So this is a 221 fireball casing.  I received my Redding 221-300die set today and expanded it to .270. then changed the cone forcer thinggymabobbit(technical term) to the .30 cal one and pushed it to .30. Much resizing lube was used and it expanded smoothly.

7.5 grains of Accurate #5
220 grain Hornady interlock .308 bullet
CCI #41 primer
Which according to quarterbore should be about 1045 FPS

Next to it is a random 5.56 I grabbed from a magazine for size reference.

Questions:
Does that look weird or what?
I did not seat the bullet all the way down to the collar because as you can see, this is the proper length. I am worried if I go the extra few mm it might cause problems in the magazine.  On the other hand, not being seated all the way in might cause the bullet to engage rifling to soon.  I do not have my barrel yet to test that theory.  It is a really long bullet, so there is already plenty of bullet inside the case.Comments? Advise?

Yes they look funny. I've got several friends with them


I want one BAD

Yeah funny and cool all at the same time.

If you ask me, I think the .223 is the funny looking cartridge with its diminuitive projectile, har har.
Nothing funny about 500gr subsonics..

Well I like it   though do these still fit in a standard 30 rnd AR mag

Yep.

I have just started on the 300 whisper a few weeks ago myself and it has been a lot of fun.  I have had to seat my bullets deaper than my usual 556 mag length because the bullets were engaging the rifliing (not a problem I was used to with 556).  Using some surplus resized 147gr bullets, my COAL was 2.16" (which was below the cannelure) and I dont remember right now what my COAL was for my 180gr bullets were.  I have some of those 220gr bullets as well, but I haven't tried them yet, though I would be suprised if you didn't need to seat them to at least the cannelure.  

Also, you may have issues with aa#5 being too fast burning to fully cycle the action.  SSK doesn't recommend any powder faster than aa#9 be used.  My barrel is 10.5" with the pistol length gas system and I have tried aa#7 and the rounds were ejecting, but the bolt wasn't going far enough back to strip the following round out of the mag.  I was using a lightened carbine buffer (one of the three weight removed), but I had a full auto bolt carrier.  I am going to try it again with the semi auto carrier, but I am also going to try using some H110 that I have on hand as well.

Thanks! I have every thing ready to go except my barrel. I am waiting on it from SI Defence. 16" carbine gas system.  I also have a gas tube with a regulator on it.

With the short OAL rounds are you having any trouble with them coming out of the magazine?

I got my load from here. First one. http://www.quarterbore.com/300whisper/subsonic.html

Down at the bottom is SSK's mention of not using anything less than #9. I don't plan on doing this load wide scale. I just happened to have 220 grain bullets and AA#5 on hand and wanted to have a round in my hand. I am going to pick up some slower powder this weekend.

My 220gr RN is seated the same as yours.  When you get your barrel, paint the bullet with a Black marker then chamber then remove. Check for Rifling marks.  You can seat some longer if you want to find where your rifling starts, then seat it deeper to use.  I use Lil Gun 9.5grs with the 220gr RN and 9.2 with Speer 200gr SP.  Each barrel can shoot a little different, so you will need a chrono to get your speed where you want it.

Are you guys getting RN bullets to feed in an AR?

I thought it didn't really work well.

I love my 300 Whisper so far but there is one annoying thing.

The damn bullets fall over from being so top heavy.  

Very nice.

I certainly hope there is no problem with round nose bullets. I have 200 of them I bought specifically for 300 whisper.

While these may fit in the mag,have you actually chamber checked these rounds??? I've seen numerous 300/221 barrels that would only accept rounds with a completed ogive max length around +/-1.60". I've got a sneaking suspicion that those rounds are a little long.

Good point

I haven't even tried to load RN rounds that heavy in an AR because I don't think they would reliably chamber but also I would have to make them way short in my rifle.

I have a pretty short throat so it's funny how it works out like Dusten mentioned above.

