Reality check on a 280 Remington load

[Nimrod84]

Hi, I'm running into what I think is good correlation between my loads and a Quickload prediction, but my brass H20 capacity is larger than what was run through QL. My question is that I don't know what difference my larger H20 capacity makes and or how to account for it. My gut says that the larger than predicted H20 capacity should lower velocity & pressure and since I'm correlated to QL prediction I must be running hotter than I think. A sanity check, education or insight would be appreciated.

I have a 280 Remington with 24" barrel:
175 grain Nosler Partition
3.33" max COAL - averages close to 3.296" as a lot of my bullets have deformed tips...
52.8 grains of IMR 4955 at an average of 2660 fps in 40-50s degree weather.
Nosler brass with an 71.2 average H20 capacity without bullet and about 61 H20 capacity with bullet which matches Noslers 61.1 grain H20 capacity.

Quickload was run using a 22" barrel, 58.781 grains of usable H20 case capacity and stock brisance. Quickload predicted 52.92 grains of IMR 4955 providing 2595 fps at 56440 psi. The data has been extremely helpful when I add 60 fps for the 2" longer barrel it matches up nicely... But that difference in H20 capacity is keeping me up at night.

 

[wingnut]

Go get some sleep.
71.2 average H20 capacity without bullet:

Cartridge          : .280 Rem.
Bullet             : .284, 175, Nosler PART SP 35645
Useable Case Capaci: 62.076 grain H2O = 4.031 cm³
Cartridge O.A.L. L6: 3.330 inch = 84.58 mm
Barrel Length      : 24.0 inch = 609.6 mm
Powder             : IMR 4955 Enduron

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

+00.0   95    52.80   2580    2586   50283  10408     96.7    1.336
+01.0   96    53.33   2604    2635   51740  10509     97.0    1.318
+02.0   97    53.86   2629    2686   53239  10607     97.3    1.301  ! Near Maximum !
+03.0   98    54.38   2653    2736   54782  10703     97.6    1.284  ! Near Maximum !
+04.0   99    54.91   2678    2787   56371  10796     97.9    1.267  ! Near Maximum !
+05.0  100    55.44   2703    2838   58006  10887     98.1    1.250  ! Near Maximum !

Other powders forecast:

Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
Alliant Reloder-26                  98.8     60.8     3.94    2880   100.0    60000   12068   1.232  ! Near Maximum !
Norma MRP                           99.6     59.5     3.85    2858   100.0    60000   12219   1.229  ! Near Maximum !
Vihtavuori N560                    101.3     59.2     3.84    2854    98.6    60000   12569   1.224  ! Near Maximum !
Accurate MAGPRO                    101.7     61.9     4.01    2847    97.5    60000   12677   1.230  ! Near Maximum !
IMR 7828 SSC                       100.1     58.8     3.81    2843    99.0    60000   12162   1.214  ! Near Maximum !
Alliant Reloder-22                 101.6     58.7     3.81    2830    99.6    60000   12061   1.231  ! Near Maximum !
Winchester WXR                     104.3     59.0     3.82    2830    99.6    60000   12080   1.231  ! Near Maximum !
IMR 7828                           105.0     58.4     3.78    2820    98.8    58450   12097   1.229  ! Near Maximum !

 

[Nimrod84]

Wingnut - Thank you I appreciate the info. At first glance it looks like I'm good and still in the 53-56K psi range. The 52.8 grain IMR 4955 data you provided is about 80 fps slower than what I'm getting.

I've been using a Powley Computer calculator to get an idea for correlating case capacity and pressure, but it gets weird at times and isn't powder specific. It has been giving me 53-54K psi but given its generality and lack of correlation with fast and sometimes slow powders I haven't been putting any trust in it.

Thank you again!

 

[wingnut]

QL allows modeling for your load's COAL to have the bullet's ogive on/into the lands (no freebore). In that case, the forecasted pressure is close to but below 58K psi and the speed is very near to what you are seeing. This may or may not be your issue.

"Powley Computer calculator..." Ken Howell old school you are. :wink:

 

[Nimrod84]

It is good to see someone recognize Powley and Ken! Technically I'm 32, but my family says I was born an 80 year old... So yes, I'm very old school and analog by nature. I'm saving up for QL and a Scott Parker tuned scale, but every time I get enough money saved up that I can splurge a little an automotive or home repair rears its ugly head.

Thank you again for the replies. Main concern was and is keeping pressure below 63K psi on a 90 degree day - I'll sleep well tonight! By my measurements I'm about 0.02" off the lands and was looking at moving a smidge closer to the lands. I'll double check and see if a machinist friend will confirm where my lands are.

 

[wingnut]

More rationalizing: Considering the small jump to the lands and that the Partition part of the bullet is like a mono-core at or near the ogive (more resistance to lands engraving), the higher pressure thus higher speed would be reasonable.

IIRC in the musings of Ken at 24hourcampfire, the Prowley computer was developed to closely model IMR powders with the slowest powder being the then state-of-the-art IMR 4831.

Get QL first. Just the lot# change in mixes of the same powder will vary the amount by more than .1 of a grain. No "super" scale needed though the electric autos are nice and quick.

