3031 and Trapdoor Springfield

[3Gunnah]

Hello gentlemen. I bet this topic has been beaten completely to death here and I apologize, but I haven't figured out the search feature yet. I just recently picked up an original trapdoor Springfield. The gun is in excellent condition. Serial number over 450,000. I am finding lots of contradicting load data on the internet regarding trapdoor rifles and IMR 3031 powder. Hodgdon load data in the 47 48 49 and 50 manual list a max of 41 grains of 3031 with a 525 grain bullet cup around 21,000. I currently load this Bullet cast from a Lyman mold sized .459 or .460, lubed with a mix of beeswax and crisco in my reproduction Sharps at 40 grains of 3031. The manuals all say this load would be acceptable for the trapdoor. Several places I have found online say you need to keep the loads below 17,000. Any experience that you gentlemen have with this would be greatly appreciated.
thanks

[Nightshift82]

Lyman cast bullet handbook has max 41.5 for 17,900 psi. For a 525 grain saeco #745.

Sent from my XT1585 using Tapatalk

[Scharfschuetze]

I load quite a few rounds annually for my original Trapdoors and H&R replica Trapdoors.

I like to duplicate either the Cavalry load (45/55/405) at 1,000 fps or the early infantry load (45/70/405) at 1,300 fps. If your rifle still has the original front sight blade, you'll find that it shoots pretty high with smokeless powder. I keep one of my Trapdoors just for smokeless with a reduced height front sight. I like the Lee 405 grain or the Lyman 405 grain plain base designs.

The only time that I've tried 3031 was under a 350 grain jacketed bullet. It worked a treat for a hunting load for a friend in a Marlin 1895. I generally like to use SR 4759 which is much like 4198 in burning characteristics in my Trapdoors.

The Lyman #49 CBH shows the following for the 535 grain Lyman #457132 bullet using 3031 in original Trapdoors.

Starting load: 36 grain for 1204 fps
Max Load at: 41 grains for 1409 fps

[KenH]

I generally like to use SR 4759 which is much like 4198 in burning characteristics in my Trapdoors.

I hear so many folks talking about 4759 for BP cartridges as the best powder. Since 4759 is no longer available, and you mention 4198 is much 4750 powder - would you consider 4198 the best substitute for 4759? I've heard that AA5744 is another good powder for BP cartridges.

Ken H>

[Scharfschuetze]

If I didn't have a supply of 4759, I'd certainly use 4198. 4759 is very bulky and fill more of the case up which seems to help with ballistic uniformity. While a bit faster, 2400 or 4227 might also be good options along with the proposed 3031.

When AA5744 first came out I bought an 8 lb jug of it. It just didn't live up to its hype and I still have half a jug left after something like 20 years. It burns awfully hot and leaves a substantial number of burned kernels in the barrel and the action when using it at black powder velocities. The only rifle that I find it to be better than 4759 in is the 30/40 Krag with 208 grain 314299 bullets. Sadly the barrel gets almost too hot to touch after only 20 rounds or so and as you know, heat is not good for barrel life. The hot burning of 5744 is probably due to it rather high nitro content.

I understand that 5744 was re-formulated after many complaints, but I've never seen anything concrete regarding that info. Perhaps another member can confirm that?

[salpal48]

I have used IMR 3031 in my Trapdoor with much success. But the loads were not using a Heavy boolit as 525Gn
300 GN cast 43 GN 3031 .
405 Gn cast 40 Gn 3031

[Larry Gibson]

I conducted a test of 3031 with different fillers a few years back for several members here. I used a commercial cast 413 gr bullet and my own cast Lee 459-405-HB weighing right at 410 gr. The 413 gr commercial cast was used for pressure testing out of my Siamese Mauser 47-70. I then tested the TD acceptable loads for accuracy using the Lee HB bullet out of my M1884 target TD. It has a tang rear sight and an aperture front sight.

Understand that the maximum "psi" we see listed using the old CUP method of pressure measurement runs from 18,000 to 21,000 +/- depending on when the measurement was taken and by whom.

SAAMI has set the MAP (Maximum Average Pressure) using modern peizo-transducer/strain gauge measurements at 28,000 psi. We also see the older figures referred to as "psi" however, Those are now referred to as CUPs to differentiate from the more modern method which are now called psi's. The two are apples and oranges and there is no correlation between them. I used and Oehler M43 to measure the psi via a strain gauge over the chamber of my Siamese Mauser's barrel.

