.310 Cadet accuracy

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JeffinNZ posted this 12 June 2019

Well, I'm back to square one.

I spent a long time trying to get my .310 Cadet to shoot with smokeless powder and reformed .32-20 brass.  Long story short, the neck thickness was insufficient and on firing the brass expanded and the massive blow by of gas caused leading and NIL accuracy.  Using correct Bertram brass with neck thickness of 11-12 thou solved the issue and fired cases need no sizing as the heel of a CBE bullet is a snug fit for thumb seating.  Instant accuracy.

Of course being an idiot I only bought 20 of those cases and recently picked up another 50 to find the walls are thinner.  ARGH.  9 thou instead of 11-12 thou.  Doesn't sound much but using EXACTLY the same load at 50m the correct dimension old brass shoots 1 inch groups.  The new brass is putting bullets sideways and not on A4 paper! 

The solution will be to hone out the heel of the mould such that it drops bullets that are a snug thumb seating fit in the fired new brass.  The heel will need to be .312 inch.  Ideally I believe Cadet moulds should be hollow base as the original swaged bullet are and likewise .22RF with the hollow allowing the base to slug up to seal the bore quickly.

Cheers from New Zealand

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pisco posted this 12 June 2019

hi i run bertram brass and have a cbe mould that throws 319 cast bullets from w/w the heel measures 312 i run 10.5 gr winchester 296 powder it must be the same speed as the original load as the elavation marks are the same i run a pistol primer at 50 y 10 shots measure 30 mm i am experimenting with unquie powder it is grouping about the same

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JeffinNZ posted this 12 June 2019

PISCO: I am going to have my heel opened out to cast at .312 in 40-1.

Cheers from New Zealand

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45 2.1 posted this 12 June 2019

I've used the RCBS bullet and one smooth sided one from a Lee GB. Match your alloy to the pressure level and your shank size won't matter too much. On recovering fired bullets, I found both varieties bumped out to full diameter and shot well (to the sights also) out to 400 yards. Remember, they had the 310 Cadet to train boys in long range shooting.

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JeffinNZ posted this 12 June 2019

I've used the RCBS bullet and one smooth sided one from a Lee GB. Match your alloy to the pressure level and your shank size won't matter too much. On recovering fired bullets, I found both varieties bumped out to full diameter and shot well (to the sights also) out to 400 yards. Remember, they had the 310 Cadet to train boys in long range shooting.

In all the original testing with converted .32-20 brass I tried different alloys to no avail. 40-1 shoots superbly with the thicker walled brass so the alloy is not the factor and with the charge of 5gr of Unique pressure will not be particularly high. Thick walled brass = good accuracy, no leading. Thinner wall brass = NIL accuracy and leading. The issue would appear to be the brief instant when the thinner case walls expand to fit the chamber leaving the heel exposed to a blow by of gases much as any under sized cast bullet is. With the thicker walled brass there is no case expansion forcing the gas to stay behind the heel.

Cheers from New Zealand

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45 2.1 posted this 12 June 2019

 "With the thicker walled brass there is no case expansion forcing the gas to stay behind the heel."

I've found that to be caused by other reasons, not that though. You really can't have a fixed cartridge and have it keep the powder pressure all behind it, even with absolutely minimum clearance (0.0005" or close to that total clearance). The internet has several videos depicting the gas blow-by leaving the muzzle before a bullet shows up. A breech seated flat base might do that though. It would seem that gas does get by as soon as the neck lets the bullet go before it enters and seals the bore... in whatever order that occurs because it's speculation. If anyone can say what it does with 100% certainty, please do so. You should look pressure curves from the powder you use and pick an alloy that is softer than you think to use for it. The target and bullet you show didn't seal and stay centered... I would say it didn't bump up, which all heeled bullets need to do, not just ride the land tops.

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JeffinNZ posted this 12 June 2019

That’s not a recovered bullet in the photo. If the alloy is at fault why does the load with thicker walls shoot so well?

Cheers from New Zealand

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45 2.1 posted this 12 June 2019

That it's not a recovered bullet is obvious... no rifling and it has lube on it. Why does it shoot so well......More guidance for the bullet shank from the case walls. The bullet shank is a little to small or it is too hard to expand to groove size.... that is an observation from what you say and the keyhole on the target. If it could expand properly, it would not keyhole like that. Smaller than optimum bullet shanks tend to do that when they are too hard to bump up..... much like what happens when GC bullets are shot without the GC, but in the Cadets case, it doesn't have enough bearing surface length to help straighten it out.

