Real Pressure Barrel and Receiver, anyone own one?

[Peter M. Eick]

I am slowly thinking about my transition into retirement and want to learn more about the pressures and internal ballistics of reloading. I am considering going the RSI route or going full hog and getting a ballistic test barrel and receiver setup.

http://www.wisemanballistics.com/product/

Wiseman is just up the road a bit from me and I talked to him a a recent show. Yes I know this is in the range of $50K to setup and get started so I am just sort of toying with ideas.

Anyone own one of these type units? How does it work, where do you get the proof ammo or the SAAMI standard ammo? How has it worked for you? Any suggestions (let me be up front that this is not going to be a quick purchase. I need time to investigate and this is just my first post on the topic)?

My real goal is to sit down and systematically measure the pressures of commercial ammo and reloads and actually develop a listing of what pressures some of our reloads really work at. Specifically I am interested in the 357 Magnum, 38/44 and 38 Special rounds to start.

 

[rsrocket1]

That looks like a really neat looking toy, especially for an amateur tinkerer. It's certainly better than buying a reclining sofa and TV as a retirement present .

The question I'll ask with the cartridges you want to test is: since you need to test in a very controlled chamber, will that translate into reliable information in a revolver cylinder?

I assume you have Quickload and learned all the ins and outs of that program. Not that it is foolproof, but it is an excellent learning tool for interior ballistics.

 

[GaryL]

I know someone who bought a used test barrel a few years back. I think he was planning on just doing some long range shooting with it. Haven't talked to him in a while, so no idea what he ended up doing with it.

The thing that would be cool though is testing with every possible powder/bullet combination in a caliber. Most companies don't have the time or resources to do that, so they will stick with the most popular or generic choices.

 

[Rule3]

$50 K? to test reloads? Wow!

Must be nice

 

[brickeyee]

Actual lab grade pressure barrels are normally minimum sized bores and chambers.

They are NOT inexpensive.

If you want to just play around, you could use a personally owned reamer and section of barrel from the blank you built the rifle and develop data for THAT rifle and chamber.

You stuill have to watch for wear though (on the reamer, chamber it has cut, and even the barrel).

When you flirt near the limits things that we are not all that concerned with can become critical.

 

[osteodoc08]

Personally. I'd just learn to use quick load and be happy with that and put the money into guns or even better, land.

 

[Dave P]

Didn't CMP have some test rigs for sale , based on 1903 rcvrs?

 

[MCMXI]

In addition to the hardware you'll need transducers (expensive), quality velocity screens, a DAQ, PC etc. Remington makes SAAMI ammunition as do other manufacturers but I don't know if they'll sell to an individual or small business. I spent quite a bit of time using this type of equipment at Remington developing a number of products and I was never tempted to purchase my own system. I had considered testing my reloads but realized that I wouldn't learn much since my chambers and barrels are different to the test barrels. I could have tried different primers to see how they would affect the time vs. pressure curve but I already know who makes the best primers. For ammunition companies such as Remington who aren't using reloading manuals to work up loads this sort of equipment is essential particularly when powders aren't off the shelf but customized for each application. For the rest of us, a chronograph, QuickLOAD, and maybe some strain gages are enough.

 

[Kp321]

Several years back, some experimenters were putting electronic strain gauges on the chambers of their rifles. Strain gauges and the associated software to interpret the data is not cheap but is considerably less expensive than a full pressure gun. The only caveat is having a known pressure load to start with for a baseline reading in your barrel.

 

[Chevota]

I used to send my loads out for testing, I mention that because you might consider doing that for people. Help pay for the equip and it's something to do. Plus you'd get experience with different loads people make

 

[LiveLife]

Several years back, some experimenters were putting electronic strain gauges on the chambers of their rifles. Strain gauges and the associated software to interpret the data is not cheap but is considerably less expensive than a full pressure gun.

The Rifleman's Journal used Oehler 43 strain gauge pressure measuring system for their primer testing study - http://riflemansjournal.blogspot.com/2009/06/primers-small-rifle-primer-study.html

With our test equipment in place, we began the pressure and velocity testing portion of this test. We first fired the reference ammunition provided by Lapua in order to verify the calibration of our equipment, an Oehler 43 Personal Ballistics Laboratory system. Our pressure readings were within 100 PSI of Lapua’s specification; this was determined to be well within acceptable limits.

