Cartridge air space

[oldred]

Probably an elementary question but after searching I still could not find a satisfactory answer, how much air space is too much? While my question is specifically about 45/90 loads it would of course also apply to the far more popular 45/70 round. My usual load is 50 grains of Varget with a 500 grain Lee cast rn and this load has the powder just about touching the base of the bullet in the 45/90 case, H4895 is about the same. These loads are a bit stiff even at the relatively low pressures so I would like to reduce the charge a bit and maybe even use some 400 grain jacketed bullets but this is going to leave some air space, substantially more than my normal load. So the question is what is the opinion of how much air space is ok without using a filler?

[DrCaveman]

I dont think there is a hard-and-fast rule about this issue. I have seen opinions run pretty wide, and my experiences have not been that conclusive either, other than the observation that you should choose your powder with your ultimate velocity/recoil/pressure goals in mind.

Straight off, if you want reduced loads you should switch to faster powders than those you mentioned. Each powder has a range that it likes with each caliber (within reason of course) and if you try to go too low with a slow burning powder I believe you start risking odd pressure spikes or at least incomplete ignition hence erratic rounds.

I have had success so far with Unique in my 45-70, loading 12 gr behind a 405 cast Lee boolit, no filler, case was about 40% full. My plans are to try out Titegroup, since it is reputedly position-insensitive within the case, which if I understand correctly, speaks directly to your concern. My initial research has found that about 10-13 gr TG behind the same boolit will shoot a medium-low load (trapdoor levels). Still needs to be triple checked.

So my best answer to your question is: it depends on the powder, and what sort of sniper-like consistency you are looking for.

Suggestions for experimenting are: Alliant 2400, Unique, Bullseye, Titegroup. Others can probably chime in with more exact recommendations but I have seen good reduced rifle loads developed with each of those powders, with and without filler.

Probably the one thing you dont want to do is take Varget and reduce the load by 40% and expect it to be all peachy. You should probably follow the load manuals' stated minimums for those slow powders.

[Larry Gibson]

oldred

Suggest you read the "sticky" filler; http://www.castboolits.gunloads.com/showthread.php?t=109280

I give some guidlines in my post. Also note I do not generally recommend a filler with jacketed bullets. I'll switch powders to a more suitable one before using a filler with jacketed.

With either 4895 or Varget in either the 45-90 or the 45-70 use a dacron filler when load density (case volume to bottom of seated bullet) is at 80% or less.

Larry Gibson

[oldred]

oldredWith either 4895 or Varget in either the 45-90 or the 45-70 use a dacron filler when load density (case volume to bottom of seated bullet) is at 80% or less.Larry Gibson

That's what I was looking for and also I read that sticky, don't know how I missed it earlier but it's a good read! The reason I chose the Varget and H4895 to use with the 500 grain Lee rn (in the 45/90) was to keep pressures at around 25,000 to 28,000 psi and still fill the case. Since data specific to the 500 grain 45/90 loadings is almost non-existant compared to more popular rounds I used 45/70 data to arrive at my figures but I guess maybe I am a bit unsure of myself because of the variables involved, different bullet types, case length, etc. I would probably switch to a faster powder if the data was out there but I just feel uncomfortable trying new powders without printed data as a guide, maybe as I gain more experience this will not bother me so much. I know 5744 is really popular for the 45/90 loads but I just don't like the air space involved and there are at least two instances of unexplained pressure spikes that stick in my mind whenever I consider using that powder. One was a friend of mine shooting a Browning BPCR, no damage done with that one, and another one involving an original 1886 Winchester that was destroyed. You most likely know about the 1886 incident because it has been on a popular shooting forum for some time now, I don't think they ever did decide what happened.



Maybe I'm just being a bit paranoid but until I gain more understanding of the factors involved I want to, as the old saying goes, "Err on the side of caution".

[bobthenailer]

Although i have a 45/70 not a 45/90 . Ive had excellent results useing 50grains of 4831 powder powder with the Saeco#020 540 gr cast bullet , and yes the powder is very slightly compressed with that charge weight , about 1325 fps from a 30 inch barrel

[Larry Gibson]

My pressure testing of the 45-70 (with M43 Oehler) show 50 gr H4895 under the Lee 500 gr GC'd bullet to give 50,900 psi(M43).

To get under 30,000 psi you need to reduce the H4895 charge to 38 gr or less with a 1 gr dacron filler under a 500 gr bullet.

Larry Gibson

[oldred]

My pressure testing of the 45-70 (with M43 Oehler) show 50 gr H4895 under the Lee 500 gr GC'd bullet to give 50,900 psi(M43).