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JeffinNZ posted this 12 June 2019

Exactly the same bullet and alloy with both loads. 40/1 is perfectly soft enough to slug up.

Cheers from New Zealand

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45 2.1 posted this 13 June 2019

OK, then answer this question.............Why did you get a keyhole when it is perfectly soft enough to slug up? It seems it didn't with the thinner brass. Recover some fired bullets and see what happened.

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Squid Boy posted this 13 June 2019

The only time I have ever seen a keyhole out of my 310 Cadet is when I tried to shoot some undersized bullets meant for a 32-20 in it. I have a CBE mold the drops a 130 grain bullet at .323 diameter with a .310 heel. I use 20-1 alloy and this will put five into a half inch at fifty yards using 4.9 grains of Viht 3N37. It is also very accurate in another Cadet re-chambered to 32-20 but with 5.2 grains of Unique. Seems very strange what you are getting. Squid

"Squid Pro Quo"

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Mike H posted this 13 June 2019

This problem of Jeff’s shows how a small change can upset a good performing load,I am confident he will sort it out,though I don’t have a .310 Cadet,I find the discussion interesting.

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Squid Boy posted this 13 June 2019

Just for fun I dug out the only original Kynock 310 Cadet cartridge I have in my collection. A hollow point no less. The case measures 1.120" and is .324" diameter measured at the upper end of the neck. The bullet is .318" diameter and the COA is 1.567". It's the only one I have so I won't be dismantling it but I thought this might be interesting. Squid

"Squid Pro Quo"

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JeffinNZ posted this 13 June 2019

Hollow base bullet?

Cheers from New Zealand

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Ken Campbell Iowa posted this 13 June 2019

hey jeff ... numbed minds want to know ::  before you hone out the base on that naughty bullet mold .. how about just drilling out some hollow bases with a drill press ?? ... about 3/16 inch dia., 1/4 inch deep should work.  your drilled holes might not be perfect, but if they improve, it might show the right direction.

to do it right, it would require a dedicated die set with a swaging pin or a drill guide .  easier to hone the mold .

i always wanted to try drilled out hollow bases, but so far have never had the problem you are finding.

**************

also, remember that those glorious 22rf bullets have a very short heel ... yours has a  very long one, almost half the mass is unsupported at ignition/brass expansion.  my benchbuddies assure me that the brass expands before the bullet moves, and just leaves it hanging there in mid-air ...

which might make it interesting for you to breech seat some shots just for fun ... ?? need a push rod in a case for a martini ??

interesting thing you have there .

ken

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Squid Boy posted this 14 June 2019

Jeff, no, a hollow point. Sorry if I wasn't clear. I had Accurate make a mold from my design, that is longer weighing 141 grains. I wanted to try having the bullet engage the rifling without breech seating. This one engages by about .010" on my rifle and the breech block finishes the job of loading. It shouldn't be very stable according to Greenhill but the Miller says it's OK and so far they are all point on at 100 with no sign of tipping. I just started testing and it's not quite as accurate as the lighter CBE but I think it may improve. Thanks, Squid

"Squid Pro Quo"

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tony1960 posted this 15 June 2019

Jeff, I must say that I concur with you. The case wall thickness is critical when dealing with this and other straight walled cases. Now that you have fire formed the new cases have you measured the inside diameter of the cases? Might be of some use to find out if you have to bump up that base, the other alternative I have thought of is to wrap PTFE tape around the heel to make a snug fit in the cases. Or would a cardboard wad under the base help with the leading? it may be just enough to offer some firewall. I will find some time tomorrow to measure my case walls and ID, I have newish Bertrams and have only fired them 3 times.

 

cheers

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tony1960 posted this 16 June 2019

Jeff, I managed to measure all of my 310 Bertram brass today, both wall thickness and ID after firing in my chamber.

The wall thickness averaged out at 0.0095 but ran between 0.009 and 0.01 with the majority on the thicker side. I would confidently say they are 0.01. I also measured my fired brass for ID without sizing and they all ran an average of 0.316, my projectiles have a heel of 0.315 - 0.317 so they are a nice fit by hand. When I chamber the case they have a nice feel on closing. I hope this helps mate.

