Load Development To Determine A Rifle’s Actual “max” Load.

[thebear101]

Max load

I would go with the book, I've learned that Max usually is not accurate, and shell life isn't good and the rifling will probable wear out quick (asame problems that factory loads do to the weatherbys), I had a coulpe of the 300WBYs and about 50 shots, the barrel starts to wear, I rebarreled to 350 Mag, big action for the carterage but shows no wear, (Max in any cal, is not good) be careful!

 

[Zak Smith]

Consider the following points:

Using book data is no guarantee a load will be under max pressure in your rifle. Thus, a reloader needs to understand a spectrum of indicators to develop a load, even if he sticks with book data only. These include the same indicators that USSR has detailed (plus or minus a few). Virtually nobody has pressure equipment other than professional ammunition manufacturers. Barrel to barrel differences mean that load "X" could be well under pressure in gun A but over pressure in gun B. Using a spectrum of indicators and observations to aid in load development is standard practice for reloaders.

-z

 

[GunTech]

Personally, I don't see why so many handloader seem to want to run at the upper edge of safe pressures. If you need the upper end, then it's probably time to look at another cartridge.

I rarely load to max pressure, concentrating on what gives the best groups. If I need more velocity, I go to a bigger case. I like a little wiggle room that allows for things like temperature and other factors. Not everyone shoots at Army Metro.

YMMV

 

[steve4102]

I would go with the book,

What book? The one that has the highest charge weight or the one with the lowest charge weight. Or do you put them all together then take an average. Here is an example of a couple of "the book" max loads using the same components.
300WSM
Win Brass
WLRM Primers
190gr Sierra MatchKing HPBT

Sierra # 5 760 65.2 Max
Lyman 48 760 62.7 Max

Sierra #5 H414 65 Max
Lyman 48 H414 61.0 Max

Sierra #5 XMR 4350 66.0 Max
Lyman 48 XMR 4350 63.5 Max

Sierra #5 MagPro 74.2 Max
Lyman 48 MagPro 75.0+ Max



These manuals are often times all over the place. As you all know it can get confusing at times. If I understand USSR and Zak correctly they are trying to tell you that these manuals are not gospel or recipes. There are just to many variables. By all means use the manuals, but the published load data in these manuals is only part of the puzzle. You need to know what pressure signs look like, measure like and feel like. Ignoring them and going strictly by the book can be a recipe for disaster. I for one like to know were Max is in my rifles. I do not necessarily run there, but I do know where it is.

 

[Afy]

USSR and Zak:

For the benifit of those of us who might not have the experience to read brass for signs of pressure could you please post pictures of discoloration and cratered primers.

Much appreciated....

Am eagerly awaiting my copy of Quickload.

 

[Wildfire]

Steve.

Hey There:
Steve, When talking to Sierra we did not discuss PSI. But if their book claims to not go over the SAAMI limits, how would they know that if they do not do any PSI testing. They may not list the presures but they have to know them.

All of this is kind of goofy any way. We all know right from wrong here. Even USSR does. He is simply stating how he has worked up his loads.

So. He likes them maybe a little on the hot side. I'm OK with that.

I simply stated that reading primers is not the way to test PSI. I am correct..
Looking for Presure signs should be a normal chore when shooting. Even with your normal loads. Brass does wear out.

It would be nice if we could all afford PSI testing equipment. But that may be way off in the future. For now we are stuck with reading primers as am I.
But It is not the best way. I do not know of a better way.

So as I said , reading primers is the only way we have for now. Till something better becomes more affordable.

I am sure most large companies have Lawyers. But useing them for every load they make is probably not the way they do things.
Some companies do cave in to Lawyers, we all know that too. They even stop making certian things because of it. Some of that may be a good thing and some of that may be stupid.

 

[USSR]

Afy,

I'm trying to get an excellent picture from a friend that shows the effect of high pressure on brass. Will post if I get it.

Don

 

[USSR]

The key factor in pressure difference is the make and type of bullet as i see it.

243winxb,

Here is the data compiled by the American Rifleman technical staff regarding the substitution of bullets, brass, and primers on pressure.

Don

 

[USSR]

Afy,

Here you go. The following is reprinted with the permission of my friend Shane. I in NO WAY advocate developing "blue pill" loads such as these, and my only intent is to show the effect of high pressure on brass for the purpose of recognition by handloaders.

Don

I ran a little test with the 30-06, to get a better idea of how excess pressure looks and feels.

I ran five rounds through the rifle, over the chronograph. I started at a known safe load, and increased powder in 1.0 grain increments.

Rem 700
30-06
22.4" Douglas 1/10 twist bbl
Norma brass
208 AMax moly'd
RL-22 powder
CCI 200 primer
3.46" oal (kissing lands)

Listed below are charge, chronographed velocity, QL calc'd pressure (lbs-psi), and indicators.

