ejection problems

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Re: ejection problems

Postby kfbrown14 » Wed Jul 26, 2017 12:17 am

i called it an a2 buffer for some unknown reason its a rifle buffer in an a2 tube === thanks for your patience !!
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Re: ejection problems

Postby Texas Sheepdawg » Wed Jul 26, 2017 7:01 am

KFBrown14,
Welcome to the forum.
Our beloved Mr LeGendre is a bit out of pocket, so I figured I would just elaborate a bit on the 450 Bushmaster cartridge and what Timothy himself has told me numerous times during our little brainstorming conversations. Timothy literally engineered the 450 Bushmaster cartridge around the AR 15 Mil Spec platform. The cartridge is engineered to function perfectly with Mil Spec buffers and springs. If you're using an A1/A2 stock, you can use the Mil Spec rifle buffer and buffer springs. If you're using a carbine collapsible stock, you should use the Mil Spec carbine buffer and buffer springs. There's a difference in the length of a rifle buffer spring and a carbine buffer spring. Make sure to match your springs to your buffers.
As for the aftermarket stuff... well. In my personal opinion, the Mil Spec springs, carbine or rifle, at times are pretty ratty.
My choice is the JP polished flat wire springs that come in Carbine and rifle length.
I'm sure that Hoot is going to chime in on this and he has also designed his own weight system for the carrier.
But generally speaking, the 450 Bushmaster is designed to used on a Mil Spec lower receiver system.
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Re: ejection problems

Postby Hoot » Wed Jul 26, 2017 7:35 am

What TSD said. I have always just used an A2 or A1 stock and the standard spring and rifle buffer. The shorter A1 stock compensates for the added LOP caused by incorporating a recoil pad. That one addition to the A1/A2 stock is the most bang for buck option you can add to this caliber. I use a black, slip-on, SIMS Limbsaver. There are permanent versions now available as well.

If you reload, the brass gets a little beat up during cycling, so I added a DIY version of the Tubbs Carrier Weight System, that's a little easier to open and close the action. I wrote a How To article on making your own, referred to as the Cheap CWS. Link. It retards the BCA cycling a small amount, both when opening and closing. Seems more gentler on the brass and unless your shooting a full auto rig, it doesn't impact functionality. Just to be clear, it is not needed for functionality, just a small enhancement. You could use a heavier buffer instead, but then the weight in motion is back there instead of right at the buffer. That means the heavier buffer will batter more on the back of the BCA, so I chose to keep the weight right in the BCA. If it interests you, the thread in the link will explain.

There are many contributing factors in the proper round insertion and extraction, or lack thereof. Probably the most complex part of the entire platform.

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Re: ejection problems

Postby kfbrown14 » Sun Aug 06, 2017 7:44 am

update--- well I went back to the drawing board which in this case is actually the reloading bench tried a few different BM friendly powders and my best failure free results were with lil gun. after several mags full of test firing I am sticking with the captured spring buffer, hornady 250 ftx and 30.5 grains of lil gun. I don't know the fps yet but I will soon. I have to admit I didn't believe it was my ole reliable buddy == alliant 2400 -- but I stand corrected rifle works flawlessly even with the combination of parts I d0ubted myself thanks for the help from everyone who replied now I am off to chase coastal black bears here in Washington state :)
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Re: ejection problems

Postby Texas Sheepdawg » Sun Aug 06, 2017 9:54 am

kfbrown14 wrote:update--- well I went back to the drawing board which in this case is actually the reloading bench tried a few different BM friendly powders and my best failure free results were with lil gun. after several mags full of test firing I am sticking with the captured spring buffer, hornady 250 ftx and 30.5 grains of lil gun. I don't know the fps yet but I will soon. I have to admit I didn't believe it was my ole reliable buddy == alliant 2400 -- but I stand corrected rifle works flawlessly even with the combination of parts I d0ubted myself thanks for the help from everyone who replied now I am off to chase coastal black bears here in Washington state :)


Can't go wrong with LilGun and the 250 grain pill. I'm saving my 2400 for my 357 Mag. LOL.
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Re: ejection problems

Postby plant_one » Mon Aug 07, 2017 9:51 am

30 grains is probably a little light on the velocity side for the 250 ftx over lil gun, but if youve got a good accurate load, are properly sighted in and know the drops - a deer wont know the difference of 200-250 fps (ish! :mrgreen: )

glad to hear you got your issues worked out.
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Re: ejection problems

Postby Hoot » Tue Aug 08, 2017 5:13 am

That's only a 69% fill ratio at 2.25 COL. The general rule of thumb is not to go below 80% so as not to increase the chance of Secondary Explosive Effect. It is hotly debated around the web. In Theory, (see signature) the up to 4X increase in chamber pressure is not supposed to happen, but it has. If you follow that path, tilt your rifle up before each shot and never point it down at the ground just before raising it to shoot. The point is not to expose any the flash hole above the level of the powder if I read it correctly.

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Re: ejection problems

Postby plant_one » Tue Aug 08, 2017 11:23 am

30grains is almost smack in the middle of the load data provided for the 250 ftx in hornady's 9th. i'm comfortable if hornady published it, its probably pretty damn safe load.

my concern was more about ballistics than safety, but you do bring up a valid - but thankfully rarely occurring - point to consider when reloading... that being achieving proper (read safe!) case fill %. that is the one data piece that i like in the nosler reloading data that hornady doesnt provide. the issue we face is that SEE's are most common with faster pistol type powders like we use in this straight walled caliber.

had a member over on the blackout forum a while back that lost a lower to a likely S.E.E.... he was playing with lighter weight subs and *kaboom*. busted lower, and one helluva bruised shoulder (and ego!) from the bcg smacking him hard. and that was with 1680. the place where he admitted he went wrong was working up on his powder charges a subsonic load and not working the charges down.
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Re: ejection problems

Postby Bmt85 » Wed Aug 09, 2017 10:34 am

I thought the same thing as Hoot, until plant_one said it was in hornady manual. So I pulled out the Hornady manual and the Lyman AR manual.

Hornady: OAL - 2.225" Lil Gun Start - 25.2gr Lil Gun Max - 37.9gr

Lyman AR: OAL - 2.225" Lil Gun Start -34.0 gr Lil Gun Max - 37.5gr

My opinion, I personally wouldn't start lower than 32gr, Maybe a little more if I chose to load out longer than 2.225". But that's just me.
Last edited by Bmt85 on Tue Aug 15, 2017 9:07 am, edited 1 time in total.
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Re: ejection problems

Postby plant_one » Tue Aug 15, 2017 12:45 am

when i did my load testing - with such a broad spread of powder charge - in an efffort to be purely economical with these nearly 70 cent bullets - i started by weighing charges from max and went down .5gr per load for 10 different charges (i fired them low to high of course)

so i really barely tested the upper half of the charge range, starting at 33.4gr and working up to a max load of 37.9gr.... i never bothered to check that data against the Lyman book.... looks like i was running right in their happy range. who knew :mrgreen:
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