67mm when people want 65 mm

[propercartridges]

this thread is to deviate from white bridges so can we have the job going from here on this topic is what i george young of proper cartridges can make i have 4 machines that load carts automatically 1x 12000 per hour 2x2500 per hour and 1 at2000 per hour now i have primed cases in the lenghs of 67 mm 69 mm 76 mm and 86mm now the question is can a 67mm opened lengh case be shot in a 65mm chamber coz if that is the situation yes i can load 67mm cases in both plastic and fibre if i have the wads to fit and yes i can buy 65mm cases but i am not sure if the super machine will allow me to do the 65mm as to tell u the truth i have enough on without trying for a dying market and have to buy more swag in to make them but i do have the gear to make 67mm so your feed back chaps thanks george

[panoma1]

There are many 65mm chambered 12 bores presently used in the shooting field and will be for some considerable time I imagine? Though, as you say the market is decreasing with the use and availability of the more accessible 70mm chambered guns.......however if you can build a reputation for top a quality product, make them easily available and can undercut the opposition on price......why would users of 65mm chambered game guns go elsewhere?

[shoot and be safe]

My sxs has a 2&1/2" chamber and although the 67mm already out there are proofed for the chamber. When I fire them, the open end of the cartridge looks a like it has been extruded down the barrel a bit. I will only use 65mm in that gun now.

Edited May 7, 2017 by shoot and be safe

[wymberley]

It would probably be a mistake to base a business decision on the relatively few members on here. As indicated above, there are probably more 2&1/2" chambered guns in current use than one imagines. What you're suggesting is known as 'cherry picking'. That's fine, no problem, but it would be unfair to criticise those manufacturers (and their prices) who continue to cater for what you consider to be a niche market.

[Sako7mm]

I really don't see it as a niche market at all. With the exception of a few auto users, everyone who uses a standard game load in a 12 bore, regardless of chamber length, could happily use 65mm cartridges if you offered them.

[propercartridges]

I really don't see it as a niche market at all. With the exception of a few auto users, everyone who uses a standard game load in a 12 bore, regardless of chamber length, could happily use 65mm cartridges if you offered them.

no sako i am afraid you are misunderstanding me i want to make 67mm but but but the magic question is would people buy them to put in 65mm shotguns

[matone]

Said it before here,Eley 2 1/2 inch Gand Prix etc were loaded in 2 3/4 inch cases for years ! That was when many more 2 1/2 inch guns were in regular use.

67 mm carts are fine in 2 1/2 inch guns.

[panoma1]

no sako i am afraid you are misunderstanding me i want to make 67mm but but but the magic question is would people buy them to put in 65mm shotguns

I for one wouldn't!

 

And as someone else pointed out any owner of a long chambered gun can use 2 1/2" cartridges in it............but no one can safely use long cartridges in a 2 1/2" chambered gun!

[Mr.C]

I for one wouldn't!

 

+1

Despite what is says on the side of the box I won't be firing 67's in mine.

[figgy]

I've used smaller loads like Hull Comp X 21g in a old London Damascus gun but wouldn't use any heavier in 67mm. Just my preference for not wanting to potentially damage it.

There are enough true 65mm carts around in suitable loads not to use 67mm carts I still have some Lyalvale 65mm Express 26g 6 fiber wads that I use in my current 70mm chambered SxS.

 

Noticed some carts have a deeper crimp so checking the fired lengthnwould be wise in a true 21/2" gun.

Edited May 8, 2017 by figgy

[rem708]

Why not pose the question can a 67mm cartridge be safely used in a 2 1/2 chamber to a proof house.

 

At the end of the day these guys are playing in this area every day

[wymberley]

Why not pose the question can a 67mm cartridge be safely used in a 2 1/2 chamber to a proof house.

 

At the end of the day these guys are playing in this area every day

I don't think that there's any doubt about the safety aspect. I believe what's in question here is the possibility that this may or may not cause higher pressures than necessary to achieve the same energy/velocity output and thus cause unnecessary wear sooner rather than later.

[Guest cookoff013]

Why not pose the question can a 67mm cartridge be safely used in a 2 1/2 chamber to a proof house.

 

At the end of the day these guys are playing in this area every day

This has already been done a thousand times. Infact they sent out a statement to address this exclusive issue.

 

http://www.cip-bobp.org/homologation/en/tdcc_public?page=1&cartridge_type_id

[rem708]

Not sure what that link shows?

 

I was referencing a British Proof House not a international Org that might have different take on specs.

[panoma1]

This has already been done a thousand times. Infact they sent out a statement to address this exclusive issue.http://www.cip-bobp.org/homologation/en/tdcc_public?page=1&cartridge_type_id

And diesel cars were, the authorities told us years ago, the way forward for the environment!

 

How would you explain the experience I had as per post #8?.......do you think CIP will reimburse me when/if the 67mm cartridges I referred to shake my gun off the face?

[Guest cookoff013]

The UK is a cip member. As are most if not all of Europe.

Read the bottom of link.

