CG Inch Action
- Thread starter medic727
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ovenpaa
Are we shooting tomorrow?
The CG INCH is a massively robust rear locking action that is already doing well in the competitions including taking first in the under 25's World Championships last year. Here in the UK the CG INCH is being used in F Class, TR and MR.
There is also a new repeater action from Action Clear based on the Remington 700 footprint due out start of next year, again designed by Robert Chombart and built by Chris at Action Clear. I did a bit of a write up here having had my hands on the prototype earlier this year.
http://shootingshed.co.uk/wp/2012/08/another-rem700-clone-no-way/
Most of the specifications are at the bottom of the page and you have Tom Myers as the US Distributor.
David
There is also a new repeater action from Action Clear based on the Remington 700 footprint due out start of next year, again designed by Robert Chombart and built by Chris at Action Clear. I did a bit of a write up here having had my hands on the prototype earlier this year.
http://shootingshed.co.uk/wp/2012/08/another-rem700-clone-no-way/
Most of the specifications are at the bottom of the page and you have Tom Myers as the US Distributor.
David
ovenpaa
Are we shooting tomorrow?
Jacques, one of the advantage of rear lockers is the overall length of Action can be kept shorter and the Rem700 footprint limits things in this respect. Also, and I hate to say this, despite the very obvious results of the CG INCH in all disciplines at national squad level (The SA team shot INCH Actions at the WLRC last year) Not every one likes rear lockers.
For me you just have to see the INCH in the flesh to appreciate how solid and yet compact the action is, also in theory the manufacture of the rear locker is an an inherently more accurate manufacturing process as everything can be done from end so removing the need to reverse the action for dimension/tolerance critical machining operations.
I will see if I can find Robert to add to this post as it is his action design.
For me you just have to see the INCH in the flesh to appreciate how solid and yet compact the action is, also in theory the manufacture of the rear locker is an an inherently more accurate manufacturing process as everything can be done from end so removing the need to reverse the action for dimension/tolerance critical machining operations.
I will see if I can find Robert to add to this post as it is his action design.
ovenpaa said:
Jacques,
The INCH can be made as a repeater and in fact, this option is already 'on paper.
The rear lodking allow all those possibilities with a shorter/handier action..It even allow a smallnore conversion for training..
The problem is accessories availability; a shorter action would need specific stock and accessories (bottom metal, etc, etc). Mass prpduction of accessories on tje Rem basis makes them affordable, but nothing exist out of this...
Reason why probanly no, or little actions have been designed specifically as repeater for the shorter and smaller calibres.
A rear locker repeater for calibres such as the .223 or BR range could be made no longer than 6 innches...
R.G.C
AJ172SBCT
Silver $$ Contributor
David and Robert,
Thank you for your quick response, I really appreciate your input and your expert opinion.
I always thought that the CG Inch incorporated a lot of very, very good features in it's design but I understand that commercial requirements may dictate a few changes. On the other hand, with great after market designers such as Eliseo, it doesn't seem to be too much of a problem to find accessories. If there is a market for it, the demand will be filled.
I hope we will see this repeater go from paper, to reality soon.
Again thank you
Jacques
Thank you for your quick response, I really appreciate your input and your expert opinion.
I always thought that the CG Inch incorporated a lot of very, very good features in it's design but I understand that commercial requirements may dictate a few changes. On the other hand, with great after market designers such as Eliseo, it doesn't seem to be too much of a problem to find accessories. If there is a market for it, the demand will be filled.
I hope we will see this repeater go from paper, to reality soon.
Again thank you
Jacques
CG Delta is here at last.....
Actionclear are proud to announce our new range of CG Delta actions and stocks. Designed by Robert Chombart and in collaboration with The Shooting Shed, they will be avaliable in 2013.
For more information please go to www.actionclear.com.au
Actionclear are proud to announce our new range of CG Delta actions and stocks. Designed by Robert Chombart and in collaboration with The Shooting Shed, they will be avaliable in 2013.
For more information please go to www.actionclear.com.au
Attachments
ovenpaa
Are we shooting tomorrow?
Bit of an update.
This is the first Model 75 to be assembled post anodising and the build process was remarkably stress free. The type 3 anodised surface is very hard and the chassis has been built to some tight tolerances so pushing two anodised parts together did leave me wondering exactly what was going to give first, I resorted to using a synthetic grease for the assembly and it works very well, dries to an opaque finish and any residue is easily removed with acetone or alcohol. I need to finish the walnut hand grip and the front and rear bag rider assemblies need finishing and anodising but apart from that the thing is just about done.
The picture really does not do the rifle justice so I will try and post some more pictures up in the next few days. One thing that needs changing is the rear butt plate tube, this is a short one so I need to fit the longer version.
Only thing now is the ‘scope rail. I have sent 6 off for type 3 black anodising to suit the chassis however the silver finished one actually looks quite good. The ‘scope in case you wondered is a KAPS 10X with 7,62×51 BDC Drum sitting in Accuracy International one piece rings, mostly because that was nearest to me once I had put everything together.