60gr, 2655 fps, 57K, no indicators
61gr, 2704 fps, 62K, no indicators
62gr, 2759 fps, 66K, slightly stiff bolt, primer cratering, slight shine on case head
63gr, 2797 fps, 70K, stiff bolt, some primer flattening/cratering, shine on case head
64gr, 2845 fps, 74K, stiff bolt, some primer flattening and firing pin pushback. brass flow into ejector, .002" web/rim expansion. Soot between primer and primer pocket indicates gas leakage.

Pic of brass, L to R, 60, 61, 62, 63, 64 grains

 

[.38 Special]

So as I said , reading primers is the only way we have for now. Till something better becomes more affordable.

This is what I disagree with, along with reading brass. These are just not reliable pressure signs -- the only thing you can really learn is that your pressures are high. How high is anybody's guess.

There is a better way, and that way is measuring case heads with a micrometer. This method is not nearly as popular, probably because it takes more effort, knowledge, and skill than just looking at your cases.

 

[steve4102]

But if their book claims to not go over the SAAMI limits, how would they know that if they do not do any PSI testing. They may not list the pressures but they have to know them.

You'll have to ask them. I was told that they do not list pressure because they do not have pressure testing equipment. I was also told that they send out some loads for pressure testing. Key word here is "some". I duno, give em a call and lets us know what's up.

 

[Afy]

Don

Thankyou for the pictures... much easier to see the flattening.

With my .300 WM I see primers pretty much like Case #1 (62 grs)
irrespective of load. Not quite sure what is going on. (Current load is 77 grs of VV N165 with 185 Scenars which is well below the max of 78.7. I suspect its because my OAL is lower than 3.339 listed.)

I will post pictures when I get back home in a couple of weeks...

 

[steve4102]

With my .300 WM I see primers pretty much like Case #1 (62 grs)
irrespective of load. Not quite sure what is going on. (Current load is 77 grs of VV N165 with 185 Scenars which is well below the max of 78.7. I suspect its because my OAL is lower than 3.339 listed.)

I believe you have that backwards. Seating deeper into the case will often times increase pressure not decrease it.
Here is QL calculations for 300WM

Cartridge : .300 Win. Mag.(W)
Bullet : .308, 185, Lapua Scenar GB432 7071
Cartridge O.A.L. L6: 3.339 inch or 84.81 mm
Barrel Length : 24.0 inch or 609.6 mm
Powder : Vihtavuori N165

+00.0 101 77.00 2917 3496 59005 11781 99.7 1.205 ! Near Maximum !
+02.0 103 78.54 2974 3633 62999 11908 99.9 1.170 !DANGEROUS LOAD-DO NOT USE!



Cartridge : .300 Win. Mag.(W)
Bullet : .308, 185, Lapua Scenar GB432 7071
Cartridge O.A.L. L6: 3.300 inch or 83.82 mm
Barrel Length : 24.0 inch or 609.6 mm
Powder : Vihtavuori N165

+00.0 102 77.00 2931 3530 60142 11735 99.7 1.195 ! Near Maximum !
+02.0 104 78.54 2988 3668 64256 11856 99.9 1.160 !DANGEROUS LOAD-DO NOT USE!

As you can see a decrease in COL from 3.339in to 3.300 increased pressure by just over 1K.

 

[Wildfire]

Try again.

Hey there:
As far as PSI goes. NASSA does do testing for Seirra Bullet Co. They make their Ballistics CDs. And that is where they get their ballistic info. Not sure about this but was told other companies use NASSA also. Just who gives NASSA their info I am not sure.

I have been reloading for 30 plus years now and have never heard of measuring the case heads. As a means of checking for PSI. Once the round is fired the case is fire formed and can not expand past that point. Even full length sizing does not get that low on the case to reduce the very bottom of the case head. I do watch for a ring just above the case head that would indicate high PSI or a weak case. Depending on how many times it was fired.

Primer flow is what we have. But can not give us any numbers . Just a visual look at what may appear to be higher PSI.

Bullet seating depth does play a big part in presure. To deep can cause soem PSI problems with certian rounds. A bullet touching the lands will also cause PSI problems and is always advised against in most hand loading manuals.

From the sounds of things here many have their own way of dealing with this issue. I am also sure none of us have the perfect answer.
What ever we do , we should always try to be on the safe side. Which is what I am also sure most of you are trying to do.
Happy loading all.

 

[USSR]

I have been reloading for 30 plus years now and have never heard of measuring the case heads. As a means of checking for PSI. Once the round is fired the case is fire formed and can not expand past that point. Even full length sizing does not get that low on the case to reduce the very bottom of the case head.