I can load a 208 grain A-Max or 220 SMK to mag length but not a 147 grain FMJ, 168, or 175 grain milsurp BTHP.

This also makes me realize how much ogive variation there is in the cheaper milsurp BTHPs.

I am going to order a Sinclair bullet comparator because I really need it for 300 Whisper.

I grabbed my dummy rounds that I use to get my seater die pretty adjusted quickly.

This will show you how varied the ogive is on my bullets.



left to right: 147 FMJBT, 168 milsurp BTHP, 175 milsurp BTHP, 208 A-Max, 220 SMK, 240 SMK

Um....

You stated that you may have to seat the bullet all the way in if it engages the rifling.

We are guessing you think all the way in is to the cannelure.

I think what he was trying to get at is that the 220 grain RN will probably need to be seated past the cannelure if you have a short throat.

Possibly well past the cannelure.

I get that, but the specific question on if I had chambered a round or not was specifically stated in the OP.  I will try it out when I get the barrel.

I can test my chamber with a 180 grain so I can see where the ogive is on these RN bullets.

This will give you a similar idea of how short it may be but obviously your 220s are going to have way more bullet in the case.

BTW, what barrel are you getting?

Hopefully they work out for you.

Definately keep posting about it as this caliber is my new disease.

SI Defense 16" carbine gas system. http://shop.si-defense.com/SI_Defense_16_300_Fireball_Barrel_p/si%20ar15-b-300f-16.htm

It is going to be a nice build. I have everything but the barrel. I ordered it 2 weeks ago.  Wait is 4-6 weeks, so we will see.

Total build:
SI Defense barrel
Standard AR upper
Adjustable gas tube
YHM low profile gas block
YHM Rifle length railed free float handguard
YHM QD suppressor mount
YHM 7.62 phantom suppressor
FDE color ladder rail covers
Black vertical grip
Magpul CTR stock FDE
Magpul MIAD grip FDE
Magpul black MBUS front and rear
Larue Eotech mount
Eotech 512
Larue magnifier mount
Aimpoint magnifier


Should be nice. I'll do a write up on it when I get the barrel and finish the build.

The last 2 boxes of Horn 220gr RN that I bought has the entire nose covered with lead and it drags and lets the lugs cut in.  Causing me some problems.  The Sierra 220gr RN looks better, but have not found any in stock.

That is what I was afraid of with these guys using the Hornady RNs in an AR based 300 Whisper.

So the entire nose is lead instead of just the tip like the ones I have?

Hmmm.  Well, I will report if I have trouble, and I only bought 200 of them, so worst case I can sell one box and use the rest in my M1A.

I have some Sierra 210 grains on order too.

What I would really like to do is find a sub sonic load using 185's
I have a ton of 185 grain bullets.

Midway's pictures make the Hornadys look like they have less exposed lead than the Sierra's.

Hornady



Sierra



If I am just punching paper I really see no need to go with the heaviest bullet if I can get a less expensive one to work.

My rifle will cycle 175 grain BTHPs at 1000 or 1050fps and carry to 300 yards.

I believe the lighter bullets will not buck the wind as well but the drop should be similar as velocity is more of a factor in drop than bullet weight.

I am not hunting hogs so I do not need the energy of the heavier rounds either.

I am working up loads with the 220 and 240 SMKs but those will be set aside for special occasions.

I agree 100%  I have a ton of 185's, 165's and 150's.  I ordered the 220's because all of the subsonic loads I find online are 200+ grains.  Do you have any lighter..yet subsonic loads you are willing to share?

Definately but remember there are so many differing factors in this caliber that you need to be careful and work the load up watching for any warning signs.

The 175 milsurp bullets I got are very inconsistent, have varied ogives, and do not replace a 175 SMK so be aware.

