Highly esteemed Sirs of the DRSS,
and Madams or Its of the Alaskan Chapter of Sir Cal Pappas:

Your opinion, please, on this: Tight hold-down on bags at benchrest versus no-down-pressure mimic of offhand hold from the benchrest,
Have I demonstrated this in target below?

Ice and snow melted off and temps were 48F to 52F while I was at the range Wednesday last, 2-19-2014.
Kind of a muddy mess, but nice to be out and about, range all to my self, hoisting the red flag.

20-Bore Double Rifle, RBL with 2.5X Leupold, 24" barrels:

I chronographed 14 rounds of factory sabot slugs. The 15th killed the the non-shielded Prochrono.

10 rounds of Winchester "Supreme Elite" chronographed. It averaged about 1700 fps for the 260-grain saboted .452-cal bullet.
Maker claims 1800 fps with this load, in unspecified barrel length.
However, there was a 232 fps extreme spread of velocities, and the two-shot groups crossed and diverged willy-nilly, mostly crossed by 2 inches at 50 yards.

Next 4 shots of Remington AccuTip 260-grainer advertised at 1850 fps were really slow at about 1500 fps with ES of 83 fps.
The 5th shot killed the chronograph by sabot strike.

Hornady SST saboted 250-grain/.452-cal is advertised at 1800 fps.
I was unable to chronograph it, but it came closest to parallel at 50 yards. Though converged, not crossing.

Here is a target that shows a tight hold down on the bags for R1 shot, then a loose hold for L1 shot.
Next came R2-L2 doing the best I could to mimic an offhand hold from the bags:



Small sample, but it is a start. It makes me believe that maybe Tony Galazan did do some regulating of the RBL,
but I suspect he used a handload, not the 3-dollars-per-pop factory stuff.
He said this was his personal gun, and he had shot it only to regulate it.

I am guessing the regulated-for velocity with the 250 to 260-grain saboted 45-cal bullets is close to 1600 fps.

I am hoping to load my own, and especially hope a .617"/350-grain roundball will work at whatever speed and 12,000 psi or less,
by SAAMI spec for 20ga. RBL regulation is adjustable by the muzzle contraption, afterall.

I'll leave the scope off and try the open sights next time, from shooting sticks, to see what that indicates about regulation,
regarding scope versus open sights.
Gun is 6#-10oz with open sights, 7#-5oz with scope and rings.
11 ounces for Leupold Ultralight 2.5X in Talley rings:

RIP

My testing confirmed similar results.
Velocity was 100 to 150 fps below advertised in my 24" barrels.
ES was all over.
Accuracy was 2" ave for slugs.
I bought an HR slugger and mounted a 4x14.5 leupold for testing.
You would expected better from $5 a pop ammo.
But it was not so

Nitro

My experience is that double-rifles are very sensitive to any holding pressure. One should always try to reproduce field offhand shooting, i.e. shoulder support (rear bag may support firing hand but not the stock) + holding hand between the forend and sandbag. Anything that modifies resistance to recoil may -often will- effect bbl. convergence. The same may happen when not respecting the "normal" timing and firing order. Usually doubles are regulated to fire R/U bbl. first, followed by the L/O bbl. within 7-10 ".

I made a triangle out of 2x4s and C-clamped it to a post next to the bench at the range and used it as a standing bench. I would rest my left arm against it just slightly to steady myself while shooting for groups.

Standing rest, right then left within 5-10 seconds ...
I may have to give the Hornady SST another try, get the scope adjusted for it,
and see where the iron sights hit.

Definitely cannot use the Winchester or Remington saboted factory loads!

I really need a uniform handload either sabot or round ball.

I sliced open the 3 different saboted bullet loads to analyze:

Remington and Winchester loads use tiny-flake powders with sabot, filler wads, and gas seal.
Winchester: 37.0 grains flake powder
Remington: 30.9 grains flake powder

The Remington case (20ga 2-3/4") has printed on the side of it "MAX 830 BAR" which converts to 12,000 psi per SAAMI,
if 1 bar = 14.457831 psi. Close to a standard atmosphere.

Hornady SST uses a ball powder and long sabot plus gas seal over powder: NO FILLER WADS.
Hornady powder charge looks like a ball powder, 32.8 grains.