To get under 30,000 psi you need to reduce the H4895 charge to 38 gr or less with a 1 gr dacron filler under a 500 gr bullet.

Larry Gibson



Wow, now that is an eye opener! I am puzzled by those pressures however because I have an old Hornady manual that lists 46.9 grains of 4895 with a jacketed 500 grain bullet for the 45/70 1886 Winchester. The Hodgdon 45/70 data also shows 55 grains of both Varget and H4895 for the jacketed 400 grain bullet at only 25,000 CUP and 26,500 CUP respectively, I had assumed (dangerous word there) that with the slightly longer case and 5 grains less powder the 100 grain heavier cast bullet should still be less than 30,000 CUP but maybe not! I have fired a bunch of these rounds and there are no indications that pressure is anywhere near 50,000 PSI, cases and primers appear to be the same as the 38 grain 5744 load I used for a few rounds and also the same as the Black Horn 209 load which was supposed to be 28,000 PSI according to the manufacturer. I will not shoot any more of the 50 grain loads in either Varget or H4895 since I am aware that the usual pressure signs are not always so apparent at the pressures these big straight walled cases normally run, thanks for the info looks as if I was pressing my luck there!

[mehavey]

Which Lee Bullet (http://leeprecision.com/bullet-casting/rifle-bullet-molds/bullet-mold-double-cavity) are you using ? (90376?)
and with what final OAL?

Pressures are highly dependent upon that factor in this case.
If you are running the Lee 457-500F (Postell design) at 3.210", then 50gr Varget/H4895 is pushing 23-25,000psi in the 2.4" 45-90 case (and you're only getting 80% burn)

[mehavey]

That said, you do not need (or even want) filler with either IMR4759 or AA5744.
Both give outstandingly consistent ignition/burn/velocities without it.


In my 1895Marlin 18.5" GuideGun/45-70:

- Beartooth 400gr LFNBB over 24.5gr/AA5744 ---> 1,238fps/±6 fps StdDev
- Beartooth 400gr LFNBB over 27.0gr/IMR4759 --> 1,485fps/±10 fps StdDev

[oldred]

Which Lee Bullet (http://leeprecision.com/bullet-casting/rifle-bullet-molds/bullet-mold-double-cavity) are you using ? (90376?)
and with what final OAL?



I am using the Lee 459-500-3R which seats quite deep compared to the Postell type. COL is 3.070 in Stareline brass and CCI standard primers.

[Larry Gibson]

Wow, now that is an eye opener! I am puzzled by those pressures however because I have an old Hornady manual that lists 46.9 grains of 4895 with a jacketed 500 grain bullet for the 45/70 1886 Winchester. The Hodgdon 45/70 data also shows 55 grains of both Varget and H4895 for the jacketed 400 grain bullet at only 25,000 CUP and 26,500 CUP respectively, I had assumed (dangerous word there) that with the slightly longer case and 5 grains less powder the 100 grain heavier cast bullet should still be less than 30,000 CUP but maybe not! I have fired a bunch of these rounds and there are no indications that pressure is anywhere near 50,000 PSI, cases and primers appear to be the same as the 38 grain 5744 load I used for a few rounds and also the same as the Black Horn 209 load which was supposed to be 28,000 PSI according to the manufacturer. I will not shoot any more of the 50 grain loads in either Varget or H4895 since I am aware that the usual pressure signs are not always so apparent at the pressures these big straight walled cases normally run, thanks for the info looks as if I was pressing my luck there!


Older "books" and even a lot of still used data have "psi" based on C.U.P. (copper crusher pressure). Those pressures are now listed in manuals as CUP's. "Psi" mentioned in newer manuals is now conidered that obtained from piezo transducers and strain gauges. Thus the 50,900 psi(M43) I measured is closer to the older psi of the CUP method. However, there is no direct correlation between CUP and "psi" measurements. Most modern measurements are in "psi" if piezo transducer or strain gauges are used and "CUP" if the copper crusher method is used. There is usually a notation as to which method is used.

For your 45-90 you might find load data for cast bullets in the 458W to better than correlating from 45-70 data.

Larry Gibson

[frnkeore]

Quick Load in 45/70 gives 28,729 psi for 50 gr H4895. I used a 500 gr 1.25 long bullet and a OA length of 3.07. If the bullet where 1.375 long, it would be 32,547.

Lyman also has listed 53.1 with a 500 gr jacketed bullet, OAL of 2.93. Pressure was 39,000 CUP so, I can't see where 50 gr would be anymore than the QL results.

Frank

[mehavey]

I am using the Lee 459-500-3R which seats quite deep compared to the Postell type. COL is 3.070 in Starline brass and CCI standard primers.Then QuickLoad predicts ~32,000psi ... in agreement with FRNKEORE above.

