Home Forums Reloading Big Game Rifles MRC 260 1-8, R17, Nosler 142gr. ABLR

Here is what I'm getting and a pic of the primers. What do you all think pressure and speed wise?

The top end might get a little sporty when it warms up. That's humming right along.

Les, this is what the QL looks like. While not perfectly tuned to your load, it may give you an idea where you are at. Your primers look fine to me, but then again, I have seen good primers and still be fairly hot.

Cartridge : .260 Rem
Bullet : .264, 142, Nosler AccuBond LR 58922 G7
Useable Case Capaci: 44.649 grain H2O = 2.899 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Alliant Reloder-17

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.177% 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 87 37.50 2559 2064 42954 8945 99.9 1.393
-10.6 88 38.00 2590 2115 44669 9014 100.0 1.368
-09.4 89 38.50 2622 2167 46445 9075 100.0 1.344
-08.2 90 39.00 2653 2219 48295 9131 100.0 1.321
-07.1 91 39.50 2684 2272 50221 9184 100.0 1.298
-05.9 93 40.00 2715 2324 52230 9237 100.0 1.275
-04.7 94 40.50 2746 2377 54324 9289 100.0 1.253
-03.5 95 41.00 2776 2430 56506 9340 100.0 1.232 ! Near Maximum !
-02.4 96 41.50 2807 2483 58783 9390 100.0 1.211 ! Near Maximum !
-01.2 97 42.00 2837 2537 61159 9439 100.0 1.190 ! Near Maximum !
+00.0 98 42.50 2867 2591 63640 9487 100.0 1.170 ! Near Maximum !
+01.2 100 43.00 2897 2645 66231 9534 100.0 1.151 !DANGEROUS LOAD-DO NOT USE!
+02.4 101 43.50 2926 2700 68940 9579 100.0 1.131 !DANGEROUS LOAD-DO NOT USE!
+03.5 102 44.00 2956 2755 71768 9624 100.0 1.113 !DANGEROUS LOAD-DO NOT USE!
+04.7 103 44.50 2986 2810 74728 9667 100.0 1.094 !DANGEROUS LOAD-DO NOT USE!
+05.9 104 45.00 3015 2866 77823 9709 100.0 1.076 !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 98 42.50 2959 2760 77654 9128 100.0 1.090 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 98 42.50 2724 2340 51253 9945 99.5 1.278

Here is what someone on the Nosler forum came up with my specs.
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 !

What is the OAL and are you loading into the lands?

What was the ambient temperature for the test?

Les that seems a little hot...I run IMR 4350, 44 grains and am getting in the 2750 fps neighborhood...

this is using a Ruger 260 Stainless, 22 inch barrel, 1 in 8 twist.

Alliant's pressure-tested data for 17 in the 260 shows it as running slower than 19, 22, and 23. That was with a different bullet (Speer Hot Core), so the speed itself may not be the same (41 grains max at 2650-ish), but that at least suggests that several of your charges are over-pressure. Unless your OAL is unusually long, if it was me I'd stay below about the mid range of the charges you loaded.

43 gr looks fine to me. What type of expansion are you getting on the case from resized to 40gr to 43gr. Quick load has built in safety margins so without all data input from your batch of brass etc it can be overly scary looking.

Oal is 2.91" into the lands .01"
Temp of ammo and rifle were around 70

I own two .260's, a NULA and a GA Precision, both have 22" barrels. Both are very accurate up to around 2,900 fps with 120's and 2650-2700 fps with 140's. Anything faster and my accuracy starts to noticeably degrade. There may be some new powders that will safely give more velocity, but I'm happy with the above limits.

I have made some minor adjustments in QL that have closed the gap between the predicted and actual velocity with my 6x47 (weighting factor and start initiation pressure) and applied the same to your load. I was running your load with the initial data you provided and didn't want to post until I had the information above, QL predicts 2844 with 42.2 grains at 60.4K.

