Home Forums Reloading Big Game Rifles Chronograph - the great truth serum

I agree with Blain's point about the chronograph... it, pressure-tested data and a conservative nature our our best resources.

What are everyon'e thought's about brass quality, ie "soft" brass?

Recently, in playing with some WW brass in my 338 WM I notice the ocassional ejector cut-out mark (M70) showing on the case head... that with book loads that are producing the velocity that should be expected. Soft brass? I hate stuff like that...

Though I hate to say this here, I have seen instances of where I did get ejector marks and or sticky bolt lift that were not associated with pressure. When the velocity is low and the powder charge is on the lower end of the recommend range, pressue may not be the cause. I have seen rough chambers and very soft brass be the cause. However, you really have to be sure before ignoring conventional pressue signs.



BTW, 4-5 years ago Stan Watson published a loading manual for the 30-06 that included extensive pressure testing. He found things like:



- Conventional pressue indicators are not reliable

- Hogdgdon Extreme blend powders really are resistant to temperatures

- 4th Edition Sierra Data's loads generated way less pressure and velocity than advertised



Blaine

Charlie - Heck, no problem from me (it's Hondo's thread anyway <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />). I'm just intrigued waiting for your results.

R-WEST

In load development for the 6.5x284, I ran into this. Norma 6.5x284 cases were very consistent and very easy to size but are softer than necked down WW 284 brass. The Norma brass and the WW gave very similar velocities with the same loads but the Norma showed some ejector marks where the WW didn't. Primers looked identical. It's too bad because the Norma was much more concentric. The WW after necking down, needed quite a bit of neck turning to get concentric.

JimF

Ringman:



That situation is pretty typical and represents the crux of the problem that we all have....we just don't know!
The point that several of us are making is that printed data plus a Chronograph are the only tools you have to answer your question.

So......the only factory tested data that I have seen using 7828 with the Nosler bullet is as follows.

Dupont lists a Maximum of 79.5 gr. of IMR 7828/3335 fps @ 62.1K PSI with the 140 Btip (24" bbl.)

Nosler Lists a Maximum of 77.5 gr. of IMR 7828/3355 fps. Pressure not stated but load is listed as Max. (26" bbl) Corrected for barrel length...probably 3300 in a 24" I think that Nosler uses 63K as absolute max. Whether this load is all the way there or not is a (??)

Your load is 2.5 gr, over Dupont and 4.5 gr. over Nosler and reports a velocity of 125-150 fps greater than either. The tools and data available would suggest pressures well over 65K. It's up to you to decide if that is safe or not.

BTW: Didja ever order that 28" bbl. ultralite 7 STW from Christiansen?

JimF

Ringman-Remingtons 7mmstw factory loads are listed at 3350fps and it is well known that remington is very conservative with their 7mmstw loads and weatherby loads among others.Hodgdons manual lists 3490 fps with 140gr bullets and 80gr of imr7828.This is only .5 gr more than duponts load yet it produces 155 fps more velocity.This hodgdons load is identical to my own load and the velocity splits the difference between what my two guns produce with it.The original load used by Layne simpson in developing the 7mmstw was 83gr of imr 7828 producing 3500fps with 140gr ballistic tips.Add in the fact that duponts load with two grains of extra powder puts out 20fps less than noslers load.Sure a lot of contradicting data out there?Who is right ?Perhaps the theory of a given load producing a given vellocity at a given pressure has some large holes in it.

The principle is intact. Bullet manufacturer's actually chrono their loads and prressure test many of them. Again, they are the ones who are usually right.

Most loaded ammo ballistics are computed, not actually measured. I am not sure about the powder companies' data, but I have always been fairly close to the bullet maker's data in terms of velocity.

When it comes to the loads developed by Simpson, who knows what pressures he had? Strain gauges were not readily available until recently. Many of the old wildcat loads were very hot. I'm sure he didn't get any of the typical pressure signs, but we now know those signs are not reliable pressure indicators.

Now, no one here is suggesting that all rifles will shoot the same loads identically. However, 155 fps is well withing the range of normal deviation for bullets travelling 3400 fps. It is less than a 5% variance. I have seen this much variation with certain types of factory ammo in the same box.

