Speed Of Sound & Accuracy...

[BCB]

Was just shootin’ some 287346’s (~140 grains) sized to 0.285” from a Super 14” Contender…

I was using 9.0 grains of Trail Boss for a blistering velocity of 1142 fps calculated to the muzzle from a Chrony set 10’ away…

The accuracy at 50 yards is petty good—at or near 0.4” …

But at 100 yards—some boolits disappear on an 8.5”x11” paper—they don’t hit it!!!...

At 50 yards the calculated velocity is 1074 fps which is a bit below the speed of sound…

At 100 yards the calculated velocity is 1019 fps…

I wonder if going the little bit extra fps below the speed of sound is causing the major inaccuracy problem at 100 yards?...

It isn’t distance problems as far as ‘scopes goes as the barrel is topped with a 3x-12x Burris ‘scope with parallax adjustment. Plus, even if it was an inexpensive ‘scope, I wouldn’t thing boolits would completely miss the paper at 100 yards…

Sub-speed of sound the problem????????...

BCB

[44man]

Was just shootin’ some 287346’s (~140 grains) sized to 0.285” from a Super 14” Contender…

I was using 9.0 grains of Trail Boss for a blistering velocity of 1142 fps calculated to the muzzle from a Chrony set 10’ away…

The accuracy at 50 yards is petty good—at or near 0.4” …

But at 100 yards—some boolits disappear on an 8.5”x11” paper—they don’t hit it!!!...

At 50 yards the calculated velocity is 1074 fps which is a bit below the speed of sound…

At 100 yards the calculated velocity is 1019 fps…

I wonder if going the little bit extra fps below the speed of sound is causing the major inaccuracy problem at 100 yards?...

It isn’t distance problems as far as ‘scopes goes as the barrel is topped with a 3x-12x Burris ‘scope with parallax adjustment. Plus, even if it was an inexpensive ‘scope, I wouldn’t thing boolits would completely miss the paper at 100 yards…

Sub-speed of sound the problem????????...

BCB
Forget the speed of sound. Your boolit is too slow to spin up and stabilize at long range. That is a long boolit and you are so far from what the twist needs with that low velocity you will never make it work until you speed it up.
You did not mention the case or twist rate of your TC.

[rogn]

Im using the same boolit in a 7WSM, with velocity estimated at 1150 or so. I still get a shrp crack(but not excessive). I think the twist is 1-9 but have ni=ot checked it, literature has said either 1-10 or 1-9". My accuracy has stayed at 1.5- 2" @ 100; 3shots. My guess(just as wild as???) is that your bullets are going subsonic and the round nose, multiband bullets are going unstable and key-wheeling off on their own. I think a bigger piece of paper would be useful at diagnostics. Also,Drop on that bullet seems greater than a 22 rimfire, so the BC is probably a real little number.

[BCB]

O.K. a bit more info...

The twist in the T/C Super 14" is 1-9"...

The B.C. of this boolit according to Lyman is 0.235...

I didn't do the Greenhill to see what the "recommended" twist might be for this boolit length...

Dang great 50 yarder though...

BCB

[Doc Highwall]

Actually the problem is you either have to keep the bullet below or above the speed of sound all the way to the target. What is happening with yours starting just above the speed of sound is the bullet has to go through the transonic period between the gun and the target which is a very turbulent velocity. If you look at small bore match ammo you will see that the highest velocity is 1080fps with a more downward trend towards 1035fps so the bullet does not have to go through the transonic period. Another thing is the speed of sound is not 1122fps at all air temperatures is is a lower velocity for colder temperatures and higher velocity for higher temperature's. High power shooters get this when they shoot the Palma Matches where the bullet is supersonic at 800-900 yds and goes subsonic at 1000 yds because they were looking more for accuracy instead of giving up some to stay supersonic at 1000 yds. I have been in the pits where a person was winning the match at 800-900yds and you could hear the bullet break the sound barrier but at 1000 yds you could hear it go subsonic and the drag on the base of the bullet being inconsistent going through the transonic period caused the bullets to lose all accuracy and open the group greatly.