QL predicts 2914 with 43.3 grains at 66K, your loads are likely over pressure even though the primers do not appear to be flat in the photo.

There are other QL data fields that were not updated for your load including actual case capacity and bullet dimensions.

Morning Cuz.
When I pick up this 260 I thought about you. I loaded up 34.5grs. R15 under a 129gr. IL and had a solid moa load clocking 2520 and lays them in there cold and clean or hot and dirty.

Les,

In my experience, the only one of the three factors you've listed for "rating" (I wouldn't say measuring) the pressure in your rifle that has any validity is the muzzle velocity.

QuickLoad pressures are the least reliable of any of its predictions, and primer appearance is absolutely unreliable--unless you blow one. That's definitely indicative of high pressures.

Explain "what" data you can validate the velocity of these loads against, that is better than QL.

RDW,

I've posted about this before, but QuickLoad is a computer simulation, not reality. Even the best computer simulations are not the same as actual results--the reason even QL's directions suggest using actual pressure-tested data whenever possible, though many people apparently ignore that fine print.

The only "hard" data in this instance is the muzzle velocity, since it's the only measured number. If the velocity of a given load exceeds the velocity of pressure-tested data for the same powder and a similar bullet, then the odds are considerable the load is exceeding standard pressure levels. It's that simple.

I've been using QL for many years, and while it continues to improve, I still often run into loads that OBVIOUSLY exceed the pressure predicted by QL--and when that happens, the velocity is also high.
But have yet to run into obvious pressure problems when loading to QL's predicted safe-level muzzle velocities.

I'm on my 6th load only neck sizing and they are still chambering as easy as ever and the primer pockets are still nice and tight. I'll take some brass to work tonight and get some actual numbers.

My experience with QL for several years matches very closely with Mule Deer's. It is a very interesting and fun program to fiddle with, but its pressure predictions are sometimes way off.

Sounds good to me. Most brass will start showing high pressure after a few loads over a certain pressure point. Primer pockets is where I usually see high pressure. If I work up a load for my 7mm rem mag for example and after 3 loadings the primer pockets are still tight on most of that batch of brass. I feel safe shooting that load. I use book loads from multiple sources. But where I normally feel the safest is with Lyman data. I go as far as loading exactly to what it says if it has the bullet I want to use. Using the old measurement style for pressure with brass expansion. Still gives a person an idea where they are. Look at primers, Measure brass for expansion, primer pocket life, scrubbing from bolt on extraction,, ejector or bolt face marks on brass, is trimming required too often. All put together give a picture of the pressure you are getting from a load. 6 loadings and tight primer pockets tell me it is not an overly high pressure load. Could be 60K PSI but I would guess less than 60K. If you are getting easy extraction. I would run them.

I get that, QL is a simulation program and I have only used it for about 6 or 7 years, but not once have I touched off a round and said "oh chit, I don't want to do that again", because I work up to the QL predictions, same as I did the first 20 years using book data. I have found no reason to go back to the books and a dozen reasons to use QL.

The statement below did not answer my question because book velocity does not exist for a 260 running a 142gr Accubond LR at 2.9" in the lands.

QL actually predicts over-pressure with 1gr less powder than indicated in the opening post, and I have consistently found lower velocity than predicted across the board with QL indicating there is a factor of safety in the simulation program.

Sorry for the de-rail Les....it is related to your post in a round about way.

For grins I grabbed my Hornady and Nosler manual and neither include the 6X47L, so I get online and check Hodgdon's data, the only load is using the 105 Scenar, 2.635" OAL, H4350, and the data uses a 30" barrel (real useful for those using 18"-24" barrels.

Hodgdon results 38.4 grains, 3,304fps vs QL 38.4 grains, 3,056fps

I run 105 Amax's in my 6X47L, in the lands, at 2.53" out of a 23" barrel. So how relevant is Hodgdon velocity data to this load?