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desert deuce
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Re: bullet tip

Post by desert deuce »

When employing the chronograph on a rifle, the first shot from a clean barrel is ignored.
What I see in the printout is encouraging and I hope you wrote the load details down.
What is important is the vertical dispersion and low ES tends to do that.
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bpcr shooter
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Re: bullet tip

Post by bpcr shooter »

16+1, It was VERY damp that weekend and I was checking every patch as I pushed my bore pig thru. bore pigs have 3 felts soaked in 10-1 water/oil. bore was getting clean enough that one more pig and a dry patch or two, the rifle was clean for the day. It was 40's/50's and rain on an off for weather.

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Re: bullet tip

Post by bpcr shooter »

desert deuce wrote: Mon May 23, 2022 3:42 pm When employing the chronograph on a rifle, the first shot from a clean barrel is ignored.
What I see in the printout is encouraging and I hope you wrote the load details down.
What is important is the vertical dispersion and low ES tends to do that.
This load will just drill a hole at 100yd, and will in less wind hold a 7in circle at 900yd ( I went out and re-shot the following week). What I'm starting to think is that, its on the edge of stability in 20mph winds. Weird thing is, my bullets are still flying nose first even at 1k, so it cant be that bad. I also tested 2 other loads.
1. 45-100 2.6 trimmed to 2.4, with a bullet trimmed in lathe to 1.415" 94.5gr of same lot 1.5F. Avg speed was 1349fps with a SD of 6.1.

2. JBA brass, bullete trimmed to 1.415, 89gr of same lot 1.5F swiss, avg speed was 1332fps with SD of 7.5.

These were just 2 loads I threw together and tried, I just tried to follow the compression I had for the orig load.

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Don McDowell
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Re: bullet tip

Post by Don McDowell »

Jba brass has a bit less copacity than Starline.
A bullet can loose stability but still be flying nose first
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Re: bullet tip

Post by bpcr shooter »

Don McDowell wrote: Tue May 24, 2022 11:08 am Jba brass has a bit less copacity than Starline.
A bullet can loose stability but still be flying nose first
.
Yes it does Don, to the tune of 4.5-5gr roughly. I think its still in my best interest to shorten the bullet .020. I will still be in the 510gr area even with 16-1 alloy. Looks like a new bullet mold is in order :D
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Don McDowell
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Re: bullet tip

Post by Don McDowell »

1.42 is about as long as we can depend on in an 18 twist in all the conditions. I had a mould shortened up from 1.45 to 1.42 and all the weird impacts not to call went away for the most part. 1.45 works great in a 16 twist.
The Jamison brass has sort of a cone shape going that last bit down to the flash hole, and I think it acts more like a shaped charge, and that's why with less powder capacity the few grains less will give the same or close enough to the same velocity as the Starline with more powder. The Jamison are also thinned at the case mouth than starline. Or at least the 4-500 of the Jamison I have are that way.
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Re: bullet tip

Post by Old-Win »

Is there any way to predict what the velocity of those two loads are doing at let's say 900 or 1000 yards? Let's suppose one of Matt's loads leaves the barrel at 1250 feet per second and one leaves the barrel at 1325 feet per second. Is the difference still 75 ft per second at the longer distances or are the speeds closer together? It is quite a balancing act that we have to maintain to get our bullets nose first into the target at 1000 yards without tipping. I wish Bruce M was still here.
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Re: bullet tip

Post by Don McDowell »

There are a number of ballistic calculators out there that will give pretty good guesstimates on the velocity when crossing the 1000 yard line. The velocity at 1000 is only part of the equation, time of flight and wind drift enter into it as well.
It is something of a head scratcher tho when you look at velocity differences of as little as 7 fps difference when the bullet hits 1000.
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Re: bullet tip

Post by Distant Thunder »

Bob,

The faster a bullet starts out the more quickly it slows down, as it slows down the rate of velocity loss diminishes. Even with the same bullet leaving the muzzle at 1100 fps or at 1400 fps there is only about 70 to 80 fps difference at 1000 yards. The faster load will have more wind drift with the same bullet and that's due to the rate of velocity loss being greater early on in its flight. The difference can be as much as 3 MOA of drift.

A higher BC bullet will arrive with a little more velocity remaining, but at these very low-end velocities with BP there isn't much difference with any reasonable starting velocity and the typical long-range bullets in use.

With a bullet having a BC of say .400 and another with a BC of .500 and if they both start out at 1400 fps, at 1000 yards there is only about 55 fps difference between the two.

There are things more important to long-range accuracy than velocity or even BC. Everything in this game is a tradeoff and balance is the key. Being human, we tend to argue in favor of what has worked for us, but what works is not the same for every shooter and/or rifle. It's always best to keep an open mind and never stop learning.

You are 100% correct, the loss of bruce was a big one. I wish I had realized the value he was to the sport sooner. His old posts are worth the time to read.
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Re: bullet tip

Post by Old-Win »

15-18 yrs ago, when the money bullet craze hit the air waves, I had Paul Jones cut me two moulds on what at that time was a copy of the original Sharps paper patch nose. One I had made at 1.4" in length that weighs about 520 grs and the other at 1.45" in length that weighs about 540 grs. The shorter one for the 45-70 and the longer one for my 45-90 Borchardt that I used in LR matches. Neither one ever showed signs of tipping. They served me well over the years for my limited ability. I picked up a PJ 540 gr. money bullet mould from a friend that can no longer shoot and it is 1.485" long but I've never shot it to 1000 yds. I think when the money bullet came out, people wanted to approach the 550 gr weight with them and ended up with too long of a bullet.
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Re: bullet tip

Post by Distant Thunder »

There is nothing wrong with the Sharp original PP nose as long as the overall length matches the twist rate and velocity. In 18-twist barrels a 1.400" to 1.430" long bullet for a .45-70 is very good and a .45-90 can handle 1.450" to 1.460".

