SAFE OPERATING PRESSURES (PSI)

[BCB]

Does anyone know what the safe maximum pressure for the Contender is when using a 30-30 Winchester cartridge?  Thanks...BCB

[Ken55]

I contacted Tim Pancurak at T/C, who gave me these CUP Limits              The small diameter .223 Rem has a CUP of 52,000.  Larger case diameters such as the 30/30 Win have a CUP of 39,000.  44 mag CUP of   36,000 and the 45/70 CUP of 28,000.

[Bullseye]

Holy cow Ken.  I am not arguing, just thinking out loud here since I am to lazy right now to go get a reloading book.  But I thought when I was looking in the IMR book the other night that about all the 44 Mag loads were up around 40,000-41,000 cup and the 30-30 was about in the same range.  I am going to have to check this when I get a chance because the numbers T/C gave you look low compared what I remember.  But then again my memory is not the best.

[Ken55]

I have been to webpages of so called experts (M.B) who list CUP much     higher than what I was told by T/C.   It is my opinion that T/C list CUP      on the low side, due to liability.   But since I myself handload I heed the    figures T/C gave me.   Contenders (TOYS) are expensive & I have no       desire to blow mine up & end up in the ER.  We all have to realize we can  only push (handload) any gun so far & still be safe.

[Bullseye]

Hey Ken I agree about not loading to the max and I was at that web page one time and you can tell by the style of writing that the writer thinks he is the only one walking on water.  Never been back.  Anyway i checked my IMR book and all those numbers look reasonable except the 44 mag.  They were showing pressures around 40,000, but those are max loads.  Other than the 357 max, my accuracy test usually find the most accurate load about midrange.  I don't hotrod it.  A target has a hole it and an animal is dead without that extra 50-100 fps.  Not to mention a little less recoil makes shooting a whole lot more fun.

[helobill]

Hodgdon lists the 44 mag max loads with 13.6gr of HS-6 behind a 330gr bullet as producing 39,000 cup (no restrictions listed as not acceptable for the contender), and the 30/30 pistol version max load as 34gr of h4895 behind a 150gr bullet at 37,200 cup. And if you look at the MV some of the rounds at different sites are advertised as getting they're exceeding these loads, sooooo somebody said on this forum that one of the shops had actually taken some barrels to failure to find out the limit. Don't remember who it was. But I think T/C is giving you a SAFE answer mostly to "cover their 6" but using common knowlege that's out there.
Not much help huh!? :grin:  
Helicopter Bill

[Sharps-Nut]

I feel realy dumb for never looking at the psi a 223 operated at.  Does this mean that the 223 is on of the highest or more dangerous contender loads?   I have loaded for several years now and have been playing with a 223 contender with reloads for 8 years.  I have always noticed it will flatten the primers long before you reach max loads.  While were on the topic the 223 barrel has always had to be bumped to get it to extract the brass.  Do I have a problem or is the nature of the beast.   I usually load 19 to 20 grains of imr 4198 for a cheap load and use winchester 748 for my accuracy work, both loads pushing 52 grain bthp that I buy from sierra's outlet store.  Minute of angle groups are very doable if the shooter does his part.  My question is this is the 223 hard on the frame, even my mild loads show a little sign of pressure..  and for just a few hunting loads maybe 15 roands total I have moved closer to max loads and really ironed out some primers out flat with those loads.   Help me if you can as I don't want to stretch my frame or even worse hurt myself or others.

[Graybeard]

Sharps-Nut. No just the opposite. The smaller case head of the .223 Rem. means far less back thrust and the higher pressures of it stress the frame much less than the larger case heads with even lower pressures. Can you load it hot enough to stress the frame? Probably if you really try hard.

Don't understand your comment regarding less than max loads always flattening primers. There are LOTS of factors other than pressure that lead to flat primers but pressure along should not flatten any brand of SR primer at the maximum SAAMI pressures for the .223 Rem. Now that's now to say that you can fill the case up with just any powder and it be a less than max load because the case isn't full yet. But no book load should flatten primers just based on pressure alone.

Primer condition is just not an acceptable way of determining what pressure your load is generating.

GB

[Johnly]

Does anyone know what the safe maximum pressure for the Contender is when using a 30-30 Winchester cartridge?  Thanks...BCB

The 375 winchester rins at 50,000 plus and is a factory chambering with the same case diameter as the 30-30.

[Sharps-Nut]

I follow the reloading book to the letter.  I don't use miltary brass but I sure get the flat primer thing if I get very close to a max load.  Its always concerned me so I just shoot it a few fps less.  Now the the quirckey part of this is I can load my 7mm tcu up fairly much to max and I have no tough expraction or appreciateble flatten primers.  But I am still lost on how you can get nearly as much velocity out of the 7mm tcu as you can the 223.  It's the same damn case, doesn't case capacity and mean anything,  why doesn't the 223 go faster than it does?

