Max pressure on a Jp enhanced bolt for 6 arc?

[padfoot 37]

Curious of the jp enhanced bolt is strong enough to handle bolt gun loads in an gas gun or not. Its stronger but enough? Gas gun loads get me all the range i need currently but hey, if i can load into br or even dasher speeds with the stronger bolt... anyway, figured id ask if anyone had experience with it or not. Cant find a pressure rating from JP or anything but figured maybe the community knew more than i do. Thanks.

 

[Ledzep]

No. You'll break lugs.

 

[padfoot 37]

No. You'll break lugs.

Thats what i figure but didnt know if anyone had tried it yet. You try it? Know someone who did? Figure someone smarter than me knows if the steonger steel is strong enough or not.

 

[Ledzep]

There's roughly 1.39x more surface area on the .445" diameter case head vs. the .378 case head on a .223. You could go off of the web diameter and it's probably not quite as aggresive but I don't have cross sectioned cases or case prints in front of me right now...

62,000psi pressure, 1.39x more surface area, You're going to have the equivalent load on the lugs of a 86ksi .223. So, if you feel kosher running proof ammo every round in a 5.56 in a JP bolt, then go for it... But in reality it just doesn't add up, and it's not worth it.

All AR-15 bolts are on a fatigue life cycle, and you're taking a bolt that should last 8,000-20,000 cycles and making it last tens to maybe hundreds of cycles. All that assumes you have proper alignment and good support with the barrel extension.

The 52,000psi limit is there for a reason, and it's not leaving much on the table in terms of bolt life/stress.

 

[Constructor]

Not only that but AR barrels have a larger chamfer at the breech, that coupled with the thin brass at the bottom will expand into the chamfer and the cases come out looking like a Grendel belted magnum.

 

[Ledzep]

Not only that but AR barrels have a larger chamfer at the breech, that coupled with the thin brass at the bottom will expand into the chamfer and the cases come out looking like a Grendel belted magnum.

People have told me otherwise but haven't produced a picture of it yet, but as far as I'm aware that problem is specific to Lapua cases. If you look at a cross section of them they have thinner webs and the shape of their final draw has less radius in the corner.

 

[proftwo]

My experience is with the JP rifle in .308 Win. I have regularly used the same loads in it and My TRG 22. At least 500+ rds. of GMM and no problems. I am not sure if this is a suitable comparison though. Some of the others might have more exp. with that cartridge.

 

[JBattles]

I have one too and was just doing load development yesterday. With N150 it was a compressed load, just below the 52k mark and shot great … maybe you split the difference and run it half way between AR and bolt.

I didn’t think too much of it either until I load tested and felt the pressure on the load work ups in an AR compared to bolt. The mechanics of an AR platform are so much more violent than a bolt gun and induce so much more wear and tear on the components. I would be just as worried about the brass life as the bolt life.

Somebody with way more experience came up with those charges for a reason, probably not best to exceed them by 20% if you want to keep your stuff in working order for long. On the other hand if you could just load them up and see what happens. Either way let us know.

 

[Constructor]

People have told me otherwise but haven't produced a picture of it yet, but as far as I'm aware that problem is specific to Lapua cases. If you look at a cross section of them they have thinner webs and the shape of their final draw has less radius in the corner.

Try it. Take the normal charge that creates apx 52000psithen start adding. An extra gr of powder may increase the charge 3-5000psi. Try it and measure the cases. . https://www.snipershide.com/shooting/threads/grendel-like-belted-magnum-problem.7112215/ First, guy says he is using Hornady then says Lapua.

 

[Ledzep]

With Lapua cases, yes. Others I have not seen it. There's (off memory here) about .080" worth of pure sidewall taking the brunt with the Lapua cases and if memory serves it's about half that much with Starline or Hornady. It has to do with the web thickness and transition to the body.

 

[whatsupdoc]

What makes people think that a JP bolt can withstand higher pressures than any other bolt?
Has this been tested somewhere?

 

[padfoot 37]

What makes people think that a JP bolt can withstand higher pressures than any other bolt?
Has this been tested somewhere?

Its made from a stronger steel. In 556 JP advertises that it does last like 3-5x longer than a standard bolt in a lesser material. How/if that transfers to higher pressure though is the subject of this thread.

 

[whatsupdoc]

"The JP Enhanced Bolts™ have become the industry's go-to bolt assembly. Made out of Superior SAE 9310 material"

Faxton "Our 9310 bolts are still magnetic particle inspected"

WMD "Case hardened 9310, shot peened, magnetic particle inspected"

Battlearms Bolt: "9130 steel Shot Peened"

Runbber City Armory "Bolt material 9310"

 

[Constructor]

That is just dishonest advertising, I believe most bolts are made from 9310 these days. I can tell you from machining them for 12 years they will not last 3-5 times longer like JP claims, lab tests showed they will withstand thrust apx 17% higher than a bolt made from Carpenter 158(mil spec). The JP is a half copy of the bolts I designed in 2009. They increased the diameter around the cam pin hole but did not increase the size of the radii at the lugs which is what made the bolts we machined stronger than the rest.
ETA- There have been other bolts made with other alloys. The Reliabolt was made with S7 tool steel but they were breaking all over the place, probably from being hardened too much which made them brittle. Seems like one was made from Aermet also but I can't remember the company.

 

[MontanaMan]

The company that uses Aermet would be Knight's or maybe LMT, as I recall.

You Ladies are making me nervous about shooting full house NATO ammo, now....................just sayin'. LOL

MM

 

[TheOE800]

The company that uses Aermet would be Knight's or maybe LMT, as I recall.

You Ladies are making me nervous about shooting full house NATO ammo, now....................just sayin'. LOL

MM

It’s LMT. KAC did use Aermet for the contract SR-16 rifles though.