325 gr. (.458 to .452) reloading experiment

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Re: 325 gr. (.458 to .452) reloading experiment

Postby Siringo » Wed Jun 17, 2009 11:32 pm

I think the pressures where up there. I will get some photos, but it may be a few days. There was no sooting and chamber wall impressions were more prevelant than with factor rounds. I had a few of those with me. The case capacity with LG, bullets seated to cannulure is 34 grs.

I did not bother with ES because I was shooting just single charges. I will load some more up and check them this weekend. In terms of accuracy, ALL shots went in a 3 inch group at 100 yards. To really assess this I need to more to 200 yards. The range that I shoot at had the KD range shut down by the police last week due to errant rounds sent skyward towards a housing area during a "F" Class Rifle Match.

I will pass on the measurement in the next day or two.
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Re: 325 gr. (.458 to .452) reloading experiment

Postby BD1 » Thu Jun 18, 2009 7:54 am

The reason I'm asking is that as Quickload doesn't seem to be following this cartridge very well once we diverge from the Hornady factory load, indicators useful for a "gut check" become more important. It would be nice if Hornady would offer a Saami load with a heavier bullet to build into the data base.
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Re: 325 gr. (.458 to .452) reloading experiment

Postby Siringo » Thu Jun 18, 2009 5:22 pm

They do make a 300 gr FXT for the muzzleloader crowd. Looks the same as the 250, but weights more. I would have to assume that this is what they would use. Just a matter or packaging/production.

I measured my brass and the base measures .4981" on the low side and .4989" on the high side. The .4981" measures the same as once fired factory ammo. The .4989 was with 31.3 and 31.6 charges, which was the highest velocity. The top charge of 32 grain measured .4985".

The last digit is estimated as my caliper only goes to .001". So I estimated between the lines. All of my once fired brass measures .4981" (pointer just over the line).
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Re: 325 gr. (.458 to .452) reloading experiment

Postby wildcatter » Fri Jun 19, 2009 6:56 am

Siringo wrote:They do make a 300 gr FXT for the muzzleloader crowd. Looks the same as the 250, but weights more. I would have to assume that this is what they would use. Just a matter or packaging/production.

I measured my brass and the base measures .4981" on the low side and .4989" on the high side. The .4981" measures the same as once fired factory ammo. The .4989 was with 31.3 and 31.6 charges, which was the highest velocity. The top charge of 32 grain measured .4985".

The last digit is estimated as my caliper only goes to .001". So I estimated between the lines. All of my once fired brass measures .4981" (pointer just over the line).


Estimating the measurement between the lines, as you say, is still very accurate and useful.

At .0008" expansion, the pressures are quite mild, that is, for your particular cartridge case. I myself use .0015" as my normal operating pressures. But until I get the chamber pressure equipment and actually get the real numbers, I am guessing that the pressures at 1.5m exp to be in the 52-55m arena, with .0008 exp most likely under 40m.

This is all useful data and MudBug is setting up the Data Records to include the before and after expansion numbers, when that gets added to the file, Siringo, make sure you get those numbers over there, we need'em.

Mud, suggestion, in addition to the expansion numbers a total difference column might also be helpful so the user at a glance could see where a particular load is at. Sometime in the near future I plan to have the numbers for all to see, what the ranges are averaging for amount of expansion. This still will be only an average as from lot to lot of brass, the pressures will change for any given amount of exp, but at least you won't be shooting in the dark totally. After you get your load, I plan to offer you guys too ship to me those loads, for actual confirmation in my production weapon.
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Re: 325 gr. (.458 to .452) reloading experiment

Postby Siringo » Fri Jun 19, 2009 7:55 am

I am going to get a hold of a micrometer instead of the caliper to take more accuracte measurements. I will post those along side of the charge/velocties that I took. That might be a week before I can get to that though. I will also be taking velocities/measurement on the two most accurate charges areas. Namely -- 29.0 to 29.3 (29.1) and 31.3. to 31.6 (31.4).

