Author Topic: contender reciever pressures (Read 2794 times)

Scibaer · « **on:** September 14, 2009, 01:58:25 AM »

i read that the contender cannot pressures any higher then any other gun, and not as much pressure as a ruger blackhawk.
i went and did a little bit of research and found two numbers claimed as the contender's safe pressure limit.
i read 48,000 cup was the limit for the reciever but one article i read said 43,000 cup was more realistic.
now, does anyone know for sure what the reciever's max cup pressure ?
does anyone load and shoot any chamberings that run higher than 43,000 cup without trashing thier contenders ?
if the pressures are limited to the 43,000 cup how close can your run to that limit without issue ?
if the contender can handle chamberings like the 445supermag, then it should be able to handle anything someone can load up ( safely ofcourse ) in .44mag or .357mag, knowing that 39,000 cup is 39,000 cup regardless..?

Gavinator · « **Reply #1 on:** September 14, 2009, 08:33:12 AM »

It depends on the diameter of the case, a 223 REM will go to 52,000 C.U.P..

Graybeard · « **Reply #2 on:** September 14, 2009, 11:05:48 AM »

There are no hard and fast specific pressure limits. The concern is back thrust on the frame and that comes from a combination of pressue and case diameter. What's a safe pressure for a .223 based case is far different than what's safe for a much larger case.

Basically then it's a particular cartridge not a specific pressure that's safe or unsafe. It depends on the round and what pressure it's loaded to.

Ladobe · « **Reply #3 on:** September 14, 2009, 12:09:07 PM »

What Bill said (mostly). Barrels have been/are chambered for borderline cartridges that are only safe on the Contender when loaded down though (an accident just waiting to happen).

Forgot to add... it's the internal diameter of the cases that dictates
their pressure limits when used in the Contender.

Scibaer · « **Reply #4 on:** September 14, 2009, 01:36:15 PM »

so, a larger case with higher pressures with have more back thrust, and could make for unsafe pressures on the frame ?
the cartridge im working with is the .44mag.

the 48th edition of my lyman maunal just shows a dash - for pressure specs when looking at load data for the contender.
i'm not sure if that means they didnt test for pressure, or pressure is not relevent or presssure data is no different then other .44mag pressure data in other guns/chamberings

for no good reason, i have this idea that the contender can take/handle more pressure then some other handgun, that must not be the case? but i would like to be able to run full power loads to max pressures in my tender if need be.
i assume ( i know

) that the tender is capable of SAAMI specs for whatever chambering TCA offers barrels in ?

kynardsj · « **Reply #5 on:** September 14, 2009, 01:39:33 PM »

There are special loading sections in some reloading manuals for Contenders and Rugers because they can handle more pressure. There isn't a 44 mag made that is loaded to specs that I would be afraid to touch off in my Contender.

Dezynco · « **Reply #6 on:** September 15, 2009, 12:04:08 PM »

If your Contender barrel is chambered in a "factory" cartridge, then any safe load is safe in the gun. The issue with Contenders is the wear and tear on the frame and the frame hinge pin. The big cases that have a rim operate at relatively low pressure, even though they can have a tremendous kick.

Take the 45-70 for example. Any reasonable off-the-shelf factory load will be safe in the Contender. It's when you start fooling around with reloads that you can get into trouble, and should pay attention to the pressure specifications.

As far as the Contender goes, I stay away from any handloads that might break the 40,000 cup range, just to be on the safe side, and to save wear and tear on my frame.

Lager · « **Reply #7 on:** September 15, 2009, 03:34:44 PM »

Ok,Dezynco,splain something to me. Im not arguing your point, just info gathering about CUP and different calibers that TC has offered in a stock configuration,wear and tear and felt recoil.
Tc offers the 223 that measures 50,000 CUP,well above Scibaer"s posting about 43-48 CUP. But the felt recoil is less then the 44 Mag in commercial loads.Meaning very manageable.
TC also offers 45-70 Govt which has a CUP rateing of only 28,000 but kicks like a freaking mule!
I would think, the wear on the frame/pin would be higher useing the 45-70 then either the 223 or the 44 mag because of the felt recoil.
Your thoughts?
Sorry Glenn, I didnt mean to hijack your post. Its just that Dez seems to know what hes talking about and it applies to your 44 mag and reloading/CUP.