[fecmech]

I don't think speed of sound has anything to do with it as you made the transition before 50 yds. I think you've got stability problems. I shoot in that speed zone exactly with my .357 rifle and have no problems out to 200 yds. I'm talking a Lee TL SWC @ 1150 fps with the BC of a rock!

[geargnasher]

I don't think speed of sound has anything to do with it as you made the transition before 50 yds. I think you've got stability problems. I shoot in that speed zone exactly with my .357 rifle and have no problems out to 200 yds. I'm talking a Lee TL SWC @ 1150 fps with the BC of a rock!

Maybe he made the transtion and maybe he didn't. He said the "calculated" velocity was 1074 fps at 50, even if it broke at 45 yards it wouldn't upset the groups that much in another 15 feet.

I've had much the same issue with .357 Magnum in pistols, accuracy great to 75 yards, then going subsonic at 80-90 and the groups going to hell. All that was needed was an increase in muzzle velocity just enough to get out to the desired range. This is, of course, not discounting other basic stability issues regarding SD, weight distribution, bearing length, twist rate, etc.

Gear

[303Guy]

The boolit design could do it. At transonic (which means that air-flow over parts of the boolit are subsonic, parts sonic, and parts supersonic) your particular boolit might be subject to terrific buffering forces. There are long range BP shooters that use a boolit design specific to overcome that transition buffering and they manage to shoot very accurately out into the subsonic zone.

Not to say the problem isn't being caused by something else! Going off the paper altogether sounds a bit extreme for transonic buffering. But the buffering would be exacerbating the instability problem. I have a 22 rifle that would should quite accurately out to 90m but the groups opened up exponentially at 100m. I eventually discovered that the muzzle was worn and when I chopped off the last bit of barrel and recrowned it, the problem went away. That would have been an unstable boolit going off-course through the transition zone.

[BCB]

My thoughts exactly about the boolit just going subsonic near 50 yards. The boolit might not have had time to go "goofy" in a short distance...

I did shoot groups at 100 yards there were in the 5-6 inch range, but a few, one of the three boolits fired didn't hit the paper...

Strange days indeed...

BCB

[44man]

1 in 9" is good but you are still too slow.
Doc is right but not with a 100 yard pistol. breaking through to subsonic before 100 is no big deal.
Since the speed of sound is around 1128 fps at ground level, the transition to subsonic with that boolit is close to 100 yards and means nothing at all and the boolits should not miss paper so stability is gone way before.
An over spun boolit will group larger at close range and tighten at long range but an under spun boolit is accurate close and will lose it at longer range.
The longer and heavier a boolit is, the faster it must go to reach spin for a given twist.
Just try to shoot a 320 gr .44 boolit at 750 fps!

[44man]

An example is my fast twist MOA 7BR. The 175 gr boolit needs to be driven 1898 fps to shoot tiny groups at 100 yards and farther.
The 7R needs 1633 fps with a 154 gr bullet.

[Larry Gibson]

Doc and the others nailed it. Your bullet is going tran sonic between 50 and 100 yards. I have seen this numerous times with various calibers and velocities in this range. It is the speed of the air around the bullet that needs to be above or below the speed of sound (what ever the speed of sound is at the local and conditions you shoot at). Given an equal velocity the air moving around a blunter bullet will will be moving faster. Thus the blunter bullet will "crack" at a lower velocity. With such loads for 100 yard shooting I like to keep the muzzle velocity at or below 1050 fps or above 1150 fps minimum but mostly 1200+ fps. With most RNs and FNs that suffices to 100 yards. The 1050 or below loads are also very accurate to longer ranges because they do not transition down through the speed of sound as they are already below it. Not all bullets are affected as much as some by the buffeting. Some lose a little accuracy and some go completely unstable.

BTW; the velocity is not too slow. I shoot a 168 gr cast bullet down to 500 fps out of my 9" twist 7x57 with very good accuracy still at 100 yards.

Larry Gibson

[waksupi]

No matter what range you shoot, if the boolit goes transonic, it will remain unstable until it can travel enough distance to go to sleep.

