Testing the Duke of Earl in Finland

Bill Calfee

Gun Fool
Testing the Duke of Earl in Finland


CYA friends:


I'm used to center-to-center group measurements at 50 yards.


The new owner of the Duke sent a wonderful letter and two test targets, which I'll admit I don't fully understand.



Here's the better of the two targets, the other was 13.5mm, this one is 11.5mm.


To me, if I rough calculate mm to inches, then subtract .222" from the total, I get the C to C group size at 50M.


Next, if I subtract 10% from the C to C at 50M total, I get roughly what the C to C group size would be at 50 yards, which I can relate to.


With my rough calculations, I get a 50 yard C to C group size, for 10 rounds, @ .203"


DSC00232%20-%20Copy%20-%20Copy.jpg



___________________


OK, the parts I don't understand:


By the way, you can read the actual size for these parameters on the test result paper below the bull.


Here's the height of the group, as I see it.


Height.jpg



______________________


Here's the width.

DSC00232%20-%20Copy%20-%20Copy%203.jpg



___________________________________


Here's the way I see the overall group size......outside to outside on all of these pictures.


DSC00232%20-%20Copy%20-%20Copy%202.jpg




________________________


Here's what confuses me:


The height of this 10 shot group, and the width, are almost identical to each other, by rough measuring the picture of this 10 shot group.


The overall group size, as I see it from the picture, is only about 15% larger than either the height or the width.



Yet look at the height, width and shot group diameter figures listed.



Anyway, 10 shots in .200" at 50 yards, if it can be repeated consistently, isn't bad at all........in the real world.

Maybe that 11 year old ratchet has some life left after all........



Your friend, Bill Calfee
 
Last edited:
I have never shooted groups to electronic targets.Only to paper.Our "big boys" has told me that electronic target shows 0,04-0,06 " bigger groups comparing to same groups measured of paper.

Even measuring group from paper from "wax marks".

Sometimes discussed if this is coming from bullets "wobbling"?????

It is very unusual to get 10 shots groups to electronic target under 0,394 " outside to outside measuring.(0,17 " C to C measuring).

BR, Timo
 
Howdy!

Yes, I admit electronic sius target print can be confusing.
Height and width are in fact vertical and horisontal mesurements of the group.
These are based on the x and y cordinates printed on the side, where the bullets
landed.
The overall group size is circumference of all 10 bullets outside edge and should be
the widest measurement, like when measuring groups, from the widest two bullet
edges.
11.5mm equals .45275 in inches. So c-c would be around 0.2307”

Funny thing, there are now three or four guns that perform excellently with same lot.
This lot was good on my Falcon and picked with it, not the best lot I have for it. The best one
was chosen by another top shooter and as I knew it might work on Falcon as we previously have
cross tested our ammo. And yes, it was/is even better on Falcon.
Looking forward to do some batch testing for both guns.

The lower bar diagram shows placement on ISSF target, where 10.9 is dead center, and every one
tenth is 0.004” off from center.

Br Tomi
 
Friend Taavetti

Howdy!

Yes, I admit electronic sius target print can be confusing.
Height and width are in fact vertical and horisontal mesurements of the group.
These are based on the x and y cordinates printed on the side, where the bullets
landed.
The overall group size is circumference of all 10 bullets outside edge and should be
the widest measurement, like when measuring groups, from the widest two bullet
edges.
11.5mm equals .45275 in inches. So c-c would be around 0.2307”

Funny thing, there are now three or four guns that perform excellently with same lot.
This lot was good on my Falcon and picked with it, not the best lot I have for it. The best one
was chosen by another top shooter and as I knew it might work on Falcon as we previously have
cross tested our ammo. And yes, it was/is even better on Falcon.
Looking forward to do some batch testing for both guns.

The lower bar diagram shows placement on ISSF target, where 10.9 is dead center, and every one
tenth is 0.004” off from center.

Br Tomi


_____________________


Friend Taavetti:


I appreciate the fine letter and targets.



Years ago I ran some spearments where I set up targets at 50 yards and 50 meters, so as I fired groups the bullets would pass through both targets.


There was no backer behind the 50 yard target, and even then there would be an errant shot on the 50 meter target every so often.


I fired enough 5 shot groups to discover, that the group size difference between 50 yards and 50 meters is exactly 10%.


Which kinda makes sense, since the 50 meter target is 10% further away.



I came up with roughly the same inches overall diameter of the 11.5mm group, then deducting 10% from it, which gives a figure of about .200" for 50 yards.



Any gun that will consistently kick out .200", 10 shot groups at 50 yards is competitive today.



As a matter of fact, in the real world there's five times more RFBR guns that won't consistently kick out .200", ten shot 50 yard groups, than there are ones that can.



I shoot a lot of 25 round groups......


And I mean through some absolutely killer RFBR guns.


It's pretty tough to kick out 25 shot groups that honestly measure no more than .200".



