Need help with 450 Bushmaster loads.

[chestpubes2ballfro]

i posted a last week about cheaper than dirt has the brass. i got 200 from them for cheaper than midway

[planensimple]

LS&B just told me maybe 12 weeks for delivery from Hornady.

[MudBug]

CTD just sent me a notice that they have ammo in stock.

LINK

Price has gone up a little though

[Siringo]

sabots again

I shot 6 loads today using the 45 caliber sabots (with 40 caliber sst bullets). Using 5744 powder -- 26.0 grains to 30.0 grains. Top velocity was 1750 fps at 28 grains. Velocity decreased with higher charges and also was a lot of unburned powder. I was hoping for 2500 fps, but it appears that will not be possible with 5744. Also, the case would eject, but action would not stay open.

I did have to modify the sabots by removing some of the rear of the cup -- about .05 inches. The skirt was too thin and was blown apart when passing over the gas hole. Trimming helped a little, but still there was a "divit". I am out of sabots -- so I will put this little experiment to rest (maybe).

[jwest]

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.

Slash,

Gotta admit - I'm a bit jealous!

jwest

[GunNut]

If you guy's are playing around with "sabots". Then, Maybe I'm not that crazy when thinking about 45 colt shot cups. This could also be a great small game gun. Maybe #4 shot for rabbit? Any ideas along this line? I just don't know where to start with something like this.

[Siringo]

If you guy's are playing around with "sabots". Then, Maybe I'm not that crazy when thinking about 45 colt shot cups. This could also be a great small game gun. Maybe #4 shot for rabbit? Any ideas along this line? I just don't know where to start with something like this.

I used 5744 powder and started low (how did I know where to start??? Just interpolated 45-70, 460 S&W reduced charges) to get to the point that the action would stay open. I never got to that point.

I don't see why you couldn't do this, as long as the shot column is contained totally in a shot cup. Most likely, the load will only be able to function as a single shot. I do not know what pressure it takes to hold the action open, but the operating pressure of the 450 is 38K. What do 410 shotgun loads run at -- 12K?

I used to play around with a TC Contender 44 mag shot barrel. I used plastic shot capsules that would get shreaded with a screw on device at the end of the barrel. I could kill grouse at 15 yards, but that was it. With the rifling twist in the 450 and no shreader -- pushing just a regular shot cup -- your patterns would be very open. A friend of mine has the Taurus Judge 45/410 and his 410 patterns are 12 inches or so at 20 feet. Patterns with the 450 would not be any better.

I saw someplace on the net that a Turkish company has made a 410 gauge upper for an AR.

[volt]

Will 230gr FMJ bullets be safe to us for plinking loads in my 450 bushmaster?

[GunNut]

Will 230gr FMJ bullets be safe to us for plinking loads in my 450 bushmaster?

They work great! with 45 gr. of LiL gun. You can thank slash2 for that load.
You might be able to go as low as 42gr. I think that was the starting point.

[GunNut]

[QUOTE=Siringo;2243173]I used 5744 powder and started low (how did I know where to start??? Just interpolated 45-70, 460 S&W reduced charges) to get to the point that the action would stay open. I never got to that point.

I don't see why you couldn't do this, as long as the shot column is contained totally in a shot cup. Most likely, the load will only be able to function as a single shot. I do not know what pressure it takes to hold the action open, but the operating pressure of the 450 is 38K. What do 410 shotgun loads run at -- 12K?

I used to play around with a TC Contender 44 mag shot barrel. I used plastic shot capsules that would get shreaded with a screw on device at the end of the barrel. I could kill grouse at 15 yards, but that was it. With the rifling twist in the 450 and no shreader -- pushing just a regular shot cup -- your patterns would be very open. A friend of mine has the Taurus Judge 45/410 and his 410 patterns are 12 inches or so at 20 feet. Patterns with the 450 would not be any better.

