44-40 PressuretraceII Videos

[Unclenick]

Interesting to note that the '63 proof set has probably aged out of reasonable powder strength or your chamber or throat or both are more spacious than it was designed for. Modern proof limits are ten-shot averages of 17,500 psi minimum to 18,500 psi maximum. The Maximum Extreme Variation is 3,400 psi, so, theoretically, you can get one round as low as 14,400 psi or one as high as 21,560 psi and still average the minimum or maximum proof limits, respectively. However, the odds against actually hitting those limits are astronomical, as it requires the other 9 rounds in the ten-shot average all to be exactly 340 psi above the minimum or below the maximum and for 3,400 psi to be the exact extreme spread for the respective averages to work out.

All this begs the question, what reading would modern proof loads with their 2-year recalibration cycle kept up to date average in your gun, so you could calibrate the Pressure Trace readings more closely?

 

[Jim Watson]

Wouldn't he do better with reference loads than proof loads?

 

[Savvy_Jack]

Absolutely, old is old and I wish I had new!!!!!

Would it not be the same with the Dupont No. 2 powder and Sharpshooter powder tests? Question is, if the velocity increases with "newer" powder, the pressures would also have to increase. Meaning that if the 1963 loads should create higher pressures/velocities, then all of the other old powders tested (pending deterioration) would also have to increase?

If the 1963 loads are decreasing in quality, would the 1960's and 1979 factory loads also possibly be effected?

If this barrel is "larger in specs" (more than likely so) than a legitimate test barrel, then all pressures and velocities would have to move linier in correction, right?

The 1917 data shows the HV proofs pressures for the 92' at 30% above service pressures and the 44 loads for the 73' at 25% above service pressures.

Related to the probability of "old powder", lets compare those years.

20" barrel .428", a;; factory loads are .4255" Winchester and .426" Remington

1963 Proof - 1,407fps @ 11,964psi x25% = 2,991psi -/= 8,973psi service load...can't be right....see below.
1975 Rem - 1,123fps @ 10,542psi x 25% = 2,635.5psi +/= 13,177.5psi proof load?
1979 Win - 1,012fps @ 7,318psi x 25% = 1,829.5psi +/= 9,147.5psi proof proof load?

Theoretically, ?

1963 Proof - 11,000psi + 25% = 13,750psi proof?
So in a perfect world, there could be a 1,786psi decline from age?

As expected, I got tons more questions out of these tests than answers!!!!

My favorite question is that, why during my tests do the black powder loads exceed advertised and all smokeless loads fall short of advertised, even new modern loads? There is a consistent pattern there....I think.

I guess we would have to have the 1963 data showing exactly what the proof pressures registered.


Another interesting note was the 44 WHV replication loads with the correct charge of 19.6gr of Sharpshooter. No deterioration there......

1,564fps advertised, 1,568fps tested, 18,000cup advertised, 18,420cup tested

 

[stagpanther]

Question is, if the velocity increases with "newer" powder, the pressures would also have to increase.

Not necessarily strictly correlated from what I've seen. Pressure trace's website has examples of "secondary" pressure spikes down the bore that may be related to a column of powder behind the bullet going off behind the bullet while it's still in the bore. There's also a theoretical pressure wave that "ricochets" down the bore to the muzzle and back, forgot what it was called but unclenick is far more more knowledgable than I on these things and perhaps might further enlighten.

 

[Unclenick]

Would it not be the same with the Dupont No. 2 powder and Sharpshooter powder tests? Question is, if the velocity increases with "newer" powder, the pressures would also have to increase. Meaning that if the 1963 loads should create higher pressures/velocities, then all of the other old powders tested (pending deterioration) would also have to increase?

If the 1963 loads are decreasing in quality, would the 1960's and 1979 factory loads also possibly be effected?

What determines the kinetic energy in a bullet is the average pressure in the barrel during the bullet base's whole length of travel, from starting position in the case all the way to the muzzle. If you have a slower powder, it will allow you to put more energy in the case and it makes more gas, which means the pressure behind the bullet is higher past the peak pressure value than it is for a faster powder. When you include that greater post-peak pressure's bullet accelerating force, you find it can get to the same average pressure, and thus the same kinetic energy and velocity with lower peak pressure than the fast powder can.

As far as the deterioration of powder goes, it is highly variable. The breakdown is caused by random molecular attempts to reach lower potential energy states triggered by randomly high points of heat concentration. This happens to both nitrocellulose and nitroglycerin. The breakdown produces nitric acid radicals. Left unchecked, these acid radicals help adjacent molecules to break down, causing a snowball effect that accelerates the overall breakdown of the rest of the powder around it. To prevent this, diethylamine or calcium carbonate are added to the powder formulation to act as a stabilizer by neutralizing the acid radicals. The exact amount of stabilizer varies by formulation and by lot, so how much powder has to break down before it is used up is variable. That means how weak the powder can get before it goes bad is variable. Because this is a heat-induced phenomenon, the lower the storage temperature of the powder, the lower the probability of random molecular vibration causing a heat concentration point that breaks a molecule and releases an acid radical. Powder kept in a freezer could well last centuries. Powder kept in a shipping container in an outdoor yard in Arizona could be bad in under two years.

