Need help with 450 Bushmaster loads.

[Slash2]

I've got a 450 Bushmaster upper coming next week, along with 200 factory rounds, but I want to load my own after the factory rounds go bang for obvious reasons, they are pricey!

Hornady says the dies will be out in a couple of weeks, but the load data may be a few months later?!?

So, given what I know - the cases are based on the 248 Winchester, the bullet is .452" 250 grains and the velocity is around 2,200 fps, how do I go about working up a load that i can use for plinking and range play.

I can size the cases with a W284 sizing die, trim the case to the same length as the factory round and seat the bullet with a .45 acp crimp and seat die, so the only "minor" thing I'm missing is knowing what powders to use and how much to start with. As you may have guessed, I've got most of the tools, I just lack experience and knowledge.

Is there any way I can safely figure out a recipe to start with that won't hurt me or the gun?

Thanks.

[C.G.]

The only "safe" way would be to contact Bushmaster and ask them, I have a feeling that you may not get too far, yet. At least find out what powder they are using and then you can pull a bullet and weigh the powder.
This is a new round so there are not too many out there. You may also want to post this question on ARF.com, nationwide there maybe more people that have experimented with reloading for this caliber.

[TonyM]

The only "safe" way would be to contact Bushmaster and ask them, I have a feeling that you may not get too far, yet. At least find out what powder they are using and then you can pull a bullet and weigh the powder.
This is a new round so there are not too many out there. You may also want to post this question on ARF.com, nationwide there maybe more people that have experimented with reloading for this caliber.

+1

Until they release dies and load data, you're really at their mercy.


Might want to buy more factory loads and keep the brass for when the information and dies come together. We've all heard "two weeks" too many times to really believe it.

[ar15barrels]

Measure the case capacity in grains-of-water and give me a cartridge drawing and I can do a quickload pass that will give you some powders and starting load data to work with.

[Slash2]

case size

The Hornady guy said they are still cooking the recipe in the labs for release and couldn't tell me what powder they are using.

So far this is the best I can do without a case. This link will send you to the drawing of a .284 Winchester case on Wikipedia along with the info I've listed below.

http://en.wikipedia.org/wiki/.284_Winchester

I also believe that they trim the case at the shoulder leaving it at 1.7" +- .003. If I had done more than doodle on my math books in school I might be able to figure out the volume of the trimmed case, but.....

I'm not looking for an exact copy of the factory load, instead I was thinking about using Rainer FP 250 gr bullets (inexpensive) at a moderate velocity, say under 2000fps. Something to shoot at the range and maybe knock down some steel at the Tactical Rifle or 3 Gun matches. I can wait for the "official" load data for when I want a round that will stop zombies and water buffalo, or zombies in front of a water Buffalo, with one shot.

Thanks for your help.

[ar15barrels]

I don't have any 284 cases.
Please take one and cut it to the proper length and measure the capacity in grains of water.
From there, I can get you starting data to work with at any pressure level you want with any bullet you want.

[Slash2]

Thanks! I'll see if I can't dig one up, trim it and get that measurement.

Once the factory rounds get here I'll sacrifice one to science and weigh the powder and measure it's volume as well.

[Slash2]

case volume

I filled the trimmed case with water and measured the water with my powder scale. 50.02 grs.

[ar15barrels]

I filled the trimmed case with water and measured the water with my powder scale. 50.02 grs.

Did you do this by setting a trimmed and primed case on the scale, zeroing the scale and then slowly filling the case with water to the top?

[Slash2]

yup.

and BTW, I really apprieciate you helping me with this, I was suprised at how little info there was considering the gun's been out there for at least a little while.

[ar15barrels]

OK, assuming 1.7" case length and 50gr of water capacity, here are some Quickload passes at different pressures.

Cartridge          : .450 Bushmaster
Bullet             : .452, 240, Hornady XTP MAG 45220
Cartridge O.A.L. L6: 2.000 inch or 50.80 mm
Barrel Length      : 16.0 inch or 406.4 mm

Predicted Data for Indicated Charges of the Following Powders.

Matching Maximum Pressure: 30000 psi, or 206 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 !

27 loads produced a Loading Ratio below user-defined minimum of 80%. 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
---------------------------------  -----------------------------------------------------------------
Winchester 296                      95.6     32.8     2.12    1961    87.2    30000    4364   1.037
Hodgdon H110                        93.4     31.9     2.07    1884    87.9    30000    3876   1.052
Vihtavuori N110                    102.9     28.1     1.82    1880    94.7    30000    3607   1.041
Ramshot Enforcer                    82.5     27.1     1.76    1853    94.9    30000    3474   1.058
Alliant 2400                        82.9     24.9     1.62    1833    93.7    30000    3372   1.064
Accurate Solo 4100                  85.2     28.3     1.83    1821    90.8    30000    3376   1.064
Hodgdon H4227                      104.8     30.3     1.96    1814    83.2    30000    3481   1.053
Vihtavuori N105                     83.9     21.4     1.39    1801   100.0    30000    2713   1.063
Alliant BLUE DOT                    88.1     21.9     1.42    1787    98.5    30000    2998   1.073
Accurate XMR 5744                   91.4     28.4     1.84    1781    77.5    30000    3366   1.071

Cartridge          : .450 Bushmaster
Bullet             : .452, 240, Hornady XTP MAG 45220
Cartridge O.A.L. L6: 2.000 inch or 50.80 mm
Barrel Length      : 16.0 inch or 406.4 mm

Predicted Data for Indicated Charges of the Following Powders.