[panoma1]

So out of all 53 gun chamber lengths, covering all calibres of shotgun in the CIP data link given above............the only chamber length (65mm or 2 1/2") which are shorter than the actual fired cartridge case length (67mm or 2 5/8") are those with 65mm or 2 1/2" chambers! Surely that cannot be right?

 

You cannot fit a quart into a pint pot any more than you can you fit a 2 5/8" long cartridge into a 2 1/2" deep chamber! Can you?

[matone]

This has already been done a thousand times. Infact they sent out a statement to address this exclusive issue.

 

http://www.cip-bobp.org/homologation/en/tdcc_public?page=1&cartridge_type_id

Non so deaf etc........

[Guest cookoff013]

The pressure values of high performance cartridges and of the superior proof are valid for all calibres.

- The cartridges made with cases of 67,5 mm maximal length and loaded with lead can be fired in chambers with 65 mm length.

 

That's what it says in the bottom.

[wymberley]

Non so deaf etc........

Apparently that is so.

Which is going to wear out your 70mm chambered 12 bore quickest - continual use of 42g or 28g?

Provided the pressures remain under PK (above) there is no safety issue. The issue is about whether or not there is unnecessarily higher pressures to achieve the same objective with all of the associated disadvantages.

[Guest cookoff013]

The sami specs for 70mm chamber length is 69.85mm +6.35mm that's way more leeway than the cip system. That's a quarter inch.

 

It's all in print.

Now an older gun may have larger chamber than what is stamped. I haven't had any measuring done. But if the older saami specs are 1/4" excess.

 

Just measure the chamber.

[panoma1]

The pressure values of high performance cartridges and of the superior proof are valid for all calibres.

- The cartridges made with cases of 67,5 mm maximal length and loaded with lead can be fired in chambers with 65 mm length.

That's what it says in the bottom.

I appreciate you are merely referring to the CIP information available......but that does not allay my concerns, given my own experience, the information given by CIP appears on the face of it physically/mathematically questionable, if not impossible!

Surely if the cartridge case, during the ignition process, extends into the guns forcing cone this extra constriction would significantly impede the wads exit from the case, at the same time building up the extra pressure required to push the wad out? Thereby increasing pressure at the breech significantly, even possibly dangerously?

I have personally seen a gun bulged at the chambers, in the area of the forcing cone through, we believe, homeloaded cartridges using oversized wads which caused an increased pressure buildup in order to push them through the forcing cone and into the barrel (which was a tight, under nominal diameter bore!) proper! Would not the scenario outlined above have the same effect?

This is, I believe the reason for the uncomfortably severe recoil and loud report blast I experienced when firing 67mm fibre wad cartridges through my light English SBS 65mm chambered gun!......and my decision not to use 67mm cartridges through my 65mm chambered gun!

Edited May 8, 2017 by panoma1

[panoma1]

The sami specs for 70mm chamber length is 69.85mm +6.35mm that's way more leeway than the cip system. That's a quarter inch.

It's all in print.

Now an older gun may have larger chamber than what is stamped. I haven't had any measuring done. But if the older saami specs are 1/4" excess.

Just measure the chamber.

SAAMI is American standards not European and certainly not pre EU English proof standards!

 

69.85mm plus 6.36mm is a clearance length between cartridge length and chamber length of 6.2mm....ergo the chamber length is 6.2mm longer than the cartridge length in a 70 MM chambered gun!...........how does CIP then conclude a chamber length 2mm shorter than the cartridge length is safe in a 65mm gun?.........beats me!

[Guest cookoff013]

thats the minimum chamber lengths quoted not the maximum.

 

if a gun is stamped 65mm, the chamber length has to be a minimum of 65mm +2mm by cip. more than likely it is more if the saami specs are greater.

the 65m hulls are actually less than 65mm same as the 70mm, the hulls are 69mm.

 

just get the chamber measured, its cast, and the cast is measured,

 

if it is infact a "very short" 65mm chamber being "less than or equel to 65mm" the you would be best to use 65mm or smaller.

 

if the chamber is measured and is actually 65.00 mm total length then you would have to think why it has been marked as 65mm which is smaller than the specifications.

hulls can streach on firing, it is not an indication of short chambers.

[Stonepark]

Birmingham Proof House, normally cites the chamber length of 65mm +2.0mm (even though a true 2.5 inch is only 63.5mm) for chamber length and 20.3mm for chamber diameter, whilst bore is 18.2mm.

 

Even if your cartridge case ends up inside the forcing cone up to almost half way (forcing cones are normally at least 12.5mm long), your are not going to endanger the gun or yourself with a plastic cartridge case that is 0.5mm to 0.75mm thick as the dimensions are not any tighter than what would occur in the true bore of the gun and your chamber/forcing cone area are heavier and thicker than the bore. You may (or may not depending on who you believe) upset the shot pattern, but other than that, little difference will be noticeable.

 

The simple way to be happy is to measure your chamber and forcing cones with a chamber or bore gauge to see what you have as I suspect some may be pleasantly surprised.