[BCB]

Thanks to all who replied...

I had been looking at much reloading data for the 30-30 Winchester cartridge and the pressures listed were from data that was used with rifles.  I suspect that any safe pressure loads listed for any 30-30 weapon would be O.K. for the Contender.  Much of this data was from older reloading guides, especially those listing cast bullet data.  The cast bullet data is my concern now.

I always reload ammo on the very conservative side.  I have actually found most of my best accuracy on the lower end of reloading data with about every caliber I reload.  The only exception is a Model 70 in 270 Winchester caliber.  It likes maximum loads in bullets of 140 or greater grains in weight.  (Except with cast bullets!!)  Thanks again...BCB

[Paul H]

Another crinkle in the 30/30 case is the thin case heads that cause case/head sepperation after a few firings when running higher pressures.

[thomas]

If TC says 39,000 is the safe limit for the 30-30 case should I throw away my 30 Herrett and 357 Herrett barrels? The loadings on both are in the 39-45,000 cup range per the IMR website. Why is TC building barrels for which the chambering their in is UNSAFE?
Think I better call TC
Thomas

[Paul H]

I wouldn't get down on T/C for offering the Herret barrels.  When they offer a wildcat barrel, theyhave absolutely no control over what type of data the re-loading companies offer for the round.  So long as you don't push your herrets to the limit, you should have absolutely no problems with the rounds.  

The Herret's are not only historic contender rounds, but they still perform near the top of the heap of more recent rounds, when used in 10" barrels.  I still kinda regret having sold my 357 Herret to Graybeard, especially after he told me how well he was able to make it shoot with the 200 gr cast bullets I sent with it.  I also have a set of 30 Herret dies and a mess of thutty thutty brass waiting for the day I get a 30 Herret barrel.

[Graycg]

Is there any chance that we are all getting stuck in conversions factors between CUP and PSI?  They aren't the same, maybe that is where the differences lie?  Unfortunately, I'm underway and don't have access to my reloading library.

regards,
 Graycg

[helobill]

Here's a link to an explanation of PSI versus CUP (Copper Units of Pressure)

http://www.reloadbench.com/gloss/cuppsi.html

According to the link, CUP (or LUP for some pistols and shotguns) is the only way to measure internal pressure and is sometimes mistakenly reported as psi. Couldn't tell you if they're right.

Helicopter Bill

[thomas]

I do not understand. Why would you NOT be able to use any Book load listed for a TC handgun?
Why would the Book loadings be ABOVE the safe pressures for the Herretts?
Something is not right about this.
You should NOT have to worry about a Book loading for a HERRETT being above the recomended CUP PSI for a TC round.
Still no answer from TC
Maybe the Cup range is up to 45,000 cup for a 30-30 type round
Not the listed above 39,000?
Tom

[PaulS]

CUP - LUP - PSI

They all measure the pressure generated in the chamber. The pressure is the same. What is being recorded is DIFFERENT. The CUP and LUP record the total IMPULSE of the pressure. The Peizo-electric crystal records the entire event of the time / pressure curve. (in the lab)

The difference becomes easier to see when you take into consideration that the lead or copper pellet (crusher) has a minimum yield strength and the crystal has a larger window of sensitivity. The crusher method is calibrated with a "standard" pressure round and results are compared to this "standard". The Peizo method is calibrated with the same "standard" round and the results are compared to it as well. Without knowing the specific pressures of each let's say that the copper crusher begins to yield at 15000 psi and continues to deform at a graduated rate to 75000 psi. The ONLY part of the pressure that can deform the pellet is the time that pressures are over 15000 psi and above it for long enough to deform the pellet. (it does take time) - So if the pressure peaks at 75000 psi but only stays above 15000 for .00075 seconds it could give a lower reading than a load that peaks at 50000 psi but stays above 15000 psi for .0015 seconds. With the peizo- crystal method it will show the entire pressure rise to peak - the length of peak and the drop in pressure all over time.

I am familiar with peizo-electric pressure sensors and know that they are sensitive enough to register less than 500 psi increments (yes five hundred) and I know that they register in increments of less than .001 ms.

I believe that the peizo systems give a better idea of what is actually going on in the chamber of a weapon and may be one reason that some loads have been reduced over the last few years.

The question has been raised whether they can be compared. Yes they can be compared BUT not with the information given in the loading manuals. In order to compare the two values you have to know what the yield strength of the crusher was and the entire curve of the pressure over time. You can then "clip" the peizo data and calculate the time to deform the crusher and come up with an accurate comparison. Do we need the comparison? NO! If we can trust the data given to us in the manuals then all we have to do is work the load up, carefully as we have always done, and find the best load for our weapon.

PaulS