 

Tony

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barra posted this 24 June 2019

I just made up some rough swagged bullets my using a plugged case to hold the lube bullet.

i have a old chamber cut back to use as a size die when making new brass or sizing fired brass.

by putting it into the sizer and using a rod . I tapped the rod to fill the throat .

the base is also expanded by the case being kept solid by the die wall.

No magical bullet grouping happened but it was not any worse either.

Just putting it out there.

I only get around an 1" at 50 yards which is about as good as I can see to hold anything with a Parkerhale #7 peep.

 

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longhunter posted this 27 June 2019

Well now that I'm the proud owner of a 310 cadet, I need to learn all about it!

Thanks for writing keep it up.

Jon

 

Jon Welda CW5 USA Ret.

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JeffinNZ posted this 27 June 2019

Making progress.  Heel of the mould opened up and now throwing a heel of .312-.313.  Leading has stopped.  Accuracy still sub par but round holes.  Tried some ACWW today with some success.  More to follow.

Cheers from New Zealand

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JeffinNZ posted this 29 June 2019

Problem solved.  Final test at 50m/55y yesterday.  Just under an inch for 5 shots.  

Blog article here.

 

Cheers from New Zealand

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RicinYakima posted this 30 June 2019

 Very excellent article, Jeff.

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Mike H posted this 30 June 2019

Congratulations Jeff,your careful and well thought approach to the problem has paid dividends,an example more should follow.

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Ken Campbell Iowa posted this 30 June 2019

great story, jeff !! ...  oh, i wouldn't be too sure those factory small-base loads shot well ....  they didn't have much of a mission.

... and also very interesting that the misfit bullets shot well with black powder ....  seems there is something more to be discerned ::  does black upset the base immediately ....or does it burn so gently that the bullet is kind of " breech seated still undisturbed " before the nasty big hotflash hits it ??

thanks   ken

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JeffinNZ posted this 30 June 2019

... and also very interesting that the misfit bullets shot well with black powder ....  seems there is something more to be discerned ::  does black upset the base immediately ....or does it burn so gently that the bullet is kind of " breech seated still undisturbed " before the nasty big hotflash hits it ??

thanks   ken

Ken, I think it's two factors at play. Rapid upset due to the black powder burn but before that something like 3/4 inch of compressed powder working as a consumable barrier.

Cheers from New Zealand

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JeffinNZ posted this 07 July 2019

Frosty morning, Took the Cadet to the range to verify some sight settings.  This is 4 shots at 50m with the new, altered bullet/mould and ACWW alloy.  Two in the white are the 50y setting, two in the black sights set between 75 and 100y.

Cheers from New Zealand

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longhunter posted this 07 July 2019

I am enjoying your story.  I have just gotten a Cadet and will be shooting it soon. I will let you know how my story goes with it.

Thanks for the info and your experiences with loading and shooting your rifle.

Jon  

Jon Welda CW5 USA Ret.

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Brodie posted this 08 July 2019

Jeff,

I first heard about the concept of "consumable fillers" on the Cast Boolit Forum.  A number of smokeless powder shooters of paper patched cast bullets used duplex loads of very slow powders to get their home wrapped projectiles to shoot at the desired velocities.  The thought was that the slower (slowest) powders needed more than just a primer to get them to work well in that particular application.  I have never tried this type of load myself.

 

B.E.Brickey

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pisco posted this 08 July 2019

hi that’s the go jeff you would have to be happy with that i had a cadet years ago before any of these sights and i had no idea what i was doing so i sold it now we talk about things like this to people all over the world and it it is so much easier to get information

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Gunnie posted this 17 July 2019

There seems to be a lot of varying thoughts/opinions on the 310 & correct diameter projectiles. A learned individual I have the honour to know, has clarified a lot of the conjecture.

The original contract order for 310Cadets for the Australian military was filled by BSA in the UK. BSA barrels were of .316" diameter & all was well. At some stage there was a problem where BSA wasn't the sole provider of barrels. W.W. Greener produced a number of barrels chambered for 310Cadet, to fill the remaining contract numbers.

