Imagine if there was a software program where you could input some specific data and it would give you a very close estimate on pressure
20 Sploder
- Thread starter urbanrifleman
- Start date
AckleymanII
Gold $$ Contributor
Then again, you could just work up a load for accuracy, watch your pressure signs, and call it done. De-prime with a hand de priming tool, to check for loose pockets, and Rock On!
urbanrifleman
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I know right?? Why all of a sudden is every load workup ever done in the history of load workups called into question??
This is dumb.
It's like the classroom brought down to the level of the class clown.
AckleymanII
Gold $$ Contributor
yeppers, you are spot on!
Not picking a fight with anyone but will throw out a couple of random thoughts. Not in any particular order but I'll start with this one.
I'm not sure what the NASA engineer or whom ever is making the statement that the bolt heads alone are rated to 150k psi.
I'll say this...I have yet to see any action/bolt stay together when you hit those numbers. It's coming apart somewhere somehow. I'll even lower that number down to around 120kpsi for a bolt gun....it's coming a part.
I've seen actual receivers split open/blown apart as well and not the lugs sheared off per say and probably won't but the lugs will get beat on and or where the back side of the lugs engage the receiver will start to get deformed from everything coming a part. Look at the attached pic....
Also when you start hitting around 80k psi you will start getting imprints from the case head into the bolt face as well. Not all the time but it will start to happen when you hit the 80k mark and higher on pressure.
Later, Frank
Bartlein Barrels
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This is a accurate statement.
Just because you don't see pressure signs on the brass itself or even hard bolt lift etc...doesn't mean the pressure is not there.
There are a lot of variables to contend with. Yes playing with the throat / FB length and even the diameter and depending on where you seat the bullet as well as bullet diameters can vary you can drive up pressures and again with out seeing any pressure signs.
I've seen in actual pressure test barrels where the reamer cut the throat only .0001" maybe .0002" undersize and depending on the bullet loaded into the round...pressures went up 6k to 10k psi. So if the max working pressure for that particular round is 63k psi your easily pushing 70k or more.
I won't say the caliber but just a couple of years ago I built a rifle and there wasn't any real loading data out for the cartridge yet. We did make test barrels for all the R&D for the cartridge for the ammo maker. So I asked if I sent some sample rounds down to them with all the load data, lot numbers for the bullets, powder and primers would they run some of my ammo thru the test barrels the next time they had that caliber set up. They did.
I loaded three different powder charges. All the same components. My heaviest powder charge was 4gr. up from my starting load. At 2gr over my starting load the rounds had reached peak pressure. At the 4gr. powder charge over my starting load the rounds where at 70k psi. No hard bolt lift, no flat primers no unusual stretching of the brass etc...
Just be careful with what you all do. Doesn't take much to make a huge pressure jump in this stuff and cause a problem.
Later, Frank
paperpuncher
Gold $$ Contributor
Oh thats the coned lug design I havents seen one of those for years
That was funny!
AckleymanII
Gold $$ Contributor
Frank's example is why the NASA engineer is coming out with the book on various action strengths.
The picture is NOT a Remington bolt, and the picture is of a one piece bolt, correct?
One of the strongest actions ever made was by Ferris Pendell, the FDC action made of 17-7 PH. Ferris drove 8 bullets down the bore of the barrel, then fired a full charge in the gun. Nothing happened, the action and barrel took the pressure. FDC actions were like a ugly step child, they did not stay around for very long in the market place. Stolle Panda and Hall M's were dominating the market at that time.
There was a big write up in Precision Shooting magazine about the test that I mentioned with the documentation. I bought three of the FDC actions, shot out a few barrels on them. Every conversation with Mr. Pendell was a 4 hour conversation, bare minimum. We had more than a few conversations on the strength of actions.
The picture is NOT a Remington bolt, and the picture is of a one piece bolt, correct?
One of the strongest actions ever made was by Ferris Pendell, the FDC action made of 17-7 PH. Ferris drove 8 bullets down the bore of the barrel, then fired a full charge in the gun. Nothing happened, the action and barrel took the pressure. FDC actions were like a ugly step child, they did not stay around for very long in the market place. Stolle Panda and Hall M's were dominating the market at that time.
There was a big write up in Precision Shooting magazine about the test that I mentioned with the documentation. I bought three of the FDC actions, shot out a few barrels on them. Every conversation with Mr. Pendell was a 4 hour conversation, bare minimum. We had more than a few conversations on the strength of actions.
Ackman
Gold $$ Contributor
These are .223AI targets, I cut them out and tape to another sheet along with the chrono tape. Same case as that sploder only. 22cal instead of .20, shooting 40gr bullets instead of much lighter 32gr. I was finding accuracy, not going for velocity. That 28.5 gr load was just where I'd stopped. Next time out I tried 1/2gr more and holes were all touching at almost 4200......no signs of overpressure, none. A 32gr doing 4100 out of that case is something you'd expect, hardly cause for alarm.
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urbanrifleman
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Yes that's a one piece bolt.
sstkmkrr
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searcher
Gold $$ Contributor
I think the 20-dollar question here is did he run the load up until he DID run into obvious signs of pressure? And how much higher was that? Is the load reduced enough from that point to ensure there will be no hot weather surprises? Without running into the visible red zone, there is no way of knowing where he truly is at with that chamber/load combo. I don't think anyone is trying to knock the cartridge - but if it is merely a .20A with zero free bore - lots of us have .20's and you can only get so much more from an ackly - free bore adjusted or not. It might work in his rifle - but it is on the hot end for that setup in general. I think that is all some are communicating. We get way too many people on this site watching what will work on your guy's rifle and just start there. So I guess it is more about protecting the ignorant than knocking your setup.
urbanrifleman
Site $$ Sponsor
I didn't post any load advice. I just posted results from a CUSTOMER.
I made no claims about performance. I was just showing groups. Others decided to micro manage what I posted.
The customer is a very experienced 20 shooter.
urbanrifleman
Site $$ Sponsor
More Keith Olson targets.
I covered the velocities so that heads won't explode.
I covered the velocities so that heads won't explode.
Ackman
Gold $$ Contributor
Because it's a public forum with second-guessers and ex-purts.
:/
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