Dezynco · « **Reply #8 on:** September 15, 2009, 05:28:01 PM »

I'm certainly not a scientist or an engineer or anything like that, but I think it's got a lot to do with the size of the base of the cartridge. The big 45-70 spreads the rearward thrust over a larger area. Works sorta like the Venturi effect (remember that from science class?). When water (or whatever) is forced through a smaller pipe, the pressure goes up, but the volume goes down. The larger the pipe, the lower the pressure, volume goes up (think of volume as "recoil")

I think that's an ok analogy?

Scibaer · « **Reply #9 on:** September 16, 2009, 12:44:27 AM »

no problem Paul, any question that helps me understand this pressure CUP issue in the contenders is a good thing.

i think that the "felt'" recoil and the actual pressures the frame has to absorb are two different things. using the 45-70 anology, it has quite a bit of felt recoil but the CUP pressures are fairly low conpaired to the pressures a 243 has on a frame. ( bottle necked cases develop more backthrust anyhow )

my question is, why can the frame handle 50,000 cup from one case, and only 30,000 from another case of different size ?
is it solely because the larger case spreads the pressures out more because of its larger surface area ?

RonF · « **Reply #10 on:** September 16, 2009, 04:32:02 AM »

The real issue with a Contender, unless you get into something really big that leaves the chamber walls or the metal between the chamber and the sight/scope mount holes too thin, is the rearward thrust on the standing breech. That thrust is a force, i.e. pounds, and it is given by

Force = Pressure (in psi) X Area (in square inches)

where the area is the area of the inside of the base of the cartridge. It is not easy to measure that inside diameter, but if you use the outside diameter you'll get a conservative estimate of the pressure (i.e. the calculated pressure will be higher than the actual to give you a little safety factor).

To run a simple example for the .223 Rem, the outside diameter at the base is 0.376", so the area is 0.1110 square inches. The maximum SAAMI pressure for the cartridge is 52,000 CUP. A CUP is not equal to a psi. For high pressure cartridges the pressure in psi is higher and in this case it might be 55,000-60,000 psi. If we use the higher figure we'd get a little over 6,600 pounds of thrust.

The same example for the .45-70 Govt. we'd use a diameter of 0.505" for an area of 0.2003 square inches. My Speer No. 13 manual says most commercial .45-70 ammunition is loaded to 21,000 CUP (which is less than the 28,000 CUP SAAMI maximum). At lower pressures the CUP value and the psi value tend to be closer, so if we assume the psi value to be 22,000 we compute a backthrust of a little over 4,400 pounds. Even at 30,000 psi we'd be at just about 6,000 pounds.

For the .30-30 Winchester operating at 38,000 CUP (estimated 40,000 psi) we'd get a back thrust of slightly less than 5,600 pounds. You can see that all these are in the same general ball park, i.e. plus or minus 10% of 6,000 pounds.

It isn't quite this simple, because bottle necked cases actually produce less back thrust than calculated, while straight wall cases tend to be closer to the calculated amount, but at least you can see the logic that larger cases have to be loaded to lower pressure.

Finally, this back thrust has nothing to do with recoil. Recoil is due to the momentum of the bullet (mass times velocity) added to the momentum of the powder gasses (their mass times their velocity, which is much higher than the bullet velocity). This is why equal velocity loads using fast burning powder have lower recoil than loads using slow powder.

So, is everyone's brain fried now?

RonF

Hopalong7 · « **Reply #11 on:** September 16, 2009, 04:51:57 AM »

Good job Ron!

Scibaer · « **Reply #12 on:** September 16, 2009, 05:04:35 AM »

nope not brain fried at all.. infact that data is great, so someone can actually, mathmatically figure backthrust on a contender frame.
recoil in ft-lbs can be calculated, as can energy in ft-lbs of any load ( bullet weight in grains x fps squared )
so we can get the load in thrust on the frame. depending on the metal and how its produced we should be able to figure out its max bearing load.
glenn

Noreaster · « **Reply #13 on:** September 16, 2009, 08:42:21 AM »

Great thread and responses. I couldn't figure out why I could shoot a 223 at 50,000 cup but my G2 couldn't handle other catridges in the mid 40,000 range.