[fecmech]

Guys--Hi speed .22 long rifles go transonic when going to 100 yds and they don't miss a piece of typing paper! I have shot them at 200 yds at a 12"x12" plate (which should give them plenty of time to go "wild") and as long as the hold is good they hit.

[Doc Highwall]

I think it could be a problem with stability but with out knowing all the parameters involved I will be surmising. BCB asked the question if the speed of sound could be causing his problem and I gave my answer but forgot to say that the bullets that start subsonic also have less wind drift vs bullets that start out just over the speed of sound and arrive at subsonic velocity at 100 yards. BCB said he sized his bullets .285" but did not say what the barrel slugged at or the alloy but that he used Trail Boss powder. I have looked at the data on Trail Boss powder with it's low velocities but it does it at much higher pressures then would be expected.
BCB what does your gun barrel slug at and what alloy did you use?

[Larry Gibson]

Guys--Hi speed .22 long rifles go transonic when going to 100 yds and they don't miss a piece of typing paper! I have shot them at 200 yds at a 12"x12" plate (which should give them plenty of time to go "wild") and as long as the hold is good they hit.

Short stubby bullets like most .22s and handgun bullets are fired out of slow tiwsts, have less RPM and are less affected. Same with larger bore cartridges with longer bullets but slower twists. A long thin bullet spun fast is more susceptable. The "buffeting" that occurs from the shock wave induced flow and pressure on the bullet changes during a transition from sonic to sub sonic. The buffeting creates a precession force applied unevenly to the spiining bullet.

BTW; Hi-speed .22LRs are less accurate at longer ranges than standard velocity (subsonic) .22LR ammunition. Any guesses why.......

Larry Gibson

[fecmech]

Larry--Respectfully, I don't think his problem is the sound barrier.

[BCB]

I use pure wheel weights and I really don't know what the barrel slugs at...

The Lyman 287346 is a gascheck boolit...

I just can't believe the accuracy at 50 yards as compared to 100 yards--night and day...

The boolits that did hit the paper at 100 yards entered with a nice round hole. I pin my paper targets on cardboard so I get nice clean impact points...

I have noticed that Trail Boss can be a bit radical at greater distances with just about everything I have tired it with, except for the 280642. BUT, it is starting at around 1667 fps from a Model 700...

[fecmech]

I think a quick way to find out if it's sound barrier related would be to back down the load a bit to start it out subsonic like maybe a half grain. If you still have your good group at 50 and it holds at a hundred that's it. Also if a half grain dumps the 50 yd grouping it's not a very stable load to start with IMO.

[Larry Gibson]

Larry--Respectfully, I don't think his problem is the sound barrier.

The concept that "perception is reality" does necessarily not mean that our "perception" of what is happening is really what is happening. The concept that some bullets go unstable as they pass back down through the sound barrier is proven. Since you don't think that is what it may be what altenative of proven fact do you offer in this case? I am always open to sound, proven alternatives. Please do not misinterpret this as an arguement or criticism, just opening the door for discusion is all.

Larry Gibson

[Larry Gibson]

I think a quick way to find out if it's sound barrier related would be to back down the load a bit to start it out subsonic like maybe a half grain. If you still have your good group at 50 and it holds at a hundred that's it. Also if a half grain dumps the 50 yd grouping it's not a very stable load to start with IMO.

Ah, fecmech, you've offered an alternative suggestion to find out, excellent!

Larry Gibson

[303Guy]

Like I said, my 22 had a bad muzzle and groups opened up exponencially past 91m. It wasn't a tack driver to start with. It was when I fitted a silencer with mis-aligned baffles that the accuracy really went to hell. Those boolits were unstable at the muzzle to start with. Different thing now. Point is, a little boolit yaw plus going transonic and anything can happen. But if the inaccuracy is caused by the boolit itself, regardless of speed, the groups are going to open up exponencially. That's because error gets added to error. Is there any chance the boolits might have internal defects? Slowing the boolits down might hide a boolit defect induced problem. Still a good suggestion though. Coupling that test with increasing velocity might be revealing.

