point of diminishing returns

[jim m]

fancy way of saying when more powder just aint doing any good. shot my .45 several hours today and experimented with powder charge. this rifle[green mtn. barrel] has always performed quite well with 65grns 3f. upped the charge to 70 then 75. all the shots grouped together, no rise in point of impact or group opening up. without a chronograph I'm guessing that anything above 65grns is just a waste of powder. what say you more experienced shooters

[BrownBear]

I ask myself two questions in choosing loads, assuming they shoot equally accurately.  How much impact do I need to do the job on game?  And how flat should my trajectory be?  


All else being equal, if I'm getting the impact I need and the trajectory I need, why should I burn more powder?  If I need more impact or a flatter trajectory, will extra powder achieve those goals?  Is even a little gain significant to my needs?  I might just as well switch to a larger caliber for more impact, rather than simply stuffing more powder under the smaller ball.  If I need a flatter trajectory, then I might even go to a smaller caliber firing a conical.  

Point of Diminishing Returns  is a fun theory for arguments, kinda like politics.  But just like politics, it has very little use in real life.

[jmforge]

052608

This is the little place I have to shoot…the concrete bench is under a tin roof pole shelter, off to one side of what is actually an action pistol shooting club with several berms off to my left.
The berm in the photo is at 50 yards, the long stretch is 300 yards, and of course target stands can be placed anywhere down it’s length.
I chronographed the .45cal today…stats are underneath the photo.



VELOCITY TESTS - .45cal Flintlock

T/C .45cal 15/16” x 32” Flint barrel
1:66” round ball twist
.018" T/C NL1000 pillow ticking
Hornady .440 balls
Wiped the bore after every shot
Pact Pro MK5 Chronograph at 15 feet
Goex 3F powder charges
Average velocity rounded off to nearest 5 fps

30grns = 1155 fps
40grns = 1290 fps
50grns = 1435 fps
60grns = 1560 fps
70grns = 1590 fps
80grns = 1720 fps
90grns = 1805 fps
100grns = 1870 fps

What was your accuracy like for each load?  also, at what point, if any, did recoil become a possible issue?  I know that recoil is normally not considered to be much of an issue with a .45, but you were getting into what some might consider to be stout load territory for a smallbore.

[erdillonjr]

bench the gun and try different loads. That will tellyou what you are looking for. Ed

[northmn]

When I chronographed my 50 I found th epoint at about 80 grains of 3f.  If you look at Roundballs results theres an interesting jump at 80 grains then a leveling off again. Maybe a usable jump to 90 grains and a questionable one to 100.  My 50 had a longer barrel and and was over 1800 fps at 80 grains.  One source I used to read, A book on ballistics I got from the NMLRA mentioned that once you get over 1800 the differences in down range velocities become less and less. In other words, going to 2000 fps may only give about a 70 fps difference at 100 yards.   Another issue that comes out is that if one is not satisfied with the performance of the round ball at approximately 1800-1900, one needs to get a larger bore.  You cannot "magnumize" a BP firearm.  A larger bore shoots a little flatter with the same velocity, has better velocity retention and will penetrate deeper.  A 45 cannot be made the equal of a 50, nor a 50 that of a 54.  Not knocking the 45 as a lot of deer and even bigger game have been shot with one.  A person just needs to stay within the limitations of the system.  Roundballs results seem a little conservative compared to one of mine, but all rifles are different.  Most like to use 65-70 grains of 3f in a longrifle.

DP   

[Dan]

RB, I believe he referred to velocity, not FPE. Chasing the FPE devil with round balls is not terribly productive in my opinion, mostly because increased drag causes more rapid velocity decay. The result is pretty much as Northmn posted, lots more thunder at the muzzle, not much velocity improvement at longer distances.  Of course, if one is shooting something up close, there will be change in that equation.

