Cooper 280AI Chamber question.

[BEEMAN]

I just got a model 52 Cooper 280AI Jackson Hunter. After measuring to see what I could load for a COAL; I found that I can't even load to mag length. I am wanting to shoot the 168 Berger classic hunter bullet. When loaded to mag length I would be .151" into the lands. I can only load to a COAL of 3.244" which is just right at the lands. Also the Redding dies are almost out of adjustment because we have to seat the bullet so deep into the case. I am at 57 gr of H4831sc and it will be compressed soon. Are all the Cooper 280AI chambered like this? Seems weird that they would offer a 1 in 9 twist and not chamber it for long heavy bullets. Any help is appreciated. Thanks.

 

[436]

I just got a model 52 Cooper 280AI Jackson Hunter. After measuring to see what I could load for a COAL; I found that I can't even load to mag length. I am wanting to shoot the 168 Berger classic hunter bullet. When loaded to mag length I would be .151" into the lands. I can only load to a COAL of 3.244" which is just right at the lands. Also the Redding dies are almost out of adjustment because we have to seat the bullet so deep into the case. I am at 57 gr of H4831sc and it will be compressed soon. Are all the Cooper 280AI chambered like this? Seems weird that they would offer a 1 in 9 twist and not chamber it for long heavy bullets. Any help is appreciated. Thanks.

Take it to a gunsmith and have him touch the throat for you, so it will accept the longer bullets.
Good luck
436

 

[BEEMAN]

Might have to I guess. Even if I could load it to mag length, it would be good. I think I am out of case capacity with this seating depth. Don't see how some guys are running up to 63 gr of Retumbo. I'd never fit that in my case.

 

[436]

Might have to I guess. Even if I could load it to mag length, it would be good. I think I am out of case capacity with this seating depth. Don't see how some guys are running up to 63 gr of Retumbo. I'd never fit that in my case.

With a 168gr and 63grs of Retumbo, perhaps a long drop tube was used.. I looked into Ackley's book #1 I see where he has a 140gr with 63gr of IMR 4350... and has he get's to the 175gr with the same powder it drops to 58grs so I'm thinking 63grs of Retumbo with a 168gr bullet would have to be a very compressed load! with the bullet(s) set "way" the hell out there.
436

 

[BEEMAN]

Was hoping some other Cooper 280AI shooters would chime in. I used the search function here; and there was lots of loads listed. Still not sure how they are getting that much powder in their cases. They must have a different throat than my Cooper.

 

[Ridgerunner665]

Retumbo is too slow for the Ackley....even with 180 grain bullets....the loads using it may be accurate, but they are slower than loads using faster powders.

IMR 7828ssc, MRP, and Reloder 22 are the ideal powders for the 280 Ackley...Reloder 25 is the absolute slowest powder that has any place in a 280 Ackley with a standard SAAMI throat....and Retumbo is too slow even with a long throat....a 28" barrel might make Retumbo worthwhile also.

That may upset some folks...but its true.

Get some 7828, MRP, or RL 22 and you'll have plenty of room...and just as much speed and accuracy, probably more even.

 

[Edd]

I would consider that chamber perfect for the bullet you are using.

 

[Ridgerunner665]

The best powders are on the top...you'll notice, Retumbo is way down the list....EDIT: oops, thats 180 grain Bergers...will do 168's down below.

Cartridge          : .280 Ack Imp Nosler brass
Bullet             : .284, 180, Berger VLD G7 #28405
Useable Case Capaci: 61.933 grain H2O = 4.021 cm³
Cartridge O.A.L. L6: 3.244 inch = 82.40 mm
Barrel Length      : 24.0 inch = 609.6 mm

Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 64000 psi, or 441 MPa
or a maximum loading ratio or filling of 107 %
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 !