New data, 60K psi max set:

Bullet             : .284, 175, Nosler PART SP 35645
Useable Case Capaci: 62.077 grain H2O = 4.031 cm³
Cartridge O.A.L. L6: 3.330 inch = 84.58 mm
Barrel Length      : 24.0 inch = 609.6 mm
Powder             : IMR 4955 Enduron

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

+00.0   95    52.80   2632    2693   58013  10399     97.8    1.242  ! Near Maximum !
+01.0   96    53.33   2656    2741   59480  10491     98.1    1.230  ! Near Maximum !
+02.0   97    53.86   2680    2790   60991  10580     98.3    1.217  !DANGEROUS LOAD-DO NOT USE!
+03.0   98    54.38   2703    2839   62545  10667     98.5    1.205  !DANGEROUS LOAD-DO NOT USE!
+04.0   99    54.91   2727    2889   64146  10751     98.7    1.192  !DANGEROUS LOAD-DO NOT USE!

 

[Nimrod84]

Wingnut - good advice and insight. Thank you for the data - I might bump things up a hair while it is still cool in the mornings.

I understand the IMR 4831 comment - part of why I don't have faith in the Powley computer. I treat it as a learning tool rather than a device that generates hard or actionable data. The Nosler Partition also changes things a little as the computer is for generic cup and core.

Quick Load has been mentioned to the family several times as a great gift if they want to pool their money. So it is on the short list.

The "super" scale and a few other things that need upgrading have not been mentioned to the family. They are, "if I get the money around before I buy something functionally equivalent on sale" items. A lot of the time I save up for a super item in this case a scale, buy a cheaper model and spend the saved money on ammo or a necessity. I haven't found any currently produced beam scales I like and buying a used one with knife-edges un-inspected, is something I'm not real comfortable with. I have a Chargemaster that works well most of the time, but dirty power and drift (especially in the winter) require that its charges are verified on an abused Lyman 500.

 

[mwess1113]

I'd try Reloder 26 with those 175 partitions


Sent from my iPhone using Tapatalk

 

[wingnut]

Alternate powders forecast using 10K as Shot Start Pressure (like the last data):

Cartridge          : .280 Rem.
Bullet             : .284, 175, Nosler PART SP 35645
Useable Case Capaci: 62.077 grain H2O = 4.031 cm³
Cartridge O.A.L. L6: 3.330 inch = 84.58 mm
Barrel Length      : 24.0 inch = 609.6 mm

Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 60000 psi, or 413 MPa
or a maximum loading ratio or filling of 105 %
These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.
USE ONLY FOR COMPARISON !

Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
Vihtavuori N570                    105.0     63.4     4.11    2834    95.2    59483   13145   1.214  
Alliant Reloder-26                  92.8     57.1     3.70    2806   100.0    60000   11370   1.208  
Alliant Reloder-25                 101.9     58.0     3.76    2799   100.0    60000   11145   1.198  
Norma MRP 2                        103.9     59.4     3.85    2788    99.1    60000   11955   1.207  
Norma MRP                           93.9     56.1     3.63    2781    99.9    60000   11569   1.211  
Vihtavuori N560                     95.8     56.0     3.63    2775    98.3    60000   11908   1.208  
IMR 7828 SSC                        95.0     55.9     3.62    2773    98.7    60000   11563   1.197  
IMR 7828                           100.5     55.9     3.62    2773    98.7    60000   11563   1.197  
Alliant Reloder-33                 105.0     65.2     4.22    2768    94.7    56147   12796   1.241

 

[mwess1113]

2800 fps with a 175 Partition is some serious medicine!


Sent from my iPhone using Tapatalk

 

[JD338]

2800 fps with a 175 Partition is some serious medicine!


Sent from my iPhone using Tapatalk

My thoughts exactly!

JD338

 

[wingnut]

Easy to do ... with a 26 in barrel:

Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
Vihtavuori N570                    105.0     63.4     4.11    2892    96.0    59483   12020   1.272  
Alliant Reloder-26                  92.8     57.1     3.70    2857   100.0    60000   10291   1.267  
Alliant Reloder-25                 101.9     58.0     3.76    2849   100.0    60000   10089   1.257  
Norma MRP 2                        103.9     59.4     3.85    2842    99.4    60000   10869   1.267  
Norma MRP                           93.9     56.1     3.63    2833   100.0    60000   10486   1.270  
Vihtavuori N560                     95.8     56.0     3.63    2828    98.7    60000   10849   1.267  
Alliant Reloder-33                 105.0     65.2     4.22    2826    95.5    56147   11718   1.301  
IMR 7828                           100.5     55.9     3.62    2825    99.1    60000   10516   1.257  
IMR 7828 SSC                        95.0     55.9     3.62    2825    99.1    60000   10516   1.257

 

[Nimrod84]

Thank you for the feed back and suggestions.

I'll see what she finagles up as acceptable accuracy, the rifles accuracy does seem to drop off a bit when the 175 grainers push past 2700 fps, 160 grainers do the same when they go past 2800 fps.