Rifle, not pistol but compared 312/308 unsized/sized RD style - shallow grooves. Total length = 961/964. Nose end front groove = 350/329 (base reference)! Band width = 090/076! Groove side angles= 45/~90 deg. Length grew very slightly ( 003) but dia (004) got moved into the GROOVES. And the leading edge of the groove moved FORWARD. Like the tectonic plates, alloy moves forward under the edge of the sizer until fore resistance exceeds aft resistance, then it moves back. L.G. is weakest point! GC shank didn't change much (284/090 vs 283x086) . Alloy is softer than 6/40 pure/isocore. Flow occurs at the lands, not chiseling. IMHO the reason high Sb doesn't shot so well. Large Sb crystals on surface tend to get chiseled and damaged. I don't think it is pressure per se but time that the alloy needs to flow and the jump the boolit needs to make. Basically most of the alloy flows into the grooves!
43-287B
- Thread starter Brad
- Start date
F
freebullet
Guest
Might be able to capture undamaged the low velocity loads in my bullet bucket. I would not care if they came out the back. Could try it on the first upper pistol pit, the nice big berm would be helpful just in case and you can get back about 45yd from the picnic table on that one. Your welcome to use or abuse it if you want.
F
freebullet
Guest
No problem. I could drop it by Thurs or something. I was going to try some low velocity x39 on it because the bucket is about due for replacement anyway.
I had a results for some measurements on the revolver.
I decided I needed to do an impact slug of the forcing cone. How was a bit of a thought exercise. Here is what I came up with.
A short rod, seen in bore, turned to a snug fit in bore. It will enter easily barely drop thru under its own weight. The other rod seen was cut to a nice fit in the forcing cone and is long enough to let the bullet get support from the recoil shield.
The drive rod was wrapped on both ends with tape to be a snug fit in the bore to keep the rod centered.
A 265 RD bullet was forced into the forcing cone with a small bar clamp until flush with end of barrel. A hammer was used to upset the bullet into the forcing cone.
Here is what I got. Easy to see how much taper is in the forcing cone. It starts at better than .445 and shows a nice, gradual start to the rifling. No sharp edges here.
I also drove a 45-70 collar button thru the bore to get dimensions on the groove diameter.
Groove diameter measured .4295. The start of the rifling near as I can measure is at .431.
Using a .432+ bullet means I am squeezing the bullet down almost .003 without taking into account how much the rifling displaces.
I decided I needed to do an impact slug of the forcing cone. How was a bit of a thought exercise. Here is what I came up with.
A short rod, seen in bore, turned to a snug fit in bore. It will enter easily barely drop thru under its own weight. The other rod seen was cut to a nice fit in the forcing cone and is long enough to let the bullet get support from the recoil shield.
The drive rod was wrapped on both ends with tape to be a snug fit in the bore to keep the rod centered.
A 265 RD bullet was forced into the forcing cone with a small bar clamp until flush with end of barrel. A hammer was used to upset the bullet into the forcing cone.
Here is what I got. Easy to see how much taper is in the forcing cone. It starts at better than .445 and shows a nice, gradual start to the rifling. No sharp edges here.
I also drove a 45-70 collar button thru the bore to get dimensions on the groove diameter.
Groove diameter measured .4295. The start of the rifling near as I can measure is at .431.
Using a .432+ bullet means I am squeezing the bullet down almost .003 without taking into account how much the rifling displaces.
Pistolero
Well-Known Member
What is throat diam? Fitting the throats if they are .432ish then means .0025 sizing in the forcing
cone, which is not working with that big nose with no place for the displaced metal to go easily.
So, just for grins what bullets shoot well in this pistol?
Is it useful to think of what works and maybe why?
Bill
cone, which is not working with that big nose with no place for the displaced metal to go easily.
So, just for grins what bullets shoot well in this pistol?
Is it useful to think of what works and maybe why?
Bill
The 305 MP bullet shot better, got 5 into 2.5" at 100 with it. It is the one shown in o of the posts in this thread.
I haven't really fired for groups a bunch with other bullets. I have some to try but need to find time.
The throats measure .4325 or so. I get a snug fit with he bullets used as sized. I can push thru the throats with my little finger but the bullets won't fall thru under their own weight.
I haven't really fired for groups a bunch with other bullets. I have some to try but need to find time.
The throats measure .4325 or so. I get a snug fit with he bullets used as sized. I can push thru the throats with my little finger but the bullets won't fall thru under their own weight.
Pistolero
Well-Known Member
Ok, there is your raw data. "all you need to do...." is figure out why.
OK, I remember the pix, no nose info from the pix due to damage. What do the original bullets look like, esp compared to the
problem children?
Hardness?
Malleability of the alloy? Hammer test on one of each?
Lube?
Checks annealed?
Load - pressure and powder (peak pr and rise time)?
Bill
OK, I remember the pix, no nose info from the pix due to damage. What do the original bullets look like, esp compared to the
problem children?
Hardness?
Malleability of the alloy? Hammer test on one of each?
Lube?
Checks annealed?
Load - pressure and powder (peak pr and rise time)?
Bill
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I did learn one thing from the measuring. With a bore diameter of .416 I realize I need to cut the grooves on the nose far deeper. I have been cutting to .420 or so and that means the lands are still moving metal in the groove. Future groove testing will begin in the .410 range, leaving some room for metal to flow without the lands acting on it.
Or . . .
Since your going to lathe cut the bullets to experiment anyway try this. Instead of cutting grooves in the nose try cutting a taper to the nose. Start the beginning of the ogive at around .414" to .415", taper the ogive to leave about .030" at full throat diameter to align the bullet with the center line of the bore. You will be displacing far less metal, the smaller nose can enter the rifling and engrave. Worth a try I think considering the Ruger has a built in bore restriction.
.
Looking at the actual slug I don't see that. I can post photos if needed. I can see the ends of the lands all hitting at the same point on a single groove on the bullet. If there is any variation it may be on a single land being ever so slightly short of that point.
I have some ideas on altering the overall nose shape beyond simple grooves. Gonna take some time to decide the what and how then make and shoot em.
Things like a taper on the front of the nose, a deeper, wider groove giving 2 narrow drive bands on the nose, a deeper V shape crimp groove, and some others.
I need to cast more to prepare for this work. I also want to see how size diameter changes the accuracy and see some recovered bullets from that too.
Things like a taper on the front of the nose, a deeper, wider groove giving 2 narrow drive bands on the nose, a deeper V shape crimp groove, and some others.
I need to cast more to prepare for this work. I also want to see how size diameter changes the accuracy and see some recovered bullets from that too.
fiver
Well-Known Member
I'm trying to figure a way to push one or a couple of your bullets into the barrel through the throat there to 'see' if we can see what/when/where the damage is happening.
I know riveting was brought up and the use of Tin to maybe stop that.
etc...
and was thinking on a way to try to push that mushed base down into the barrel.
you know rods and about 1/32" at a time, cut bullets,,
I know riveting was brought up and the use of Tin to maybe stop that.
etc...
and was thinking on a way to try to push that mushed base down into the barrel.
you know rods and about 1/32" at a time, cut bullets,,