63 loads produced a Loading Ratio below user-defined minimum of 90%. These powders have been skipped.
Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
Vihtavuori N560                    102.5     59.8     3.87    2877    99.3    64000   12547   1.212  ! Near Maximum !
Norma MRP                          100.7     60.0     3.89    2876   100.0    64000   12085   1.218  ! Near Maximum !
Accurate MAGPRO                    102.7     62.4     4.04    2872    98.5    64000   12683   1.218  ! Near Maximum !
IMR 7828 SSC                       101.2     59.4     3.85    2866    99.6    64000   12112   1.203  ! Near Maximum !
IMR 7828                           107.0     59.4     3.85    2866    99.6    64000   12112   1.203  ! Near Maximum !
ADI AR 2213                        102.2     59.0     3.82    2852    99.5    64000   12028   1.201  ! Near Maximum !
Alliant Reloder-22                 102.7     59.3     3.84    2851    99.9    64000   11985   1.219  ! Near Maximum !
Winchester WXR                     105.5     59.6     3.86    2851    99.9    64000   12010   1.219  ! Near Maximum !
ADI AP 2214                        106.1     62.9     4.08    2849    99.7    64000   11861   1.198  ! Near Maximum !
Ramshot Magnum                     102.5     63.8     4.13    2835   100.0    64000   11417   1.212  ! Near Maximum !
Alliant Reloder-25                 107.0     60.8     3.94    2832   100.0    60451   11548   1.238  ! Near Maximum !
ADI AR 2209                         99.1     56.2     3.64    2810    99.9    64000   11360   1.210  ! Near Maximum !
Alliant Reloder-19                  99.6     56.9     3.69    2808    99.9    64000   11427   1.218  ! Near Maximum !
Alliant Reloder-17                  90.2     54.0     3.50    2803   100.0    64000   10627   1.223  ! Near Maximum !
Ramshot Hunter                      95.1     56.1     3.63    2795   100.0    64000   10944   1.226  ! Near Maximum !
Hodgdon H4831                      104.9     58.2     3.77    2789    99.0    64000   11364   1.215  ! Near Maximum !
Hodgdon H4831 SC                   100.8     58.2     3.77    2789    99.0    64000   11364   1.215  ! Near Maximum !
Vihtavuori N570                    107.0     64.4     4.17    2787    94.9    53594   13370   1.303
Norma 204                           94.5     55.7     3.61    2785    99.8    64000   11140   1.219  ! Near Maximum !
Norma MRP 2                        107.0     61.1     3.96    2774    99.1    55771   12285   1.296  ! Near Maximum !
Vihtavuori N550                     92.0     53.7     3.48    2770   100.0    64000   10602   1.237  ! Near Maximum !
Norma URP                           94.7     53.5     3.46    2769   100.0    64000   10458   1.233  ! Near Maximum !
Winchester Supreme 780              98.3     59.2     3.83    2765    99.8    64000   10876   1.224  ! Near Maximum !
Accurate 4350                       93.7     53.5     3.47    2763   100.0    64000   10398   1.251  ! Near Maximum !
Alliant Reloder-33                 107.0     67.1     4.35    2759    94.9    52606   13192   1.315
Vihtavuori N165                    105.0     59.3     3.84    2758   100.0    64000   10633   1.229  ! Near Maximum !
Accurate 3100                      102.8     58.7     3.80    2755   100.0    64000   10488   1.253  ! Near Maximum !
IMR 4831                            99.3     54.3     3.52    2751   100.0    64000   10228   1.242  ! Near Maximum !
Hodgdon H4350                       97.2     54.3     3.52    2746   100.0    64000   10473   1.224  ! Near Maximum !
Vihtavuori N160                    105.2     57.6     3.73    2745    99.4    64000   10725   1.224  ! Near Maximum !
IMR 4350                            95.4     54.2     3.51    2745   100.0    64000   10445   1.225  ! Near Maximum !
Hodgdon Hybrid 100V                 97.1     53.6     3.48    2723   100.0    64000    9639   1.236  ! Near Maximum !
ADI AR 2217                        107.0     60.4     3.92    2716    98.7    54728   11535   1.287
Hodgdon H1000                      107.0     60.4     3.92    2716    98.7    54728   11535   1.287
ADI AR 2225                        107.0     61.4     3.98    2674    99.7    47959   11964   1.368
Hodgdon Retumbo                    107.0     61.4     3.98    2674    99.7    47959   11964   1.368
Vihtavuori N150                     95.0     51.2     3.32    2661   100.0    64000    9128   1.249  ! Near Maximum !
ADI AR 2218                        107.0     65.1     4.22    2650    91.8    47630   13021   1.367
Vihtavuori N135                     91.2     47.2     3.06    2608   100.0    64000    8415   1.263  ! Near Maximum !
Vihtavuori 24N41                   107.0     65.1     4.22    2607    86.9    50380   11558   1.345
Norma 217                          107.0     60.2     3.90    2592    98.4    42475   12062   1.461
Vihtavuori N170                    107.0     60.4     3.92    2571    92.0    50011   11002   1.381
Hodgdon H870                       107.0     63.1     4.09    2569    93.2    42657   12216   1.454
Alliant Reloder-50                 107.0     66.1     4.28    2533    89.7    40123   12490   1.510
Hodgdon US 869                     107.0     65.1     4.22    2431    82.8    40931   10791   1.490
Hodgdon 50BMG                      107.0     62.0     4.02    2429    78.6    41190   10751   1.485
Accurate 8700                      107.0     63.7     4.13    2359    86.1    36829   10567   1.559
Vihtavuori 20N29                   107.0     65.7     4.26    2337    82.7    35447   10628   1.591

