Cream of Wheat filler in the Trapdoor

[mooman76]

Even so called nosensitive powders shoot more consistant when positioned at the base or back of the complete round.

[Larry Gibson]

I conducted the test today. The rifle is a Siamese Mauser I converted to 45-70 back in the ‘70s. It has a 24” Star Barrel and is steel bedded in a Fajen Stock. The scope is a 2.5X Leupold with a heavy duplex reticle. I built the rifle for going into pole patches after elk. The cross hairs cove close to 4” at 100 yards so really fine aiming is difficult. However I can consistently shoot close to 2 MOA with it. The M43 Oehler was attached and set up. The targets were at 100 yards and I was shooting off a rest on a very, very solid cement benchrest. There was a slight wind of 2-3 mph coming out of 10-11 o’clock. The test went without any hitches. I have the targets and the Oehler printout data, if you want to see it let me know and I’ll scan/photo and post. The COW filler for the 5744 load was measured with a Lee 108 dipper (my dippers are the old one and not in CCs.), for the 3031 load it was measured with a 069 dipper. The COW was about 1/8” below the case mouth with both and was compressed seating the bullet.

Data is listed as;

Load wad/filler FPS/SD/ES psi(M43) in thousands, hundreds/SD/ES(0’s left off) group size; ctc

Notes are listed with loads where appropriate.

Control load was the standard load I use in my H&R Officers Model TD with this bullet. It is a smokeless duplication of the service rifle load of 1873 with the Midway cast bullet. Data is’

36-milsurp 4895......¾ Dacron filler.....1391/15/38......22,4/1,2/4.3......2.3” for 10 shots
Note; the above is an accurate load in the OM and also in this rifle. This was a 10 shot group. The following test groups are 5 shots except where noted.

25-5744......no filler.............................1166/4/13 ..............18,4/7/1,9........2.1”
25-5744....... ¾ Dacron filler .............. 1226/4/13.......... 22,4/9/2,1......... 1.45”
25-5744......... 2.5 gr Dacron compressed........ 1245/5/10...... 22,3/6/1,5...... 2.3”
25-5744....... ¾ Dacron wad + COW filler........ 1288/5/14...... 27,1/9/2,5....... 3.7”

35-3031...... no filler.................... 941/21/45............ 13,6/7/1.5.......... 3”
Note; this is for 4 shots with no effort made to “position” the powder. I thought this was pretty low data and was suspecting if I had 3031 or 4891. On the 5th shot I elevated the barrel and that shot gave 1223 fps and hit 9” higher. I then shot the next 5 shots elevating the barrel after loading before each shot.

35-3031........ no filler/muzzle elevated............ 1203/31/71........ 18,4/1,5/3,6.......... 3”
35-3031........ ¾ Dacron filler................. 1230/18/51.......... 19,1/5/1,2 ......... 2.1”
35-3031......... ¾ Dacron wad + COW filler ................... 1179/9/26............ 19,0/6/1,4....... 3.5”

You all can draw your own conclusions. I’ll only note that while the SD & ES were not the smallest the control group and the other test groups where only a ¾ Dacron filler were used gave the best accuracy. Thanks guys for asking me to conduct this test, it was informative to me and I look forward to your discussion/comments.

Larry Gibson

[The Double D]

Define 3/4 dacron?

[Larry Gibson]

3/4 grain piece of it. When used as a filler it is pushed into the case without tamping it down on top of the powder. It is fluffy stuff and fills the air space between powder and bullet base when the bullet is seated.

Larry Gibson

[The Double D]

Thanks Larry, didn't know if you were filling 3/4 of air space or some thing.

[405]

Thanks Larry for taking the time, putting in the effort and resources to test the loads! .... very useful info.

A couple of questions.

1) Any reason you didn't use the "all CoW" filler load? That bolt gun would surely handle higher pressures than any of our TD single shots. I know that some shooters just load powder with lightly compressed CoW on top.

2) The pressures you recorded (for all the 5744 loads) seem high compared to published pressures for comparable loads as listed by Lyman. Any thoughts? The trends appear to track as expected but the base line pressures seem high for the 5744 loads. The velocities however compare well with the published data.

Example: the Lyman data for 405 cast over 26 gr. 5744 (no filler) shows 1189 fps and 12,200 CUP. 12,200 CUP translates way below the 18,400 PSI in your test. I think 12,200 CUP is equivalent to something quite a bit less than 10,000 PSI if my math is working.