So, no, you can't count on age in years to tell you the state of a particular lot of powder. The only generalization you can make is that it weakens with age until the stabilizer is consumed. After that, it either weakens rapidly and starts to corrode cases with acid radicals or, if the powder relies on deterrent coatings to keep its burn rate down, the acid radical can destroy some deterrents faster than the nitrocellulose or nitroglycerin, in which case the burn rate is radically increased. Board member Slamfire had some information posted about the Navy aging powder at, IIRC, 140°F for 18 months and having the peak pressure of 7.62 ammunition thus aged increase by about 150% (again, IIRC; from CUP's in the upper 40,000s range increased to the 70,000s range). There were some photos online of a Garand action destroyed by late 1940's production ball ammo that probably hadn't been stored well. On the other hand, a lot of folks have fired much older ammo than that without damage.

So, there is a big random element to the condition of aging powder. Unfortunately, the only way I can think of to determine what original lots produced is to contact their manufacturers to see if old records still exist to be mined for historical data. You can contact SAAMI to see how their standard for the 44-40 may have changed over the decades (if it has).

You might try contacting SAAMI to see if you can get permission to buy some current reference ammunition to calibrate your test barrel with. They don't normally allow non-manufacturers to obtain it. They used to but found the lots would tend to be exhausted too quickly and could come up short when a manufacturer needed them. However, since you have a site and do a lot of work devoted to this one cartridge, you might be able to ask them for an exception.

 

[Savvy_Jack]

Thanks guys, your replies are greatly appreciated!!!

 

[Savvy_Jack]

Unclenick,

I know sometimes we get all caught up in pressures for factory loads and the ordeal they have to go through. I also tend to forget that what most of us here are trying to do is simply compare our handloads to factory loads, or even more, use this data to improve our handloads as much as we can.

How are these SAAMI "deviations" working out for those who publish handloads like Lyman and Hornady?

Not sure what I am asking here myself, but looking for your thoughts.

 

[Unclenick]

The SAAMI system depends on the cross-calibration of pressures and velocities between manufacturers based on their reference ammunition method. SAAMI reference ammunition is made by a manufacturer assigned to the cartridge in question. A lot of ammunition is produced by that assignee with no particular pressure or velocity values except that they fall within the normal range. To establish it as a reference lot, samples are sent to various industry SAAMI members who have pressure guns and SAAMI standard pressure and velocity barrels for the cartridge in question. Copper crushers use copper slugs calibrated by tarage tables and transducers are calibrated hydraulically as described in the SAAMI standard. The participating facilities all equilibrate their guns and ammunition sample to standard temperature conditions and then fire ten rounds, handling each one by SAAMI's prescribed method to keep powder back over the flash hole.

The measurement results from the above are provided by the participating facilities on a standard reporting form. Unless a set of readings is too far different from those achieved by the other test facilities, it and all the readings from other participating facilities are averaged and the average results are declared to be the characteristic peak pressure and velocity produced by that lot of reference loads in a SAAMI standard pressure and velocity barrel. The lot is rechecked this way every two years to compensate for the effects of aging until the lot is consumed and a new lot has to be made.

The maximum pressure listed by SAAMI is called the Maximum Average Pressure (MAP) and the name refers to the average peak pressure measured, and not to the average pressure as the bullet travels down the whole length of the barrel. When a test is done of some lot of ammunition or a test loading, the gun and ammunition under test and a sample of reference ammunition are equalized within a specific temperature range that is not quite as stringent as is used for evaluating reference loads. Ten rounds of reference ammunition are fired, and the resulting average pressure and velocity readings are divided into the pressure and velocity the reference ammo has been established to produce by the multiple facility testing. This results in a relative correction factor which is multiplied by all the subsequent readings taken from that test setup for any lot of ammunition or load samples being tested during that session. This is how the industry calibrates pressure readings to match what the other manufacturers would get.

So, for example, if you could get your hands on some current reference ammunition and you got it and some ammunition you were testing into the right temperature range, and you measured 10 shots of the reference ammunition on your Pressure Trace to average, say, 9,500 psi, but the lot said the pressure average was 10,200 psi by transducer, you would divide 10,200 by 9,500 and the result would be 1.07, and you would then multiply all your subsequent pressure readings by 1.07 to get industry standard psi. If the lot had a copper crusher rating of, say 11,900 CUP, you could also divide that by your 9,500 psi reading to get 1.25 and you could multiply all your Pressure Trace readings by that number to estimate what the copper crusher average would be, and this is probably the only way to get some idea how your load is comparing to old pressure readings done by copper crusher.

The only other detail is that SAAMI pressures are chosen by industry consensus. It is conceivable they have changed as guns have aged. Give SAAMI a call and ask if the first and oldest standard they had (from the 1930s) for the 44-40 can be looked up in their archives or if they know it to be the same as it always was.

 

[Savvy_Jack]

I have acquired two different 44-40 Winchester manufactured "Proof" loads. One being from 1963 and one being from 1974. Each loaded with different powder and different velocity results. Unfortunately I was only able to pressure test the 1963 loads.

According to SAAMI, the 44-40 Proof loads should be Min Avg 17,5000cup to Max Avg 18,500cup. (other data excluded) (indecently 18,000cup to 23,500cup was the service pressures for the 44 Winchester High Velocity ammunition from 1903 to 1945 which achieved 1,564fps).

The 1963 Q4175 44-40 loads resulted in only 14,142cup (est.) and 1,401fps from a 20" barrel platform. Although I did not pressure test the 1974 D4440 loads but they only came in at 1,224fps fired from a 26" barrel from a rifle...(obviously not SAAMI spec. equipment).

This has been the greatest inconsistency in any 44-40 pressure test or test in general that I have come across.

Again I have more questions than answers.