If you are considering a milder load, I again recommend a 400gr (GC or PB/your choice) and either AA5744 or IMR4759 -- no filler.

[oldred]

Then QuickLoad predicts ~32,000psi ... in agreement with FRNKEORE above.

If you are considering a milder load, I again recommend a 400gr (GC or PB/your choice) and either AA5744 or IMR4759 -- no filler.

Dang, I guess my "assumption" was not close enough! Like I said I was really concerned because too many variables were involved but that seating depth makes a much bigger difference than I had imagined. 32,000 PSI is not all that much of a mis-calculation but it's 4,000 PSI above what I had set as my limit so I will pull the rounds I already have loaded and I will not shoot any more of these. The 38 grain load of 5744 was probably a much better choice but given the seating depth of the bullet I am using is it possible I may still be exceeding the 28,000 PSI limit?

Thanks guys, this was not what I wanted to hear but it certainly is what I needed to hear and that's far more important!




:EDIT: That was supposed to be 32 grains of 5744 not 38!!!!! Don't know what I was thinking but I also said 38 grains earlier when I meant 32 both times.

[Larry Gibson]

I don't know about Quickload as I've not run it. However, here is the Oehler M43 actual psi test. Several tests run before and after this one with nothing out of ordinary or any anomolies. The velocity and psi are in line with other sources.

Larry Gibson

[oldred]

Larry I can't get that chart to re-size, it comes up the same size and is too small to read. No matter however I take your word for it and when I said I was puzzled at the pressures you came up with I in no way meant I was doubtful. I have taken the info you provided very seriously and the 50 grain Varget/H4895 loads I had were all pulled last night and I will not shoot any more of them, I am going to reload the 50 grain charges (Varget) with Remington 405 grain JSP bullets which according to Hodgdons data would be less than 25,000 CUP in the 45/70 case so it should be even less than that in the 45/90 case?

[robroy]

I'll take measured pressure over predictions any day.:brokenima

[frnkeore]

I'll take measured pressure over predictions any day.:brokenima

Regarding the M43 test results, I don't believe they can apply here. They are for a 45/70 to begin with, OAL isn't given and they don't agree with published data from known sources.

The disagreement between the M43 and other published sources needs to be worked out before they can be taken seriously. There is at least one other cartridge that the M43 doesn't correlate to published data also.

If you study what publish data there is out there, I think you'll find in this case that the QL figures are very close to actual published results.

Frank

[Doc Highwall]

The burn rate for the powder in Quick Load has to be adjusted to match your velocity readings to be useful. I learned this using AA5744 powder in my 308 and this affects pressures. How do you know if the lot of powder you bought is on the fast side or the slow side + or - 10%. Only by adjusting the BA rate to match your velocity can you gat a some what close reading of pressures and a strain gage is a lot more exact when it come to real world pressure readings in your gun.

I have a pressure trace attached to my 308 Win, that I am using right now and it will open your eyes as to what is happening when you pull the trigger.

I have seen secondary pressure spikes near the muzzle with a load that only had 15 fps extreme spread, or a .5 millisecond delay after the primer went off with over 5000 psi and still had less then 20 fps extreme spread that resulted in a flyer.

I have said it before, using low extreme spreads over a chronograph as a indicator of a good load should be taken with a grain of salt. It does not take into consideration barrel vibrations.

The target in the end is your most reliable piece of equipment when it come to accuracy.

[Larry Gibson]

Regarding the M43 test results, I don't believe they can apply here. They are for a 45/70 to begin with, OAL isn't given and they don't agree with published data from known sources.

The disagreement between the M43 and other published sources needs to be worked out before they can be taken seriously. There is at least one other cartridge that the M43 doesn't correlate to published data also.

If you study what publish data there is out there, I think you'll find in this case that the QL figures are very close to actual published results.

Frank

Have to disagree frank, the M43 is quite reliable with the 45-70 and with all other cartridges where the strain gauge is in the proper place and properly affixed. My data with that load and many other loads correlates to a lot of published data taken with piezo transducers and strain gauges.

The OAL is known and listed not only in my M43 test but with other test data that is available.

Pray tell, what is the "other cartridge"?

Larry Gibson

[frnkeore]

As I pointed out in this thread,

http://castboolits.gunloads.com/showthread.php?t=157542&highlight=psi+cup&page=2

Post #39, your M43 or maybe all M43's do not correlate to Lymam's testing. It seems that they have done extensive test in this area.