No big deal just curious if any ideas about the high recorded pressures.

BTW that 1.45 5shot @ 100 is impressive by any standard!

[longbow]

Interesting report Larry, thanks for that.

I have been using COW filler in .303 British over Unique, IMR 4227, IMR 4198 and IMR 4895 under a Lyman 314299 without gas check resulting in groups about the same size as no filler and boolit with gas check.

Groups are running 1 1/2" to 2" at 50 yards using Enfield No. 5 with stock sights. Not match winning accuracy but a big improvement from the 4" to 6" groups I was getting. Now that I have gotten acceptable groups I will try to do a run them over the chronograph to see how they do.

Is there a reason for using dacron and COW rather than just dacron and just COW? Just curious about the combination is all. One of the reasons I use COW is I am lazy and it pours in like powder ~ no tearing, no tamping, just scoop and pour.

Anyway, thanks for that and I'll see if I can add my results here too. Maybe a week or so though.

Longbow

[felix]

405, it is just the opposite. Piezoelectrics produce an excellent transient response and the devices are quite linear in that response. This is in opposition to copper crushers, which are quite sluggish in any kind of transient force. However, the crushers produce a fine, but well rounded, average peak pressure. When I want a pressure trace, I want a piezo gadget. When I want to measure damaging pressures, I want to see CUP, not the PSI measurement. For example, the latest Marlin lever guns are proofed to 80K PSI, but operated normally 40K CUP. Guns can tolerate a lot of peak pressures provided the peaks are really short in duration. Modern steels, anyway. ... felix

[405]

felix,
Agreed, they are different. The piezo recorded pressure in PSI is a one point peak pressure effect reading while the CUP is a dwell response indirect index measurement of pressure effect.

But, the 25 gr 5744 powder test of 18,400 PSI recorded pressure seems to exceed the published comparable load pressures by both Lyman and Accurate Arms. Lyman's pressures for these loads are listed in CUP so there is room for debate about the validity of the conversion formula between PSI and CUP.

However, AA uses PSI. AA's PSI pressures using 27 gr 5744 under one style 405 cast shows 16,100 PSI and 27.5 gr 5744 under another 405 cast shows 18,000 PSI. AA data also shows 28.5 gr 5744 under a 420 cast at 16,100 PSI.


Here's a compendium of trapdoor recommendations by bullet/powder companies...... makes me scratch my head for sure

Lyman states that trapdoors should not be loaded to pressures beyond 18,000 CUP.

Accurate Arms states that trapdoors should not be loaded to pressures beyond 18,000 PSI.

Hodgdon states that trapdoor loads should not exceed 28,000 CUP.

IMR indicates about a 28,000 CUP max for the trapdoor.

Vihtavuori indicates about 25,000 PSI max for the trapdoor.

Barnes re-states an 1878 US Arsenal max black powder load pressure for the trapdoor of 28,000 PSI. (I didn't know that they had direct PSI measurement capability back then- maybe? dunno).

Hornady seems to indicate about a 25,000 CUP max for the trapdoor

Speer states 28,000 CUP max for the trapdoor

NOTE: corrected the Lyman, AA units of measure typos for their TD max recommendations.

[Larry Gibson]

[QUOTE=405;401344]Thanks Larry for taking the time, putting in the effort and resources to test the loads! .... very useful info.

A couple of questions.

1) Any reason you didn't use the "all CoW" filler load? That bolt gun would surely handle higher pressures than any of our TD single shots. I know that some shooters just load powder with lightly compressed CoW on top.

One good reason; I mentioned I was short of 5744 and I ran out of 5744. If you guys want a repeat or a refinement of this test let me know. I need to get some more 5744 anyways and I can run that test.

2) The pressures you recorded (for all the 5744 loads) seem high compared to published pressures for comparable loads as listed by Lyman. Any thoughts? The trends appear to track as expected but the base line pressures seem high for the 5744 loads. The velocities however compare well with the published data.

Example: the Lyman data for 405 cast over 26 gr. 5744 (no filler) shows 1189 fps and 12,200 CUP. 12,200 CUP translates way below the 18,400 PSI in your test. I think 12,200 CUP is equivalent to something quite a bit less than 10,000 PSI if my math is working.

