Kelby's Prometheus Action

I wonder why the Sako extractor? I thought they were the least desirable out of the various external extractor designs.
It's my understanding that the primary knock on Sako type extractors is the potential for an over-pressure situation to make a projectile out of the extractor. Last year, when Kelbly's switched all their bolts from the sliding gate type extractor they previously used to the new Sako type system, they spent a good deal of time and testing making sure their design was trapped in the bolt by the action body and thus could not be ejected in an overpressure situation. They did some destructive testing to this end.

The Prometheus looks like an interesting new action. I'll have to come up and take a look when I get a day off. Last year I was planning on doing a little Kelbly action update to talk about the new extractor and switch to one piece bolt design but then... Covid. I should be able to make it up some time this summer though. I find the Kelbly actions quite interesting not just because they are one of the most precisely manufactured but also because they offer a mechanical ejector paired with an non-claw type extractor. This gives them substantially more case head support than claw extractors allow and I think leads to better brass life while still allowing the benefits of a mechanical ejector.
 
The new Anti-Shear bolt stop design, is also a direct drop in to the current set up on the Atlas actions. If you ever run into a issue with the old design, we will get you the new one. We put it through the ringer and it stood up to all the abuse we could give it! This will also, eliminate the need for the extreme duty bolt stop as well. If you have any questions on it or anything else, please always let us know!
 
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CANT WAIT

DT
 
The new Anti-Shear bolt stop design, is also a direct drop in to the current set up on the Atlas actions. If you ever run into a issue with the old design, we will get you the new one. We put it through the ringer and it stood up to all the abuse we could give it! This will also, eliminate the need for the extreme duty bolt stop as well. If you have any questions on it or anything else, please always let us know!
Ryan, what exactly was changed with the new anti-shear design?
 
Ryan, or Ian, can you shed anymore light on what BigJimFish said regarding your Sako extractors? Are they, somehow, captive?
The Sako that we use is a lot bulkier than a standard Sako, they are designed beefier to resist fragmentation. In all of our pressure testing we have yet to have one fragment or come out of the bolt. On a typical Sako there is very little material between the body of the extractor and the circular hook that holds it into the bolt, whereas ours is very thick in that area. I think a lot of people are confused between a Sako and an M16 style extractor. The way the Sako fits in our bolt, there is no way for gas that comes out of the primer in a catastrophic failure to get behind or underneath the Sako. Whereas an M16 extractor has to be cut into the firing pin channel making it susceptible to catching high pressure gas and becoming shrapnel in the same scenario.

Before we launched these actions to the public they were pressure tested at 130,000 psi. This load caused the case's primer pocket to open up and become almost triangular. The extractor stayed in place as well as the ejector. All edges of the boltface retained their shape and lug setback was only measurable to a 0.001" difference. In pressure testing we are looking for the action and bolt to stay intact. We are also looking for any abnormal deformation, which was not present on either design. Lug setback is always expected in extreme pressure scenarios or in scenarios of excessive sizing. The setback is because we use a softer bolt than action, which is critical in ensuring the actions stay together in catastrophic failures. Everything we design is made for reliability and safety. We have a few thousand of the Sako extract bolts out in the wild and they are by far our most reliable setup. We have also seen instances of pistol powder being accidentally used in a rifle cartridge and in all of those cases the extractor and ejector stayed in place as well.

So to answer your question. It is not captive it is just built beefier. It is also positioned to the bottom of the action at the 7:30 position when the bolt is closed. So for it to ever come out of the action it would have to push outward of the bolt head, the backward up and over the closing cams. If it were to ever be scenario that extreme, then it is about mitigation (ie. catching the bolt, directing gas away from the shooter)
 
Ryan, what exactly was changed with the new anti-shear design?
The anti-shear bolt stop is made with a longer bolt stop screw hole which allows the bolt stop to slide back and impact the action body instead of the bolt stop screw. We also added material on the back side to reinforce the new impact area. In all of our testing this setup has not failed.
 
