Trailboss/Unique hitting high

[DirtyOz]

Quite a while back I cast and fired some 44 mag loads using Trailboss, unique and w296. If I remember correctly I used the TB 70%formula. Unique was 7 gn, and w296 was a near minimum load. All were pushing Lee’s 430-310RF I believe.
I shot these from both a 14” Contender and a Ruger 96/44, and maybe my 1894 Marlin was in the mix as well.
I don’t own a chrono yet, but the W296 loads were a much higher velocity than the fast powders according to the load data.
My question is why is the point of impact so much higher with the slower velocity fast powders?
In my mind I’m trying to attribute that to muzzle flip caused by the quick burn rate.
Any thoughts on this?

[tommag]

Lower velocity means more time in the barrel. Even though the recoil is slight, the muzzle rises farther before the projectile exits the barrel.

[DirtyOz]

That does make sense. I’ll have to see how those work in my new 240 gn mold from Accurate.
I just put a Skinner peep on my 1894, so hopefully I’ll have enough elevation adjustment to shoot slow and fast powders.

[Wayne Smith]

Lower velocity means more time in the barrel. Even though the recoil is slight, the muzzle rises farther before the projectile exits the barrel.

What he said. That's one of the most concise and accurate ways I've heard it explained.

[Shuz]

Lower velocity means more time in the barrel. Even though the recoil is slight, the muzzle rises farther before the projectile exits the barrel.

tommag nailed it!

[DougGuy]

fast powders and the Lee 310 aren't a good match at all..

[Wheelguns 1961]

They call that dwell time

[mdi]

Yep, as the fellers above say, "barrel time". The time the bullet is in the barrel is longer therefore recoil/barrel movement has more effect on point of impact...

[JoeJames]

Lower velocity means more time in the barrel. Even though the recoil is slight, the muzzle rises farther before the projectile exits the barrel.It's even more obvious in a revolver. I ran some fairly light loads in my Ruger SA 44 Special. They shot so high I could not crank my rear sight down far enough to compensate.

[DirtyOz]

fast powders and the Lee 310 aren't a good match at all..

The 310 was the largest diameter gas check Lee had to offer. It also has to be driven hard in a 1 in 38 twist in the Marlin. It slugs at .430 groove. These boolits fell near .431 so at least i was able to lube and seat the checks. I’m an experimenter, so I had to see for myself. And yes you are right, not good with fast powders.

[robg]

Tommag said it all

[David2011]

When I first got a Contender with a 14” barrel I loaded up some standard .44 Specials and some full bore magnum loads- 250 grains @ 1600 FPS. The magnum rounds hit about 30” lower than the Special rounds at 50 yards.

[unique]

Most likely related to your grip...I'll explain but first need to disagree about what has been stated above about lower velocity and higher poi of impact (for given bullet weight) as this is easily proven wrong by mathematics.

If you look at recoil, velocity, and point of impact (poi) for a given bullet weight then if a bullet has higher velocity then it has higher recoil and higher muzzle flip. If a bullet has a lower velocity then it has lower recoil and lower muzzle flip. There is a linear relationship and they exactly cancel. This isn't my findings but documented by Hatcher way back in the 1930's.

Now if your grip is tighter or you are fighting the recoil more on the heavier loads then you will absorb some part of the muzzle flip.

Think about it...

[DirtyOz]

I am going to do a bench test with grip as one controlled condition. Powder type and load, of course will be the other variable. Boolit design and weight will be the same. I’ll use the contender as any flip issues will be more apparent. I replaced the factory grip and forend with these. Seemed like it reduced the barrel rise a bit but hits the palm or heel of my trigger hand a good bit with hot loads.222549

[unique]

Here is reference material from Hatchers "Textbook of Pistols and Revolvers"...

222588

222589

[DirtyOz]

I don’t disagree with the book. However, I can’t say what tommag stated was false either. In the end, the alignment of the bore to the intended target when the bullet leaves the muzzle is what is going to make the difference. Grip might help close the gap, but I don’t think it will solve for it either. Just my prediction for today’s test.
I’m going to try Trailboss at 6 gr - subsonic
2400 at 18.5 gr - estimated 1300fps
W296 at 22.5 gr - estimated 1500fps
I don’t shoot the contender very well while standing yet, so I’ll be at the bench for this.

[unique]

Please keep us informed as there is always something new to learn...

[DirtyOz]

So my test ended up being somewhat limited. I only did a single 5 shot group of each. Range was about 60’
I did not shoot any Unique loads as the range was very busy. Grouping was not good IMO as I just got this mold and have not worked up any loads as of yet. I did try some 2400 loads at 50 yds that show promise.
The flyer in the upper right group was probably the result of a muzzle breaked 338 Lapua about 8 feet away.
Yes, we shot in unison. Lol. I thought I was acclimated to friendly range fire, but that one was a real
***********! At any rate,I do see about a 3” difference in elevation between fast and slow powders.
The difference In grip really only showed up in the 2 groups using W296. And that difference was slight.
Once I get more accurate loads worked up I think a 50yd test would be more conclusive.
222648

[DirtyOz]

I don’t believe the Trailboss boolits were keyholing. Just the paper sticking to the pallet when I tore it off

[jonp]

Lower velocity means more time in the barrel. Even though the recoil is slight, the muzzle rises farther before the projectile exits the barrel.

^+1 That has been my experience

[unique]

The 296 loads look like there is ignition problem. Where did the 2400 loads hit?

[unique]

I ran the 296 load thru Quickload and it shows 44,000 psi & 1600fps. Seems a bit high for minimum starting load? It also shows this to be a compressed load at 104%. Are you using magnum primers? That much 296 is going to need a magnum primer and heavy crimp to get good ignition. As I stated previously you maybe having ignition problems?

222695

[DirtyOz]

I’m using published load data from Lyman 4th edition. The mold I have is not listed there so I substituted the Lyman 429667 bullets data. Mine is Accurate’s 43-240AG. Minimum load for the Lyman is 22.5 of H110.
Primer used are WLP’s. I do have some CCI 350’s I have not tried yet. I am pretty new to casting and if I’m approaching dangerous conditions, I certainly need to realize that.
I’ll have to compare mold specs and check case fill again.

[unique]

My mistake, I used 300 gr based upon first post. I will rerun with 240 gr cast.

[DirtyOz]

I didn’t even notice that. Where do I find that calculator? Would it be safe to use that using different bullet designs of same weight?

[unique]

Quickload is purchased piece of software. For cast loads seating depth is more important than bullet profile...

[DirtyOz]

Interesting. Im having trouble finding brass that allows me to achieve case length listed in the manual. To a accumulate any quantity I chose to trim 1.280”. I’m getting about + .007 after resizing. So when you say seating depth, are you talking about the resultant case fill percentage Or distance from rifleing?

[unique]

Here is pressure/velocity curve with 240gr cast which seems much more reasonable. Sorry about the misunderstanding on previous graph.

222744

Seating depth refers to how much of the bullet sits in the case. The more in the case the higher the pressure.

For the graph above I have seating depth at 0.415.

[DirtyOz]

Roughly .38 here with gas checks seated and sized. 1.280 case length.
222750