No big deal just curious if any ideas about the high recorded pressures.

The pressures are in line, it's just that you've got it backward. CUP pressures are always lower than transducer, piezo or strain gauge readings. Some try to make a correlation between CUP and current psi.. It can be done to an extent but is not reliable. Modern MAP and PAP (Maximum Alloable Pressure/Peak Average Pressure) for the 45-70 in a TD is 28,000 psi. The 18,400 psi(M43) is where it was supposed to be with that load. A further example is the 30-06 GVM'T. Under the old psi converted from the crushed cylinders of the CUP system the PAP was listed at 47,000 psi. Under the measuring system the PAP is 60,000 psi when measured with transducers, piezos and strain gauges.

BTW that 1.45 5shot @ 100 is impressive by any standard!

That it is! Photo below. I never should have looked through the spotting scope after the 4th shot....made the 5th shot very difficult!

Larry Gibson

[Larry Gibson]

Interesting report Larry, thanks for that.

Is there a reason for using dacron and COW rather than just dacron and just COW? Just curious about the combination is all. One of the reasons I use COW is I am lazy and it pours in like powder ~ no tearing, no tamping, just scoop and pour.

Anyway, thanks for that and I'll see if I can add my results here too. Maybe a week or so though.

Longbow

It was requested. I ran out of 5744 before I could load just the powder and COW. If some requests further refinement tests I'll include it. Need more 5744 anyhows. Glad you enjoyed the test results.

Larry Gibson

[Larry Gibson]

405

Now you have me looking.....

"Agreed, they are different. The piezo recorded pressure in PSI is a one point peak pressure effect reading while the CUP is a dwell response indirect index measurement of pressure effect."

I believe you also have this one backwards. The piezo records the not only the peak pressure but the time pressure curve. The CUP measures the amount of "crush" done to a copper cylinder based on a given tarage tabel. It measures the peak pressure only.

"But, the 25 gr 5744 powder test of 18,400 PSI recorded pressure seems to exceed the published comparable load pressures by both Lyman and Accurate Arms. Lyman's pressures for these loads are listed in CUP so there is room for debate about the validity of the conversion formula between PSI and CUP.

However, AA uses PSI. AA's PSI pressures using 27 gr 5744 under one style 405 cast shows 16,100 PSI and 27.5 gr 5744 under another 405 cast shows 18,000 PSI. AA data also shows 28.5 gr 5744 under a 420 cast at 16,100 PSI."

Obviously different styles of cast bullets plus the hardness of the alloy among other thisgs effect pressures. As I mentioned in the earlier post trying to do a direct correlation between CUP and current PSI can be misleading. The psi was within limits of industry variation standards. Please do not expect actual test results to agree exactly with published pressures. Like velocities taken of two different strings of the same ammo in the same rifle will disagree so do pressures from any given chamber/barrel system.


"Here's a compendium of trapdoor recommendations by bullet/powder companies...... makes me scratch my head for sure

"Lyman states that trapdoors should not be loaded to pressures beyond 18,000 PSI."

That is probably old Lyman based on CUP, new Lyman says 28,000 psi with the new Lyman #48 listing 18,000 CUP for the TD 45-70 loads.

Accurate Arms states that trapdoors should not be loaded to pressures beyond 18,000 CUP. That is about right for CUP

"Hodgdon states that trapdoor loads should not exceed 28,000 CUP.
IMR indicates about a 28,000 CUP max for the trapdoor."

Yup, that's what Hodgdon says and it sure is enough to make one scratch his head! This is a prime example why I always say that manuals are a guide and not the gospel! 28,000 CUP would be 37-40,000 psi which in definately in Marlin lever action territory.

"Vihtavuori indicates about 25,000 PSI max for the trapdoor."

"Barnes re-states an 1878 US Arsenal max black powder load pressure for the trapdoor of 28,000 PSI. (I didn't know that they had direct PSI measurement capability back then- maybe? dunno)."

That was based on the CUP method with that "psi" made from tarage tables. Arsenals up to the 7.62 NATO used that same CUP system. It was standard for the ammuntion industry and SAAMI still uses it. With the 7.62 NATO the arsenals began using gas piezo-electric transducers placed at the case mouth.

Hornady seems to indicate about a 25,000 CUP max for the trapdoor"
I found Hornady's "these loads did not exceed 25,000 CUP in our pressure barrel" to be interesting.

