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CG INCH in the USA

An unconventional action design was introduced to the US market in 2009 called the CG INCH. Designed by Robert Chombart it featured his preferred primer ignition system of Belleville washers rather than the more common coil spring. Having bolt lugs at the rear facilitated a shorter action overall length, making a more ergonomic prone position possible whereby shooters could work the bolt with a minimum of disturbance to their position.

A small number of these actions were imported into the US, most bearing a 308-size bolt face, a few with bolts fitted to that of the 223REM cartridge. I was fortunate to obtain one of these INCH actions with a 308 bolt face, have shot it every year but one since 2011 either in a Palma-barrel configuration or in 2016 fitted to shoot Robert’s 284INCH wildcat, a 7mm based on the 308WIN case.

(In it’s first competition outing that year, shooting the 284INCH cartridge I succeeded in tying the US NRA Senior Long Range Any Sight record held by Bud Solis and Stacey Tamulinas at Winnequah Gun Club’s annual Gillespie Memorial Long Range Individual Championship, 200-15x.)

Last year however, fitted again with its original Palma barrel, I began having issues with misfires and failure-to-fire that had not previously been a problem.

Before the introduction of the CG INCH to these shores I’d befriended via e-mail Robert Chombart when I endeavored to convert an RPA Quadlite action over to Belleville-actuated ignition system. His help in resolving the FtF I was challenged by resulted in our resolving the hurdle a few weeks ago when he supplied me with a set of Belleville washers of a new design of his specifically intended for this action.

It seems that batch of INCH actions imported in 2009 were equipped with 31 Belleville washers when the original specification called for 33. Mr. Chombart’s new design washers are thinner than the originals so more of them are required but the result is greater impact energy when the sear is released as well as lessened effort for bolt lift.

I’m currently fielding my INCH in 308 configuration with 41 of these new washers actuating its firing pin while he’s indicated 43 meets his new design spec. for firing pin energy. And yes, the reduction in effort for bolt lift is remarkable!

Should any current owners of the CG INCH action here in the USA wish to contact Mr. Chombart about upgrading their firing pin actuation with a set of these new washers, you can PM either of us here (Robert) or e-mail me for his contact information.
 
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are you selling one? (complete action)

No, I’m very happy with mine for long range shooting.

I cross-posted my initial comments over on the US NM LR Forum also, where it’s received more replies. Robert Chombart added background to his INCH’s history, offers to replace the OEM washer stack with the updated components (at his expense), and made mention of US-based licensing with a well-known manufacturer here... so we may see some news about this action in the US once again.
 
It might get more replies if it wasn't in the classified section. (Buy/Sell/Trade). Just saying! Interesting post though.
 
It might get more replies if it wasn't in the classified section. (Buy/Sell/Trade). Just saying! Interesting post though.

Yeah, you’re probably right about that!

I was rushing to get it posted before I left for work yesterday, wasn’t paying as close attention as I should have. Thanks for pointing it out though! I’ll see if I can get an Admin to move the whole thread.
 
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Update:

I received in the mail today (courtesy of Mr. Chombart) two sets of the new Belleville washers referred to in my initial post.

They're available - free - for the asking, for US INCH owners who wish to upgrade.

Please contact me via PM here or at <hipowershooter at gmail dot com> and provide your mailing address as well as the serial number of your INCH action.

(I had the Admins move this thread late last week; my apologies for inadvertently starting it under the wrong heading.)
 
What is the reasoning behind using a stack of bellvilles rather than a coil spring? Seems like a lot of trouble.
 
What is the reasoning behind using a stack of bellvilles rather than a coil spring? Seems like a lot of trouble.

Hardly any trouble, just a different approach to storing then releasing energy.

Here's a link to a blog entry R. Chombart posted about his engineering. Scroll to the bottom entry dated 4/15/2017.

In summary he suggests: more compact spring mass (potential for shorter action), and lighter than equivalent coil spring; adjustability (by adding or subtracting washers); less likely to 'take a set' when left compressed (cocked) for an extended period; faster 'lock time' from less mass as well as no potential for harmonic vibrations that coil springs can induce.
 
Hardly any trouble, just a different approach to storing then releasing energy.

Here's a link to a blog entry R. Chombart posted about his engineering. Scroll to the bottom entry dated 4/15/2017.

In summary he suggests: more compact spring mass (potential for shorter action), and lighter than equivalent coil spring; adjustability (by adding or subtracting washers); less likely to 'take a set' when left compressed (cocked) for an extended period; faster 'lock time' from less mass as well as no potential for harmonic vibrations that coil springs can induce.

Thanks, I was not aware of his blog. I've got one of his triggers (which is really nice, in spite of his disappointment with his issues distributing/manufacturing them). Seems like a very smart fellow.
 
Thanks, I was not aware of his blog. I've got one of his triggers (which is really nice, in spite of his disappointment with his issues distributing/manufacturing them). Seems like a very smart fellow.

You're welcome, and my pleasure in turning you towards it. At 25 pages currently there's a lot of information there for the taking.

