Insite from DR. Franklin Mann "" The Bullets Flight""

So far it is all very interesting ! I know his writings and investigations were highly respected by the big name ballistics men and shooters of that era.
100 yards and less it would not mean a whole lot with a cylinder slug but eventually air resistance / drag would make a horrible rainbow drop.
Does this book have any photos / drawings of the massive rifle rests that were used in the test firings?   Saw some in a book and I was much impressed what they used to lock a rifle into the recoiling equipment. 

He started his 40 year adventure with two goals. One was to achieve best possible accuracy and the other to identify the cause of the off shot in a group. To those ends he dedicated much of his life and recourses. He recorded every test many of which were photographed. The book for the most part is a collection of the tests with evaluation of the results and all photos taken.
The standard he set for group shooting was 100 yards. He was only concerned with accuracy to that range and not beyond though they were applying lessons learned to their woodchuck guns a sport that apparently was popular enough at the time that there were clubs and resorts dedicated to the endeavor. His primary goal was to positively identify the cause of the too frequent off shot in a group. In his testing he dispelled may common beliefs that he proved myth.
I have prepared some smooth side bore diameter bullets cast in pure lead that I now must try breach seating in my 38-55. My mind is a clutter of ideas to try being guided by his work. We are really cold right now so much that work has been all inside for a few days but Lord willing when it warms I have some shooting to do.
Mike you mean what they dubbed " the Gibraltar rest" for its ruggedness.  Yes it is well represented in both description and photograph.

The trapdoor and Krag were already in existence when the Gibraltar was built. They did use it to test the Krag cartridge and arsenal bullets. Something interesting is the concentric mounting system developed to precisely replace a barrel after it had been removed from the rest. The test barrels were made to fit the rest and each had a short cylindrical chamber that allowed the barrel 360* circular travel in the rest. This allowed testing to determine if the bore was concentric to the barrel. Shooting a group and turning the barrel 1/4 revolution between shots told the story. In this regard Pope barrels were very good even after considering the fact that in comparison he used rather primitive machinery to make them.
A barrel that is .010" non concentric will shoot a 20"group at 100 yards in that test just owing to the non concentricity of bore to barrel. We have here a modern production rifle made in Europe that is a copy of the 1885 Winchester chambered in 45-70. It was purchased for conversion to 50-90 but after the purchase it was discovered that the bore is so non concentric to the barrel that on the thin side will not make the minimum required barrel wall thickness of .100" to bore to 50 caliber. The outside diameter is more than adequate but the defect is so acute that it rendered the conversion unsafe. Now considering the stark difference between the tooling and machinery Pope had to work with and what the maker of the afore mentioned 45-70 rifle had to work with the quality of work turned out by Mr. Harry M Pope is quite astonishing.

I hope that my work in my business is considered as such.

Now an interesting development. In late 1904 through 1905 it was decided to move from black powder to smokeless powder. The powder used was Sharpshooter an early fast (for rifle) burning powder. The switch from black to smokeless powder changed the pressure dynamics and it was then discovered that pure lead no longer shot best. Through further testing it was proven that alloyed lead now shot better than pure lead which is the reverse of black powder.
At about the same time in 1905 they started testing jacketed bullets which also again changed the pressure dynamics.
I am impatiently waiting on some warmer weather to try a few things I have prepared for my 38-55 roller. Yesterday I made a breach seater to seat the bullets fully into the barrel ahead of a charged case. I have ready two different bullets one a custom tapered grooved bullet and one a smooth. These are sized to bore diameter accept for the very base band of the grooved bullet being groove diameter. This base band idea is something else extensively tested by Mr. Mann that seemed to consistently give best results. I have bullets cast in pure lead to be tried with black powder as well as alloyed for use with smokeless powder. The smokeless powder I will try is Trail Boss which has already proven accurate with a 300gn tapered spitzer bullet from the same rifle. A number of years ago I won a postal match with that load putting 10 shots into something around .75" at 100 yards with the old roller mounted with an old Weaver T-20 with custom reticle. That more modern scope looks a bit out of place on the roller but it sure works good for testing loads. Once loads are developed I mount an early Parts Unknown long range vernier sight for general target and long range shooting.
I doubt if I will shoot jacketed bullets in the 38-55 as I progress with the book but when I get to that point I have a very accurate 308win for that purpose.
Interestingly when the switch was made to jacketed bullets he stayed with bore diameter , at least to this point in late 1905.

Good Morning
The simple joy of applied labor (study also) sure makes a day shine in the heart.
The elements will certainly be a hinderence in your pursuit.
I remember a 2nd model 1873 in 44 WCF I spent several months gathering parts for some years back. The final Monday I had free before return here was 12 degrees and windy. Did not take long to abandon the 100 yard elevated rifle spot for a slightly less windy 25 yard target space.
Some feller built a small "shack" on skids he could move to different distances on his personal range. Just being out of the wind (or wet) is a big help.

very nice group!!!! even if it was windy!!!