As posted in another responce, your data is to small to read and to smal to see the OAL figure. A lot of 45/70 data based on <2.6, the OP has a 45/90 and his OAL is 3.07 and that is the figure that needs to be used. I have found Hodgdon published 45/70 loads with a 400 gr jacketed bullet, 2.54 OAL with 55.0 gr H4895 and only 26,500 cup.

Frank

[Larry Gibson]

frank

Correlating PSI and CUP
Denton Bramwell

That article and method has been debunked so many times it's pathetic. Any ballistician will tell you there is no correlation between CUP and PSI measurements. That's why the two different methods are listed separately by Lyman and all other current manuals.

Of course my testing does not "correlate" to Lyman's testing. Lyman's test data for the 45-70 CBH #4 and LRH #49) are measured with C.U.P. (you might want to read the "data"). My measurements are with a strain gauge which gives measurements in "psi". Look in Lyman's manual and you will see they use both methods for some cartridges. The reason is they do not "re-shoot" all loads for a newer manual but use previously tested data for the new manual. The "psi" loads listed are for newer cartridges or new powders or bullets for older cartridges. The 45-70 has been around a long time and Lyman's C.U.P. listed pressures run consistent through the last several manuals where the pressure has been listed.

Look at Lyman's C.U.P. data for the TD level loads; All the max loads are under the 20,000 CUP MAP that is now the accepted max for TD level loads. The PSI MAP for piezo-transducer/strain gauge is 28,000. There is a difference. Oldred (the OP) quoted Hodgdon data in CUP but the referenced “PSI” from other data. He had been using 38 gr 5744 under a 500 gr bullet? 25 – 28 gr 5744 under a 500 - 535 gr cast bullet will be about max psi of 28,000 for a TD load. The confusion was using C.U.P. abd “SPI” data interchangeably. Doing that is not good and one should not attempt to "correlate" C.U.P. data into "PSI" data. Oldred does not say what rifle (or I've missed it) h is using either which further exasperates the problem here. However, he is interested in reducing the load. My suggestion for H4895 and the Dacron filler sill stands regardless.

Larry Gibson

[oldred]

Larry if you go back and check my posts you may notice I corrected a typo a couple of days ago, I did indeed say I was using 38 grains of 5744 in two different posts but I was going from memory for the few loads I shot from about a year ago and that was actually supposed to be 32 grains to which I made the correction. It does not matter however since apparently even the 32 grains is too high and the fact there seems to be a bit of confusion about this powder is just one more reason I decided not to use it. For instance 28 to 32 grains is commonly stated as a good load for the 500 grain 45/90 but Lyman gives a 40 grain charge for this loading! I could be wrong about the starting load since I don't have the data in front of me right now but I think their starting load is 38 grains, but don't hold me to that one, the 40 grain load however I am sure of. Another thing I am sure of is that 40 grains of 5744 under a 500 grain cast bullet is waaaay too much even if they seem to think it is ok. At this point I am going to just shoot FFG black powder (the real stuff) until I better my education on choosing the right smokeless, this is a custom built Highwall that was tested to Ruger no.1 pressures so I should have been safe enough but the fact remains the loads I thought were fairly low pressure were apparently well above the 28,000 PSI limit I had chosen, this limit was because that seems to be the top of level 2 (lever action) for the 45/70-90.


About the CUP vs PSI.

This has been confusing for me and I am all too aware that they can not be used interchangeably, I used CUP when the numbers I quoted were given in CUP and PSI when the data was listed that way. Hodgdon gave the Varget and H4895 in CUP but the Blackhorn data I mentioned was in PSI, I wish they would get their act together and use one or the other!

[Larry Gibson]

oldred

What rifle(s)?

Much "better" with 32 gr as mentioned but if for TD level loads its still high. 45-90's are in stronger actions which explains most of the difference beside the small increase i capacity. Lyman tops out at 28 gr 5744 in the 45-70 for TD level loads under both the 500 and 535 gr cast.

Hopefully all will eventually switch to piezo-transducer and/or strain gauge in the futere and drop the C.U.P. pressure measurements.....it sure does cause a lot of confusion.