Lager · « **Reply #14 on:** September 16, 2009, 03:03:08 PM »

Interesting reading.
This means, the max CUP the Contender can handle safely has nothing to do with the reciever, or its hinge pin. But of the internal pressures of the barrel it self?
During the ignition of ,lets say the 223 and its bottle neck design. The force is directed rearward and forward,thus reduceing its felt "rear push". Is it safe to call that " felt recoil"?
Now in the 45-70 Govt cartridge, since its a straight wall design.Has no front wall or bottle neck to help counteract the internal pressures. Thus the lower CUP and more "rear push".
Getting back to Scibaer's original question about up loading the standard 44 mag cartridge, but still staying safely in the CUP range?
Now we know that the CUP rateing is for internal pressures of the barrel itself, and the large bore gets us pretty close to the grip screws( Weak point)
Since he is looking at the hunting aspect/knock down power.
What are your thoughts about different burn rates of powders as compared to bullet weights to possibly even reduce CUP ?

RonF · « **Reply #15 on:** September 17, 2009, 01:41:43 AM »

A couple of comments:

1. Yes, you can compute back thrust, but the computations are just approximations to reality, and I wouldn't want to cut it too thin and ruin a frame based on the computations.

2. The pressure ratings, whether CUP or psi, are just standards that insure safety of ammunition in various guns. In the Contender, unless you get into really large cases, the dominant failure mode is that the back thrust on the standing breech causes frame stretching, not barrel blowout, hence my focus on that computation.

Also, the comment above about recoil is incorrect; please refer to my original post.

RonF

Hopalong7 · « **Reply #16 on:** September 17, 2009, 02:24:34 AM »

Much of Mr. P.O. Ackley's writings/experiments/theories are directly related to this very topic. He was generally working with the back-force on the bolt of a bolt action rifle(area of most failures), but it's pretty much the same thing. Of course his theory(much simplfied, so I could half way understand it) was that his "improved" case designs(closer to straight wall vs tapered) greatly reduced the back force on the bolt/standing breech. Supposedly, he fired one of his "improved" rounds successfully with No bolt behind it

I agree with RonF that this is NOT an exact science, and, real life experience and lots of common sense need be applied liberally. Probably what makes it so interesting for most of us!

GOOD SHOOTIN', Walt

Scibaer · « **Reply #17 on:** September 17, 2009, 03:12:42 AM »

the frame strength issue is what i am interested in. the G2 has a re-enforced frame, where the contender will wrinkle and crack if pushed to hard.
the frame failure is from the barrel pounding the frame on recoil and i was trying to figure out where that limit is, when the frame will fail.

this thought process got me to this wanting to know the contender limits: i reload for myself and a hunting buddy, we have taurus and rugers, model 44/raging bull and blackhawk/vaquero. with full power loads of H110, you can feel the difference between the taurus and ruger. the ruger can handle the rounds much better.
now i was under the impression that the contender should be at least as strong as the rugers, but with no cylinder gap the muzzle velocities will be higher in the contender and felt recoil should be more too. now, how hard can i push the contender with SAAMI specs. loads. it is safe to push the contender , to all the recoil i can handle or am i limited to the taurus levels ?

kynardsj wrote: There isn't a 44 mag made that is loaded to specs that I would be afraid to touch off in my Contender.
i basically want to know, if that statement is on par or, like Dezynco said " As far as the Contender goes, I stay away from any handloads that might break the 40,000 cup range, just to be on the safe side, and to save wear and tear on my frame."

i know i'm probably making more of this then i should be, but when i work up loads for my new 44 barrel, i want to know where i need to stop, unless the recoil or muzzle blast tells me to stop ( assuming i get the bullet performance / accuracy i want )

Hopalong7 · « **Reply #18 on:** September 17, 2009, 03:49:05 AM »

Any standard(factory) load or any reload from established and proof tested reloading manuals such as Lyman, Hornady, Hodgdon, etc...for the .44 Rem Mag should be quite safe in any .44 Rem Mag Contender reguardless of frame style or age. Of course as a reloader you already know to begin with starting loads and work up to max. Some think that the G-2 is a stronger frame than the older ones.

. TC themselves do not state this and it has never been proven that I'm aware of. I know they made a muzzle loader barrel that will fit the G-2 and nothing else, but Gonic built muzzle loader barrels for the older Contenders for years too. Maybe there is a slight difference, I don't know and really are not very concerned with. If we need more, that's what we have Encores for. I personally know of several old Contender frames that have withstood the pounding of literally thousands and thousands of near max .44Rem Mag loads and are still ticking quite well. I have one frame myself(serial # 237,XXX) that has fired many thousands of 45-70 rounds and it has held much better that the old pair of hands and arms that was holding it. GOOD SHOOTIN',

Walt

Ladobe · « **Reply #19 on:** September 17, 2009, 12:38:36 PM »

Quote from: Scibaer on September 17, 2009, 03:12:42 AM

...
I know i'm probably making more of this then i should be, but when i work up loads for my new 44 barrel, i want to know where i need to stop, unless the recoil or muzzle blast tells me to stop ( assuming i get the bullet performance / accuracy i want )
...