Here I am going to ramble on a bit about shooting my 6mm BRM today partly because I want to share what I am learning and partly because the site needs to generate a little chatter. Todays shooting revealed some interesting results and also confirmed some of the conclusions Dr. Mann came to in his extensive testing of bullets tipping in flight and the results it can cause. One thing that stuck with me as I read his book is that he stated that at some point in its trajectory arch that all bullets become tippers.
There are different causes of bullet tipping one being inadequate rotational velocity caused by too slow a rifling twist rate for the bullet length being used. Dr. Mann as have I demonstrated that when a bullet is borderline stable or I should say borderline unstable that stability can be improved by increasing the muzzle velocity but obviously there are limits.
By shooting through paper screens at 10 foot intervals for 200 yards he also demonstrated that for such a marginally stable bullet that it will print perfect nose forward holes at various ranges and at all ranges inbetween will show signs of tipping, interesting!
Todays shooting for some reason broke with protocol and instead of starting at 100 yards started at 60 yards. The reason was that I didnt want to walk all the way out to the shooting bench (100 yards) to test a couple shots to see if the load was worth perusing. For that reason the two shots I had to try I walked the 25 yards to my pick up and shot over the hood. Those looked good so I put a shooting bag on the hood and resting the forend on that I shot a 5 shot .431" group  that I was quite pleased with so loaded more for testing at 100 yards.  If I had started shooting at 100 yards as usual I likely would have abandoned the load for poor performance and never known how good it shot at 60 yards.
I guess I should point out my purpose for wanting to develop a very light load in the 6mm BRM which is to exterminate the gophers that will be appearing soon about my garden plots. The load tested today was with the 100gn RCBS bullet over 4.5gn Red Dot sparked by a CCI large pistol primer.
OK so when I got to testing the load at 100 yards I was unpleasantly surprised to find that adding another 40 yards to the range cause a very accurate 60 yard load to fall apart and shoot 1.8" at best for 5 shots. WHAT!!! I thought when I walked to the target expecting to se a group somewhere around .75" What happened? Then I started thinking about DR Mann and what he said about all bullets becoming tippers at some point in their trajectory arch. On close inspection of the target the telltale sign was there of the tipping bullet. What Dr. Mann pointed out is that as a bullet slows its trajectory curve becomes more acute and as the angle of drop increases the bullets angle of flight is changing from it forward motion and so has more frontal area exposed so is battling increased atmospheric drag. The bullets attitude weather up following its original line of fire or down following its center axis and staying point on in its trajectory arch either way is not in line with its forward motion. If the bullets attitude is upward from its forward motion the air resistance is pushing its nose upward and if the bullets nose is following its trajectory curve the air resistance is pushing the bullets nose downward. Either condition at some point causes the bullet to wobble which also increases drag which slows the bullet more rapidly so adds to the drop angle and air resistance. WOW!!! That was hard to explain.      Oh yea I should add that the additional 40 yards from 60 to 100 yards caused 9" additional bullet drop from 60 yard zero.
Anyway I believe from what I have learned from his book that I can stretch the 60 yard accuracy to 100 yards buy increasing the velocity but that gets a little tricky when using powders that are near a max charge with about half a dozen grains. I think the trick will be something I learned from Harvey Donaldson's book where he pointed out that when a volume charge is found to work good when going to a heavier bullet do not change the volume but just go to a slower burn rate at the same volume. Well I am not going with a heavier bullet but by going to a slightly slower powder may give enough longer push that the velocity might increase enough to get the holes on target to be round at 100 yards. Possibly a combination of slightly slower burn and slightly increased charge weight. What I have found in the past is that when going to a slower burn rate but staying with the same volume the charge weight is increased because the slower burn rate has a higher density.
So thats about all that happened today before I got run out by a nasty snow squall that is presently occupying my shooting range. At least I found a super 60 yard load and most shots at garden pests are within that range.

Some I re-read 3x and then know I will need to re-think it all.

Gary you are my friend and because you are may have an inflated image of my abilities. I dont always figure it out but I am always trying. After I read you post I started thinking about transonic turbulence as another possible cause my widening groups at 100 yards. I have been so focused on Dr. Manns experiments that I didnt consider other possibilities. So far at about 3/4 through his book he has not addressed transonic turbulence but he might in the last chapters, we shall see.
Anyway as I was shooting I was thinking that the velocity of the load was probably somewhere around the speed of sound at about 1100 fps at my 6000 ft. elevation. The idea that the bullet maybe starting out at a supersonic speed and remaining supersonic out to the 60 yard target but then in the next 40 yards of travel possibly going transonic had not occurred to me until after I read your post. I didnt have the chronograph out because of the bad weather. It may be interesting to chronograph at three points one near the muzzle, one at 50 yards and one at 100 yards. That might tell me something. If it is a possible source of the groups widening a possible cure might be to either keep the velocity subsonic or supersonic for the bullets entire flight and avoid a combination of both.