"Speer states 28,000 CUP max for the trapdoor""

My Speer #11 refernces the 28,000 CUP as for the marlin lever guns and 1886 Winchesters and that is about correct for them.

I've had an interesting time with the M43. I've gauges attached to 21 of my own rifles. I've found old loads that I thought were high pressure weren't. I've also found some of my old favorite loads that I thought were within pressures are actually over pressure. I quickly found my favorite '06 hunting load is running 62, 800 psi(M43)! I'll probably not back that one off in my new M70 as it also uses cartridges with a 65,000 psi PAP. However in my old M98 Mauser which has already devoured a couple thousand of this load I'll probably back it off. Interesting to know though.

Larry Gibson

[Molly]

Fascinating data! I'll have to study on it a bit, but I'm curious what happened to the staged levels of CoW?

> So we'll try 35 gr 3031 with 3/8, 3/4 and 1" of COW, any particular flavor?

Molly

[Larry Gibson]

Fascinating data! I'll have to study on it a bit, but I'm curious what happened to the staged levels of CoW?

> So we'll try 35 gr 3031 with 3/8, 3/4 and 1" of COW, any particular flavor?

Molly

I very quickly found that there was just a little more than 3/8" of space between the dacron wad and the bottom of the seated bullet when using 35 gr of 3031. The 069 Lee dipper of COW (not very much COW BTW?) then filled the case to within 1/4" of the case mouth and the next dipper filled it to the case mouth. The bullet when seated compressed the COW. As I said earlier, I gave up on COW years ago (a lot of years ago!) and probably am not doing this quite like you guys do. I'd be glad to retest or conduct further tests for you guys. I'll obviously need a little more detailed direction in exactly how you want the reloads assembled. I've no problems with that as this test is for you guys so doing it your way is best.

Larry Gibson

[405]

Larry,

You're correct... I fixed my typos in the above post for the Lyman and AA max TD units.... had them reversed... doh!.

Thanks for staying on top of this! I've looked at the data you generated with the current "filler" tests and can see no problem with it. Everything seems to track correctly. The only anomaly I noticed was in the pressures of the 3031 powder with the dacron plus CoW load. May just be an artifact of load technique???

I don't think I'm looking at the comparison between PSI and CUP backwards. The conversion from one unit of measurement to the other may make it seem so tho.

The main reason for staying on this PSI vs CUP thing as the published data compares to your data is that I shoot a lot of old originals and need to make absolutely certain of each load I try. I'm sure many others are in the same boat.

I am familiar with both the copper crusher method and the piezo electric method for determining relative pressure values. Kinda like apples vs oranges in interpretation. Seems like the conversion formula breaks down a little as the pressures drop towards the lower useful threshold of the CUP method. I think that's one reason the LUP method was used for the lower pressure cartridges

Anyway, the accepted conversion formula is PSI = (1.51586 X CUP) - 17902
the statistical reliabiblity of this has been tested at about .93 which is pretty good.... but may start to break down at the lower pressures we're talking about here.

Wish all data was in PSI. Would certainly simplify life as a reloader.

Yes, I understand about running low on 5744. Would still like to see the 25 gr 5744 load with only lightly compressed CoW on top of powder. In addition to the pressure data, it may also shed some light on the case stretching issues as brought up by others.

[Larry Gibson]

405

"Thanks for staying on top of this! I've looked at the data you generated with the current "filler" tests and can see no problem with it. Everything seems to track correctly. The only anomaly I noticed was in the pressures of the 3031 powder with the dacron plus CoW load. May just be an artifact of load technique???"

I've no idea why the velocity was lower as was the pressure than the same load with just dacron. I though you guys would tell me?

"I am familiar with both the copper crusher method and the piezo electric method for determining relative pressure values. Kinda like apples vs oranges in interpretation. Seems like the conversion formula breaks down a little as the pressures drop towards the lower useful threshold of the CUP method. I think that's one reason the LUP method was used for the lower pressure cartridges

Anyway, the accepted conversion formula is PSI = (1.51586 X CUP) - 17902
the statistical reliabiblity of this has been tested at about .93 which is pretty good.... but may start to break down at the lower pressures we're talking about here."