Wildfire,

I have read about it, as I have been reading about various aspects of reloading for nearly 50 years, but it is not done as much as it was in years past. You have hit upon it regarding the die not resizing that far down the case, and that is exactly why it works. The brass in the web area being so thick and hard, it takes some serious pressure to expand it there (normal loads don't do it, hence there is no need to resize that portion of the brass), and once expanded, does not spring back quite like the annealed portion of brass does.

Don

 

[NCsmitty]

Interesting thread and information. All my jacketed loads are setup at .010-.020 off the lands regardless of caliber. That's my base criteria and I work my loads from there. Unlike my early years, I rarely venture even near maximum load data, for as we gain knowledge with years we realize most often less is more in the final analysis.

NCsmitty

 

[steve4102]

As far as PSI goes. NASSA does do testing for Sierra Bullet Co. They make their Ballistics CDs. And that is where they get their ballistic info.

You lost me on this one. What "Ballistic CDs" does Sierra market, sell or use that is based on internal ballistics? I may be out of the loop here, but the only Sierra ballistic software that I am aware of is their Infinity CD which it is strictly external. Without internal ballistic capabilities their Infinity is nothing more than a drop chart. No way to calculate pressures with this kind of software. Maybe if they used QuickLoad they would have something to go by. Infinity, No Way.

 

[gtmerkley]

most guns have psi rateings that can be sound if you right the compuny.

 

[Afy]

Steve,

Yes I suspect that the shorter OAL is why I am getting signs of pressure. I do need to seat to a higher OAL.

I dont know why I have been seating to shorter OAL's. But need to rectify this.

 

[Wildfire]

Try this.

Hey again:
Steve, I made no mention of Their program discussing PSI or internal ballistics.

I said "We did not talk about PSI". As far as "quick load" ? I was under the impression from some that it was not all that trustworthy.

USSR, Ok . But best I know the brass sits in the chamber all the way and the head can only expand as far as the chamber walls. Once at that size, then what ? I can not see where measuring the head will tell ya much.
May be I am wrong but I assumed the case head was At that size after firing.
I have read about doing this in the past and blew it off. Even if we did get a size change , what ? still no real numbers . I agree that it would take more PSI to move the brass at that part of the case, But how much more?

 

[steve4102]

Steve, I made no mention of Their program discussing PSI or internal ballistics.

Sorry, maybe I misunderstood your previous post.

As far as PSI goes. NASSA does do testing for Sierra Bullet Co. They make their Ballistics CDs. And that is where they get their ballistic info.

To me this meant that NASSA makes Sierra's Ballistic CD and that is where they(Sierra) gets their ballistic info, from the CD.

 

[USSR]

...best I know the brass sits in the chamber all the way and the head can only expand as far as the chamber walls. Once at that size, then what ?

Wildfire,

As I said, I have never used that method myself, but hopefully somebody who has will chime in with the mechanics of it. What I suspect is, that at normal pressure there is zero expansion of that part of the brass because it is hard and thick. So, at high pressure that part of the brass does expand, and because that part of the case is not annealed, there is no spring back.

Don

 

[Vern Humphrey]

the brass sits in the chamber all the way and the head can only expand as far as the chamber walls. Once at that size, then what ? I can not see where measuring the head will tell ya much.

Actually, the head is not in the chamber -- since there must be room for the extractor. And there is always some slop back and forth -- if there is too much, you have excessive headspace, if not enough, you can't close the bolt on some rounds.

The head is thrust back against the bolt on firing, and there is both room for expansion and pressure to make it expand -- think of it being "squashed" against the bolt.

Of course, you can also get set-back of the bolt lugs, creating more headspace.

 

[Ol` Joe]

http://shootingsoftware.com/ftp/dbramwell july 19 04.pdf

 

[Wildfire]

Mystery for now.

Hey there:
Maybe this is just gona have to be a Mystery for now. My rounds are set at .002" headspace. I guess we could call that "some room to move back"
I don't think my bolt moves very much as they were lapped in where they sit.
But I do understand your point. This is likely true for most standard rifles.

And Steve, I'm hoping I did not miss lead you on the CD thing. I may have missunderstood the whole subject to start with. OPPPs.

PSI is a guessing game for all of us. If some one could prove that measuring the head was a good way of testing for PSI signs I would likely use it. I must say I rarely ever load heavy loads. So that may not be an issue. My .308 PSS has a scope that requires 168 grainer at 2600 FPS. so loading past that defeats any use of that scope. My .223 PSS and other 700s are extremely accurate even at extended ranges with the use of my turrets and the handy little charts on the side of my stocks. So My loads for my rifles have been chiseled in stone for some time now. But I do , do a lot of loading and testing of other rifles for other people. Some want the most they can get from them.

So this has been informative and interesting. And nothing I have said was intended to be any kind of an argument with any of you.

It is intersting though, That for as long as I have been at this I have never heard of measuring the head of a casing like that. Heck , I have been writing a book on the subject for most of 2 years now and this a new one on me.