With my seating depth I was coming up with 48.8grs usable capacity.

 

[Dwh7271]

I saw on the original QL the barrel length was 22"?
That will make a difference on the speed if that is not correct.
I ran this run coordinated with your case capacity, COAL, and speed at 42.5 gr that you saw.
I also used a 65k pressure threshold.

Cartridge          : .260 Rem
Bullet             : .264, 142, Nosler AccuBond LR 58922
Useable Case Capaci: 48.109 grain H2O = 3.124 cm³
Cartridge O.A.L. L6: 2.920 inch = 74.17 mm
Barrel Length      : 22.0 inch = 558.8 mm
Powder             : Alliant Reloder-17 ?

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.176% 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

-11.8   81    37.50   2533    2022   44680   9807    100.0    1.317
-10.6   82    38.00   2561    2069   46391   9881    100.0    1.294
-09.4   83    38.50   2590    2115   48167   9954    100.0    1.272
-08.2   84    39.00   2618    2162   50012  10027    100.0    1.251
-07.1   85    39.50   2647    2209   51922  10098    100.0    1.231
-05.9   86    40.00   2675    2256   53892  10169    100.0    1.210
-04.7   87    40.50   2703    2303   55926  10239    100.0    1.191  ! Near Maximum !
-03.5   88    41.00   2730    2351   58031  10308    100.0    1.171  ! Near Maximum !
-02.4   89    41.50   2758    2398   60210  10375    100.0    1.152  ! Near Maximum !
-01.2   90    42.00   2786    2447   62468  10442    100.0    1.134  ! Near Maximum !
+00.0   91    42.50   2813    2495   64806  10508    100.0    1.116  !DANGEROUS LOAD-DO NOT USE!
+01.2   92    43.00   2840    2543   67229  10573    100.0    1.098  !DANGEROUS LOAD-DO NOT USE!
+02.4   94    43.50   2867    2592   69740  10637    100.0    1.081  !DANGEROUS LOAD-DO NOT USE!
+03.5   95    44.00   2895    2642   72342  10700    100.0    1.064  !DANGEROUS LOAD-DO NOT USE!
+04.7   96    44.50   2921    2691   75039  10762    100.0    1.048  !DANGEROUS LOAD-DO NOT USE!
+05.9   97    45.00   2948    2741   77837  10823    100.0    1.032  !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     91    42.50   2855    2570   71252  10334    100.0    1.077  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba     91    42.50   2761    2403   58336  10719    100.0    1.162  ! Near Maximum !

 

[Leslil]

Thank you. I'll load some at 42 and 42.5 and see what the accuracy looks like.

 

[gerry]

Thank you. I'll load some at 42 and 42.5 and see what the accuracy looks like.

Sounds like a good plan, I think 2750-2800 fps would be a good top speed. You should be able to gt some good accuracy around there.

 

[Leslil]

I have to say that it is a sleek looking round.

 

[gerry]

They certainly do look nice and sleek. I tried the 129 gr ABLR in my 260 a few years back and they shot well seated deep (.110 " off the lands) Another guy I know said they shot well for him close to the lands so experimenting with seating depth would be a good thing to try.

 

[SJB358]

Very nice looking rounds buddy. I saw you posted this on 24HCF as well and saw the same as Dewey did. 2800 seems pretty good for that bullet. If the BC is close to true it should have some amazing reach.

 

[Cleveland48]

Those rounds sure do look sexy! Your making me wanna try some in my Creedmoor!


Sent from my iPhone using Tapatalk

 

[Leslil]

Sorry to leave you all hanging.
After several range trips I settled on 43grs and started on seating depth. In this barrel the ABLR likes to jump. I got to .07" off the lands and decided to take it out to 425. I only had time for 4 rounds before I had to head out of town, but here you go. I sent 3 to the paper and fired a fourth at the plate.

 

[longrangehunter]

I'd like to say one thing about this, and that is you should have started with finding your seating depth first. The reason for that is even the slightest change seating the bullet further into the case will drastically increase the pressure if you're already starting at a max load.

I accidently seated a single round a few thousandths deeper and I saw the velocity go up with RL-17 in my own 260.

I wouldn't just throw caution to the wind if you're still eager to push a 140 gr. bullet out of your 260 to 2900 fps unless you somehow grow the barrel length to 26". Or just use a bigger case like the Mashburn for that matter.

 

[shoots_5]

For what it's worth....Bryan Litz measured the G7 BC of the 142 at 0.293. I would try that number in your ballistics solution and you should be pretty close to what you'll see in real world conditions.