To the extent possible, SAAMI testing procedures were used as a guide for our testing. However, there are many variances from those procedures. Most notably our use of a strain gauge pressure measuring system (Oehler 43) rather than the SAAMI standard copper crusher or piezoelectric transducer method as both of these are beyond the scope of our budget and facilities ...

... Table 1 summarizes the results of the test firings for pressure and velocity. Each primer test was fired twice, the test sessions being one week apart ... in both tests, firing was conducted in a manner calculated to minimize the effect of barrel temperature changes and barrel temperature was closely monitored.

We collected data for muzzle velocity (gross, SD and ES), chamber pressure (gross, SD and ES), area under the pressure curve which is a measure of total energy produced, and rise time, which is a measure of the time from ignition to peak pressure.

... both muzzle velocity and chamber pressure showed the variances that reloaders have come to expect from different types of primers.

Much more at link.

 

[Peter M. Eick]

The strain gauge approach is the RSI method. It appears to work reasonably well, but it is a calibration issue I have not gotten comfortable with yet. Going with a real pressure gun and speced barrels allows me more precision and accuracy.

I can see the point that I don't know the pressures in "my gun", but I would argue that if I were running say 20klbs on the pressure barrel for say 357 magnum, I am pretty mild and could work up more power for my N frames. This is an issue I am still working on and thinking.

Regarding the costs, yeah, 50 to 100K is a slug of money but one thing I have noted in my peers is those that handle retirement well have something to do. Right now, my lifelong hobby has been reloading so I am thinking of taking my hobby to the next level. What I have thought of was a program of testing the actual pressure level of book level reloads and writing some articles or web posts about the "reality" of current data vs. historic data.

Really, how high pressure was Speer 8 38 special load data? And visa versa, how low pressure is current Speer 14? Few in the industry really know and those that do don't seem to talk a lot. Would it not be fun and interesting to spend several years just documenting with proper equipment the pressures actually developed in commercial and modern reload data?

Anyway, that is my hobby thought for retirement. And I can add that as of yesterday I can now retire with full benefits so while I don't plan on bailing right away, I need to work on my plans for the transition.

 

[John C]

Peter;

Regardless of which method you choose for your research, the RSI method or an actual pressure barrel, I'm damned interested in reading about your findings. I also have the same questions about the pressures used in the older publications.

Congratulations on your retirement milestone! I also agree with your ideas on having a passion to pursue in retirement. Go for it!

Thanks,

-John

 

[Reloadron]

Congratulations Peter on the retirement. I went out in May of 2013 and like you have looked at different shooting related things to keep me busy. Pressure has always fascinated me so I also will be interested in what you come up with. I also looked at strain gauge methods. My background was electrical engineering so if you need and help with electronic data acquisition methods let me know. I wish you the best in this endeavor and would, like others, love to follow your progress.

Ron

 

[brickeyee]

Calibrating piezo or strain gauge systems relies on the use of VERY standardized cartridges.

Without those reference cartridges to calibrate against you have no way to tell if what you measure is correct.

It takes multiple shots and averaging even on a real pressure gun.

Even the old copper crusher method suffered from calibration issues.
The momentum of the pieces altered the readings.

With strain gauge temperature affects are a PITA.

Strain gauges are not all that linear for brief fast impulses compared to steady state strain, and the bandwidth of the electronics limits what can be seen and how quickly the system responds to brief fast pulses.

And with any system the equipment can only operate accurately within its elastic limits.

 

[Reloadron]

Calibrating piezo or strain gauge systems relies on the use of VERY standardized cartridges.

Without those reference cartridges to calibrate against you have no way to tell if what you measure is correct.

It takes multiple shots and averaging even on a real pressure gun.

Even the old copper crusher method suffered from calibration issues.
The momentum of the pieces altered the readings.

With strain gauge temperature affects are a PITA.

Strain gauges are not all that linear for brief fast impulses compared to steady state strain, and the bandwidth of the electronics limits what can be seen and how quickly the system responds to brief fast pulses.

And with any system the equipment can only operate accurately within its elastic limits.

Bingo. Short of a major investment this will not be an inexpensive project or for the faint of heart. I had given some thought to playing around with strain gauges but sort of discounted it for the very reasons mentioned. No shortage of variables and variables is what you want to eliminate.

Then I looked at Series 117B Charge Mode Conformal Ballistic Sensors thinking that maybe I would just experiment with 308 and 223. Not quite inexpensive sensors considering I was only interested in this as a form of amusement.

All in all interesting stuff but I lack the guts to tell my wife I want to deplete our savings and investments by 50K plus so I can play around with measuring chamber pressures.