Pertinent Rifle Specs-
10.5" SS barrel 1x8 twist chambered and finished by Teppu Jetsu
Pistol position gas port 0.125” diameter
0.75" 3 position adjustable gas block by Paladin Machine Services

Four main subsonic loads so far:
175 milsurp BTHP, H110 powder, 9 grain charge, Win SR primer, LC case trimmed to 1.355", COAL 1.14" - 1010 fps in 90 degree weather
175 milsurp BTHP, H110 powder, 9.5 grain charge, Win SR primer, LC case trimmed to 1.355", COAL 1.14" - 1062 fps in 90 degree weather

208 A-Max seconds, H110 powder, 9 grain charge, Win SR primer, LC case trimmed to 1.355", COAL 1.25" - 983 fps in 90 degree weather
208 A-Max seconds, H110 powder, 9.5 grain charge, Win SR primer, LC case trimmed to 1.355", COAL 1.25" - 1030 fps in 90 degree weather

All four of these loads cycle my rifle with the gas wide open and lock the bolt back with my suppressor on.

The 175 loads work even without my suppressor but I need to test the 208 loads without it to see if they lock the bolt back as well.

I am working on figuring out the real world drop and so far I am estimating a 3.5 mil (25.2") drop at 200 yards and a 7.5 mil (81") drop at 300 using the 175s and 9.5 grain charge of H110.

These drops have not been 100 certified as I had a good 10+mph wind but should be pretty close.

A few things then:

-I would not load up too many rounds of anything until you have a barrel. You're still dealing with a wildcat here. We've talked about seating length, but there is also neck thickness and the shoulder to consider. More then likely you won't have a problem, but it would be a shame to get a bunch loaded up and then discover they won't work.

-Also noticed that you're running carbine gas. I can almost assure you that AA#5 will not cycle the action. You probably need to be looking at powders along the lines of AA1680 to ensure it cycles. While there are plenty of loads out there with faster powers, I would consider AA#9 about as slow as I would want to go with carbine gas, and even here the loads may be finicky.

Thanks!

Looks like I need some powder.
I have AA5, AA2520, AA2230, Varget, Titegropup, Clays, TrailBoss, HS-6

Nobody mentions those powders as viable.   Figures

Thanks.  Yeah I only loaded 4 rounds. I will wait for my barrel to come before doing much else.

Yeah I picked up a pound each of H110, AA#9, and 2400 as they seemed to be the most commonly referred to for loads.

Some people say H110 is very temp sensitive but I have not had a chance to test in varied temps.

Ok.  I just placed a midway order.
Alliant 2400 Smokeless Powder 1 lb
Hodgdon H110 Smokeless Powder 1 lb
Accurate 2015 Smokeless Powder 1 lb
Accurate No. 9 Smokeless Powder 1 lb

Nothing makes you spend money like ARFCOM.

I threw in the AA2015 because I see that in some supersonic loads and I'd like to try my hand in that and since I have to pay the hazmat fee anyway I might as well throw it on there now.

Not sure if you had seen this link here or on Quarterbore but it is the Sierra page for 300 Whisper loads.

http://listmequick.com/300/Sierra300whisper.pdf

Outstanding! Thanks!

Now these look a little more proper.

180 grain bullets with 9.5 grains of H110
.223 rem brass reformed and trimmed to 1.355"

The whole dang gun is ready except the barrel.  Still waiting.  I have a bunch of brass, bullets and now proper powders to start trying things, but no barrel.

I only made 5 and will not make any more rounds until the barrel comes in.

I will have to try and form some nickle cases from .223.  I know nickle is more brittle though and probably a no-go.

I like the contrast with the black bullets, don't see that very often with Whisper loads.  For me H110 was a little finicky with subosnics with my carbine length gas.  I ended up going with AA1680 and have had good results with 220gr and even 150gr subsonics.  I still use the H110 in supersonic 125gr loads.  

I've been hearing Lil Gun mentioned and am planning on picking up some to try in the Whisper and my 450 Bushmaster.