Yes you are, way more. You can over anaylize this until the cows come home and you'll still just be shooting a 44MAG in your Contender. Yes I said "just" a 44MAG. Typical pressure signs with the cartridges themselves will tell you when to stop as you work up a load.

To add to what Walt suggested, the G2 is TC's Lawyers Frame (trigger), nothing more. It looks like a Encore in outward appearance to tie them together, not to make it stronger. Despite armchair speculations, nobody has ever proved the G2 is stronger and I doubt they ever will. If the G2 frame was in fact stronger than the Contender frame I'm sure it would have been advertised as such by TC. In fact that would have helped them get the old crew of TC users (like me) to "swallow" the G2 better than we did.

Keith L · « **Reply #20 on:** September 17, 2009, 02:20:43 PM »

TC never claimed it to be stronger. One of the aftermarket barrel makers does, but I have never seen test data to prove that. It is a styling change. not intended to be the stronger frame some claim. Ladobe is right: if it were stronger TC would have sold it as such.

Dezynco · « **Reply #21 on:** September 17, 2009, 03:10:58 PM »

Good point! I'm glad that some of you guys can explain CUP better than I can. It's hard to explain "recoil" vs. "pressure". I have a 12" pistol barrel in 7.62x39 (a little-bitty cartridge) that is borderline being too much pressure for the Contender. Go figgur'.

Lone Star · « **Reply #22 on:** September 17, 2009, 03:14:53 PM »

The most common frame failure location - especially on the original pre-EasyOpen frames - was at the breech/frame rail junction. The frame was thinnest at this point, and excessive case head thrust would stretch the frame until it cracked (don't ask me how I know this). The EasyOpen frames were a little thicker there, but that is still where they'd fail.

With the G2 that same area is now thicker than much of the rest of the rail, so I doubt the frame would still fail at that location. But I wouldn't assume that the G2 is significantly stronger than the Contenders were either. If you want a stronger frame - get the Encore.

.

Keith L · « **Reply #23 on:** September 17, 2009, 08:24:37 PM »

Quote from: Lone Star on September 17, 2009, 03:14:53 PM

If you want a stronger frame - get the Encore.
.

There it is. You have a choice now.

RonF · « **Reply #24 on:** September 19, 2009, 01:32:15 AM »

I believe Lone Star has it right. Someone said the G2 was a lawyer's Contender because of the trigger. That may be true, and I believe their gusseting on the G2 frame was to make it stronger, not for the purpose of adding heavier calibers (which the Encore takes care of), but to satisfy the lawyers by increasing safety factor for the calibers in which it was already chambered. The similar gusseting on the Encore is not just styling, it is to strengthen the frame sufficiently in that area to handle the more powerful calibers for which it is chambered.

Someone else said "the barrel's pounding on the frame...". Wrong! There is (small, hopefully) clearance between the barrel and the standing breech. It's the cartridge head that pounds on the frame.

RonF

Keith L · « **Reply #25 on:** September 19, 2009, 01:37:27 AM »

Quote from: RonF on September 19, 2009, 01:32:15 AM

I believe their gusseting on the G2 frame was to make it stronger, not for the purpose of adding heavier calibers (which the Encore takes care of), but to satisfy the lawyers by increasing safety factor for the calibers in which it was already chambered.
RonF

I think you will find that the one and only reason for the gusseting was to make the Contender and the Encore look alike. Just marketing.

Hopalong7 · « **Reply #26 on:** September 19, 2009, 04:22:38 AM »

I agree Keith.

Lone Star · « **Reply #27 on:** September 19, 2009, 02:59:57 PM »

Quote

Someone else said "the barrel's pounding on the frame...". Wrong!

Well, half-right actually. The barrel lug 'pounds' the hinge pin and the case head 'pounds' the breechface. Without both there would be no frame damage (or no bullet leaving the muzzle for that matter)...

.

Ladobe · « **Reply #28 on:** September 19, 2009, 03:35:26 PM »

Speculate all you want, but if you were there at the time asking the questions you'd have a different opinion.

I still chuckle when I think back to the 2000 SS when Tim and Ken discreetly handed me the G2 prototype under the table (literally) to get my opinion of it. Ken's way long gone from TC now, Tim's gone now too but I kept the promise I made to both of them that day... I still do not and never will own a G2.