I have three of his triggers in fact. Looking forward to reviews of the new Geissele Super 700 soon to be released, maybe even trying one myself on one of my two RPA Quadlites.
 
If one were to retrofit an action with washer ignition to the same energy level as the original coil spring, would there be a difference in cocking effort? If there would be, would it increase or decrease?
 
If one were to retrofit an action with washer ignition to the same energy level as the original coil spring, would there be a difference in cocking effort? If there would be, would it increase or decrease?


Boyd,

Normally, an action for Bellevilles has to be designed specifically. Except the Swings-Paramounts and an other brand were possibly modified for Bellevilles. Swings and Paramounts with great success, the other, I do not think it has ever done.

SP Clark modified a Gilkes-Ross and he already expressed what he thinks about the system.

No washer under ½ inch is suitable . This mean a bolt bore diameter of .510 minimal

With those washers, the FP rod is to be .250 inch. Impossible to envisage a smaller diameter, and this condition the OD of the washers, then the bolt bore diameter .

The number of washers, their characteristics and stack height depend o the FP stroke.

For the C.G, it is 43 washers 12,5mm diameter, for a stack height os 21,5mm cocked and a cocked energy of 28 ft/lb an energy at impact of 21 ft/lbs. Adding or reducing a pair of washers increase/reduce the energy by some 10%.

Note I pointed energy at impact . This is the point where the FP tip hits the primer cup . For the C.G system, this FP travel at impact (total FP stroke LESS protrusion) is 2,6mm (.102) . For comparison, a common action with a total FP stroke of .270 will have a stroke at impact of 5,4mm (.215,small diameter FP tip).

FP stroke at impact being more than double for the coil spring system, you can already see one of the reasons for which the locktime can be significantly reduced. Add to this the extra obtainable energy and you can see the final result.

Question bolt lift, with the new system, it remain quite comparable with a coil spring system equipped with a spring of same force .

R .G.C
 
Boyd,

Normally, an action for Bellevilles has to be designed specifically. Except the Swings-Paramounts and an other brand were possibly modified for Bellevilles. Swings and Paramounts with great success, the other, I do not think it has ever done.

SP Clark modified a Gilkes-Ross and he already expressed what he thinks about the system.

No washer under ½ inch is suitable . This mean a bolt bore diameter of .510 minimal

With those washers, the FP rod is to be .250 inch. Impossible to envisage a smaller diameter, and this condition the OD of the washers, then the bolt bore diameter .

The number of washers, their characteristics and stack height depend o the FP stroke.

For the C.G, it is 43 washers 12,5mm diameter, for a stack height os 21,5mm cocked and a cocked energy of 28 ft/lb an energy at impact of 21 ft/lbs. Adding or reducing a pair of washers increase/reduce the energy by some 10%.

Note I pointed energy at impact . This is the point where the FP tip hits the primer cup . For the C.G system, this FP travel at impact (total FP stroke LESS protrusion) is 2,6mm (.102) . For comparison, a common action with a total FP stroke of .270 will have a stroke at impact of 5,4mm (.215,small diameter FP tip).

FP stroke at impact being more than double for the coil spring system, you can already see one of the reasons for which the locktime can be significantly reduced. Add to this the extra obtainable energy and you can see the final result.

Question bolt lift, with the new system, it remain quite comparable with a coil spring system equipped with a spring of same force .

R .G.C
Thank you for your detailed reply. I have no history or plans to be involved any any part of shooting where lock time is much of an issue so there would seem to be little advantage to attempting a conversion, plus the diameter requirement would require a custom bolt.
 
SP Clark modified a Gilkes-Ross and he already expressed what he thinks about the system.

In actuality, I first converted an RPA Quadlite action to employ a Belleville stack after reading somewhere what potential advantages were.

Robert assisted me in choosing suitable washers from what were commercially available here in the US at that time.

(I also asked John Whidden to provide a stainless bushing to take up some of the space left previously occupied by the coil spring. The washers chosen, in a number appropriate for force required, left ~ 5/8” empty space....)

The success of that endeavor led me to begin looking toward doing similar with a Gilkes-Ross action. Robert and I discussed by e-mail what would be necessary.

With the more complex mechanism of the bolt and striker of the G-R’s design the work required was too intimidating for me (I’m no machinist) so I chose to leave well enough alone.

It was about that time I learned that a small number of Robert’s CG INCH actions had been imported here, and that Gary Eliseo was making his CG-1 stock kit to fit them. The rest is history.
 
if its a superior design it wont be long and it'll be a very popular item/ conversion. all it has to do is prove itself on the line and everybody will flock to it like lemmings.
 
if its a superior design it wont be long and it'll be a very popular item/ conversion. all it has to do is prove itself on the line and everybody will flock to it like lemmings.

Dusty,
The most significant result I can pass is the Palma Match of 2011/Brisbane (from informations passed by the officials):
On the Palma Match firing line, 51 actions out of the 96 on the line were C.G systems.
In the Worlds Individual 10 finalists, 1rst, 2d, 4th, 5th,7th were also.
R.G.C
 

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