______________________



Now, I'm a worn out old RFBR schmidt that's going to give some recommendations about a rifle that I've not thoroughly inspected since I built it eleven years ago.




If I had the DUKE OF EARL in my shop today, here's what I'd do:




The first thing I'd do, would be to put an indicator on the barrel and check the bedding.........there should be zero movement.


If there were bedding movement, I'd do whatever it took to eliminate it.


_______________



The second thing I'd do, would be to check the firing pin tip protrusion, with the breech bolt de-cocked.....there should be a minimum of .030".


If there were less than this, I'd do whatever it took to fix it.

I'd also check the firing pins mechanical stop clearance......it should be at least .010".......


___________________


The next thing I'd do, would be to check the pin tip for mushrooming.......


E Turbos, from that period, still used 416 stainless pin tips, which were prone to mushrooming over time.


If the pin tip were mushroomed, I'd reshape it, making sure I maintained at least .030" protrusion, with .010" mechanical stop clearance.



_______________________________



Then I'd pull the barrel so I could examine it up close.



I'd first inspect the crown.......if there were any doubt at all of its condition, I'd re-crown it, right then, before I proceeded.


There's a reason for this....

Should I wind up de-glazing the bore, I don't want to have to re-crown afterwards......I want the de-glazing to take place through a pristine crown.




If the bore showed no damage, then, depending on how much wear was present, and how the bore slugged "to feel", I'd make the decision whether to de-glaze the bore, or not.


In my opinion, as old as the ratchet on the Duke is, and knowing it must have lots of rounds through it, I'd more than likely cast a lap and de-glaze the bore.


Properly casting a lap and de-glazing a bore can bring back accuracy levels to the "almost new" level.


If I did wind up de-glazing the bore, I'd, as the final step, lightly re-polish the chamber/leade........this to eliminate any possible contamination of the leade from the lapping.




Friend Tomi, a gun like the DUKE OF EARL, even if the bore is worn, and not damaged, can be brought back close to its accuracy level when new, by doing what I've just described.


Thanks again for your letter.



And best of luck with the DUKE..



And always remember:


Nothing can stop, the DUKE OF EARL


Your friend, BC




Dukecomplete.jpg
 
Last edited:
We Know The Lion By His Paw

Not to take anything away from the Duke but there is a reason the Calfee rifles are sought after and demand high prices. I thought I would share a Lapua Test center target from my Calfee rifle "Faith".

I'll try to repost the attachment, it doesn't work.

Well it does open but in another tab and I'm not sure how to fix it. Sorry.
 

Attachments

  • Faith 24 Lapua Test Ctr Group.pdf
    399.7 KB · Views: 565
Last edited:
Friend Az_Speed

Not to take anything away from the Duke but there is a reason the Calfee rifles are sought after and demand high prices. I thought I would share a Lapua Test center target from my Calfee rifle "Faith".

I'll try to repost the attachment, it doesn't work.

Well it does open but in another tab and I'm not sure how to fix it. Sorry.


________________________



Friend Az_Speed


Steve, which barrel did you have on FAITH?


David or Goliath?


(David is a 25 1/2" 8 groove Muller and Goliath is a 27 1/4" 4-MI Muller)


Your friend, BC


The .494", C to C, 10 shot group at 110 yards is extremely impressive.


I have to use C to C group measurements so I can relate to it, after a lifetime of doing it like that.



DSC00241.jpg


________________________


PS:


I've got to add something here:


If you believe you own a double bad RFBR gun, try this:


Put up a target at 110 yards and see how long it takes you to kick out a "truly honest" .494" ten shot group.


A suggestion:



Start at daylight with plenty of ammo and a flashlight, cause you'll need the flashlight to see the target when it gets dark.
 
Last edited:
Bill,

I use the same Sius targeting system in my test range to test and tune our complete rifle builds. Below is a sample screenshot showing how the targeting system software calculates the values. The Height and Width values are calculated from the square box shown in the picture, these values calculated from the center points of the shots within the group. The Mean Point of Impact is the distance of the group center from the absolute center of the target. The Shot Group Diameter is calculated by the diameter of the circle encompassing the outer edges of all of the shots fired. Just thought this might help show how well that rifle still shoots.

Best Regards, Anthony

 
Friend Bill,

It was David and I thought Goliath shot well. I'm waiting for the next shipment of M+ to test Goliath again. As you will recall Goliath had a group at 6.88 mm but it was CTC not outside to outside. They both shoot and I attribute it to the "touch of the master's hand". Thank you so much for all you've done and continue to do to advance rimfire accuracy. It is a pleasure and a thrill to shoot this rifle.

Your Friend,

Steve
 
Interesting target

Hi Az_Speed

An interesting point with your target is the last shot fired was pretty close to the center at 50M but then by the 100M it had curved to the outside edge at either the 12, 4, or 8 o'clock position.

This means either the bullet flies in a straight or more correctly a curve due to gravity from the muzzle to the 50M target then starts to curve to the outside.