Well, I'm sold on it. It looks excellent.

The only thing I don't like is the name. Terminus and ARC are already using names from the Greeks to name their actions.

What if you called it the "Tac Bear"? It's built specifically for tactical competitions right? It's likethe black bear, but tactical.
 
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Well, I'm sold on it. It looks excellent.

The only thing I don't like is the name. Terminus and ARC are already using names from the Greeks to name their actions.

What if you called it the "Tac Bear"? It's built specifically for tactical competitions right? It's likethe black bear, but tactical.
When we launched our Arcas series rifles almost ten years ago was the first time we used a Greek name. Atlas and NYX are also Greek names. Prometheus is the brother of Atlas, so it was only fitting that we used Prometheus.

Nanook is the inuit god of hunters (a polar bear). He is the decider of if you would harvest an animal or not.
 
When we launched our Arcas series rifles almost ten years ago was the first time we used a Greek name. Atlas and NYX are also Greek names. Prometheus is the brother of Atlas, so it was only fitting that we used Prometheus.

Nanook is the inuit god of hunters (a polar bear). He is the decider of if you would harvest an animal or not.

Well now I know.

I'm really interested in this action. I like what you guys did with the Sako type extractor. It seems like it would be really good at ejecting brass more horizontally. My brass hits the windage knob pretty often with the m16 type extractor.

Is the bolt handle shorter on the Prometheus vs the Black Bear?
 
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I would be shocked if the bolts were not only the same size, but interchangeable.

I had light primer strikes at a match and a friend had a spare bolt. I borrowed his bolt and finished the match with no problems. Old firing pin spring with over 10k round finally wore out. Finished the match with no discernable difference in accuracy or headspace.


GL
DT
 
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Well now I know.

I'm really interested in this action. I like what you guys did with the Sako type extractor. It seems like it would be really good at ejecting brass more horizontally. My brass hits the windage knob pretty often with the m16 type extractor.

Is the bolt handle shorter on the Prometheus vs the Black Bear?
The bolt handles and bolts are exactly the same. All of our bolts are the same and are interchangeable. We wanted to make it as easy as possible for our customers. You can also use Atlas barrels on the Prometheus or Nanook.

Thank you!
Ian Kelbly
 
The bolt handle length is the only thing that bothered me on the Atlas. It made the lift incredibly easy but I personally would have wanted an option for a shorter handle.
We have three options for handles now. A tactical which is 2.5", a teardrop which is 2.5", and a ball which is 2". So we have you covered if you want a shorter handle!

Thank you!
Ian Kelbly
 
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I wish this thread would gain some traction here.. I would like to build my first custom this winter sometime and have been kind of planning on going Impact 737.. My stipulation is that it must have an integral rail and lug. My research has led me to believe Kelbly actions are highly underrated, I would love an Impact but I wouldn’t mind having something different than everybody else either, and this one has some nice features..I do feel a kindred spirit towards Ian as I grew up in Northeast Ohio..would be awesome to see some more video footage of this thing running down and dirty in the future.. This action would be a do all for me including choking through Idaho moondust in search of mule deer
 
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I've been wondering when you guys would come out with an integral rail and recoil lug. I've loved the Atlas for a long time. I'll be looking for one of these. I'm thinking of the NRL Hunter series with the Nanook but wonder how it would run with an AICS mag. I'm guessing it would work but have you guys tried it?
 
I've been wondering when you guys would come out with an integral rail and recoil lug. I've loved the Atlas for a long time. I'll be looking for one of these. I'm thinking of the NRL Hunter series with the Nanook but wonder how it would run with an AICS mag. I'm guessing it would work but have you guys tried it?
I know, we finally decided to catch up to the 700 Footprint integral party! This action would be great for the Hunter series. The action will work great with the AICS magazines, you will not be able to run the double stack magazines but you will have no issues running the single stack mags. out of the ADL/BDL magazine cutout!
 
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