BTW -- I purchased a .454 sizing die so I could go from .458 to .454 to.452. Still tough for this bullet. Must have a thicker jacket than most. Maybe I should buy a .457 from Lee and hone it out to .456 and do this in 3 steps. Also, the bullets I recovered out of the sand held together with no jacket separation and that was going from .458 to .452 in one step.
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Re: 325 gr. (.458 to .452) reloading experiment

Postby BD1 » Fri Jun 19, 2009 8:43 am

I found some of the 325s at Bass Pro yesterday. I'm waiting on a .454 die for my star as I'm not sure the handle will take going from .458 to .452 in one go. It's already bending a bit resizing the .459 cast to .452 in one go. I'll try them over H110 to add to the database. I'm really hoping to get a good load with cast somewhere around 300 grains and 2,000 fps. The Hornadys at 60 cents a pop could put a crimp in my retirement plans.
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Re: 325 gr. (.458 to .452) reloading experiment

Postby Siringo » Fri Jun 19, 2009 9:07 am

You had a mold made -- correct. Maybe after all of this we can come up with the ultimate 450B cast boolitt!
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Re: 325 gr. (.458 to .452) reloading experiment

Postby wildcatter » Fri Jun 19, 2009 9:29 am

Siringo wrote:I am going to get a hold of a micrometer instead of the caliper to take more accuracte measurements. I will post those along side of the charge/velocties that I took. That might be a week before I can get to that though. I will also be taking velocities/measurement on the two most accurate charges areas. Namely -- 29.0 to 29.3 (29.1) and 31.3. to 31.6 (31.4).

BTW -- I purchased a .454 sizing die so I could go from .458 to .454 to.452. Still tough for this bullet. Must have a thicker jacket than most. Maybe I should buy a .457 from Lee and hone it out to .456 and do this in 3 steps. Also, the bullets I recovered out of the sand held together with no jacket separation and that was going from .458 to .452 in one step.


Ok 'ol man, your going to have a hard time honing from 457 to 456, I think that's in reverse, ain't it?. Suggestion, get another .454 and moto-tool, flap it out to 456. For those of you that don't know what I'm talking about, here goes. This is not for Siringo, he's an 'ol hand at this stuff and probably has a better method anyway and if any of you do, I want to hear all about it..us 'ol dogs, can be taught.

Your Dremel Type tool, with a 1/8th inch collet, will polish quite nicely. Making a flap wheel is easy as it is effective. I use a 1/8 x 3" Cotter Pin, but a wood doll rod with a lateral slice can also work well.

Take a sheet of emery cloth and rip about a one inch wide. Spread the cotter key, just enough and insert one end of the strip of emery only enough to have the pin hold the strip. Rap the emery strip around the pin, so the grain is exposed. After you have rapped the pin and inserted it into the moto-tool and assuming you have it rapped in the right direction, insert this rapped pin into the hole to be reamed. This should have some resistance while the pin is rotating. If you have too much cloth, rip some off. Now, with the tool spinning at high speed, just stroke the flap rig in and out, but never coming all the way out, until you're done. This all can be done with a drill motor too, it's just much slower.

To flap out 2 thou, which is allot, start with 180 grit, nothing coarser, because those heavy grains will score your surface more the the 2 thou you're trying to take out and you'll never be able to hone out those scratches, without going over the desired bore diameter. Graduate to 240 grit and then 360, you'll usually never need to go finer than 360 to get a mirror finish, but if you do, do it. Measure often and you'll get to the desired bore diameter and it didn't take too much to get there either.
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Re: 325 gr. (.458 to .452) reloading experiment

Postby BD1 » Fri Jun 19, 2009 10:17 am

Siringo wrote:You had a mold made -- correct. Maybe after all of this we can come up with the ultimate 450B cast boolitt!


That's my hope! But it may take more than one try to get there. If we can identify the issues, we can solve the problem.
If you want to play with boolit design, go to:

http://www.mountainmolds.com/

-and fiddle with the online bullet design software. Dan has really made this process so much easier than it used to be.

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Re: 325 gr. (.458 to .452) reloading experiment

Postby Siringo » Fri Jun 19, 2009 11:26 am

Silly me! No wonder I booted out of Engineering School.
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