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 Post subject: .280 remington with 150 grain BT running slow
PostPosted: Sat Nov 21, 2020 4:04 pm 

Joined: Fri Dec 08, 2017 7:10 pm
Posts: 2
I have been reloading for a couple years now and recently purchased a labradar to try and get serious about longer range shooting. Finding out that my loads are not as fast as I thought. My gun has a 26 inch bartlein barrel on it and I am struggling to touch the nosler load data with IMR4831. I have found an acceptably accurate load for this deer season but an curious as to the wisdom of exceeding the nosler.com max load of 55 grains of IMR 4831. I don't have quick load so I am stuck with cross referencing as many reloading manuals as I can get my hands on.

For example nosler says 55.0 grains for 2978 fps. My complete reloading manual has IMR 4831 max of 57 grains @2930. And and older IMR published manual from 2004 shows 57.5 grains @ 2990 yielding 51600 CUP. I understand that difference testing platforms result in different outcomes.

Not wanting to get crazy velocities or abuse my brass to the point I can not get more than 2-3 reloads before it is trashed. Just wondering if others have reloaded to the published velocity or just stick to the max load recommended? My gun is getting avg of only 2894 fps with 55 grains of IMR4831 shooting the 150 grain Combined technology BT using winchester LR primers loaded to a length of 3.328 which gives me a jump of approx .038.

Could my labradar be off or is my gun just slow? Thanks for any suggestions.


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 Post subject: Re: .280 remington with 150 grain BT running slow
PostPosted: Sat Nov 21, 2020 4:59 pm 

Joined: Wed Nov 08, 2006 2:49 pm
Posts: 33223
Location: Northern British Columbia
Just a note. I'll post a QL projection with some of your recommended loads for a starter.

Code:
Cartridge          : .280 Rem.
Bullet             : .284, 150, Nosler BalTip 28150
Useable Case Capaci: 60.002 grain H2O = 3.896 cm³
Cartridge O.A.L. L6: 3.330 inch = 84.58 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : IMR 4831

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   98    51.75   2840    2687   50503   9172     99.9    1.319
-09.0   99    52.33   2869    2742   52234   9225     99.9    1.299
-08.0  100    52.90   2898    2797   54023   9273    100.0    1.280
-07.0  101    53.48   2926    2852   55873   9317    100.0    1.261  ! Near Maximum !
-06.0  102    54.05   2954    2907   57787   9358    100.0    1.242  ! Near Maximum !
-05.0  103    54.63   2982    2963   59766   9398    100.0    1.224  ! Near Maximum !
-04.0  104    55.20   3010    3018   61815   9437    100.0    1.206  ! Near Maximum !
-03.0  105    55.78   3038    3074   63935   9476    100.0    1.188  !DANGEROUS LOAD-DO NOT USE!
-02.0  106    56.35   3066    3130   66130   9514    100.0    1.171  !DANGEROUS LOAD-DO NOT USE!
-01.0  107    56.93   3093    3187   68402   9551    100.0    1.154  !DANGEROUS LOAD-DO NOT USE!
+00.0  109    57.50   3121    3243   70756   9587    100.0    1.137  !DANGEROUS LOAD-DO NOT USE!
+01.0  110    58.08   3148    3300   73194   9623    100.0    1.121  !DANGEROUS LOAD-DO NOT USE!
+02.0  111    58.65   3175    3358   75721   9657    100.0    1.104  !DANGEROUS LOAD-DO NOT USE!
+03.0  112    59.23   3202    3415   78341   9691    100.0    1.089  !DANGEROUS LOAD-DO NOT USE!
+04.0  113    59.80   3229    3473   81057   9724    100.0    1.073  !DANGEROUS LOAD-DO NOT USE!
+05.0  114    60.38   3256    3531   83875   9755    100.0    1.058  !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    109    57.50   3215    3442   84541   9231    100.0    1.061  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    109    57.50   2975    2949   57113  10011     99.3    1.241  ! Near Maximum !


Bear in mind that the loads listed in the reputable manuals have been pressure tested. QL is accurate given the input you give it. You will note that up to a charge of 55.2 grains of IMER 4831, pressure is projected to be well within the parameters set (64K psi maximum chamber pressure). I suspect that most of the loading manuals you consult are using either a 22" or a 24" barrel, which means that you need to allow ~25-35 fps for each inch difference, whichever way you go. Another factor to bear in mind is that powder burn rates vary, sometimes dramatically with different lots of powder.

My first .280 (I've owned three) was incredibly slow, never quite matching listed velocities. That condition continued for ~300 rounds down the tube, at which point the rifle began to deliver velocities I anticipated.