I nearly forgot to mention the graphics. look carefully and you will see this at the end of the CG Model 75 text. This is the new ‘Chombart Inside’ logo complete with Roberts signature which I thought was fitting for this build. The ‘signed’ chassis are a limited run for the first few builds.
This is the first Model 75 to be assembled post anodising and the build process was remarkably stress free. The type 3 anodised surface is very hard and the chassis has been built to some tight tolerances so pushing two anodised parts together did leave me wondering exactly what was going to give first, I resorted to using a synthetic grease for the assembly and it works very well, dries to an opaque finish and any residue is easily removed with acetone or alcohol. I need to finish the walnut hand grip and the front and rear bag rider assemblies need finishing and anodising but apart from that the thing is just about done.
The picture really does not do the rifle justice so I will try and post some more pictures up in the next few days. One thing that needs changing is the rear butt plate tube, this is a short one so I need to fit the longer version.
Only thing now is the ‘scope rail. I have sent 6 off for type 3 black anodising to suit the chassis however the silver finished one actually looks quite good. The ‘scope in case you wondered is a KAPS 10X with 7,62×51 BDC Drum sitting in Accuracy International one piece rings, mostly because that was nearest to me once I had put everything together.
I nearly forgot to mention the graphics. look carefully and you will see this at the end of the CG Model 75 text. This is the new ‘Chombart Inside’ logo complete with Roberts signature which I thought was fitting for this build. The ‘signed’ chassis are a limited run for the first few builds.
ovenpaa
Are we shooting tomorrow?
The longer rear butt tube is on, the pistol grip fitted and the new latch assembly is in place.
We timed the break down and assembly of the rifle last night. I can remove the back end of the rifle and the bolt in under ten seconds if the latch thumb screw is fitted. Reassembly takes slightly longer but still comfortably sub fifteen seconds. For some markets a quick release is not acceptable so cap hex head screw is used which will add some time. Removal of the barrel takes twenty seconds.
What this means is you have an F Class/Bench Rest or Target rifle that can be stripped down in well under a minute without the need for any hand tools and stored in a short range bag, the limiting factor being the length of barrel so if your barrel is 31″ long allow for a range bag with internal dimensions of around 32″ x 14 If you are shooting Bench Rest with a 26″ barrel then that is the length of range bag you need.
But do you really need a competition rifle that can be carried in such a way? The easy answer is of course not however what you do need with a tube rifle is the ability to remove the rear section to enable removal of the bolt for cleaning and maintenance plus you may have reason to remove the bolt at the range. Here in the UK a safety flag is quite acceptable to demonstrate the rifle chamber is empty, in addition to this I prefer to travel with the bolt removed and stored separately and if the rifles are to be left locked in the car for any reason such as when we are signing in then I keep the bolt with me. This makes life so much easier.
OK, but why remove the barrel? With a barrel that can be swapped out this easily you can easily shoot say 6,5×47 in the morning and come the second detail decide to move to .308. You no longer need to bring a second rifle to the point, just bring a second barrel. Change over is simply a matter of unscrewing one and screwing the second one in. For me this is a massive benefit as it means you will no longer have to invest in a second rifle system to shoot a different discipline which in turn means a saving in the cost of ‘scope and accessories.
The final plus for me as a Brit is I do not have to go out and buy a long range bag and extra tall gun cabinet, this rifle will fit in a 36″ cabinet and in my AR range bag!
More to follow.
We timed the break down and assembly of the rifle last night. I can remove the back end of the rifle and the bolt in under ten seconds if the latch thumb screw is fitted. Reassembly takes slightly longer but still comfortably sub fifteen seconds. For some markets a quick release is not acceptable so cap hex head screw is used which will add some time. Removal of the barrel takes twenty seconds.
What this means is you have an F Class/Bench Rest or Target rifle that can be stripped down in well under a minute without the need for any hand tools and stored in a short range bag, the limiting factor being the length of barrel so if your barrel is 31″ long allow for a range bag with internal dimensions of around 32″ x 14 If you are shooting Bench Rest with a 26″ barrel then that is the length of range bag you need.
But do you really need a competition rifle that can be carried in such a way? The easy answer is of course not however what you do need with a tube rifle is the ability to remove the rear section to enable removal of the bolt for cleaning and maintenance plus you may have reason to remove the bolt at the range. Here in the UK a safety flag is quite acceptable to demonstrate the rifle chamber is empty, in addition to this I prefer to travel with the bolt removed and stored separately and if the rifles are to be left locked in the car for any reason such as when we are signing in then I keep the bolt with me. This makes life so much easier.
OK, but why remove the barrel? With a barrel that can be swapped out this easily you can easily shoot say 6,5×47 in the morning and come the second detail decide to move to .308. You no longer need to bring a second rifle to the point, just bring a second barrel. Change over is simply a matter of unscrewing one and screwing the second one in. For me this is a massive benefit as it means you will no longer have to invest in a second rifle system to shoot a different discipline which in turn means a saving in the cost of ‘scope and accessories.
The final plus for me as a Brit is I do not have to go out and buy a long range bag and extra tall gun cabinet, this rifle will fit in a 36″ cabinet and in my AR range bag!
More to follow.
