2f or 3f 777 in 50cal?

[txhunter58]

How will they ever know you used 3f?

The only difference in 2f and 3f is granule size. So you are using more "weight" when you use the 3f. If you weighed charges, there should be no difference because it is exactly the same stuff! I would definitely use less volume and 10% less would be a good starting point.

I use 85 gr of 3f and a 460 gr bullshop in several of my rifles (don't own a CVA)

 

[MrTom]

The only difference in 2f and 3f is granule size. So you are using more "weight" when you use the 3f. If you weighed charges, there should be no difference because it is exactly the same stuff! I would definitely use less volume and 10% less would be a good starting point.

The burn rate is significantly faster with the 3f and it will generate its maximum pressure faster. 3f is considered pistol powder....short barrels require faster burning powder to burn completely and develop the energy needed to be effective. Using the same volume or weight of 3f as 2f will develop a lot more pressure faster. Gotta be careful here. That's why I suggested the 10% reduction in the powder charge and I'll clarify, that would be for the 240 grain pill. I personally would cut back by 20% as a starting point if I were going to push a 300 grain using 3f T7 granulated.

From what I have seen charted for different powders the T7 2f, rifle/shotgun powder, generates pressures very close to the Blackhorn 209 powder for equivalent charge sizes between the two and both generate the highest pressure faster than Pyro or most black powders [I say most because I haven't seen all listed for comparison]. 3f T7will generate its maximum pressure faster because its burn rate will be faster. In a given charge with a given bullet weight in a given barrel length, the T7 3f will peak much quicker and its the spike in the pressure with a very short duration that will make id way more sensitive to play with. If you're working with 3f T7 in lieu of 2f the loads have to be backed off to start for safety sake. You can always work up in charge slowly. Assuming it is "exactly the same stuff" could have some not so nice results.

 

[GM54-120]

Warning: The above graph depicts 150 grain volumetric loading pressure traces measured under laboratory conditions via radial transducers. These loadings that MAY be in excess of manufacturer’s recommendations. The highest pressure load combinations depicted here are recommended and touted by many: Knight Rifles, Hornady, Thompson, and others. I do not suggest their use, for obvious reasons.

Now here is the kicker. 85gr by weight of BH209 (roughly 120grV) and a 300gr sabotless wont even break 27kpsi in a 45cal.

 

[MrTom]

According to the top chart that GM has posted I'll stand corrected.

I saw some other charting elsewhere and will try to locate it again but it would be maybe a year and a half old now.

 

[GM54-120]

It is odd isnt it. One would think that T7 3FG would create significantly higher pressures than T7 2FG.

CHART A indicates peak pressure at equal charge volumes.

 

[james 14]

And what's the maximum safe pressure for a ML? Assuming 27kpsi in a 45 is below that point.

 

[txhunter58]

That chart is interesting because I would have thought 3f would have given more pressure too. However, unless I was misled, the only difference between 2f and 3f is the size of the granule, so the same volume of each, 3f should weigh slightly more because the smaller granule should pack down tighter. So I would think at least you would be more velocity out of 3f.

And talking about BH 209, if it has basically equivalent pressure to 777, why does it have some much more blowback?

 

[sabotloader]

Are you guys pulling & cleaning your breech plug every time?

After shooting at the range I do - but during hunting season not a chance until the hunt is over of if I feel the bore got wet...

 

[CatamountRob]

And talking about BH 209, if it has basically equivalent pressure to 777, why does it have some much more blowback?

Different pressure curve maybe? Maybe the peak pressure is the same but maybe BH209 spikes sooner?

 

[sabotloader]

And talking about BH 209, if it has basically equivalent pressure to 777, why does it have some much more blowback?

Different pressure curve maybe? Maybe the peak pressure is the same but maybe BH209 spikes sooner?

I would suggest the opposite of that... In most cases BH never reaches the same peak pressure that T7 or Swiss does. BH is a smokeless 'progressive burning' powder. With the 'progressive burning' properties BH burns slower and longer - so while it doesn't reach the peak pressure that T7 does (when loaded grain for grain, but it burns longer and creates more total pressure creating a higher projectile velocity - DEPENDING on the weight of the projectile. 120 grains of BH will normally create about 100/150 FPS with a 300 grain bullet than does the same load of T7. As the weight of the projectile goes down so does the efficiency of BH.

 

[txhunter58]

I just know that there is a lot more indication of blowback pressure on the primers, sometimes to the extent of expanding them so they are hard to remove from some breechplugs.

 

[Dougs136Schwartz]

Why does triple 7 pellets create more pressure than loose powder ?