I saw someplace on the net that a Turkish company has made a 410 gauge upper for an AR.[/QUOTE

The shot cups hold (3) 00 @172gr + 7 1/2shot between balls = 193 grs.
I'll try getting the bolt to function will a 185gr bullet first.
Then work on the feed problems with the shot cup.
I think I will start with 25grs of LIL Gun.
13grs with1/2oz of shot = 12K psi;.
I looked @ the turkish T-15 or AT-15. gas piston, duel rod. Bolt is complex and not sure how long it will last.

[Siringo]

General question on AR operation

This question has to do with applicable powders/pressure/bullet speed regarding the AR15 system as used for the 450 Bushmaster. I understand the system is a balance between certain powder burning rates, generated pressure and the time in which the bullet is in the barrel. My concern is using a powder that is faster or slower than Hornady used and a bullet speed that is slower. Meaning the bullet is still in the barrel when the action is trying to open. For instance, if I use a 400 grain bullet that exits the barrel at 1/2 the speed of the factory 250 grain load, but the pressue is realitively the same -- can that stress the locking lugs?

[Siringo]

This question has to do with applicable powders/pressure/bullet speed regarding the AR15 system as used for the 450 Bushmaster. I understand the system is a balance between certain powder burning rates, generated pressure and the time in which the bullet is in the barrel. My concern is using a powder that is faster or slower than Hornady used and a bullet speed that is slower. Meaning the bullet is still in the barrel when the action is trying to open. For instance, if I use a 400 grain bullet that exits the barrel at 1/2 the speed of the factory 250 grain load, but the pressue is realitively the same -- can that stress the locking lugs?

I think I answered my own question. I shot some 400 gr cast bullets today using 4198 and 5744 powder. I started at 19 grs with the 4198 and 20 grs with the 5744. I increased the powder charge 1 gr for 10 rounds each. Action stayed open on all of the powder charges. Velocity was around 900 fps on the low end and at the high charges the velocity around 1400 fps. Lots of unburned powder -- especially with 5744.

I noticed on the upper end of the charges, with both powders, that the cases had shave marks on the base (bottom) from the extractor groove in the bolt face. Indicating to me that two things were happening -- 1. Chamber pressure was now high enough to seal the case against the chamber walls -- 2. Chamber pressure was still high when the bolt was trying to open, most likely because the bullet had not exited the barrel yet.

Primers showed no pressure signs and actually looked very mild. I had used CCI 450 Mags (Small Rifle Magnum).

Velocity maybe needs to be at least 1700 fps (lowest velocity in Hornadys load data) to provide proper timing for bullet exit prior to chamber opening.

Any comments??

[MudBug]

What buffer are you using?

Maybe messing with buffer weight will help with the timing.

[Siringo]

What buffer are you using?

Maybe messing with buffer weight will help with the timing.

I am using the one that came with the rifle from bushmaster (fixed A2 stock). I had an endine hydraulic buffer for a while -- but it was defective and I sent it back to them. HUM!!!! Never got a new one back yet --

[GunNut]

I think I answered my own question. I shot some 400 gr cast bullets today using 4198 and 5744 powder. I started at 19 grs with the 4198 and 20 grs with the 5744. I increased the powder charge 1 gr for 10 rounds each. Action stayed open on all of the powder charges. Velocity was around 900 fps on the low end and at the high charges the velocity around 1400 fps. Lots of unburned powder -- especially with 5744.

I noticed on the upper end of the charges, with both powders, that the cases had shave marks on the base (bottom) from the extractor groove in the bolt face. Indicating to me that two things were happening -- 1. Chamber pressure was now high enough to seal the case against the chamber walls -- 2. Chamber pressure was still high when the bolt was trying to open, most likely because the bullet had not exited the barrel yet.

Primers showed no pressure signs and actually looked very mild. I had used CCI 450 Mags (Small Rifle Magnum).

Velocity maybe needs to be at least 1700 fps (lowest velocity in Hornadys load data) to provide proper timing for bullet exit prior to chamber opening.

Any comments??

No expert here! but, I think we are looking at the same thing. timing! I think the powder has to be fully burned before the bullet passes the gas block! and not exiting the barrel.