I know there are plenty of Barnards imported and it does not seem hard to get one!
Robert, didn't Sinclair import a few millenium actions? Mine has been great and wish I could find another.... Maybe you need to find a big name company that can import hundreds of actions and release them to the public instead of placing individual orders for small quantities and waiting forever.
Robert, didn't Sinclair import a few millenium actions? Mine has been great and wish I could find another.... Maybe you need to find a big name company that can import hundreds of actions and release them to the public instead of placing individual orders for small quantities and waiting forever.
sparker
Silver $$ Contributor
Robert, has the case stretch issue been addressed? When I last corresponded with Warren Dean, he commented that it was an issue. He said that the stretch was running about .004". It was an interesting figure as that was the figure I had calculated using modulus values for the bolt steel. While the design has many advantages, case life is not one of them.
Scott Parker
Bakersfield CA
Scott Parker
Bakersfield CA
sparker said:
Scott,
First time I heard of case stretching in a INCH, except when you sent me your thoughts, which I duly commented at the time.
The Inch is commonly used in all the hottest Magnum calibres and is no more hard on cases than any other action, and probably quite les than some....
Before working the Inch, I studied the 4 widespread models of rear locking actions, mostly the Schultz-Larsen, highly regarded in Europe by Match Rifle shooters, and no user consider case stretching as an issue. This is practical observation, not unappropried theory.
The myth of case stretching came from the SMLE, but just have a look on the springy receiver, bolt cross sections and screwed bolt head to understand why it stretch.
There is other factors possibly causing case stretching, having to do with case metallurgy and its variation in successive uses , chamber and dies adequation and reloading techniques.
R.G.C
sparker
Silver $$ Contributor
My understanding is that the stretch is caused by compression of the column of steel ahead of the locking surfaces. The compression is proportional to the column length. Hence, the longer the column, the greater the compression. That is my understanding of it. I am by no means a mechanical or structural engineer.
Scott Parker
Bakersfield CA
Scott Parker
Bakersfield CA
*sparker said:
Scott,
I took that as a friendly conversatjon, no problem. Just the king of conversation I enjoy
Without going into full calculation, which I think was already made for our long exchanges at the time, compression is expressed in kilogrammes per square millimetre or pounds per square inch.
Section, length of the section and mechanical properties of the material play their role.
To simplify, resistance under compression is usually considered as being 75% of the
Rm.
On the INCH, the bolt is a plain tube (the ideal section) of a steel treated at 180 kgs/sq mm.
The smallest crossection is 270 sq/mm over a 22mm length to the lugs. Ahead it is
310sq/mm and increase in steps forward. The only section then to consider is the smallest and only over a length of 22mm.
Therefore : 270 x 180 x 0,75 = 36,45 metric tons compression resistance.
A Magnum case at 4450 bar (max CIP pressure) has a rear internal surface of 1,15 square centimetree, therefore, backthrust is : 4450x1,15 = 5120 bar, say 5,2 metric tonnes.
Forgive me if I use measures I am better used to!!
With the SMLE for instance, the problem is not only the thin tube, but also with buckling of a thin not surrounded bolt, a situation not to consider for a stiff match single shot action who surrounder the bolt almost completely.
Friendly
Robert
sparker said:
Scott,
Thanks for the fair comment
Hereunder is an Email I received from Warren at the time, and I cannot pass a better answer.
Sincerely yours
Robert
''Robert,
Good morning. I have now returned from our national championships and have good news to report. The issue of case stretching has proven to be a non-issue with my match brass. I shot 260 rounds of 200 gr. Berger Hybrids through the rifle at the matches and they shot very well, indeed. I, however failed to read the wind very well and finished a dismal 24th.
Upon returning home, I measured 20 random cases and to my delight found they did not stretch at all. As you can imagine, this is very good news to me. I was worried that perhaps the bolt might be soft, but that is not the case at all. I am guessing that the many-times fired load development cases that were stretching and on the verge of separating were basically worn out from accidental excessive shoulder bumping and stout charge weights. They have all been thrown out so that I won’t mistakenly reload them.
The cases I shot in Lodi were 3 times fired and had not been subjected to excessive shoulder set back by my own error. I’ll not make that same mistake again. J
Thank you for your insights and help. I hope to have better results to report, score wise, next month.
Cheers!
Warren
Scott,
In addition:
Scott,
A friend interested in this technical point just passed me the dimensions of the SMLE, the origin of the case stretching myth for rear locking actions.
The cross section of the bolt is 97 sq/millimetre….almost the 1/3 of the INCH.
I will be generous in considering the Enfield bolt material having the same high specification as the Inch and can say the later is 3 times more stress resistant…deliberately ignoring the receiver differences,…..
Sincerely yours
R
In addition:
Scott,
A friend interested in this technical point just passed me the dimensions of the SMLE, the origin of the case stretching myth for rear locking actions.
The cross section of the bolt is 97 sq/millimetre….almost the 1/3 of the INCH.
I will be generous in considering the Enfield bolt material having the same high specification as the Inch and can say the later is 3 times more stress resistant…deliberately ignoring the receiver differences,…..
Sincerely yours
R
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