The ballisticians at Sierra advised me to cautiously increase the charges until I began to approximate the velocities recorded in the various manuals. It is advise that I've used in other instances with good results. In this instance, however, I chose to polish the barrel with JB non-embedding bore cleaning compound. Several judicious applications of this remedy upped my velocity significantly. Eventually, it was simply time and multiple bullets down the barrel that finally lapped the barrel enough to attain the velocities I anticipated.

In the interim, though I was sending bullets downrange at a greater reduced velocity, deer kept dropping each time I pulled the trigger. Velocities are up where I want them to be now, and I must say that the deer don't die any quicker now than they did when hit with lower velocity bullets. And I haven't noticed that they are any deader.

I doubt that your Lab Radar is out of calibration. You could check against a chronograph if someone has one to lend you.

By the way, welcome to the forum.

I thought I'd throw in a QL projection with the BST and IMR 4831 to give you a more accurate idea of what you could expect.

Code:
Cartridge          : .280 Rem.
Bullet             : .284, 150, Nosler CT BalSilTip 51110
Useable Case Capaci: 59.989 grain H2O = 3.895 cm³
Cartridge O.A.L. L6: 3.330 inch = 84.58 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : IMR 4831

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   94    49.95   2750    2519   45460   8976     99.5    1.384
-09.0   95    50.51   2778    2571   46966   9041     99.6    1.364
-08.0   96    51.06   2806    2623   48520   9101     99.8    1.344
-07.0   97    51.62   2834    2675   50125   9158     99.9    1.324
-06.0   99    52.17   2862    2728   51782   9210     99.9    1.305
-05.0  100    52.73   2889    2780   53493   9258    100.0    1.286
-04.0  101    53.28   2917    2834   55261   9302    100.0    1.267  ! Near Maximum !
-03.0  102    53.84   2944    2887   57087   9342    100.0    1.249  ! Near Maximum !
-02.0  103    54.39   2971    2940   58974   9381    100.0    1.231  ! Near Maximum !
-01.0  104    54.95   2998    2994   60924   9419    100.0    1.213  ! Near Maximum !
+00.0  105    55.50   3025    3048   62939   9457    100.0    1.196  ! Near Maximum !
+01.0  106    56.06   3052    3102   65023   9493    100.0    1.179  !DANGEROUS LOAD-DO NOT USE!
+02.0  107    56.61   3078    3156   67178   9530    100.0    1.163  !DANGEROUS LOAD-DO NOT USE!
+03.0  108    57.17   3105    3211   69406   9565    100.0    1.146  !DANGEROUS LOAD-DO NOT USE!
+04.0  109    57.72   3131    3266   71712   9600    100.0    1.130  !DANGEROUS LOAD-DO NOT USE!
+05.0  110    58.28   3158    3321   74098   9634    100.0    1.115  !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    105    55.50   3125    3253   75331   9089    100.0    1.114  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    105    55.50   2872    2747   50742   9773     98.5    1.308


Just a few thoughts that may help you work through your dilemma.

_________________
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 Post subject: Re: .280 remington with 150 grain BT running slow
PostPosted: Sat Nov 21, 2020 5:42 pm 

Joined: Mon Apr 06, 2009 10:27 am
Posts: 796
Location: Northern CO
I’ve had two Bartlien barrels... both of them were about 100fps “slow” for the first hundred rounds or so. What velocity are you thinking you should be getting?

If you’re really trying to get into LR shooting.... you should be looking at the 150 ABLR, or ELD.... or the 162/168 class of bullets. BC makes a big difference when you extend out past 500-600 yards, and simple switch in bullets could buy you .100-.150 in BC.... that A LOT of wind bucking, and will cut drift by as much at 30-40%.



My last .280 shot 162s at 2850 out of a 24” barrel.

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 Post subject: Re: .280 remington with 150 grain BT running slow
PostPosted: Sun Nov 22, 2020 9:16 am 

Joined: Fri Dec 08, 2017 7:10 pm
Posts: 2
Thanks for the data. This gives me a little more confidence in my thinking on where to go next with my reloading.


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 Post subject: Re: .280 remington with 150 grain BT running slow
PostPosted: Sun Nov 22, 2020 10:40 am 

Joined: Thu Nov 17, 2005 6:16 pm
Posts: 2549
Location: Oregon
You should be able to hit 3000fps with 150s out of a 26" tube. I'd keep working up in .3g increments or so, and watch for pressure signs, while also paying attention to velocity.


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