quote:

Originally posted by michael458:

quote:

That's why it would be such a great demo to actually see and compare!

Talked to Dan and Ken, They are going to do some BBW#13 Solids.........

quote:

Originally posted by michael458:
Good morning Double guys! Sam and I pretty much concluded our "Barrel Strain" test work with the 470 Nitro yesterday. Starting right off we had a broken wire on the strain gage, almost shut us down completely. Sam managed to sort it out and we did get some additional readings on the 500 CEB BBW #13 Solids, copper and brass. While yesterdays readings were a tad higher than some previous readings, they were still equal to the 500 Woodleigh Soft Point--the benchmark bullet. Average of the BBW #13s both brass and copper still below that Benchmark, as are the North Fork Solids as well. In the end we lost the strain gage on the 470 Nitro and Sam will be removing it.

Here are the final results from everything, and later I will post this on the B&M website to replace the existing pdf document with this updated one.

Just FYI and make of it what you will!







Michael

quote:

Originally posted by michael458:
Now that I had a really consistent, good connection I proceeded to go to work. You may take note that on Mondays work the numbers are much lower than on the previous work, for whatever reason, whether it is environmental, electrical, or maybe the way I was holding my mouth at the time, this is the way it is. And the reason if one is comparing a run of bullets, have to do them all at once to get that days comparisons, especially with little built up data over a long period of time, which we do not have, nor does anyone else on the planet! Now in addition to this, with such close numbers on any given test the ranking can change from one test to the next.

For example of this on your data sheet below, take a look at 480 CEB 3 Band at 11653 and the 480 CEB 4 Band at 11695. That is no difference, the next test that could easy turn around in ranking and be the other way around. Even a few hundred PSI difference is nothing to even look at.

Now, I am trying to learn right along with you guys. From all I gather from you double guys is that a Woodleigh Soft is a relatively "DOUBLE SAFE" bullet, and that most all of you are fine with that. So I use that as a "BENCHMARK" bullet. If a bullets strain on the barrels is less than a Woodleigh Soft, and that is consistent, then it must be OK. It strain comes in OVER that Benchmark Bullet, then I think I would look at that with a serious concern. Even with some of the bullets that are very close in test to test, the overall rankings fall pretty much in line with both .458 and the 470s that Sam and I did. I have taken the liberty on one of the data sheets to combine the different tests in 3 different rankings so you can see that some things cross lines regardless of caliber or barrel.

This was Mondays work. Now to continue this I am planning on next week doing a chamber pressure test on all the most important bullets used. With that we will be able to see what bullets have the lowest pressures as well. This data will be added when that is complete. From there, I really don't know where to go with this.



Michael

quote:

Originally posted by michael458:
Sam and I had our work cut out for us yesterday, we spent from around 8 am to around 5:30 pm or 6 on the range. It was a long day to say the least.

When we first started the pressures and barrel strain work we had a short test of fillers, dacron and foam backer rod. Of which there were some major differences in pressures and velocities of those, much to our surprise. Yesterday we investigated this with some different fillers with the same load.

Here are the results of that;




As you can see there are some EXTREME differences with some of these fillers that could drive pressures beyond safe limits and cause lot's of issues for you!

Michael

quote:

Originally posted by Norsk:
High barrel strain with cast bullets.... Does that make sense? What is "barrel strain" a measure of then?

quote:

Originally posted by Norsk:
High barrel strain with cast bullets.... Does that make sense? What is "barrel strain" a measure of then?

quote:

Originally posted by Norsk:
Thank you. So that means it is only relevant as possible indicator of stress that may contribute to the unlikely event of barrel separation? I would belive hardness/surface area/pressure, and most of all type and ammount of gunpowder is responsible for normal barrel wear. Say non banded brass bullets with a steel core in high pressure rounds being worst and soft cast low pressure rounds being easiest on the barrels?

quote:

Originally posted by Norsk:
High barrel strain with cast bullets.... Does that make sense? What is "barrel strain" a measure of then?

quote:

Originally posted by Philip A.:

quote:

Originally posted by Norsk:
High barrel strain with cast bullets.... Does that make sense? What is "barrel strain" a measure of then?

There are a few things to consider in this case, two of them being:

- Lead has a higher friction coefficient than copper, which in turn has a higher coefficient of friction than bronze

- The "low pressure" bronze and copper bullets tested here have driving bands, i.e. thin ridges that insure obturation with minimum displacement of metal. Lead bullets, on the other hand, are subject to plastic deformation of the base (think Minié), being basically subject to continuous swaging as they ride down the bore.