Larry Gibson

[oldred]

oldred

What rifle(s)?Larry Gibson


As I mentioned it's a custom built Highwall and the receiver and barrel are both 4140, the barrel being a heavy octagon machined from a Green Mountain raw blank and the receiver was machined from a block of 4140HT instead of a casting. This rifle was proof tested with Hodgdon 45/70 max loads for a ruger no.1 (yep I shot 45/70 rounds in it for the 4 proof test shots). I think there may have been a slight drop in the published pressure due to the long freebore resulting from using the short 45/70 case in the 45/90 chamber but I doubt it would be very much, in any case these were for proof firing (remotely) ONLY and I would never consider using loads that heavy or anywhere near that heavy! I feel that given the fact this rifle is probably over-built and proofed to the levels it was it should be perfectly safe at the 28,000 PSI limit I have set for it and probably even higher but I have no intention of going any higher. My original aim when I started this thread was to reduce my load a bit but at this point my goal has changed to determining the best powder to replace the mis-judged loads I was shooting. I really like that 500 grain Lee and it does a good job for me in this rifle but apparently I was using the wrong powder for the job so as not to exceed my pressure limits. What I need now is to choose another powder that will reliably function at these pressure levels so I guess maybe I will give 5744 another look, not my first choice however.

[oldred]

Ok, I E-Mailed Accurate Arms and presented the problem to them complete with all the info, 2.4" case, 500 grain Lee 459-500-3R seated to a COL of 3.070 with a 28,000 PSI max pressure limit. They sent this info,

Accurate -- 5744®.

Bullet weight: 500 grains.

Start load: 29.0 grains (1225 – 1265 Fps)

Maximum load: 32.5 grains (1350 – 1450 Fps).


Accurate -- 2015®.


Bullet weight: 500 grains.

Start load: 38.0 grains (1400 – 1500 Fps)

Maximum load: 43.0 grains (1550 – 1650 Fps).


Accurate -- 4064®.

Bullet weight: 500 grains.

Start load: 45.0 grains (1500 – 1600 Fps)

Maximum load: 50.0 grains (1650 – 1750 Fps).


Accurate -- 2495®.

Bullet weight: 500 grains.

Start load: 42.0 grains (1500 – 1600 Fps)

Maximum load: 46.0 grains (1650 – 1750 Fps).


Info for the 45/90 is REALLY hard to find on the net but I now have this to work with and hopefully maybe someone else can benefit.



Also a couple of other E-Mails pretty much confirmed that the 50 grains of Varget in this round and configuration is running about 32,000 PSI. While in this particular situation the pressure is still well under the rifle's tested pressure it is still much higher than I had estimated based on the data I could find mostly on the 45/70 case, the major flaw seems to be that although I was basing this on 500 grain cast bullet data I underestimated how much pressure difference that the deeper seating bullet would cause. I guess it's mistakes like this that can lead to serious problems so I sure appreciate the info you guys gave me, it has been a real learning experience for me!

[Larry Gibson]

Oldred

Those loads from AA correlate well with what should be loads within the 28,000 psi you want based on my testing the same powders in the 45-70.

Larry Gibson

[frnkeore]

Larry says, regarding his M43 data sheet,

"The OAL is known and listed not only in my M43 test but with other test data that is available."

Since you didn't give the actual OAL when I asked for it, I enlarged your thumb nail results and it looks like your OAL is 2.7?, not anywhere near (approx .300 short) the OP's posted info of 3.07. The OAL is much more important for a straight case. Shorter OAL will raise pressures VERY quickly in straight cases. The loading data you gave for H4895 was much like posting 357 Mag data when asked for 357 Max data.

In a reverse stituation that would be very, very dangerous.

Frank

[Larry Gibson]

Frank

The OP was correlating psi's from the 45-70 to the 45-90 (While my question is specifically about 45/90 loads). My test was with the 45-70, thus the same loads will give less psi in the 45-90 all other components being equal. Thus the "reverse" would not be the case and the information I gave would not be "dangerous". We all appreciate your concern though.


You did not “ask for” the oal, you simply made a statement that it was too small to read. Should you ask a question of me please use a question sentence format and not a statement format and follow the question with a “?”, please. This will avoid some amount of confusion for you in interpreting what I say, perhaps.

Have you read the thread; http://www.castboolits.gunloads.com/showthread.php?t=166088 yet?

There is no need to :hijack: this thread, is there?

Larry Gibson

[frnkeore]

I made a statement that the OAL wasn't given (readable), you replied with a misleading statement,

"The OAL is known and listed not only in my M43 test but with other test data that is available."

It can't be listed if it can't be read.

There is no way that you can predict the pressure with your M43 , only that it will be less and there is no of knowing how much less. This is where a program like QL can be extremely useful.

Frank

[Larry Gibson]

There is no way that you can predict the pressure with your M43 , only that it will be less and there is no of knowing how much less. This is where a program like QL can be extremely useful.

If you say so frank, I'm sure you know more than Dr. Oehler. It does appear the OP could read it and understood it though.

BTW; can you tell us which ammunition manufacturers use QL? Which ones use one of Dr Oehler's strain gauge models? If you can provide an answer to those two questions (or even if you chose to not answer) we'll just let it end there, ok?

Larry Gibson