 

[Ridgerunner665]

Cartridge          : .280 Ack Imp Nosler brass
Bullet             : .284, 168, Berger Hunt VLD G7 #28501
Useable Case Capaci: 63.212 grain H2O = 4.104 cm³
Cartridge O.A.L. L6: 3.244 inch = 82.40 mm
Barrel Length      : 24.0 inch = 609.6 mm

Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 64000 psi, or 441 MPa
or a maximum loading ratio or filling of 107 %
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 !

57 loads produced a Loading Ratio below user-defined minimum of 90%. These powders have been skipped.
Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
Norma MRP                          101.8     61.9     4.01    2979   100.0    64000   12419   1.180  ! Near Maximum !
Vihtavuori N560                    103.6     61.7     4.00    2977    98.9    64000   12830   1.175  ! Near Maximum !
Accurate MAGPRO                    103.8     64.3     4.17    2969    97.9    64000   12935   1.181  ! Near Maximum !
IMR 7828 SSC                       102.3     61.2     3.97    2965    99.2    64000   12396   1.165  ! Near Maximum !
Alliant Reloder-22                 103.8     61.2     3.96    2952    99.8    64000   12290   1.181  ! Near Maximum !
Winchester WXR                     106.6     61.5     3.98    2951    99.7    64000   12312   1.181  ! Near Maximum !
ADI AR 2213                        103.3     60.8     3.94    2951    99.1    64000   12298   1.164  ! Near Maximum !
ADI AP 2214                        107.0     64.7     4.19    2942    99.3    63745   12118   1.163  ! Near Maximum !
Ramshot Magnum                     103.6     65.7     4.26    2934   100.0    64000   11714   1.173  ! Near Maximum !
IMR 7828                           107.0     60.6     3.93    2933    99.0    61718   12315   1.184  ! Near Maximum !
Alliant Reloder-17                  91.3     55.8     3.62    2910   100.0    64000   10928   1.184  ! Near Maximum !
ADI AR 2209                        100.1     58.0     3.76    2910    99.7    64000   11646   1.172  ! Near Maximum !
Alliant Reloder-19                 100.7     58.7     3.80    2908    99.7    64000   11714   1.180  ! Near Maximum !
Alliant Reloder-25                 107.0     62.0     4.02    2902   100.0    58156   11813   1.220  ! Near Maximum !
Ramshot Hunter                      96.2     57.9     3.75    2897   100.0    64000   11249   1.187  ! Near Maximum !
Hodgdon H414                        90.8     56.0     3.63    2896   100.0    64000   11299   1.188  ! Near Maximum !
Winchester 760                      90.8     56.0     3.63    2896   100.0    64000   11299   1.188  ! Near Maximum !
Hodgdon H4831                      105.9     60.0     3.89    2885    98.6    64000   11604   1.177  ! Near Maximum !
Hodgdon H4831 SC                   101.8     60.0     3.89    2885    98.6    64000   11604   1.177  ! Near Maximum !
Norma 204                           95.5     57.5     3.72    2884    99.6    64000   11416   1.181  ! Near Maximum !
Vihtavuori N550                     93.0     55.4     3.59    2873   100.0    64000   10897   1.198  ! Near Maximum !
Norma URP                           95.7     55.2     3.57    2872   100.0    64000   10754   1.194  ! Near Maximum !
Accurate 4350                       94.8     55.2     3.58    2867   100.0    64000   10700   1.211  ! Near Maximum !
Winchester Supreme 780              99.2     61.0     3.95    2862    99.6    64000   11134   1.185  ! Near Maximum !
Vihtavuori N165                    106.1     61.2     3.96    2856    99.9    64000   10907   1.190  ! Near Maximum !
Accurate 3100                      103.9     60.5     3.92    2855   100.0    64000   10778   1.214  ! Near Maximum !
IMR 4831                           100.4     56.0     3.63    2854   100.0    64000   10517   1.203  ! Near Maximum !
Hodgdon H4350                       98.2     56.0     3.63    2845    99.9    64000   10756   1.186  ! Near Maximum !