The tendency to chase the 550-grain bullet has led many to shoot bullets that are too long for their ROT. That is even more problematic when you go to a long slender nose like the later Money designs where an even longer bullet is required to get to the magical 550 grains.

It puzzles me that so many shooters ask, "What weight bullet should I shoot in my .45-?? with an 18-twist barrel?". It is the overall length that matters, though nose length/profile and velocity have a smaller part to play in the calculation.

I struggled for years with my 18-twist .40-65 because I had NO understanding of what it takes to have a stable bullet over the range it would typically be used. I was eventually able to apply what I learned about bullet stability shooting my .45-70 and .45-90 at long-range to deal with the slow twist rate of my .40-65 and I designed a bullet that has performed very well out to 600 yards.
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kenny sd
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Re: bullet tip

Post by kenny sd »

Hey Dist. Thunder.
you mentioned the length of the bullet and then talked about your 40 65.
You didn't mention the length of the bullet you recommend in the 18 inch Shiloh twist.

I'm using a 390 grain .409 in my 40 70 SS and I'm interested in your expertise.
thanks..Ken
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Re: bullet tip

Post by Distant Thunder »

kenny,

What I do is to run the bullet length to twist calculation through one of the online ballistic programs. That gives me a maximum bullet length for a given rate of twist that will be stabilized at a given velocity for that caliber.

In the case of my 18-twist .40-65 the program said 1.240" was maximum at 1300 fps (kind of my default). You have to keep in mind that I shoot PPB and I like to seat my bullet very shallow in my powder capacity challenged cases like the .40-65 and the .45-70. So I tend to figure velocity a bit higher than might be attainable with GG bullets.

While the big factor is length, there are other things that come into play such as bullet shape, center of gravity vs. center of pressure, the % of OAL that the nose is and the maximum range the rifle will be used at.

With my .40-65 I was planning on mid-range BPTR and BPCRS, so 600 yards was my maximum range.

What I usually do once I have a program generated length is I will subtract a little from the maximum length for the twist. How much is kind of a guess based on the minor factors I mentioned above and years of shooting bullets that did and didn't work.

For my .40-65 I decided to go with 1.250" because it was a mid-range rifle and the bullet was designed to be the heaviest I could get in that 1.250" length in order to help with knocking down rams. That all meant a more blunt and shorter nose. So my design was very easy to stabilize and I was able to get 1345 fps. The results have been better than I even hoped for.

For my 18-twist .45-70 long-range rifle at 1300 fps, the program said 1.455" (if I remember correctly). I (eventually) made the mold at 1.435" because I had a longer, slimmer nose to give me a bit higher BC and I was just able to reach the 1300 fps threshold (1296).
I believe it is best to error on the shorter side rather than try to push the maximum length. It doesn't take much to cross the line either, .020" in length can and has made a difference in my experience. Keep in mind I am looking for a bullet that will not only remain stable in mild, stable conditions, I want my bullet to hold up as well as possible even when it's tough conditions, like quartering head winds.

Following what I said here has resulted in excellent bullet performance in both my .40-65 and my .45-70. I am currently working through the same exercise with my .44-77. It will be interesting to see where that leads.

I have been lucky in that for many years I worked as a tool and die maker and I had access to machines that allowed me to make and modify my own molds until I was satisfied with the results. Now that I am retired I have just a few simpler machines, but I can still adjust some things for hopefully better results. Even with the machining ability it can be a slow process to fine tune a bullet to a specific rifle and purpose. I have not been able to just run some numbers, tweak them a bit and then make mold or have one made and have the perfect bullet. There are just too many variables that have to be tested by actual shooting.

I hope this gives you an idea of what is involved, the process I go through in designing what I hope will be the best bullet for my rifle that I can. Paper patching does, I believe, make the process easier, but YMMV!
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Re: bullet tip

Post by bpcr shooter »

Ive decided to not change the mold, but to make a new mold, this one will be .020 shorter OAL (1.41) and have .020 removed from the base but added to the body making the nose a bit steeper or not as long. That should then give me .100 in the case, giving me a bit more capacity and helping me with those bad Lodi winds!!

I will update when I get said mold...
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Re: bullet tip

Post by SchuetzenDave »

Caliber 0.451 Inches
Bullet Weight 550 Grains
Bullet Length 1.435 Inches
Barrel Twist 18 Inches/turn
muzzle velocity 1317 fps
Temperature 50 degrees Fahrenheit (59 is standard)
Pressure 29.92 inches of mercury (29.92 is standard)

Sg = 2.44

Your gyroscopic stability is over 2.0 meaning you are overspinning your bullet which is desired to compensate for drag for shooting long distances (1,000 yards).
The Don Miller calculation does not indicate your bullet is too long for your 18:1 twist and your velocity is adequate.
Bullets that are too long would have a Sg below 1.4.
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