Or the bullet is wobbling (spiraling) from the muzzle to the 50M target but just happens to pass through on the same wobble each time but due to velocity differences arrives at the 100M target on a different part of the increasing wobble.

This may be why a tuner can change the vertical and horizontal spreed ratio.

You imagine this if you can see a kids toy top spinning and while it is still spinning it starts to wobble and this wobble processes around in a circle.

You can also see the general shape of the group irrespective of it's size is a little different at 50M than at 100M

Regards
Graham
 
Friend Az_Speed

Friend Bill,

It was David and I thought Goliath shot well. I'm waiting for the next shipment of M+ to test Goliath again. As you will recall Goliath had a group at 6.88 mm but it was CTC not outside to outside. They both shoot and I attribute it to the "touch of the master's hand". Thank you so much for all you've done and continue to do to advance rimfire accuracy. It is a pleasure and a thrill to shoot this rifle.

Your Friend,

Steve

______________________


Friend Az_Speed


It was David..............


Steve, if I could have what I believe to be the best RFBR accuracy barrel being made today, for my new Turbo pistol, it would be a Muller corrugated 8.....just like David.


The Muller corrugated 8, has the most pure accuracy potential of any RFBR barrel being made today.


Your friend, Bill Calfee
 
Last edited:
Friend AD

Bill,

I use the same Sius targeting system in my test range to test and tune our complete rifle builds. Below is a sample screenshot showing how the targeting system software calculates the values. The Height and Width values are calculated from the square box shown in the picture, these values calculated from the center points of the shots within the group. The Mean Point of Impact is the distance of the group center from the absolute center of the target. The Shot Group Diameter is calculated by the diameter of the circle encompassing the outer edges of all of the shots fired. Just thought this might help show how well that rifle still shoots.

Best Regards, Anthony



_________________


Friend AD:


Thank you.....



I'd love to see what Tomi could have done with the Duke back 11 years ago when it was brand spanking new....


Although, if the bore of the Duke's ratchet isn't damaged, doing the freshening up that I suggested, especially de-glazing the bore, would most likely bring it back to 95% of when it was new....at least for a while.....


AD, when I de-glaze a worn bore, I'm not trying to bring the surface of the bore back to brand new, that's impossible.


What I'm trying to accomplish, is to make the bore carry wax uniformly again, like it did when it was new.


This is why I de-glaze using very course grit......


Your friend, BC
 
What de-glazing can do...

What de-glazing can do...


AD, the best example of what de-glazing can do for the bore of a barrel has to be Jeff Carroll's HOT STICKS.


hot%20sticks.jpg



Jeff, through cleaning, had completely removed one land from the leade forward, for about three inches, from the bore of Hot Sticks.


He thereafter changed his cleaning method.



Anyway, Jeff asked me to fit a new barrel, which I ultimately did.



But first, I advised Jeff that I'd like to cast a lap and de-glaze the bore on the defective barrel, and he said to go ahead.




So I cast a lap and using some 120 grit I de-glazed the bore, concentrating on the rear third of the bore.


I use silicon carbide which breaks down, as one laps, to finer and finer grit.....


Therefore, I only made four of five passes after charging my lap, then I pushed the lap to the muzzle, wiped the excess grit off, then recharged the lap again so as to make sure that full sized 120 grit did all the cutting.



When I finished I had placed lines in the washed out section of that bore, as well as the rest of the bore, emphasizing the most in the rear third of the bore.

These new lines allowed the washed out part of the bore to carry wax again......the remaining three lands could fully rotate the bullet just fine.



The last time I re-charged my lap I made four full length passes, breech to muzzle, then withdrew the lap.


I wanted the final scratches in the bore to be full length from breech to muzzle.



So how did the barrel shoot after de-glazing the bore as I did?




The first time Jeff shot that de-glazed barrel he kicked out a "pretty" 2500.



I'd love to have eight hours in my shop with the DUKE OF EARL......


I guarantee Tomi would wear folks out with it..........which he may do anyway.



Your friend, BC
 
Last edited:
I love challenges

I love challenges


CYA friends:


Since I've been discussing de-glazing, I've got to thinking...


I have the 4-MI off of Raging Inferno, the first 12,000 plus PSL score ever fired, by Chuck Morrell.


( There's now been two 12,000 plus PSL scores fired, and both by MD-PAS ignition actions, which is not really surprising)


Anyway, here's a picture of the leade and bore of the Inferno's Muller MI....


DSC08307.jpg




Here's what I've a mind to do.......


I'm going to contact Chuck and see if he'll sell me this barrel.


He may just want to keep it for historical preservation.


But if he'll sell it to me, here's what I'm going to attempt to do:



I've already ran a tight patch through the bore, and the cleaning rod does rotate all the way back through the chamber....


What one would consider a medium fitting patch, won't keep the cleaning rod rotating all the way back through the chamber.



I'd like to go in there with an extremely full lap, using maybe even some 80 grit, and see if I can bring this fine Muller back to life again.



Your friend, BC
 
Back
Top Bottom