I tend to also like the frugal approach to solutions.  And you sure reached it.  Do you not have a "ballistic" cross hair marked scope ? I would think 10 yards from the muzzle there is little noise.

That looks like pellet gun velocity. We have a .25 caliber Hatsun and a .177 Blue Streak that get used for gophers and pests. My idea is if it weights more than 15 pounds the .25 gets the call. So far works out real well to 50 yards.
Out to 100 yards we have not tried as our residence for the last 12 years when north only offered 50 yards of needed extermination.

Today between melting pots of lead I was able to do a little shooting load work toward the gopher load project. I decided to go right about in the middle of the powder burn rate chart and since I have a very comfortable supply went with IMR 4895. Starting at 17gn things looked pretty good but since I could see a little more than normal powder residue in the barrel I kicked it up to 18gn. At 18gn it was shooting very close to 1" at 100 yards. Three 5 shot groups averaged about 1 1/8" to 1 1/4"
Not bench rest accuracy but more than adequate for staying inside a 2" wide gopher at 100 yards.
This shooting was done with the RCBS bullet that I weighed at 96gn lubed with gas check. A couple days ago I cast more of the RCBS bullets because I was about out and I also ran a few 100 of an LBT spitzer design that runs about 76gn with lube and gas check. Right at the end of my shooting session I decided to substitute the RCBS 96gn bullet with the LBT 76gn bullet but staying with the 18gn IMR 4895 powder charge. I first loaded three rounds of the 5 pieces of brass I had dedicated to this project and shot a tiny cluster that made my heart skip a beat all making a single about 40 caliber hole. That got me motivated so went back inside and loaded the other two pieces of brass and went out and fired them into the same group. The end result of that was that one of the last two went into that same 40 caliber hole and one went about 3/4" from its center. That is what I was really hoping for but didn't dare expect. I will certainly be looking more closely at that load and it comes none too soon either because I spotted the first gophers of spring from the reapers roost today.
The down side to this load is its noise level. This rifle an EAB model 97-D has one of his designed breaks that looks like it was scaled down from a tank cannon. It goes a long way in helping to spot my own shots as it does seem to greatly reduce muzzle flip. What it also does is direct the sound right at the shooter so makes the report seem extra loud. With a low noise load I can sometimes get off several shots before they wise up but the big boom gets them running for a hole in one, good in golf but not so in popping pests. Maybe its a good thing having to wait a little longer between shots so the barrel wont heat up in hotter weather if there is such a thing.
So that is about where I am at with this right now and I am really liking what I think I am seeing with the LBT bullet. It may not do as well as the heavier RCBS bullet for longer range shooting out to 300 yards or so but this project was all about getting good consistent 100 yard accuracy and I think I may be closing in on that goal.

A couple related points I forgot to mention, the rifle has an 8" twist, holes on paper showed no sign of tipping, and though I did not chronograph I estimate the velocity at about 1800 fps with the 96gn RCBS. In assessing the results of shooting the two bullets the RCBS 96gn and the LBT 76gn with the same 18gn charge of 4895 and since the lighter bullet seemed to group a little better might indicate that the 18gn charge is a wee bit over the top for the heavier bullet. To me that means that accuracy with the heavier bullet might be improved by either slightly reducing the powder charge weight for the heavier bullet of go to a slightly slower powder burn rate.
This is where the wisdom of Harvey Donaldson comes into play. According to his advice with my powder drop set to throw 18gn of 4895 powder leaving it at that setting and going to a slightly slower powder burn rate should or has great potential to produce the desired results. Using the powder burn rate chart from Hodgdons 2021 annual load guide they assign IMR-4895 with # 96 so going to something with a slightly higher number but close may improve accuracy results. Sometimes consecutive numbers will have identical burn rates so jumping ahead by a few numbers may be practical. Jumping ahead by 5 places puts us at IMR 4064 on the chart so may be something to try if I have some. If not simply staying with the 76gn bullet and 4895 seems like maybe not at all a ban plan.

i don't the 6BRM or how much does it hold, but if it is 60% or less i'd try a tuft of dacron.

when i shot the 444, it was a 300gr fn gc with 24.0gr of 2400 and a tuft of dacron. i forget what case capacity 24.0gr is (is it 30-40% full?). i tried the 20 - 25.0gr of just 2400 and i found +2.5" +/- increase of its accuracy and 100-150fps+/- of extreme spread.

i use dacron in my 35/30-30 too (200gr fn gc with 20gr of 2400/tuft of dacron).