[pdawg_shooter]

Short stubby bullets like most .22s and handgun bullets are fired out of slow tiwsts, have less RPM and are less affected. Same with larger bore cartridges with longer bullets but slower twists. A long thin bullet spun fast is more susceptable. The "buffeting" that occurs from the shock wave induced flow and pressure on the bullet changes during a transition from sonic to sub sonic. The buffeting creates a precession force applied unevenly to the spiining bullet.

BTW; Hi-speed .22LRs are less accurate at longer ranges than standard velocity (subsonic) .22LR ammunition. Any guesses why.......

Larry Gibson

+1 Larry, going trans-sonic ALWAYS upsets a bullet. The longer the bullet the more upset.

[44man]

I have told this story before. I was shooting a TC 30-30 with a cast GC boolit and it was so accurate I could hit nickels and pennies at 100 yards.
I ran out of checks so tried them bare base and every single boolit hit sideways at 50 yards. Boolits were HARD but I lost the bearing surface to match the twist. Sure, I could have worked loads but I needed the boolit to knock off rams at 200 meters. It seems to me the little added width of the GC was important for the proper spin.
Then working loads for my 45-70 BPCR with a heavy boolit gave me a little over 1" at 200 yards but I could not hit a ram at 500. Boolits went everywhere. These started under the speed of sound with no transition.
This is what the TC did at 100.

[BCB]

Thanks all…

I’m still reading…

It seems there are major opinions on the sonic, transonic and subsonic velocities…

There is probably no doubt that I am encountering all of them with the load that I am shooting…

I have never had such problems, but I have never really messed with rifle stuff at these slower velocities. Only handguns and they are shot at closer ranges. (Except of the 429650 (325 grains) in the 44 Magnum—might have to look at the ballistics a bit closer on this one)…

I am going to increase the speed a bit and slow it down a bit (at least with the Trail Boss) just to see if the speed of sound and whatever might be the issue…

Thanks again…BCB

[felix]

Keep in mind that the crown might have something to do with it too. Changing powders should sort that out easily if the problem is NOT around the sound barrier. Also, there is nothing wrong when using checks for verification per 44man. ... felix

[Bass Ackward]

Absolutely. And there are two factors to crown. Gun muzzle and bullet base. Actually three if you don't have a strong fit in the throat. Fast powder on a long, heavy for caliber slug can ruin that relationship either at the beginning or departure.

Changing powder aught to tell.

[BCB]

Just got back from my range and I increased the velocity a bit…

I didn’t chronograph them but according to the T/C Reloading Manual, I was most likely between 1650 and 1900 fps. So the boolit didn’t go to subsonic at 100 yards…

I was using SR-4759 powder which has not been the most accurate powder for me. (I know, it is supposed to be a good on for cast boolits!). But I selected it as I could increase the velocity a bit over the velocity achieved by Trail Boss…

Anyhow, the boolits stayed in at 2.5” or a bit less—mostly not a bit less!!! Still, they all stayed on the paper. So maybe the slow velocity at the 100 yard mark with the Trail Boss was the problem…

I have had pretty good luck with the 287346 using WC-844 and H-335 so I think I will give them a try also…

Why am I going this route again if I have already been there? The reason, I am now sizing the boolits and using Carnauba Red. Before I was shooting “as cast” using LLA…

One thing that I did note was the fact there were little dots of Carnauba Red on the targets. Is this an indication of problems?...

Greenhill shows a 1-12 twist for the 287346, so the 1-9 should be more than O.K.

Unless something really great happens with the H-335 or the WC-844, I don’t think this boolit and the T/C 7-30 Waters are going to win any accuracy contests…

BCB

P.S. I have noted greatly with Trail Boss that accuracy is very good at shorter distances with any caliber I have chosen to use it with. The exception was the 270 Winchester. I like Trail Boss, but it ain't gonna win any long range events...

[fecmech]

BCB--are you going to try a slight reduction in TB to start subsonic??

[BCB]

BCB--are you going to try a slight reduction in TB to start subsonic??


I will as the weather gets a bit better...

I have shoot 8.0 grains and it starts out at around 1062 fps. I really never stretched it out to 100 yards though...

It gets difficult switching from lower to upper velocities as the points of impact at 100 yards vary considerably and 'scope adjustments are needed...