All three sabots shed in flight to release the bullet.
The Hornady sabot has only 3 petals. The Remington and Winchester sabots have 4 petals.

Nuts!

Sounds like I need to try BLUE DOT & ROUND BALL.
KISS principle.
First in a Savage 220 bolt action with scope,
with shielded chronograph,
then in the RBL.
Tracking the trail of nitro450exp.

Does a shedding sabot confuse a chronograph at 4-5 yards, producing a wide range of velocities with a randomly trailing sabot behind bullet?
I do know the plastic sabot is an effective chronograph killer at 4 to 5 yards.
I have bagged 2 chronographs so far with shotguns.

Try the Rottwell Laser + sabot, hands down the best slug I have tried.

Not a fan of Remington sabots, have not tried Winchester in years, had poor results with Hornady

http://www.ruag-usa.com/produc...rottweil-laser-plus/

Kebco,

That is a great idea.
Rottweil is using the Hammerhead sabot slug made by Slugs-r-us.

www.slugsrus.com

The combo pressure wad sabot stays with the Hammerhead slug until impact with game,
which will protect the chronograph.

http://www.ruag-usa.com/produc...rottweil-laser-plus/



20ga uses a 350-grain lead slug with 60-grain pressure wad sabot. 410-grain projectile ejected.

I have purchased some of those 20ga pressure wad sabots and can shove .430-call bullets from 240 to 300 grains into them.
300 to 360-grain projectile will result.

Slugs-r-us says to use 27.0 grains of Blue dot with the 410-grain projectile to get 1500 fps.
That is supposed to be less than or equal to 12,000 psi SAAMI max.

From reading shotgun slug load tables:

Dropping slug weight by 50 grains with the same powder charge usually results in minimal velocity gain (less than 50 fps)
but with pressure drop also, of about 2000 psi.
That was with Winchester 571 ball powder in a 12ga.
Alliant Blue Dot flake powder is right next to Winchester 571 on my burn rate table.

Combining this with the Slugs-r-us data, I think am safe to play with Blue Dot.

Other important info from handloading research:

A difference in roll-crimped COaL from 2.350" to 2.300" in loaded shell length
can increase pressure by about 2000 psi and raise velocity by about 50 fps,
with no alterations made to the load other than 0.050" length difference.

So I can fine tune velocity by changing the length of roll-crimped shell, with same projectile, and same powder charge.
Gotta do a uniform roll crimp, practice, practice ...

The light-weight plinker could be a 240-grain lead bullet (pennies) in the Slugs-r-us pressure-wad-sabot (35 cents),
with 27.0 to 30.0 grains of Blue Dot roll crimped to proper velocity.
That would be a 300-grain projectile aiming for parallel to infinity,
or at least to 50 yards, then dropping like a shuttlecock!
Get that right then try 265-grain bullet for 325-grain total with pressure-wad-sabot,
then split the sabot in quadrants so as to shed from the ballistic tipped bullet at the muzzle.
That might make it parallel to 100 yards, and be better than Winchester and Remington caviar slugs,
much higher retained velocity.


Round ball trick:
Forget the wads and just use a stack of gas seals, however many needed to get the right roll crimp length of loaded shell,
for proper velocity to shoot parallel,
whatever that may be with 350-grain ball,
same weight as the Rottweil 20ga Hammerhead lead slug inside the plastic,
but now with all the plastic below the ball.
Plastic is plastic, parts is parts, gross weight ejected nearly the same.

I mastered handloading for a Merkel 470 NE over a decade ago.
Getting the RBL 20-bore DR handloaded correctly is turning into something more complicated.
Fascinating, obsessional craziness.
Gotta be crazy about something or life is dull.

I will buy some of those Rottweil 20ga 2-3/4" Laser Plus "sabot slugs"
and chronograph them without fear for the Oehler screens at 5-yards from the muzzle.

Loading nitro bore rifle cartridges to regulation - especially with this sabot business, it can be tedious.
I like black powder. Big charges of coal, simple wad columns, forgiving ballistically, consistent -- and lots of smoke!
Boom!!

Good you've got the adjustable barrels too.
when you find accuracy at the velocity you want the fine tuning will really cinch the deal.

Have fun!