Yes it is like apples and oranges. As Dr. Oehler has written it would be nice if published pressures were also annotted as to the type of measurement it is based on. Since there is some statistical variations in the different methods of psi measurement it would be nice to know.

That is indeed the current accepted correlation formula but as you've noted there are discrepancies. Some are indeed at the bottom but there are also some at the top end. The 93% figure is "statistically good" but it still leaves 7% error. So far we have no way of telling when that "error" will happen until after we shoot it. A 7% error on a 60,000 psi load could mean as much as a 4,200 psi overpressure. Makes me wonder what those blown primers in my younger and dumber reloading days were really pushing for psi! Wonder is all I'll do because I won't go there now as I haven't for some years.

"Wish all data was in PSI. Would certainly simplify life as a reloader."

That it would, that it would!

"Would still like to see the 25 gr 5744 load with only lightly compressed CoW on top of powder. In addition to the pressure data, it may also shed some light on the case stretching issues as brought up by others."

Looks like I need to get some more 5744 and load some up.

Larry Gibson

[The Double D]

Is this powder being used XMP 5744 or AA5744?

[Molly]

I very quickly found that there was just a little more than 3/8" of space between the dacron wad and the bottom of the seated bullet when using 35 gr of 3031. The 069 Lee dipper of COW (not very much COW BTW?) then filled the case to within 1/4" of the case mouth and the next dipper filled it to the case mouth. The bullet when seated compressed the COW. As I said earlier, I gave up on COW years ago (a lot of years ago!) and probably am not doing this quite like you guys do. I'd be glad to retest or conduct further tests for you guys. I'll obviously need a little more detailed direction in exactly how you want the reloads assembled. I've no problems with that as this test is for you guys so doing it your way is best.

Larry Gibson

Larry,

Mis-communications are generally the fault of the speaker for lack of precision in his speech. Mea Culpa. I should have explained that when I measure CoW, it's as loosely poured, with a little shake or a light benchtop tap to settle it.

That said, I was expecting loads where the dacron was pressed down sufficiently to allow the specified volume ('inches') of CoW to be added and contained within the case before the bullet was seated. Seating the bullet would then compress the dacron sufficiently to accomodate the settled volume of CoW. The dacron will then keep the CoW at the base of the bullet, and act as a separator over the powder charge, keeping the CoW and the charge from mixing. In early work, before I realized how little CoW would do the job, if I needed to tamp the dacron down a little more to get all the CoW in the case, so be it: that's what I did. Not according to proper experimental protocols, but still quite effective.

I expected the amount of dacron to be set by sight at the time of loading. As a rule of thumb, when I was loading 45-70, I'd pluck out a wad that would bulk up to the (seated) bullet base with little tamping, and check weigh it. My mesurement of force wasn't too precice: If the dacron would hold up a wood pencil, I figured it was tamped enough to hold up the CoW charge. Then I'd pull similar sized wads of dacron to use as I went along, with only a visual comparison to the first wad, and an occasional check weigh to assure reasonable consistency. It's amazing how uniform the weights can be by such a primitive 'measurement'. It's also amazing how much the dacron can be compressed without affecting results.

FWIW, when I was first starting the CoW work, I did my 45-70 work in a Numrich Rolling Block, which was watched carefully for signs of excessive pressures. I have actually fired some fairly substantial loads of IMR 3031 (enough for recoil to be objectionable in an 18 lb rifle) with CoW poured in to the top of the case, and a 500g cast bullet seated over it, compressing the CoW substantially. While I had no pressure measuring equipment, I know the significance of the pressure ring creeping closer to the head of the case, and I can tell a flattened primer from a normal primer. These loads didn't produce any signs of increased pressures (over comparable loads with no CoW) that I noticed - and yes, I looked for them. My techniques didn't have the sensitivity that yours have, but they were not totally without merit either. That's why I was really interested in the results of various CoW levels.

[The Double D]

Molly,

If I read what you wrote correctly, you are using the dacron as a filler and CoW as a under bullets wad, is that correct?

Interesting concept. Bet it seals better than a card.

[Larry Gibson]

Molly

Ahhhh....soooo....grasshopper now understand! New tests under way. Was using last of 2 jugs of XMP5744...that may well explain difference in reported psi (always going to be a slight difference anyways as previously discussed). Maybe 10-12 days (sorry guys but I've got to go away for 6 days to work) before I report back, ok?

Larry Gibson