I found 3031 to be very position sensitive and gave erratic performance unless a filler was used OR the load was way to heavy for use in TDs. Of the fillers tested Dacron proved to be the best. Using a 3/4 - 1 gr Dacron filler over 35 gr of IMR 3031 proved to be the best load. Velocity was right at 1300 fps out of the 29" M1884 TD barrel and the measured psi was 26,100 psi(M43).

Here is the 100 yard test target;

Attachment 197134


Larry Gibson

[3Gunnah]

I'm really hoping my current load is going to be acceptable. I have almost 20 lb of 3031 powder on hand and at least a hundred rounds currently loaded for the sharps. As long as it's not loaded too long I think it should work and I appreciate all the responses so far.

[KenH]

Larry: Thanks for the info on pressure using 3031 in 44-70. I have found 3031 to be somewhat position sensitive myself with light loads - determined by chrono'ing loads. lifting barrel to position powder to primer before firing tends to give a lower ES.

You mention 35 grains of 3031 gives 26,100 psi - I'm "assuming" this is with the 405 grain cast bullet? I think I've read that Quick Load's pressure for straight case cartridges (like 45-70) isn't very good on pressure calculations - compared to your measured pressure this is true. Using the above 35 grain 3031 with a Lee 457-405-F cast bullet with 2.55" OAL and 29" barrel, QL gives 1356 fps (which is pretty close), but only 13,479 psi which is only half your measured pressure. Just gives an idea how "off" QL is for straight case PSI calculations.

Velocity is a direct function of PSI (with other variables of course), so with QL giving the same "range" of fps as your measured fps, then the PSI should be close to the same - correct?

[Larry Gibson]

Does QL take into account the dacron filler?

Is QLs "psi" based on CUP or piezo-transducer/ strain gauge pressure measurement?

Larry Gibson

[M-Tecs]

Larry as you posted in the link below the 45/70 is the exception .

SAAMI was established in 1923. I don't know when the SAAMI spec for the 45/70 was set but I do find it interesting that per SAAMI 28,000 is the same whether measured in CUP or PSI.

I think that is only instance where CUP and PSI pressure are the same.

http://castboolits.gunloads.com/show...AAMI-pressures9

[Larry Gibson]

Lyman #3 CBH says; "Loads greater than 15,000 C.U.P. should be used only in Springfields (the so called trapdoor Springfield) in good condition and should not exceed 17,000 C.U.P." It lists a load having 34 gr 3031 under a 420 gr cast as having 11,000 C.U.P.

Lyman's #4 CBH states; "The following data is held to a pressure level 18,000 CUP (or PSI, as the 45-70 is one of the few cartridges that have the same CUP and PSI levels) for use in the Model 1873 Springfield trapdoor." Lyman #4 lists 11,100 C.U.P. for 34 gr 3031 under a 405 gr cast bullet. So where did Lyman come up with 18,000 CUP/PSI for both?
None of Lyman's pressure measurements for the M1873 TD exceed 18,000 CUP.........no where near the 28,000 CUP/PSI SAAMI gives for both........


Very confusing, isn't it?

Larry Gibson

Post Script; Let me just say this; comparable loads listed as 18,000 CUP give close to 28,000 PSI measurement when I test with the Oehler M43 using a strain gauge.

[KenH]

The QL programs uses "psi" to indicate pressure - in the instructions it says when entering a new cartridge, be sure to list what pressure units are used, psi CIP, psi SAAMI, or CUP units. I "think" those units are only to indicate max pressure of cartridge and not actually used in calculation - but I am NOT sure.

No, the Dacron filler is not taken into considering in calculations. Would it work to add weight of dacron filler to weight of bullet to have the dacron factored in? OR - would it work differently?

Lyman #3 CBH says; "Loads greater than 15,000 C.U.P. should be used only in Springfields (the so called trapdoor Springfield) in good condition and should not exceed 17,000 C.U.P."

That says loads "greater" than 15,000 CUP, does that mean lighter loads should NOT be used in Trapdoors?

The whole idea of C.U.P units vs PSI is VERY confusing - regardless of what some folks say, I'm not at all sure there is a valid conversion factor to change from one to other. I personally like the idea of the strain gauge method which allows display of not only peak pressure, but how the pressure holds all the way down the barrel. Larry - I really admire your setup and LOVE to read about your tests and results.

Larry - have you personally with your setup had a chance to load up 70 grains of BP behind a 405 grain cast bullet and measure the psi with your strain gauge setup? Does it come close to the SAAMI spec of 28,000 psi (same as 28,000 CUP)?

I'd LOVE to see a whole spreadsheet of test measurements.

