300 AAC Blackout

[mikegideon]

Right but being as the whisper and fireball are older cartridges I just figured they might have been considered in the algorithm.

Nope. The algorithm is generic.

[Caster]

Nope. The algorithm is generic.

So it does NOT know specific internal geometry for a given case? Hmm, I can see why you say it's a place to start but not gospel.

[mikegideon]

So it does NOT know specific internal geometry for a given case? Hmm, I can see why you say it's a place to start but not gospel.

Yes. It knows detailed geometry of the case as specified. It doesn't know the slight difference between Winchester and Lapua brass. It knows the bullet geometry and weight. Look at the fields in the screen shot, and you can figure a lot of it out.

BTW, you can edit most of the database fields.

Edited June 27, 2012 by mikegideon

[mikegideon]

Starting the get fired up. Over half of the rifle parts just arrived. I'm thinking it's gonna be a great build. The DD rail is a work of art. The barrel looks great too.

[Caster]

When you get it done, be sure to post some pictures so I can be reminded how broke I am.

[mikegideon]

I will. I'm gonna toss a Nikon scope on it for now so I can check accuracy and work up some loads. Then I may stick a red dot on it. It's gonna be a light carbine.

Edited June 27, 2012 by mikegideon

[Guest nysos]

Starting the get fired up. Over half of the rifle parts just arrived. I'm thinking it's gonna be a great build. The DD rail is a work of art. The barrel looks great too.

Only heard great things about DD rails. On my SBR build I am probably going to get the omega X rail.

So spanning your build out over the next couple months turned into under a week? Sounds like something I would do.

Edited June 27, 2012 by nysos

[atlas3025]

Back to the question of subsonic powder, I have been having good luck with 4227. I am running a 10 inch barrel with pistol length gas tube, cycling fine. I have run it with 200grain, 208 Grain, and 220 Grain bullets. It is pretty quiet compared to 5744 and 1680.

[mikegideon]

I have an Omega on one of my 5.56 carbines. They're great too. The think I really like about the Lite rail is the fact that the gas tube doesn't go thru the barrel nut. So, you torque it to optimum. It's also one piece. The Omega is two piece, so it has flat head screws thru the left and right rails.

Yeah. I was gonna drag my feet on this one. Worked out like all the rest.

[MacGyver]

Yeah. I was gonna drag my feet on this one. Worked out like all the rest.

I can see how having a girlfriend works out to be a better arrangement for you.

[mikegideon]

I can see how having a girlfriend works out to be a better arrangement for you.

Wouldn't have it any other way.

[Caster]

Max case length = 1.368

Minimum = 1.348

So 1.358 would be a good trim length you think?

MIdway is out of the Lee 300 BLK trim tool, but, being the impatient one I am.

I had an extra .308 Win so I cut it down and made one. I cut it down to where it cuts brass right on at 1.358 OAL.

I've got a few hundred to make now, should have them in the tumbler polishing tomorrow afternoon. If I only had the gun

On a side note, I have a new [to me] mold that'll drop a 130g gas check boolit. Should kick butt in the little BLK.

Edited June 28, 2012 by Caster

[Dolomite_supafly]

I am going to use a spare 7.62x39 trimmer to make mine.

Dolomite

[Dolomite_supafly]

Also, my gun will only be firing the heaviest cast bullets I can find. And despite all this talk about using a 8 twist I went with a 10 twist. The reason is it WILL stabilize the 230 grain cast bullet I ordered a mold for. I will be copper plating the bullet to keep leading down. I will be shooting mostly cast, at all weights, which will stabilize better than a jacketed bullet even if both are the same length. A 10 twist will also stabilize jacketed 220 grain bullets as long as they are not the VLD types.

And why choose a 10 twist over a 8 twist? Because, as with AR's, too fast of a twist and the bullet will just pass through the "soft" target. And with the bullets travelling as slow as they are the penetration will be measured in FEET, not inches, with the BLK. Here is a good chart showing velocity vs. penetration with 30 caliber bullets:

http://stevespages.c.../bestbullet.jpg

Notice the Sierra ProHunter penetrating over five, YES 5, feet when the velocity drops below a ceratin point. And even the Remington at 1,400 fps still makes it 21". And these number are in flesh, not newspaper or ballistic ge

With a 10 twist almost every bullet I shoot will tumble inside a "soft" target rather than just pass through. And when they tumble I will have a wound channel that will be over 1" in most cases versus a pass through wound channel that isn't much larger than the bullet if at all. And even as velocity drops tumbling becomes more likely while HP's it becomes less likely.