BCB

[fecmech]

I wouldn't go through that much trouble, just put another target under he one you're shooting at to see if the group holds up. Windage shouldn't change much just drop.

[BCB]

I wouldn't go through that much trouble, just put another target under he one you're shooting at to see if the group holds up. Windage shouldn't change much just drop.


Yea, sometimes I use legal sized paper and put the dot near the top. That gives me plenty of "drop" room...

I'll get some groups in the near future--but the weather here in Western PA ain't gonna cooperate over the next few days...

BCB

[44man]

I have the Wichita 7R and it is so close to the Waters being made from a 30-30 case it is funny why we have both calibers. The large case capacity makes it hard to find a good powder for my 10" barrel.
Now I use jacketed but it should be OK with cast too but I don't have a mold to test because my gun was for IHMSA.
I tried every powder made and only 4759 made the gun work. I use the 154 gr Hornady with 18.4 gr of 4759. 1634 fps.
I decided to use the gun for deer with the Hornady SSP 120 gr but could not get it to hit anything. I kept fooling around and found 34.5 gr of Varget turned it into a tack driver---YES, VARGET!
I have the MOA 7BR and had the same problems with a light bullet. This gun has shot 3/8" groups at 100 yards with the Hornady 175 gr bullet but the 120 was a bust, a REAL bust. I called Hodgdon and asked about a load for Varget and they told me it will not work, too slow. I tried it anyway and it shoots like a house afire with 32.5 gr and gives me 2175 fps from a 10" barrel.
Just why Varget makes a gun work with the wrong twist rate for light boolits drives me crazy! :bigsmyl2:
The MOA 7BR thrives with the 154 gr Hornady and 18 gr of 4759 but I go to H322 for the heavy bullets.
Both guns have shot 40 after 40 at IHMSA shoots.
First is the Hornady SSP 120 gr bullet at 50 yards with Varget.
Then 100 and 200 yards with both guns. The circled group was 3/8" at 100 using a 175 gr Hornady from the MOA.
Can you shoot cast good---YES, think outside the box with powders. Why the heck Varget works in these small guns is baffling and even Hodgdon does not know what a great powder it is.
All along you guys thought only the revolver was my game! [smilie=s:

[WILCO]

some boolits disappear on an 8.5”x11” paper—they don’t hit it!!!

I just pictured a few folks ducking and diving in an alternate universe.........

[Bass Ackward]

So maybe the slow velocity at the 100 yard mark with the Trail Boss was the problem…

One thing that I did note was the fact there were little dots of Carnauba Red on the targets. Is this an indication of problems?...


Well, if the higher velocity loads aren't flinging the lube off until it gets to 100 yards, what do you think is happening to the slower rounds?

So how much lube weight does it carry and you have how much weight is outta balance. So the farther you shoot, the worse it will be unless you spin faster. Coarse spinning faster is going to bring your bullets back to balance.

You are learning about lube and bullet design here. Ever wonder why slow speed revolver bullets have one WIDE lube groove vs multiple small ones on higher velocity designs? Clear the lube.

[VenomBallistics]

Ive seen this phenomena a quite a bit.
When an object exceeds the speed of sound it creates a shock wave. as the object slows and crosses the sound barrier the shock wave will catch up with the object and impart force upon it.
in your case, either an objective of a 1050 FPS MV or raising the MV to 1300 - 1450 should avoid the problem.

[44man]

You are learning about lube and bullet design here. Ever wonder why slow speed revolver bullets have one WIDE lube groove vs multiple small ones on higher velocity designs? Clear the lube.
Now I just have to bash you over that! :bigsmyl2: My most accurate boolits have 2 to 3 lube grooves and like you say, higher velocities but I have a lot of boolits with one wide groove and they never shoot as good at any velocity.
Even a light and slow TL design with the right lube will out shoot any boolit I have with one wide GG.
Lube purge is important but smaller grooves will purge better. Hard lube in a large groove is the worst.

