Highest Velocity 180gr POWDER in my AR

[Pablo]

Longshot?

A #9?

BlueDot?

I have to know. Go!

(yes I know I need a chrono)

[The_Shadow]

It depends how you want to push it LongShot has been used in SwampFox Ammo up to 10.6 grains with 180 Gold Dots

180gr  Speer Gold Dot JHP    1340 fps    LongShot    10.6 grains
180gr  Remington GS BJHP    1325 fps    LongShot    10.0 & 10.2 grains (I stop my load @ 9.4 grains with the 180's)

200gr Hornady XTP       1240 fps   LongShot      9.4 &   9.6 grains  (I stop my load @ 9.4 as SMILES have occurred above this charge weight in some makes of brass)
200gr Hornady XTP       1325 fps   LongShot      9.7 &   9.9 grains  (these were known to be too much for some guns and setups)


The longer barrel will be much higher velocities and not sure how the AR will handle the impulse...So use at your own risk!

[Pablo]

Thanks!

I've done 10.5gr Longshot and 180gr with no issues at all. Gun loved it!

Have you seen anything for Blue Dot or #9?

[Benchrst]

PP, 800X, Blue Dot, #9 - They'll all get you there, but Longshot does it before pressure issues raise their ugly head.

At least in a short barrel.

[DM1906]

Blue Dot

HS-6

Unique

AA7

In that order. Longshot plateaued much earlier than the others before maximum case capacity (well above published maximum). 2400 and AA9 were the climbing performers, but ran out of case capacity before reaching comparable velocities. Testing was with a Mechtech 16.25" barrel, which is blow-back action. YMMV.

[The_Shadow]

Blue Dot loads I personally load and shoot are all hand weighed and verified from my S&W 1006 5", how they do from the AR I have no info, so that's on you and your setup!

180gr  Hornady XTP    1325 fps    Blue Dot    11.2 grains COAL 1.2525" CCI 350

200gr  Hornady XTP    1225 fps    Blue Dot    10.6 grains COAL 1.2525" CCI 350

[sqlbullet]

While there are guys on here that will argue with me, the physics is pretty clear.  The powder that provides the best velocity in your Glock will also provide the best velocity in your AR.  The amount of additional "burn" or gas expansion that occurs after the first .5-.75" of travel is inconsequential compared to the increasing volume of the cylinder that gas has to fill.

To put this in perspective.  Assuming a 180 gr XTP bullet loaded to 1.250" the initial case volume is about 0.804 cc.  By the time the bullet has traveled a 4.6" barrel while burning about 9.5 grains of powder, the volume of the cylinder has increased to 9.504 cc.  That is an increase of 1,082%.  Between 4.6" and 16" the volume increases to 32.938 cc.  The increase in volume is 4X as much, 3,995% original volume, as the original increase between ignition and the 4.6" barrel travel.  In order for a powder change to have a meaningful impact the powder would have to be expanding in volume at an explosive rate, not a burn rate, after 4.6" of travel.  Gunpowder doesn't work that way.

Someone who doesn't agree with me will be along and cite a couple of guns they have and how one with a longer barrel turns in a much better velocity with a slower powder while the one with the shorter barrel likes a bit faster powder better.  I don't doubt that is true.  That is why we have a wide variety of data in load manuals...Some guns will "like" one powder better than another.  I would respond that IF they were willing to take a hack-saw to that longer barrel, it would still like the slower powder better the shorter it got, and if there were a way to grow the short barrel without changing it's characteristics, it would continue to like the slightly faster powder better.

Handloader runs an article on this about once each decade.  They take a test barrel, work up the best loads and start cutting down, and when they get to the bottom the same loads that were fastest in the longer barrels are still the fastest in the short barrels.  Any deviation is well within the margin of error.

800X, #9 or Longshot are going to shine.  #9 will be the most expensive by about 2 times, and 800X won't meter well.  And Blue dot will be about 50-100 fps behind, but will be available, meter well, work well across all your magnum pistol calibers.

[Pablo]

Awesome information. Thoughtful thread!

[The_Shadow]

The Glock 29 with the 3.78" factory barrel shows slightly less velocity than the Glock 20SF factory 4.6" and basicly they are the same just shorter.  However 800X showed closer velocity numbers using those two with the same loads.

Blue Dot, does better with a hard crimp that's not available with the 10mm, but the accuracy has been amazing.

[Benchrst]

Blue Dot

HS-6

Unique

AA7

In that order. Longshot plateaued much earlier than the others before maximum case capacity (well above published maximum). 2400 and AA9 were the climbing performers, but ran out of case capacity before reaching comparable velocities. Testing was with a Mechtech 16.25" barrel, which is blow-back action. YMMV.

Really? HS-6 & 180's haven't worked worth a squat for me (5.15"). In fact, my experience has been HS-6 / Unique / #7 all shine with 155s & down.

[Pablo]

#7 no good for velocity in 10mm.

People are claiming BD the fastest, and I struggle with that.

[The_Shadow]

BD is good powder and makes good velocity at reasonable pressures, however LongShot and 800X will make higher numbers realistically! 

[Benchrst]

#7 runs right there with Longshot behind 155s, at least for me. Just added N105 & N350 to the repertoire, look forward to wringing those two out.

Gonna run the 180 XTPs with Longshot up to 9.6 next chrono session. Hopefully the Pressure Trace II is ready for it's maiden voyage by then (PT II in hand, barrel & 'platform' design in a skilled machinist / gunsmith's hands).

[DM1906]

Blue Dot

HS-6

Unique

AA7

In that order. Longshot plateaued much earlier than the others before maximum case capacity (well above published maximum). 2400 and AA9 were the climbing performers, but ran out of case capacity before reaching comparable velocities. Testing was with a Mechtech 16.25" barrel, which is blow-back action. YMMV.

Really? HS-6 & 180's haven't worked worth a squat for me (5.15"). In fact, my experience has been HS-6 / Unique / #7 all shine with 155s & down.

I don't generally use HS-6 or AA7 for anything 10mm. I don't usually use Unique for 10mm either, but I have loads worked up for everything I shoot. I worked up loads for my son's .40SW Mechtech, and it was HS-6 all the way for 155 gr. Barnes and 180 gr. XTP rounds. I was working up the load for the 10mm Mechtech and thought what the heck, and tried them. They did well, but I discarded both as prospects. As you said, they do very poorly in short-barrel 10mm, in my experience (including the LWD tactical length barrel, which I use a lot), but the question was in regards to rifle load experience.

Unique is listed and kept as a prospect only, well, it's Unique. It may not produce the highest potential of most rounds, but it will produce respectable performance in ANY round. Rifle, shotgun, and handgun.

[TonyRumore]

11.9gr N105 behind a 180gr Speer GD went 1391fps from my 6" Witness.  CCI300, RP cases, 1.260"

I only fired three shots.

1390fps
1392fps
1389fps

In the 6" 40 Super, running 15gr of N105, it will drive the 180 to 1565fps.

Do not try these loads unless you start low and work it up in your gun.

Tony