IMR 4350                            96.4     55.9     3.62    2844    99.9    64000   10731   1.186  ! Near Maximum !
Vihtavuori N160                    106.2     59.3     3.84    2841    99.0    64000   10965   1.185  ! Near Maximum !
Vihtavuori N570                    107.0     65.7     4.26    2837    93.2    51474   13393   1.288
Norma MRP 2                        107.0     62.4     4.04    2833    98.3    53427   12448   1.280
Hodgdon Hybrid 100V                 98.2     55.4     3.59    2827   100.0    64000    9912   1.196  ! Near Maximum !
IMR 4007 SSC                        90.5     53.5     3.47    2825    99.9    64000   10601   1.195  ! Near Maximum !
Alliant Reloder-33                 107.0     68.5     4.44    2807    93.3    50521   13200   1.300
Hodgdon VARGET                      90.2     50.9     3.30    2803   100.0    64000    9920   1.188  ! Near Maximum !
IMR 4064                            90.6     49.9     3.23    2793   100.0    64000    9714   1.193  ! Near Maximum !
Accurate 2700                       90.7     55.2     3.57    2780    99.9    64000   10029   1.199  ! Near Maximum !
Hodgdon H1000                      107.0     61.7     4.00    2774    97.7    52810   11670   1.268
ADI AR 2217                        107.0     61.7     4.00    2774    97.7    52810   11670   1.268
Vihtavuori N150                     96.0     52.8     3.42    2763   100.0    64000    9376   1.208  ! Near Maximum !
Hodgdon Retumbo                    107.0     62.7     4.06    2727    99.1    46185   12159   1.351
ADI AR 2225                        107.0     62.7     4.06    2727    99.1    46185   12159   1.351
Vihtavuori N135                     92.2     48.7     3.16    2711   100.0    64000    8657   1.221  ! Near Maximum !
ADI AR 2218                        107.0     66.4     4.30    2689    89.5    45956   12917   1.351
Vihtavuori 24N41                   107.0     66.4     4.30    2653    84.9    48662   11478   1.327
Norma 217                          107.0     61.4     3.98    2637    97.2    40680   12174   1.446
Vihtavuori N170                    107.0     61.7     4.00    2623    90.4    48222   11002   1.363
Hodgdon H870                       107.0     64.4     4.17    2610    91.3    40985   12180   1.439
Alliant Reloder-50                 107.0     67.4     4.37    2567    87.4    38314   12385   1.498
Hodgdon US 869                     107.0     66.4     4.30    2470    80.6    39471   10667   1.472
Hodgdon 50BMG                      107.0     63.3     4.10    2469    76.4    39728   10613   1.466
Accurate 8700                      107.0     65.1     4.22    2393    83.7    35504   10437   1.538
Vihtavuori 20N29                   107.0     67.1     4.35    2369    80.2    34093   10470   1.570

 

[stanley52]

Might have to I guess. Even if I could load it to mag length, it would be good. I think I am out of case capacity with this seating depth. Don't see how some guys are running up to 63 gr of Retumbo. I'd never fit that in my case.

People use Retumbo and have highly compressed loads. Retumbo does give great velocities with my 280AI with 168gr bergers, but my redding comp seater doesn't like how compressed it is. I use 58.5gr H4831sc and it shoots lights out.

 

[BEEMAN]

Just got finished shooting. Worked up to 58.5 gr of H4831sc seated at 19 thou off the lands. COAL of 3.225". Speeds were 2892, 2892 and 2879 fps. First two shots was a ragged hole and the third opened it up a bit. Probably need a better operator. Thanks for all the replies and nice charts Ridgerunner. Looks like I am right in there for speeds. My gun also has a 24" barrel. It wasn't showing any pressure signs, but I think I will stop there for now. Limited time and hunting season is just around the corner here in Manitoba. Thanks again for all the help.