[Bass Ackward]

My most accurate boolits have 2 to 3 lube grooves and like you say, higher velocities but I have a lot of boolits with one wide groove and they never shoot as good at any velocity.
Even a light and slow TL design with the right lube will out shoot any boolit I have with one wide GG.
Lube purge is important but smaller grooves will purge better. Hard lube in a large groove is the worst.



I had a private in the Army once that could only do things one way, and he NEVER forgot the first way that he was taught. He was inflexible no matter how many times he was shown. Harris, his name was Harris, would stand against a wall and bang the back of his head off the wall when he was getting counselled. I asked him why he would do that? He said that he looked so forward to stopping and just how good it felt when he did. Harris said that over the years he developed a preference for drywall as opposed to concrete or concrete block.

Why is this applicable to you?

Ask yourself: why are these molds still sold and used today if they are crappy? And why did the other designs come about?


Answer: A. Some learn. B. Some don't. B people have to hope for drywall.


Lube groove size, depth, and angle all make a difference for the lube that is to be used. If they negatively affect the CofB for the velocity wanted, then losing the lube doesn't make a lot of difference, does it?

But why mold good bullets if you just throw them out of balance with lube? Nope, lube on the muzzle, not the 100 yard target. :grin:

[BCB]

I just pictured a few folks ducking and diving in an alternate universe.........


Naaaa, I have rather large backstops at my shooting range!!!

BCB

[BCB]

Well, it appears I am going to have to do some more shooting and try to figure this accuracy thing out!!!

The faster velocity did help with the accuracy as I mentioned, but still 2.5” at 100 yards isn’t real impressive to me from a T/C topped with a 3x-12x Burris ‘scope--plenty of optics to help with the shooting. This 7-30 Waters will shoot <M.O.A. at 100 yards all of the time with the Hornady 120 SSP bullet. But, it won’t shoot groups as good as those you show 44man. But the handguns are different in design sort of…

Now then, it appears there are a couple of opinions of the lube letting marks on the 100 yard target, but not the 50 yard target. Is the lube to leave the boolit or is it to stay in place? All of the handguns (revolver types) that I shoot, the lube looks like it was just put on after I found the boolit. Not a bit was cleared from the grooves…

As I mentioned previously, I only used LLA on the rifle type boolits. Maybe that is why I had fairly good luck with them. The lube never moved so there was not a balance problem? Maybe at faster speeds, the Carnauba Red wants to fly off? It sure doesn’t in the revolvers—44 Magnum, 357 Magnum, and the 45 Colt…

Good thing I have several 5-gallon buckets full of wheel weights as I can see it is going to take that much to figure this cast boolit stuff out!!!...

Ahhhh, I’ll just shoot big clubs out of the revolvers and think it is great to hit targets at 25 yards!!! Although, the 44 Magnum SRH with the 429650 (‘bout 320 grains) will hit a life-sized groundhog silhouette at 150 yards with a good rest and a good day and the Burris ‘scope working O.K. Mostly, I shoot it at 100 yards as I don’t miss there and it causes less disappointment and great encouragement…

I’m still reading the replies. And I have some other loads to shoot in the Waters, probably tomorrow. I would be very happy with a 1.25” group at 100 yards with some consistency…

And so it goes…

BCB

[BCB]

Well, did some minimum shooting yesterday. Mixed results for sure!...

I tried H-335 and IMR 3031 and the velocities should have been near or slightly over 1900 fps. I didn’t chronograph them as I generally don’t do that until I find a combination that I might stay with. Neither of these powders will be used again! 2.5 to 3 inch groups at 100 yards. More later...

But, I did drop the Trail Boss charge to 8.0 grains which should have left the boolit exit the barrel below the speed of sound. (Chrono’ed previously at 1056 fps) It shot 2 groups (all the reloads I took with me as they were only test stuff) that were less than 1.25” and a bit greater than 1.1”. Not too bad. I loaded a dozen of them up to try this morning…

The interesting part about this and the H-335 and IMR 3031 is the fact that they shot fairly well years ago. I think it has to do with shooting them “as cast” and only sizing the check to seat it. The lube was LLA also…

No, I didn’t slug the barrel as I don’t know if I have instruments that are precise enough to measure the end results, although I probably do if the number of riflings and grooves is an even number. Sterrett micrometers and calipers should be good enough. Didn’t check to see in the T/C. Probably knew years ago, but that memory is gone. But I think it is an even number…

If the ones I have loaded today with 8.0 grains of Trail Boss shoot as they did yesterday, I will us that as a plinking load in the Waters. The only problem is the rainbow balistics. Too darn much hold over or too darn high impact at 50 yards to hit cans at 100 yards. If not, the project might be sacked. Too dang many variables to work with!...