Matching Maximum Pressure: 35000 psi, or 241 MPa

Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
Winchester 296                     100.0     34.3     2.22    2061    89.7    35000    4620   0.970  ! Near Maximum !
Hodgdon H110                        98.0     33.5     2.17    1981    90.3    35000    4115   0.985  ! Near Maximum !
Ramshot Enforcer                    87.1     28.6     1.86    1947    96.7    35000    3668   0.990  ! Near Maximum !
Alliant 2400                        88.0     26.5     1.72    1931    95.7    35000    3592   0.994  ! Near Maximum !
Vihtavuori N110                    105.0     28.6     1.86    1917    95.5    31879    3682   1.014  ! Near Maximum !
Accurate Solo 4100                  89.8     29.8     1.93    1915    93.0    35000    3585   0.996  ! Near Maximum !
Alliant BLUE DOT                    94.1     23.4     1.51    1881    99.4    35000    3172   1.003  ! Near Maximum !
Vihtavuori N105                     88.9     22.7     1.47    1880   100.0    35000    2809   0.999  ! Near Maximum !
Accurate XMR 5744                   96.5     30.0     1.94    1880    80.3    35000    3638   1.002  ! Near Maximum !
Accurate No.1680                   104.5     35.8     2.32    1859    73.2    35000    3586   1.002  ! Near Maximum !

Cartridge          : .450 Bushmaster
Bullet             : .452, 240, Hornady XTP MAG 45220
Cartridge O.A.L. L6: 2.000 inch or 50.80 mm
Barrel Length      : 16.0 inch or 406.4 mm

Predicted Data for Indicated Charges of the Following Powders.

Matching Maximum Pressure: 37500 psi, or 258 MPa

Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
Winchester 296                     101.9     34.9     2.26    2105    90.7    37500    4727   0.942  !DANGEROUS LOAD-DO NOT USE!
Hodgdon H110                       100.0     34.2     2.22    2024    91.3    37500    4217   0.956  !DANGEROUS LOAD-DO NOT USE!
Ramshot Enforcer                    89.2     29.3     1.90    1989    97.3    37500    3747   0.962  !DANGEROUS LOAD-DO NOT USE!
Alliant 2400                        90.3     27.2     1.76    1975    96.4    37500    3684   0.965  !DANGEROUS LOAD-DO NOT USE!
Accurate Solo 4100                  91.9     30.5     1.98    1957    93.9    37500    3674   0.967  !DANGEROUS LOAD-DO NOT USE!
Accurate XMR 5744                   98.8     30.7     1.99    1924    81.5    37500    3760   0.972  !DANGEROUS LOAD-DO NOT USE!
Alliant BLUE DOT                    96.8     24.0     1.56    1923    99.7    37500    3243   0.974  !DANGEROUS LOAD-DO NOT USE!
Vihtavuori N110                    105.0     28.6     1.86    1917    95.5    31879    3682   1.014  ! Near Maximum !
Vihtavuori N105                     91.2     23.3     1.51    1915   100.0    37500    2852   0.972  !DANGEROUS LOAD-DO NOT USE!
Accurate No.1680                   105.0     35.9     2.33    1870    73.5    35658    3615   0.994  ! Near Maximum !

Without knowing the exact case length, we can't determine the exact case capacity, but these will show you the types of powders, pressures and velocities you are looking at.
I went with the 240gr Hornady XTP because it's a good bullet.
If I had specific dimensions of your plated bullets, I could model those as well.

[ar15barrels]

I think that the 1.7" case length is too short.
In the pictures I have seen, the case looks like it should be more like 1.9" long to have the bullets seated to around 2.2" overall length.
250gr 0.452" bullets just are not that long.

[Slash2]

Great! Thanks for the info! And I think you are right about the case length, it does seem short for that OAL, but then again a flat nose bullet would be shorter than their pointy nosed SST wouldn't it?. I haven't tried to find anything on the length of their bullet compared to a Rainier 250 gr. FP.

I'll study your data, I should be getting the factory rounds Thursday, then I can dissect one and clear up any assumptions I've made. How much below the Quickload data should I start? 10%? 20%?

[ar15barrels]

I should be getting the factory rounds Thursday, then I can dissect one and clear up any assumptions I've made. How much below the Quickload data should I start? 10%? 20%?

Wait until you take a round apart and give me proper dimensions and capacity.
Then start 10% under the max pressure you want to run at.
I have a backthrust calculator that helps determine thrust loading.
I would not run over 35,000 PSI and expect bolts to survive long.
You have to be real careful with this cartridge because you will not get traditional pressure signs before you are over-loading this cartridge.

[Slash2]

Once again, thanks. I'll certainly aim any business I can your way and I'll follow up on the 450 B when I've got more information.

Now the hard part, waiting for the UPS truck!