What I am trying to get across here is there is no ballistic free lunch. It takes a certain pressure over a certain amount of time to accelerate a given bullet to a given velocity in a given length barrel. The variations are much less than we'd all like to think. Add to that the absolute unreliability of conventional brass reading techniques for determining pressure, and aside from a starin gauge (which is accurate to what, +/- 5%), the chrono is our best pressure tool. When you reach the point where the velocities start to increase out of proportion to the powder load increase, you are at the max--maybe even past it.

If you want, check out www.reloadingpro.com for certain observations pertinent to this subject. Especially note what I have under Measuring Pressure. I'll have something more to say on this subject in a couple of days after those of you who want have had a chance to check out the information on my website.

Here is an interesting perspective on the subject of pressures from the previously mentioned article by John Barsness. It happens that this article uses a 7 STW as one example. I'm sure there are others that are equally dramatic. The article starts with a description of a handloader who is a bit of a hotrodder and who regularly shot loads of well beyond reasonable velocity expectations. Eventually, he blew up a rifle with a load that he thought was safe as he had used it hundreds of times. (caliber and load obviously not specified). Following are excerpts from farther along in this excellent article.

"Modern bolt actions can withstand thousands of rounds at normal pressures of 60-65K PSI. If we start using "apparently" safe loads that average 70K PSI, the action will work fine - for awhile. But, eventually, metal fatigue takes it's toll and the action comes apart as it did for.....(the subject)."

"When the 7mm STW was still wild, (wildcat) many users claimed well over 3,500 fps for 140 gr. bullets with "loads that appear completely safe." When factories started testing these loads in pressure barrels, however, they found many produced over 70,000 PSI. This why even the fastest loading-manual recipies for the STW barely reach 3,400 fps,........"***

John Barnsness may not be the world's foremost authority on reloading, pressures, or the 7mm STW. Nevertheless, he knows one hell of a lot more than me. I respect his judgements and procedures and would personally consider his position on these subjects to be fairly definitive. My own thinking on this subject has gradually altered over several years to follow more along the conservative procedures that he generally espouses.

If one chooses to follow a different path, it's his choice and ultimately his risk.

I'll mention again, that I'm not intending to decry the STW, or it's fans. I use it in as an example within the context of the discussion of pressures and the Chrony and loading practices in general.

***Quotes.....Handloader # 219 "Pressure Guessing" by John Barsness.

JimF

John B's experience with pressure testing are similar to Stan Watson's and I'm sure Charlie Sisk will find much of the same thing.

BTW, did you check out Stan's website?

Jimf, I called the company which makes the barrels for Black Star. It is Walther or something like that. The fellow gave me a bad report on the Christensen barrels they sent to them.

I ordered a 7 STW from Brown Precision. It will have a nine twist #4 28"Shillen with an Answer Products brake. Mark told me he can keep the weight at seven pounds with my 3 - 15X Sightron II in the Burris Signature rings. I am one of those rediculous customers who told him if he can get the Remington trigger to two pounds, fine. If not, replace it.

Lets start with a quote by barsness

"

This why even the fastest loading-manual recipies for the

STW barely reach 3,400 fps,........"*



First of all I can prove this statement wrong by referring to hodgdons loading manual 26th edition page 308.

load #1 h-1000 -82gr-3497fps

load#2 -imr7828-80gr-3490fps

load#3-r-22-79gr-3483fps



I for one will believe hodgdons before believing barsness.After all hodgdons should know their own product.After all they are experts in the field while Barsness is merely a writer.



A quick check of the alliant website reveals that they do not show a 140 gr load for the 7mmstw.But they do list a 7mmstw load for the 160gr partition using 79gr of r-25.The velocity is 3300fps with a pressure of 62,000psi which is well below the design limit for the 7mmstw of 65,000psi.If you check the nosler table they list a maximum of just over 3100fps for the 160gr partition.Again you have contradiction.Now nosler is supposed to know their bullet but then again alliant should know their powder.



Well then since 3400fps seems to be the number barsness and others like to use for a safe load for the 140gr 7mmstw load lets just add 155fps to 3400fps to arrive at 3555fps and since according to AFP:



"155 fps is well withing the range of normal deviation for bullets travelling 3400 fps"



As long as your 140gr loads for the 7mmstw loads do not chronograph above 3555fps you need not worry about having a load that is operating at excessive pressure since as AFP asures us:



".I think a chrono is the most reliable pressure measuring tool most of us handloaders have"



There since I combined my own thoughts with those of AFP and Barsness as well as the resources of hodgdon,alliant and nosler and everybody is represented we should all be content.