This was not initially of concern until cadets began complaining of noticeable problems with the ammo, or more accurately,  firing of the factory ammo. What was found was that the Greener barrels were of a larger bore size, typically .318-.321". Ammo was keyholing on hitting the target, any wonder!

The powers that be decided the easiest (read 'cheapest') fix was to modify the ammo. A larger lead projectile was used in place of the factory jacketed. To keep the case as is, the projectile decided on was a heeled design. The base was the original dimension & fitted into the case mouth. Whereas the front section of the projectile was the correct size to suit a Greener barrel. Being lead it would also swage down to suit bores of BSA manufacture.

Now, here's where folks come to grief these days when reloading for their Martini Cadet. Does it have a Greener barrel or a BSA barrel? I have three Cadets all all will shoot .314" cast projo's very well. I have also tried heeled versions of 128gn & found them to shoot well. I use a pistol powder (AP70N) aand found it to work well with good accuracy out to 300m.

Great little cartridge, fantastic rifles.

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lotech posted this 17 July 2019

I don't know anything about these guns, but have a friend who picked up one years ago. It was chambered in .32-20. I doubt he's ever fired his gun, but I did, using my regular .32-20 loads for  a Marlin and a Winchester low wall. It's been a long time ago, but the .312" or .313" bullets (cast from a Lyman 115 gr. flat nose gas check mould) seemed to shoot with at least reasonable accuracy.    

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JeffinNZ posted this 17 July 2019

Gunnie:  The .310 Greener (Cadet) was always a heel bullet cartridge from it's inception.  Jacketed bullets were loaded in AU to comply with the Hague Convention for Home Guard use during WW2.

Mine has a BSA barrel.  I would be keen to see chamber measurements from a Greener barrel if you have one.

Cheers from New Zealand

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Bud Hyett posted this 17 July 2019

The experiences of we shooters competing with the .32-20 CPA may be of help. NOE offers molds from 119 grains to 214 grains, you can select dependent on your twist. They offer molds from .312 to .321 diameter.

The Stevens 44 1/2 barrels on my rifles are .319 (1:16 twist) and .320, (gain twist), breech-seating which could be a problem with the Martini action. One can always use a plugged case to breech seat and then load a case with the powder held by a wad.   

Farm boy from Illinois, living in the magical Pacific Northwest

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barra posted this 17 July 2019

 

Something like this maybe.

‘My gun with heeledbullet using a plugged case using a heeled bullet.

 I also do some paperpatched bullets.

 

I’m running hot and cold at the moment with fixed thou.

 I changed primers and I was getting three into one of those 20mm target dots at 50 yards but last time it was all over the shop.

humph

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Gunnie posted this 18 July 2019

Ah, the humble 310Cadet.

 

Doubled up my posts.

Jeff, I knew about the Greener & heeled projectile requirements, though thought the jacketed projectiles were from the inception. I recall seeing a packet of military issue 310Cadet ammo with a very early year of manufacture and it was all jacketed. Price put me off otherwise I would have bought the packet just to have  the collection. I do have a couple of packets of military FMJ, I'll have to have a look at what the DoM is.

Unfortunately I don't have a Greener Martini but I do know someone with a few so I'll drop round and see what he has. Might be a Greener amongst them. 

I do have one unusual Cadet in the trio. It was problematic with firing Bertram brass reloads. There would be either none or a very light primer strike. Had me buggered for a day or so. Found out that at some stage someone has deepened the rim on the chamber to accept the thicker rim of a 32-20 case. Thing is though the chamber won't take a 32-20 case! So I shortened 32-20 cases to the same as a 310Cadet case and the problem was solved.

I'll weigh the cast pills I'm using and will have to spend some time on the range comparing the various projectiles I have on hand. I'm yet to throw any casts from from my T E Buggs mould but believe it is supposed to be a 128gn .318" but will confirm once I get the mould back. I've sent it to a mate so he can run up a stock of projectiles for his Cadet.

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linoww posted this 30 June 2023

I know this is an old thread, but for some reason, my cadet keeps landing an occasional bullet sideways. I'm using the r c b s cadet bullet. So it looks like it gets down to undersized base?

"if it was easy we'd let women do it" don't tell my wife I said that!

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barra posted this 01 July 2023

Longer brass may help.

I try for a snug fit.

