M99 and 750gr AMAX

[50boomer]

Sorry do not frequent this forum that often,shooting the vv20n29 with my personal trials if the weather is below 90 degs.( the round below 90 degs.) The powder does not burn as consistent as if heated. The actual cut off of temperature is debatable, but shooting the same ammo loaded on the same day and shot in the summer heated above 90 and shooting in April without heating 48-50 degs. the accuracy was amazingly worse in April,I had several rounds fall short of target and have never had it happen before. Again some say this is blowing smoke voodoo but several of the top notch record holders use this technique. Although they are alot more experienced shooters than myself( as far as being accurate and amount of rounds down range at 1,000 yrds. Also would like to invite any interested shooters or observers to the shooting match at Quantico this June 20-21 with practice Friday afternoon, more info if needed contact me at 50boomer@gmail.com or go to the FCSA home page, easily found with a search. Cell phone is 352-302-3911.

[flyjets]

Just a stab at this but I'll try and explain.

When the Bullet is projected outward from the casing the powder sets off a charge amount. If the charge goes uniform it's frequency is different threw the barrel. A uniform burn rate produces more consistant results.

What I mean by that is similar to a rock hitting the water. We have all seen the rings or shock wave effect. The same thing happens inside your barrel.

It's critical that the Bullet exit the Muzzle at a time when the Barrel is at it's smallest. This is why a figure exists for optimum barrel time.


Hopefully this makes sense to everyone and explains why Powder Charge combined with Barrel frequency are critical.

Ian

[Shadow]

Sorry do not frequent this forum that often,shooting the vv20n29 with my personal trials if the weather is below 90 degs.( the round below 90 degs.) The powder does not burn as consistent as if heated. The actual cut off of temperature is debatable........

Well, in addition to barrel harmonics (which is an explanation to another reality, in precision shooting), the optimum temp. for "vv20N29" IS about 120-130 deg. F. Some precision shooters use a thermal sensor (or whatever they're called, nowadays) to measure the temperature of their ammo. If not warm enough you could warm it in the sun (or use car heater).

IMO, H50BMG has proven to be a temperature-stable propellant that is consistent in velocity over a wide variety of temperature variations. 20N29 is great powder but it's consistency is limited when NOT maintained at a constant temperature over 90 degrees. Using such powder when its temperature stability is critical for hunting and/or tactical applications, just doesn't seem prudent. Unlike match shoots, these applications don't lend themselves to keeping ammo at a uniform 120-130 deg F.

As for me, I've never been bothered with such mental gymnastics, I only shoot that cheap frenchy ammo.

[Hognuts]

I bet

[flyjets]

Another day of Testing the 50BMG

Today I tried another series of loads at 575 yards.

Conditions
90F
80% Humidity
10 mph 90 degree x wind.

750 Amax seated at 5.750
210gr H-50 powder
CCI-35 Primer
Brass was Barrett

M99 32" Barrel
NightForce 5.5*22*56 zerostop
Bipod supplied with the M99 and the Monopod option.


Shot 3 series 5 shot groups
Best one measured 2.35 at 575 yards.

There is room for improvement using a front precession rest and a rear rest.

Under ideal conditions I now think it may be possible to break the 4" 1000 yard M99 record.

Ian