PLEASE do not take stubblejumper's last post literally.

Do NOT exceed any maximums in any reloading manual. Please start at 10% below max and move up incrementally. Handoading is serious business, and involves some risk. Please be prudent, and refer to various reloading manuals ONLY in determining proper powders and charges thereof.

This website is NOT an appropriate source for determining load data. Do NOT rely on data posted here as a basis for handloading any ammunition.

Rick

RickBin -You are precisely right .Handloading is a serious business and can have serious consequences if you are not aware of the hazards and how to control them.Use the published starter loads and work up watching out for any pressure signs that may occur.Do not assume that any published maximum loads are safe in your gun and do not believe that because a chronograph reading agrees with a published velocity that the load is safe in your gun.Even the various manuals published by the bullet and powder companies often contradict each other and they have much more data and equipment to assist them than the handloader does.Accordingly it is not reasonable that we should expect to know more about handloading and ballistics than these companies.

My last post was made to show that as much as people interpret data to support their beliefs and twist it to suit their purpose, reloading is not as cut and dried as many would like it to be.Making assumptions can result in unexpected surprises that can be damaging to equipment and dangerous to the operator. If however you use good judgement and use the proper equipment only for the uses that their manufacturers intended ,reloading can be very interesting and rewarding.

Assuming because you see no conventional pressure signs that your load is safe is a dangerous assumption. But it is very likely that a chrongraphed load that equals bullet maker data does so at similar pressures.

A big concern is believing your gun is exceeding published velocites at safe pressures.

Look for the velocity spike with your chronograph, and back down a bit from that. Chances are, you will see that before you see any other pressure sign.

Rely on bullet maker data over powder company data.

This is way more cut and dried that at least one poster here wants to believe <img src="/ubbthreads/images/graemlins/tongue.gif" alt="" />

AFP,

We meet again. The other day I counted up the wildcats I have or have made. There are an even dozen. Only one had listings in relaoding manuals. It was the 7-.300 Weatherby. How does one proceed with a wildcat without published data?

Interesting citation. Although you don't cite a bullet weight, if you look at the 27th edition Hodgdon manual you will indeed find only one load exceeding 3400 fps -- and that is 82.0 gr. of H1000 behind a 120-gr. Sierra. Their fastest 140-gr. load is 3284 fps. Makes a good case for using the freshest available data.



Not sure which Nosler data you're looking at -- their current manual doesn't show any 7mm STW loads with RL-25. They do show RL-22 but Alliant doesn't. So there aren't any comparable loads listed for that bullet.

John

John fraser-The 160gr loads did use different alliant powders.The point with the 160gr loads was that nosler could not obtain much more than 3100fps with any of their loads yet alliant could obtain 3300fps with the same bullet with safe pressures.200 fps is a huge difference at this velocity which again shows that even the companies producing loading manuals show very large differences in the potential velocity of the same cartridge using the same bullet.It also suggests that if alliant can safely produce 200fps more out of the same bullet perhaps they know something that nosler doesn't.After all nosler was able to produce more velocity with 140gr loads out of the 7mmremmag than with the 7mmweatherby mag in spite of the weatherby's larger case capacity.They also produced more velocity using r-22 with 140gr bullets out of the 7mmremmag than with the same powder and bullet in the 7mmstw.In fact nosler was barely able to acheive 50fps more velocity out of a 140gr bullet with the 7mmstw than with the 7mmrem mag with any load in spite of the 7mmstw's 2" longer barrel and much larger case capacity. This is contrary to every other data or website that I can locate.Common sense would tell you that this shows a problem with their data.

All data was taken from the nosler reloading manual number 4

Stubblejumper, I really scratched my head when I saw that Nosler manual data on the 7 Remmag vs. 7STW. It just doesn't add up--where did all those cubic inches go? Sort of made me question Nosler's methodology, and reminded me why you need at least 6 manuals to do proper sanity checks on data <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

Steve-The strange nosler data for the 7mmstw and the weatherby cartridges is one reason that I invested in several other manuals to use as a reference for these cartridges.As you just stated the nosler data just doesn't add up.