30grns = 1155 fps
40grns = 1290 fps
50grns = 1435 fps
60grns = 1560 fps
70grns = 1590 fps
80grns = 1720 fps
90grns = 1805 fps
100grns = 1870 fps

Did a little examination of your numbers and I don't see anything extraordinary with the 70-80 grain crossover.  Without knowing the particulars of your strings I won't be leaping to conclusions from your data, but what I saw was an average velocity change of 87.85 fps for each increment, with a low of 30 and high spread of 135 from the 30-40 grains increment. From 30-100 grains it looks like this:

30 grains @ 1155 fps
40  + 135 fps
50  +   45 fps
60  + 125 fps
70  +   30 fps
80  + 130 fps
90  +   85 fps
100+   65 fps

I see nothing there to indicate a pattern of diminished returns on muzzle velocity from increasing charge.  A couple of blips that are probably inconsequential...and I'd be more suspicious of the low numbers than high.  Could have been the result of bore swabbing or some such.

[hanshi]

Just a thought but could it be that, say, 40, 60, 80 & 100 grains could be "sweet spots"?  Seems a lot of shooters use those charges and swear by their accuracy.  I've been using 40 grains in my .40, 60 in a .45 & 80 in a .50 and so on.  I need to break out my chrony & see what happens.  Only times I've ever checked fps was AFTER I'd settled on a load.

[Dan]

The step I was referring to that seemed really odd was from 60 to 70.

Yep, if I had half a brain I'd be....something, I forget what though.

[jim m]

interesting replies. I'm not always real scientific and sometimes a little lazy on testing. I was working up a hunting load. 65grns of 3f gave good results out to a 100yds with only a 2" drop with a 6 o'clock hold at 100 and an 1 1/2" high at 50yds and 6 o'clock hold.  70 and 75 grns showed no appreciable difference. so in my finite little mind I'm thinking why burn the extra powder. with the .45 I keep my shots under 75yds if I'm where I might get longer shots I always take the .54. I'm talking whitetails here, if I were hunting mulies or elk it would be nothing smaller than a .54

[hanshi]

I've always used my .50 when hunting in a field and, like you, save my .45 for the woods; that's where I hunt the most.  The one 75 yard deer taken with the .45 was in a small field, me at one end and him at the other.

[northmn]

Sorry should have stipulated 1800 feet per second.  The Lyman book posts the 45 at 2000 fps at the muzzle hitting at 1066 fps at 100 yards and 990 at 1800 so that you see a gain of 76 fps at 100 yards for 200 fps at the muzzle.  Most experienced 45 shooters like to keep their shots at 75 yard or under on deer.  The ball at 75 yards will be traveling at  between 1100-1200 fps. Again this is based on tables out of the Lyman Blackpowder Handbook.  This was a 445 RB, the 440 RB that Roundball used had a difference of 75 fps.  A 495 RB driven at 1700 fps at the muzzle will arrive at 100 yards going at 995 fps, or slightly faster than the 445 at 1800 fps MV.  One reason you cannot "magnimize" a smaller bore to match a bigger bore.   The 76 fps at 100 yards would not be a significant difference.  Considering that shot placement is the prime requirement at any velocity, the big issue at these velocities starts to be one of trailing the critter after shooting it as they likely would not leave a very substantial trail.  I had different results than Roundball when I chronographed my 32 inch 45 but seem to have lost the results.  Seems like 70 grains gave over 1800 fps.  Lyman handbook lists 70 grains in a 32 inch barrel at 1970.  Not arguing with Roundball's results just pointing out that you can get quite a variation from rifle to rifle.


DP

[Dphariss]

I ask myself two questions in choosing loads, assuming they shoot equally accurately.  How much impact do I need to do the job on game?  And how flat should my trajectory be?  


All else being equal, if I'm getting the impact I need and the trajectory I need, why should I burn more powder?  If I need more impact or a flatter trajectory, will extra powder achieve those goals?  Is even a little gain significant to my needs?  I might just as well switch to a larger caliber for more impact, rather than simply stuffing more powder under the smaller ball.  If I need a flatter trajectory, then I might even go to a smaller caliber firing a conical.  