‘how is the bore condition?

 I bored out my base band on the RCBS mold to 0.315" to fit my 32-20 shortened brass.

Shoots well without having to resize or tamper with brass.

I cast on the softer side and use plenty of soft lube.

 

 

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barra posted this 01 July 2023

 

Trying  some work up loads with adi 2207 as suitable powders are not available.

Left much unburnt powder but shot O.k.

The original sights are hard on my eyes, so I take what I can get.

ha

The 3 outliners could be the loose nut behind the butt.

Or being seated on unburnt powder kernels or rough unsorted cast bullets that I shoot.

Most likely a combination plus a loose bullet in the case fit.

I’d be in the master class if I could hold this good during the service shoots.

 I have loaded some more and even used the side of the bench to roll the case mouth to tighten some of the bullet fit.

‘All the modern conveniences..

While playing around I did find that with just a small rifle primer as a charge, it does nearly fully upset the heel to full diameter.

 

 

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linoww posted this 01 July 2023

bore is as mint as can be.The case length is 1.1" and pretty close but not quite to full length. Bullets are my plainbase 32-40 alloy of 20-1. I thought about heel diameter as well.I may open up the heel thanks!

"if it was easy we'd let women do it" don't tell my wife I said that!

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JeffinNZ posted this 01 July 2023

Longer brass is often the answer.

Brass for the .310 Cadet | Cast Bullet Association | Online Forum | Bullet Casting Forum

Cheers from New Zealand

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linoww posted this 02 July 2023

that's the thread I had been looking for!

thanks a bunch

"if it was easy we'd let women do it" don't tell my wife I said that!

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JeffinNZ posted this 02 July 2023

Also worth considering is your .32-40 bullet may be too long for the Cadet twist rate of 1-20 inch.  

Cheers from New Zealand

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linoww posted this 02 July 2023

it's the RCBS 120 cadet bullet,not a 32-40 bullet.

"if it was easy we'd let women do it" don't tell my wife I said that!

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barra posted this 02 July 2023

I would be putting the cleaning rod down the muzzle of the closed action and marking the rod at the muzzle.

‘I would be then seating a cast bullet and measuring the distance the rod goes down between the muzzle and that line.

That should be your overall length of loaded round.

 

I would personally test with breachseated bullets and a loaded case before I opened the heal of the mould.

the extra length may be a bit narrower.

‘With everyone making and using reamers for fitting the swapped barrels the dimensions can be far from perfect ideal blueprint drawings.

just my 2 cent’s worth.

 

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linoww posted this 02 July 2023

I just got back shooting 50 rounds and no tippers! it's so frustrating because it's intermittent.

"if it was easy we'd let women do it" don't tell my wife I said that!

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JeffinNZ posted this 03 July 2023

Something else to consider is using softer alloy.  I cast exclusively in 40/1 for the Cadet.  Slugs up great.  Approx 7.8 BHN whereas your 20/1 will be nearer 10 BHN.

Cheers from New Zealand

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linoww posted this 03 July 2023

I'll try softer. once I had nearly all bullets tumble. I modified a Lee 32-20 Collet crimp die to crimp the heel. Well..I squished them into hourglass shaped heels and made them undersized a bunch. live and learn sometimes

"if it was easy we'd let women do it" don't tell my wife I said that!

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JeffinNZ posted this 04 July 2023

I thumb seat bullets in unsized brass with great success.  Crimping I consider to be best avoided.

Cheers from New Zealand

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linoww posted this 04 July 2023

I also do not size cases ,I just finger seat.

"if it was easy we'd let women do it" don't tell my wife I said that!

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Ken Campbell Iowa posted this 04 July 2023

we need to do a study of finger seating vs. thumb seating ...   i betcha one is better than the other ...

ken ...    ( hey, it's the 4th of July ! ) ....

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JeffinNZ posted this 04 July 2023

we need to do a study of finger seating vs. thumb seating ...   i betcha one is better than the other ...

ken ...    ( hey, it's the 4th of July ! ) ....

I double dog dare you to try toe seating!

Cheers from New Zealand

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linoww posted this 05 July 2023

some prefer to be fingered rather than thumbed. (comment will be Mod.deleted I'm sure)

"if it was easy we'd let women do it" don't tell my wife I said that!

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