In other words, once the rifling is engraved in a bronze bullet's ridges, which happens as soon as the bullet enters the bore, that bullet basically rides down the barrel without much deformation or strain. On the other hand, a lead bullet will exert pressure outwards on the barrel's walls due to the "swaging" effect, all the while riding on a much larger surface with higher friction.

quote:

Originally posted by cal pappas:
M458:
You have my apologies if I offended you but I am not looking down my nose at you as I don't know who you are. When this topic was brought to my attention I reviewed the posts. My introductory comment was in reference to my original viewing of the topic. From a couple of sentences you wrote you seem to have a bit of displeasure toward double rifles. They may not blow "all to hell tomorrow" but they can sure be plagued by OSR if one is not careful. As to your comments to Chris, he is a fine gent.
Again, my apologies if I offended you. The same if my doubles cause a bit of contention, although I doubt I will trade them for a stainless, fluted, synthetic, whiz-bang magnum in the near future. And, I don't look down my nose at anyone--known or not.
Cheers,
Cal

....Mac >>>===(x)===> MacD37, ...and DUGABOY1
DRSS Charter member
"If I die today, I've had a life well spent, for I've been to see the Elephant, and smelled the smoke of Africa!"~ME 1982

Hands of Old Elmer Keith

quote:

Originally posted by Todd Williams:

quote:

Originally posted by ELeeton:

I would like to appeal to your scientific curiosity when I pose the following. When we test in the lab we attempt to replicate the circumstances under which the original problem occurred. I think 450 NE No2 in his posts a few pages back highlighted a critical variable that was missed in the recent lab tests about bullets causing OSR. I think his, Cal's and Mr. Wright's et. al. observations of OSR have occurred in DR's yet efforts to replicate have been conducted in single barrel guns. As 450 NE No2 points out the DR's have two barrels joined together by the rib which changes how the barrels respond and how they respond to one another. Is this the variable that would permit the replication of OSR in the lab?

Eleeton, the problem with the theory of it only occurring in double guns because of the solder joint is that my Ruger M-77 in 338WM had those barrel stripes. Most definitely a single barreled bolt action rifle. And once again, it came from the factory that way. Wasn't caused by a monometal bullet being fired down the tube!

Cheers.

....Mac >>>===(x)===> MacD37, ...and DUGABOY1
DRSS Charter member
"If I die today, I've had a life well spent, for I've been to see the Elephant, and smelled the smoke of Africa!"~ME 1982

Hands of Old Elmer Keith

quote:

Originally posted by Biebs:
Mac, I think you have OCD, not OSR :-) Hope you're taking are of my Marcel Thys 577!

quote:

Originally posted by MacD37:

quote:

Originally posted by Todd Williams:

quote:

Originally posted by ELeeton:

I would like to appeal to your scientific curiosity when I pose the following. When we test in the lab we attempt to replicate the circumstances under which the original problem occurred. I think 450 NE No2 in his posts a few pages back highlighted a critical variable that was missed in the recent lab tests about bullets causing OSR. I think his, Cal's and Mr. Wright's et. al. observations of OSR have occurred in DR's yet efforts to replicate have been conducted in single barrel guns. As 450 NE No2 points out the DR's have two barrels joined together by the rib which changes how the barrels respond and how they respond to one another. Is this the variable that would permit the replication of OSR in the lab?

Eleeton, the problem with the theory of it only occurring in double guns because of the solder joint is that my Ruger M-77 in 338WM had those barrel stripes. Most definitely a single barreled bolt action rifle. And once again, it came from the factory that way. Wasn't caused by a monometal bullet being fired down the tube!

Cheers.

Todd, we had that discussion way back, and I know you remember it. I told you then that the Ruger M-77 with strips on the barrel had nothing to do with hard bullets. As you say that rifle came from the maker that way, and it did. The reason for those stripes was from Hammer forging of the barrel that were not polished completely off at the factory. The high points originated on the outside of the barrel, while OSR originates from the inside out, and are sometimes very hard to see, and even harder to photograph. Those patterns like those on the M-77, are on all barrels that are hammer forged, but most makers polish them off before the rifles are sold, but some are left on the top six or eight inches end in front of the action for decoration. I know you do not believe OSR exist, and that is simply because you have never seen it, but I have and so have several other members of the DRSS , that was not there when when the double rifle was new.

Over and out! Carry on!
......................................... MacD37

quote:

Originally posted by MacD37:

quote:

Originally posted by Todd Williams:

Eleeton, the problem with the theory of it only occurring in double guns because of the solder joint is that my Ruger M-77 in 338WM had those barrel stripes. Most definitely a single barreled bolt action rifle. And once again, it came from the factory that way. Wasn't caused by a monometal bullet being fired down the tube!

Cheers.

....Mac >>>===(x)===> MacD37, ...and DUGABOY1
DRSS Charter member
"If I die today, I've had a life well spent, for I've been to see the Elephant, and smelled the smoke of Africa!"~ME 1982

Hands of Old Elmer Keith