I have done a lot of testing in the past with subsonic 308 bullets and before I shot 180 grain bullets I shot out of a 7.62x25 bolt gun. That bullet at 1,050 would tumble in 6"-10" of water with the 10.625" twist. I am hoping to duplicate whcih it should because the difference between the two calculations using the Miller formula is .07, 1.89 vs. 1.82. And the 180 Tokarev load was a 1/2" shooter at 100 yards. I am very hopeful my cast bullets will do at least twice that.

I will probably use a 17" barrel and make it similar to my wife's 45 ACP bolt gun. I am thinking I will make install iron sights and zero them for 50 yards. Then I may add a Matech sight and check the 200-600 yard elevation adjustments to see what ranges they correspond to with the subsonic 230 cast bullets. I may also try an optic while testing but I think I will use irons because of a newfound respect for iron sights. I have spent the better part of a decade looking through optics and up until recently I have forgotten how fun, reliable, accurate and useful they really are

Dolomite

[jcoosi]

They have a 17" 1:12 twist in stock what would be issues to going to that twist rather than staying in the 1:10?

http://savage-barrel...m/inventory.htm

Nevermind checked more on the sight and a 1:12 are ideal for up to 170gr bullets

Edited June 28, 2012 by jcoosi

[mikegideon]

Mine wound up being 1:8.

BTW: Where can I find a stock of UMC supersonic ammo at a decent price around Nashville?

[Dolomite_supafly]

Nothing wrong with 8 twist but I feel 10 twist is better suited for what I am doing with it.

I just made a case trimmer for the BLK using an extra 7.62x39 trimmer. I had to drill the hole for the pin a little deeper to support the pin. After trimming the body of the case trimmer back the pin fell out. But now it is done and looks great. I tried using solder to hold the pin in but I ended up just staking it in place. Time will tell if it is durable but it should be good enough for now.

It will trim at 1.360". I could go shorter but I want as much neck as possible to support the cast bullets I will be shooting. And I suspect with the subsonics I plan on shooting the pressures will not be excessive which should keep case growth in check.

I am going to use a Harbor Freight mini chop say to cut cases. I just did one and it will be easy to do providing I keep my fingers out of it.

http://www.harborfreight.com/bench-top-cut-off-saw-42307.html

And now I am totally done for the day. Already did too much today so now it is time to go back to bed for a few hours to try to make my back tolerable again.

Dolomite

[mikegideon]

If I wind up doing my own cases (and that's a big if), I have an RCBS power trimmer that was made for this kind of stuff.

[mikegideon]

Parts are all here! Time to make a rifle.

BTW... I wound up with a spare upper receiver. CMT flat top with parts kit installed and NO M4 feed ramps. Wound up going with a stripped Yankee Hill with M4. Found it after I ordered the other one. Slim pickin's out there.

[Guest nysos]

Parts are all here! Time to make a rifle.

BTW... I wound up with a spare upper receiver. CMT flat top with parts kit installed and NO M4 feed ramps. Wound up going with a stripped Yankee Hill with M4. Found it after I ordered the other one. Slim pickin's out there.

I used a stripped yankee hill a3 flat top with m4 feed ramp on my build and was very satisfied with it. I was disappointed in finding a minor ding on the underside of the forward assist where they slipped installing a pin.

When can we expect pictures?

[mikegideon]

I used a stripped yankee hill a3 flat top with m4 feed ramp on my build and was very satisfied with it. I was disappointed in finding a minor ding on the underside of the forward assist where they slipped installing a pin.

When can we expect pictures?

If they installed a pin, then it wasn't stripped. I have to install the forward assist and flapper. I'll probably have it done tonight if I can get started. It will take more time to straighten up the gun room and bench than it will to build the rifle. I have all the tools, and don't have to look at the instructions.

[Guest nysos]

If they installed a pin, then it wasn't stripped. I have to install the forward assist and flapper. I'll probably have it done tonight if I can get started. It will take more time to straighten up the gun room and bench than it will to build the rifle. I have all the tools, and don't have to look at the instructions.

"Partially assembled" is how I think they are labeled, dust cover and forward assist installed. No bcg or anything else. I still consider it stripped as the forward assist and dust cover are so minor.

Edited June 28, 2012 by nysos

[dlm37015]

i have both lee and redding dies i think lee work best in the 300 blackout

[Caster]

David's right, the Lee dies work very well. I made several today.

Months ago when I wanted to get into this caliber I bought a set of Forster dies. Money NOT considered, the Lee dies I bought from David are leaps and bounds better. Add to that being cheaper, WIN!!

[mikegideon]

I'll get mine from David.

My upper is built. May start on the lower tonite too.