BCB

[Larry Gibson]

BCB

If the velocity was 1900+ fps then you are accellerating that cast bullet pretty fast in the 14" barrel, even with H335 and 3031. Also with the 9" twist the bullets are pushing past the RPM threshold. If the bullets aren't holding up to the accelleration then the RPM is going to cause them to be inaccurate. Sad to say but there it is again.........[smilie=b: Drop the velocity down into the 1700 -1800 fps range and you probably find better accuracy. I'd also switch to H4895 or perhaps Varget.

Larry Gibson

[BCB]

Well, thanks for all the advice and the information…

I have tried a few of the suggestions—some with success…

But, it appears there are many parameters and eventually it gets to the “rocket science” stage. To me that is when a hobby becomes work—unless you are a rocket scientist…

But, the 7-30 Waters in question does shoot “J” bullets very well so at least it is not a total lose. But, the slower velocity cast boolits did do fairly well and with some consistency…

Maybe another boolit design would be better, but soon it gets out of control with designs and molds…

Now to try the 30-30 Super 14” barrel again. I have had limited success with it also, but I have learned quit a bit since beginning to shoot it with cast…

I continue to move forward…

Thanks…BCB

[fecmech]

But, I did drop the Trail Boss charge to 8.0 grains which should have left the boolit exit the barrel below the speed of sound. (Chrono’ed previously at 1056 fps) It shot 2 groups (all the reloads I took with me as they were only test stuff) that were less than 1.25” and a bit greater than 1.1”. Not too bad. I loaded a dozen of them up to try this morning…


If the ones I have loaded today with 8.0 grains of Trail Boss shoot as they did yesterday, I will us that as a plinking load in the Waters. The only problem is the rainbow balistics. Too darn much hold over or too darn high impact at 50 yards to hit cans at 100 yards. If not, the project might be sacked. Too dang many variables to work with!...

BCB

BCB--Did you shoot those additional subsonic loads the following day?? Did I read your post correctly that you shot 2 subsonic Trailboss groups of less than 1.5"@100 yds where the previous supersonic group did not hit the paper??

[BCB]

fecmech,

That is correct. But the group locations were not at the same point fo impact. Difficult to explain, but they were a bit diffent locations. Contenders can be very discouraging at times...

The problem with that subsonic load is the fact that it is a rainbow! It is difficult to know the hold over at various ranges. If zeroed at 50 yards, the drop is amazing at 100 yards...

But still, it would be a good 50 yarder for whatever purpose...

BCB

[fecmech]

What I was trying to get at is when the load( trailboss) went supersonic it did not group at all at 100 yds correct??,( wide dispersion??) but when subsonic all the way it grouped well albeit low. If that's the case then the transition did affect the accuracy badly.

[BCB]

What I was trying to get at is when the load( trailboss) went supersonic it did not group at all at 100 yds correct??,( wide dispersion??) but when subsonic all the way it grouped well albeit low. If that's the case then the transition did affect the accuracy badly.

Yep, it would seem that starting below sonic did the trick...

Accuracy is more than acceptable for 12-ounce cans at 50 yards, but probably would get a bit iffy at 100 yards...

The reason I say that is the fact that, and I'll try to describe. If one draws a line that is verticle with the center of the designated aimpoint on the target, one of the groups will be on the line and a bit to the left, and another will be on the line and a bit to the right. I suppose this could be just "normal" dispersions--Don't know that...

So, even though a given group might be under 1.5" or near 1.25", two of the groups put side by side by laying one target over the other and holding up to the light, the group might widen out to slightly over the 2" mark, maybe a tad bigger...