Lessee, 19 grains of Red Dot is equivalent to 3 drams of FFg black powder,
velocity-wise for 1-1/8 ounce shot load in a 2-3/4" 12 guage ...
... and a whole lot less recoil than the coal burner for sure!

quote:

Anything that modifies resistance to recoil may -often will- effect bbl. convergence. The same may happen when not respecting the "normal" timing and firing order. Usually doubles are regulated to fire R/U bbl. first, followed by the L/O bbl. within 7-10 ".

Ok, I do not own a DR one have I fired one. So not being a SA when I ask this question.

So here goes.
If the second shot is fired after recovering from the recoil of the first shot - seems like this is required to properly reacquire sights and intended POI, why does it make a difference which barrel is first fired?

And yes I do understand it is more natural and faster to fire the front trigger first and back trigger second but I don't see how that would have any impact upon regulation.

Yes RIP, but with a 20bore of this relative power there isn't any recoil to speak of any way you load it - especially in the 2-1/2 to 3-1/2 dram range.
Just a love tap from the buttplate and you're on the way.

quote:

Originally posted by capoward:

quote:

Anything that modifies resistance to recoil may -often will- effect bbl. convergence. The same may happen when not respecting the "normal" timing and firing order. Usually doubles are regulated to fire R/U bbl. first, followed by the L/O bbl. within 7-10 ".

Ok, I do not own a DR one have I fired one. So not being a SA when I ask this question.

So here goes.
If the second shot is fired after recovering from the recoil of the first shot - seems like this is required to properly reacquire sights and intended POI, why does it make a difference which barrel is first fired?

And yes I do understand it is more natural and faster to fire the front trigger first and back trigger second but I don't see how that would have any impact upon regulation.

Jim,
That is supposedly due to the dynamics of heat transfer and expansion of metal with heating and contraction with cooling,
and the pattern might be different left to right than it is right to left,
as to the way the soldering, ribs, wedge and barrels contact and affect the regulation,
changing things from a cold state to a hot state.
Or there may be no significant difference.
Some DRs may work fine whatever sequence the barrels are fired in.
Some DRs might be more forgiving than others in the time between shots too.
That is my 2 cents worth on that, FWIW.

a.tinkerer,
Right! That is the whole idea of the RBLil'gun.
Love taps, RBLove. Round Body Launcher.

Thanks Ron. Very interesting...

The recoil of the right bbl. will swing the rifle to the right, and the contrary happens with a shot from the left bbl. Both shots are pulled apart laterally and this is compensated for when regulating bbl. convergence. Shoot the bbls. in the opposite order and you will negate the regulation. For O/U rifles, the process is the same, R bbl. becoming U bbl., etc. and the initial impacts divergence being vertical instead of horizontal.

There is no difference in POI between shooting off the bench and offhand.I have proven this to myself a few years back.

As usual, shootshimselfinthefoot lives up to his name. What a scientific approach... Lawful fact derieved from a minimal of personal experience. A few rounds with one load with one rifle at one range by one idiot...and you have data representative for all rifles. I have experienced the opposite and ignoring the fact that I am a better person in general and shooter in paricular, all non moronic persons understand the only right answare is the humble version you obviously don't comprehend....


"In my limited experience......I have found that.......is the case......

Perhaps a Magnetospeed with a custom mount, to use on the bench would solve the "chrono kill" problem.
It is available, saw pics of one mounted into a front rest, idea could be adapted to a tripod in front of you, for shooting off sticks.

quote:

Originally posted by shootaway:
There is no difference in POI between shooting off the bench and offhand.I have proven this to myself a few years back.

In one simple sentence, you go against HUNDREDS of years of institutional knowledge and the findings of HUNDREDS of real experts, who went to the trouble of finding out for themselves.

That's either genius or Neanderthal stupidity.

I'll leave the choise up to you.

Messrs. Rigby, Holland, Webley and Leonard, to mention only a few, are spinning up to ever increasing revolutions in their respective graves as I'm typing these words.

quote:

Originally posted by shootaway:
There is no difference in POI between shooting off the bench and offhand.I have proven this to myself a few years back.

So-called member shootawhey is a legend in his own mind alright, but to the rest of all-inclusive ar.com,
only his ignorance is legendary.

Can shootaway be banned from DRSS membership? Is that possible?