Ken H>

[Adam Helmer]

I use a cast boolit in my M1884 Trapdoor rifle and IMR4198. My rifle shot high at 100 yards, so I replaced the front sight with a higher M1903 Springfield sight which printed my 100 yard hits LOW. A morning at the bench with a file and I judiciously reduced the front sight height until my boolit was on point of impact/point of aim at 100 yards. The M1903 front sight is higher and will not allow affixing my bayonet. I can hit what I aim at 100 yards now and the bayonet is in the vault along with the original front sight.

Adam

[Larry Gibson]

Larry as you posted in the link below the 45/70 is the exception .

SAAMI was established in 1923. I don't know when the SAAMI spec for the 45/70 was set but I do find it interesting that per SAAMI 28,000 is the same whether measured in CUP or PSI.

I think that is only pressure CUP and PSI are the same.

http://castboolits.gunloads.com/show...AAMI-pressures9

M-Tecs

I'm still not quite sure why SAAMI has both CUP and PSI at 28,000 listed for the 45-70. I can only speculate that the 28,000 psi figure was obtained from the later smokeless loads that were available for the M1888. However, the 28,000 psi figure is conducive to the pressure measurement of such ammunition and comparable reloads using a peizo-transducer or strain gauge system. According to Lyman CBH #4 loads generating 21,000 to almost 28,000 CUP are up to the SAAMI MAP of 28,000 CUP.......yet these loads are "For use in Winchester M1886 and 1895 Marlin Only"......those loads are definitely too much for use in TDs.

So why the discrepancy with the SAAMI MAP? I don't know.

Larry Gibson

[Larry Gibson]

KenH

Had a reply for you, lost Internet service for a while and lost message. Too much for phone, will post when service is back up.

Larry Gibson

[KenH]

Thanks Larry - I'll be looking forward to your answer when you get a chance.

[Larry Gibson]

KenH

"Larry - have you personally with your setup had a chance to load up 70 grains of BP behind a 405 grain cast bullet and measure the psi with your strain gauge setup? Does it come close to the SAAMI spec of 28,000 psi (same as 28,000 CUP)?"

I was wondering if that was going to be asked; yes I have tested straight 70 gr BP loads under my own 405HB Lee bullets (16-1 alloy) and commercial cast 415 gr (20-1 alloy) lubed with SPG. I used Winchester and Starline cases, Federal 215 primers and 70 gr Goex Cartridge, FFg and Fffg powders. Rounds were loaded in Lee dies (5 die set from Wolfe) with powder pre-compressed. The psi as measured in my Siamese Mauser 45-70 via strain gauge with the Oehler M43 PBL gave MAPs of 18,000 to 22,000.

All the manual max loads for TD level 45-70 loads with several different powders have given M43 measured MAPs of 27,000 to slightly over 28,000 psi(M43). Lyman's CBHs for the same loads give the max CUP at 16,500 to 18,000.......

Lyman also lists CUPs of 21,000 to 28,000 as only being safe in "Winchester Model 1886 and 1895 Marlin only" . Lyman CBH #4 also states that the 45-70 CUP maximum for the TDs is 18,000 because the "45-70 is one of the few cartridges that have the same CUP and PSI levels".......yet SAAMI says it is 28,000.......?

So we must ask the obvious here; if the SAAMI CUP and PSI MAPs are the same at 28,000 why doesn't actual test measurements reflect that? Perhaps SAAMI should revisit their CUP test data? My own testing reveals that 28,000 psi is probably a good psi (peizo-transducer/strain gauge) MAP and was probably based on the availability of smokeless loads that were used in TDs toward the end of the 18th century and into the 19th century. Those same loads would have actually given the 16,500 to 18,000 CUP measurements.

It is blatantly obvious the SAAMI CUP MAP for the 45-70 cartridge is incorrect. I'm of the opinion the SAAMI CUP MAP for the 45-70 should be 18,000 CUP. The SAAMI MAP for peizo-transducer/strain gauge measurement should remain at 28,000 psi. I offer that as an opinion based on the correlation between the actual psi pressures I have measured and the published CUPs of those same loads. I do not have a CUP test fixture so I can not make a direct comparison.

Again, very confusing isn't it?

Larry Gibson

[3Gunnah]

So based on the information provided here. And going back and rechecking the manuals. It looks like other than the overall length, which I have slightly elongated my load should make about 16,850 cup. That should be a perfectly acceptable level for the trapdoor?

[M-Tecs]

If you want to make your head hurt

http://castboolits.gunloads.com/show...65#post3943965

https://www.shootersforum.com/handlo...up-vs-psi.html

http://thehunterslife.com/forums/arc...p?t-13148.html

http://castboolits.gunloads.com/show...pdoor-Strength

https://www.shootingsoftware.com/ftp/psicuparticle2.pdf