Now then, I blame some of that on the Contender. They can be the most finicky shooters to get to be consistant of any other weapon that I own...

So, when I say it isn't 12-ounce can accurate at 100 yards, that is the reason. Yet, it will shoot a group of 1.25" to 1.5" most of the time...

But, as mentioned, it is obvious that the slower velocity did help in the long run...

Thanks...BCB

[fecmech]

Thanks for the reply. Now I've got to do a little work. For a long time I've blamed the 30" twist in my Rossi for the inaccuracy of the Lee 158 rnfp at 100 yds, and that still may be the case BUT. It is very similar to what you experienced, tight grouping at 50 yds and inability to hit the backer at 100 yds with tumbling. Muzzle velocity about 1150 fps. Sooooooo this coming week I shall slow that load a bit and reshoot it to see what happens. What is interesting is that 2 different SWC's ( Lee TLSWC and BRP's Hornaday clone) run great in that range. Maybe those designs handle the transition better.

[Char-Gar]

There are so many variables in this stuff (velocity, barrel twist, bullet shape, etc. etc.), that at times, the cause of bullet instability is hard to determine. Was it one of the variables, or the bullets dropping below the sound barrier, or both? At times these discussions get all of this jumbled up and lumped into one theory or another.

[BCB]

Thanks for the reply. Now I've got to do a little work. For a long time I've blamed the 30" twist in my Rossi for the inaccuracy of the Lee 158 rnfp at 100 yds, and that still may be the case BUT. It is very similar to what you experienced, tight grouping at 50 yds and inability to hit the backer at 100 yds with tumbling. Muzzle velocity about 1150 fps. Sooooooo this coming week I shall slow that load a bit and reshoot it to see what happens. What is interesting is that 2 different SWC's ( Lee TLSWC and BRP's Hornaday clone) run great in that range. Maybe those designs handle the transition better.

Is that a 357 Magnum?

BCB

[fecmech]

Is that a 357 Magnum?

BCB

Yes it is. At 50 yds the rifle will group 1-1.5" and not stay on a 2' X4' backer with the Lee rnfp @ roughly 1150 fps. the Lee TLSWC and BRP Hornaday clone will run 3-4" for 10 shot groups@ 100 yds. Both of the SWC's are stable and linear out to 200 yds at the same speed.

[BCB]

Yes it is. At 50 yds the rifle will group 1-1.5" and not stay on a 2' X4' backer with the Lee rnfp @ roughly 1150 fps. the Lee TLSWC and BRP Hornaday clone will run 3-4" for 10 shot groups@ 100 yds. Both of the SWC's are stable and linear out to 200 yds at the same speed.

I have a Marlin 1894C in 357 Magnum and it was terrible to get to shoot at 100 yards…

Fifty yards it will shoot quarters with not too much problem, depending on the day for me...

I tried jacketed and cast, although my selection of cast that I tried was not many…

I finally—after almost throwing the little carbine in the bushes—did get it to shoot with the 358429 @ 170± grains…

The best load was using SR-4759 with 13.0 grains for a muzzle velocity of 1554 fps…

With an inexpensive variable ‘scope on it set at 9x, it will keep ‘em in 2” or a bit less at 100 yards. I think it would do better, but I think the trigger pull must be 20 pounds—literally…

The only problem is that the case must be trimmed shorter than indicated as the “trim length” to get it to cycle…

I use it for deer once in awhile, and did shoot a small doe at about 25 yards, but I have really not tested it with critters other than a groundhog or dozen. It is mostly used as a plinker that the Mrs. shoots from time to time. Off hand, she can hit 12-ounce beverage cans at 35-40 yards with amazing consistency. That is more than acceptable accuracy as far as I am concerned…

Good-luck with your Rossi…

BCB

[pls1911]

Bump your muzzle velocity to 18-1900 fps in your TC... I shoot 7MM TCU with the 145-SIL from RCBS , heat treated to 20+ at this velocity with very good results and no leading, and it's normally effective on rams at 200 meters.
I concur that your bullet is stable at 50 yards and wobbling like a poorly thown foot ball at longer ranges discussed.