Tricks to loading extruded va ball powder?

[C.W.M.V.]

If you don't trickle with non ball. You're wasting your time looking for accuracy.

RCBS chargmaster combo disagrees.

[Kwikvette]

RCBS chargmaster combo disagrees.

I run the same, but feel inclined to buy one of these - https://www.amazon.com/FX-120i-Preci.../dp/B00GP0IMPO

[C.W.M.V.]

I run the same, but feel inclined to buy one of these - https://www.amazon.com/FX-120i-Preci.../dp/B00GP0IMPO

Well, ahem...you do that lol

[smoothy8500]

What's interesting is over the years I have read articles in American Rifleman or other shooting periodicals that checked the powder weight "precision" in various ammunition such as Federal Gold Medal Match. Everyone uses Fed GMM as the standard for accuracy. Yet, when broken down it has a swing of .2gr +/- from the average. Hmmm, that's almost a half grain....anyways, who reads magazines anymore?

[C.W.M.V.]

What's interesting is over the years I have read articles in American Rifleman or other shooting periodicals that checked the powder weight "precision" in various ammunition such as Federal Gold Medal Match. Everyone uses Fed GMM as the standard for accuracy. Yet, when broken down it has a swing of .2gr +/- from the average. Hmmm, that's almost a half grain....

[OpenSightsOnly]

What's interesting is over the years I have read articles in American Rifleman or other shooting periodicals that checked the powder weight "precision" in various ammunition such as Federal Gold Medal Match. Everyone uses Fed GMM as the standard for accuracy. Yet, when broken down it has a swing of .2gr +/- from the average. Hmmm, that's almost a half grain....anyways, who reads magazines anymore?

FGMM has brand new brass with consistent neck tension or bullet hold for some

The 2/10th of a grain variance may or may not matter depending on the rifle.

What I would like to see is the vertical of FGMM and rifle combo at 600 yards.

[CK_32]

RCBS chargmaster combo disagrees.

You do realize that trickles at the end of the charge poor right?

[smoothy8500]

What I would like to see is the vertical of FGMM and rifle combo at 600 yards.

You are absolutely correct, we never see that tested. We always see write-ups at 100, maybe 200yds.

[C.W.M.V.]

You do realize that trickles at the end of the charge poor right?

Ah ha I see what you did there lol


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[tonyjr]

OpenSightsOnly
FGMM = ?

[Kwikvette]

OpenSightsOnly
FGMM = ?

Federal gold medal match.

[tonyjr]

Thank you , I had FGM = Federal gold medal , was not sure if the same and you know about assuming .

[C.W.M.V.]

Well, I suppose if it’s in one of those ‘flat spots’ it wouldn’t matter.
I didn’t believe the ‘flat spot’ thing till my own data showed it.


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If I may quote myself-this whole flat spot stuff planned out again this weekend.
A2520/CCI 41 at 24.1-25.5 and Tac/CCI 41 23.6-25.0
The spots were small, only 3-5 grains wide, but definitely there. Possibly because it’s 5.56 vs a heavier round? Smaller weight bullet, smaller capacity, powder charge, primer etc?

Anyway, there was a low node at about 24.3 with a2520 and a high at 25.2. The low node was not as solid and had more variance than the high where velocity only changed 2fps. This was also the spot with my best group of .6 in other tests with 2520. Velocity was 2786 (holy f$&@!).

With Tac I had the start of s node at 24.4 grains, this was the start of s flat spot and my best group in an earlier test with Tac, .5 MOA. Velocity of 2716 FPS.

So it looks like A2520 is the powder for me. Good velocity and regardless of charge rarely gives me a group larger than 1 inch. Last time I ran it I shot 6 5-round groups, all but one sub MOA (and I called the flyer) average overall 6 groups was .880.

Also shot some BH mk262 red box, 2731fps at ~60* from my Douglas SPR barrel.

So accurate and faster than mk262-I’ll take it.

[divingin]

RCBS chargmaster combo disagrees.

CM does trickle.

[divingin]

It doesn't seem intuitive that the harmonics is purely length and bullet speed related. My instinct says that barrel stiffness (thickness) would also play a role in determining the harmonics,

Barrel harmonics are primarily affected by the material they are occurring in. Stainless and CM barrels are pretty close in how pressure waves propagate through them, so you can pretty much treat them as the same. Stiffness may limit how much swing you get out of the barrel, but the speed will be the same.

Theory, as I understand it, is this: When you set off a cartridge, the initial explosion sends a shockwave through the steel of the barrel. That wave propagates to the muzzle, and gets reflected back to the breech, and repeats the travel several times, all while the bullet is moving towards the crown. You want to get the bullet to leave the muzzle when the shockwave is towards the back end of the rifle, as it will have less effect on the muzzle at that point. Powder tuning is all about catching that lull at the muzzle and tuning to get the bullet to exit at that exact time. This also explains why you may have several nodes: you catch one lull or the next, depending on the bullets barrel time.