Point of Diminishing Returns  is a fun theory for arguments, kinda like politics.  But just like politics, it has very little use in real life.

Where I live I tend to go for a flat trajectory to 120-140 yards 3-4" +- to that distance allows "no hold over" on deer sized animals. Just hold center and shoot.
Power is hard to gain with a RB unless the diameter is increases. Most loads fall to about 1000-1100 fps at 100 yards anyway.
Look at the powder charges some heavy bench RB guns use....
I would like to make some more comments on velocity vs charge weight but I need to have some fresh data to use  . But then my old Oehler needs new sky screens. It won't clock 22 bullets over about 2900 fps anymore.
IIRC my 16 bore starts to go flat at about 120 grs of FFG swiss. It has a 29" barrel less the breech.
I have a friend who has done a great deal of detailed chronograph work with a lot of different powders and has found there is a point of diminishing returns.
But then we are back to what does the rifle want to shoot well and what does the shooter need from it. Then all the diminishing returns/bore volume stuff is just something to discuss on web sites

Dan

[northmn]

IIRC my 16 bore starts to go flat at about 120 grs of FFG Swiss. It has a 29" barrel less the breech.
I have a friend who has done a great deal of detailed chronograph work with a lot of different powders and has found there is a point of diminishing returns.
But then we are back to what does the rifle want to shoot well and what does the shooter need from it. Then all the diminishing returns/bore volume stuff is just something to discuss on web sites

Dan

It is a little more than "funstuff" to discuss on the internet. You are using a very large bore and working up an adequate load for balancing recoil, trajectory with power almost an irrelevant issue.  To make a comparison start talking about shooting about 300 grains to get it to shoot flatter for longer ranges.  A person shooting a medium bore is trying to push the limits to get reasonable trajectory and adequate accuracy at the longer ranges.  A 45 is not a 120 yard gun maybe but one might try using a 50 at that range.  One sees some pretty heavy loads used in the medium bores that may not produce.  Until I chronographed I used 90 grains of 3f in my 50.  I found out that 80 grains was so close I cut back to 80.  As far as accuracy is concerned both were more than adequate for hunting.  I am still playing with my 54 on this issue going between 3f and 2f and possibly Swiss as I shoot to about 120 yards.  Very large bores above the 58 do not have the same issues as the medium bores and comparing notes is helpful.

DP

[northmn]

Another reason to comment on this is that I have seen some ridiculous loads worked up even with conical bullets.  For those working up hunting loads it is a very important concept to understand.  I have always preached that there is a point where a bigger bore is needed, but most are better off shooting a medium bore as they give the best balance of recoil, power and trajectory which permits accurate shooting for them.  Also we are talking about advantages of using the same rifle that is shoot at get togethers for hunting.  One they are familiar with.  Before working up a hunting load or long range match load one needs to know the limitations or that there are some, which is very practical knowledge, not just internet sophistry.

DP

[Dphariss]

IIRC my 16 bore starts to go flat at about 120 grs of FFG Swiss. It has a 29" barrel less the breech.
I have a friend who has done a great deal of detailed chronograph work with a lot of different powders and has found there is a point of diminishing returns.
But then we are back to what does the rifle want to shoot well and what does the shooter need from it. Then all the diminishing returns/bore volume stuff is just something to discuss on web sites

Dan

It is a little more than "funstuff" to discuss on the internet. You are using a very large bore and working up an adequate load for balancing recoil, trajectory with power almost an irrelevant issue.  To make a comparison start talking about shooting about 300 grains to get it to shoot flatter for longer ranges.  A person shooting a medium bore is trying to push the limits to get reasonable trajectory and adequate accuracy at the longer ranges.  A 45 is not a 120 yard gun maybe but one might try using a 50 at that range.  One sees some pretty heavy loads used in the medium bores that may not produce.  Until I chronographed I used 90 grains of 3f in my 50.  I found out that 80 grains was so close I cut back to 80.  As far as accuracy is concerned both were more than adequate for hunting.  I am still playing with my 54 on this issue going between 3f and 2f and possibly Swiss as I shoot to about 120 yards.  Very large bores above the 58 do not have the same issues as the medium bores and comparing notes is helpful.

