Can anyone tell me the maximum distance for a 10.5" barrel with 1:7 twist, shooting a BlackHills 75 or 77 grain bullet?  I looked in the ammo oracle, but didnt see anything that addressed this specific set-up.  Thanks, Jim

Somthing I would like to know as well!  Heeelp!

Ok, does anyone know where I can get velocities of .223 ammo out of a 10.5" or 11.5" barrel?  It can be with any weight bullet.  Trying to decide if it's worth registering my BM as a SBR.  Thanks

Without the velocities you want I can tell you it'll be worth it if you can afford to have both.  Once you reg. the lower as SBR you can put ANY length upper on it.  16" or longer obviously AND andything sub 16".  When you register the lower just write in the space for bbl. length.  "Less than 16 inches"!  Then you have one lower for multiple uppers.  FUN!!!

You will get good frag from a 10.5 barring you don't use it for 100 yrd shots!

I posted the data in a recent thread (within the last month or so).

Forest!  Do you remember the post title?

Unfortunetly not.  BUT I did find an old backup of my PC that had a copy of the Hornady Tests:

Velocity measured at 21'(feet), tests done at 1800' ASL.

Hornday TAP (75gr OTM) from an 11.5" 1:7 twist barrel, velocity is 2361 with a SD of 17.

I posted in somebodys thread the answer a while back--

11.5" Bushmaster- '90 era barrel:

3131A- 2788
SB SS109- 2693
23gr H322, 55 FMJ- 2612

7.5" DPMS:

3131A- 2382
SB SS109- 2345

Either of you guys no how to calculate velocities at various distances with these numbers you provided?   Say up to 50y. or so?  Just curious. Thanks!

Hornady used to have a brochure or something about max. recommended ranges with their rounds from various barrel lengths- I only remember one figure from the brochure but luckily its the one you're looking for!
According to them the 75 gr. TAP round is effective to 50 meters from a 10.5" barrel.

Thank you Sir!  I was hoping for at least that and that is good!

To find velocity at variouse differences you'll need two more items.

1) The BC (ballistic Coefficient) of the round you're interested in (Hornady & Nosler should have them published on their websites).

2) A decent ballistic calculator program.
Here there are lots of FREE options.  Go to [url]http://www.md-ar15.com[/url]
In the Zeroing Methods section (read the text) you'll find two links to online calculators (I'll use the first link occasionally).

If you are a site member (its free & easy) you can download the ones in the Documents section.  I have an Excell based spreadsheet and a Palm/Handspring software product that is good up to 500yards.

In general when using a ballistic calculator you'll need the following:
Velocity of the round
Distance at which the velocity was measured
Ballistic Coefficient of the bullet (BC)
Mass of the round (in grains)

In addition for a more accurate chart you'll need the environmental conditions such as the altitude, temperture, humidity, barometer reading when the measurement was taken.  This is 'nice to have' info, but for most people its really not needed.

Thank you too Forest!  I'm a member at the MD. site as well.  I'll go check it out!  Take care!

Horik

You mean this thread?

[url]www.ar15.com/forums/topic.html?b=3&f=16&t=161182&w=searchPop[/url]


HTH,
--LS

LS,
That was one of them.

IIRC DevL asked (around the time of that thread) for more information and I posted in there.  IIRC I may have posted a chart with either MV or 'effective range' vs barrel length.