Ron

 

[MCMXI]

Calibrating piezo or strain gauge systems relies on the use of VERY standardized cartridges.

To be even more specific, piezoelectric transducers for ballistic testing are typically calibrated onsite using an hydraulic pump or similar. Once installed in a barrel, the barrel "offset" is determined using reference ammunition.

 

[Peter M. Eick]

I look at it this way, Rolex watch or a pressure barrel setup? Both are around the same dollar value and one I will use (and it won't be the watch).

The calibration issue is what gets me with the RSI from what I can tell. It is comparative meaning I can tell if I am putting out more or less pressure than my reference ammo, but it does not tell me a real number for the pressure that I can compare to say the SAAMI standards chart or say Quickload.

I have some experience with load cells and strain gauges so I understand the reference system. What I think I will have to do is incorporate a business (when I get around to retiring) and then get an FFL license to manufacture ammo and work with ammo so I can legally buy and sell materials. That way I can run a business doing pressure work on contract and still learn as I go. Even if I never made a penny I would have a lot of fun playing with the system and hopefully I could get access to non-canister powders for testing from the manufacturers.

Like I said in my original post, I am just starting to really research this. I figure I will work at most another 6 years or so but in the mean time i can start accumulating hardware for fun. I decided years ago that I wanted to learn more about reloading during my retirement so that is my focus.

I will keep Ron and John in mind as I work this project. You will see me post about it as I go. I think my first step will be a run up to College Station and talk to Wiseman face to face so I can learn what I am getting into.

Another option is to go back and get a college degree in ballistics. Anyone do that route?

 

[Reloadron]

Cool and you may also want to give this a read. They cover the SAAMI method in use today which uses the transducer I linked to earlier. Interesting stuff.

Ron

 

[Peter M. Eick]

Fascinating link. Thanks! I had not really delved into the CIP standards yet. I really liked the CIP links on the bottom of the page. It is interesting to study the rounds they have listed. For example I see they have 38 AMU. What an esoteric round that I have a box on the shelf for.

 

[GaryL]

Another option is to go back and get a college degree in ballistics. Anyone do that route?

My suggestion would be to skip college and do the research on your own. Basic ballistic calcs are pretty simple, and once you master those (if you haven't already) you can take on the effects of aerodynamics and ballistic coefficients.

Bullet Mfg BC's are made on basic assumptions, which can change quickly when you factor in manufacturing variance and tolerances, not to mention a reloader deforming the bullet in final crimp. If the bullet has the BC of a brick, nothing short of smashing it with a hammer will make much difference. But for the high BC stuff, whole different ballgame.

Anyway, I have an engineering degree, and I know that there are a lot of things I learned in college that are important in being a well rounded engineer able to tackle a lot of different tasks and apply appropriate engineering principles. But I also know people who barely graduated HS who are experts in a given subject. They are self taught, they applied themselves and learned everything they could both hands on and by doing background research. They stayed focused and excelled in that area of focus. Which is a somewhat like getting a PhD.

I'm looking forward to seeing you post up what you learn along the way.

 

[Owen]

on the college route, I do not think there is a university in the United States with a ballistics program. The knowledge base lies within the government and industry. The only school I know of that has actual internal ballistics curriculum in Cranfield University in England, and its a Master's Degree/PhD.

http://www.cranfield.ac.uk/courses/masters/gun-systems-design.html

If you want to do mathematical modeling of internal ballistics, the software you want is PRODAS.
http://www.prodas.com/

As far as I know, its the only software that lets you design propellants and isn't dependent on empirical data. I'm pretty sure you can purchase just the internal ballistics and stability models. I believe it will even allow for tweaking the arrangement of powder grains inside the cartridge (some large guns have powder grains the size of soda cans).

 

[GaryL]

owen caused me to realize a brainfart. Wasn't considering the powder structure side of it and finite analysis of pressure generation. Oh well. Carry on....

 

[klausman]

A few years ago while working on a history project, I had chemical analysis done on several old powders. I really wanted some calorimetric tests done as well. Unfortunately, it seems that no one other than powder companies had calorimeters that were designed for 'energetic' materials. Ultimately, I decided that the calorimetric testing was just not that important to the historic nature of the project.

In many ways, you are on your own when you get into this stuff that deep.

Good luck, and please do share your results when you get them.

 

[steve4102]

You could always save Thousands and get a Pressure Trace gauge.

http://shootingsoftware.com/pressure.htm