DP

There is no reason to shoot 300 grains of powder in a 16 or 14 (69 cal). 140 grains will give me a 130 yard point blank on deer sized animals. This is about 1/3 ball weight, 300 grains is a load for a 8 or 6 bore.
The velocity the 16 bore (.662 ball) makes with 140 gr is nearly identical to what Forsythe got with his 14 bore based on his trajectorys with he tested carefully.
The bigger bores are more efficient and the balls have a slightly higher B.C. The 16 bore with a 30" barrel (1" of this is the breech) makes about 1600 at 140 gr of FFG Swiss and 150 gives about 1650.
A friend of mine killed a doe with a 45 caliber at 120 yards last fall complete pass through breaking a rib going in and another going out.
I have killed deer at 140 plus with both 50 and 54 caliber RBs. I used to the shoot 90 and 100 gr of Goex FFFG respectively but have reduced this to 90 gr of FFFG Swiss for the 54. In the 38" barreled 54 this made jsut over 1900 IIRC. I neglected to write it down.
I was shooting 75 FFFG Swiss in the 50s but one is off on consignment and the other is out of service right now. Did not check the speed on either rifle.
Dan

[Mike R]

fancy way of saying when more powder just aint doing any good. shot my .45 several hours today and experimented with powder charge. this rifle[green mtn. barrel] has always performed quite well with 65grns 3f. upped the charge to 70 then 75. all the shots grouped together, no rise in point of impact or group opening up. without a chronograph I'm guessing that anything above 65grns is just a waste of powder. what say you more experienced shooters

...as you can see there are alot of opinions on loads...I just thought I'd bring in a little history.  In the "old days", from everything I have read, loads were typically lighter than many shooters use today--the modern trend has been toward "magnum" loads.  In other words our pioneer forefathers survived quite well with what many modern shooters would call "reduced loads".  Just one example that I came across recently was a quote from old Black Bill Walker, gunsmith and hunter of the Great Smokies in the late 1800s.  Black Bill's personal rifle was ~.53 and he said his powder charger held 60 gr [most likely ~ ffg].  Although he did admit to Horace Kephart that when needed he"double charged".  Most MLer rifles are most accurate when the ball velocity is 1400-1600 fps. These velocities for most calibers also give adequate trajectories and penetration. Evidence for what most shooters considered max loads in the old days is that powder and lead was shipped and carried in a ratio of 2:1 lead to powder by weight.

[northmn]

[/quote]

^{A friend of mine killed a doe with a 45 caliber at 120 yards last fall complete pass through breaking a rib going in and another going out.
I have killed deer at 140 plus with both 50 and 54 caliber RBs. I used to the shoot 90 and 100 gr of Goex FFFG respectively but have reduced this to 90 gr of FFFG Swiss for the 54. In the 38" barreled 54 this made jsut over 1900 IIRC. I neglected to write it down.
I was shooting 75 FFFG Swiss in the 50s but one is off on consignment and the other is out of service right now. Did not check the speed on either rifle.
Dan}[/quote]

Few really would push a 16 bore to 300 for most uses but those with medium bores push to higher powder/ball percentages to try to either get more "killing power" or more range.  Iron sights really do limit the range for practical distances.   About the time one makes a statement about a caliber you get the usual comment about someone who killed a deer like your friend.  A 45 is still somewhat iffy at longer ranges.  Mostly its a matter of finding them after you shoot them if they run a ways.  I have seen people talking about using 150 grains behind maxi balls in a TC 50.  Etc.  As we understand what constitutes a reasonable load we get away from such things and either go to a bigger bore or limit our ranges or both.
DP