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 POI question on different BP loads?

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Bwana71



Number of posts : 2
Age : 48
Location : Whip-poor-wil, MO
Registration date : 2014-07-10

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PostSubject: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 11th 2014, 12:24 pm

I was shooting my T/C 54 Cal Hawken trying different loads for hunting season. I always have shot 60 grains of FFF BP with a .015 patch and Hoppes Patch lube. At fifty yards it shoots nice groups about four inches high. It shot it with the same gear but just put 80 grains and it shoots good groups but the POI is 6 inches lower than the 60 grain load. Why? Just don't make since to me.
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OldMtnMan

OldMtnMan

Male Number of posts : 10394
Age : 76
Location : Buena Vista, Colorado
Registration date : 2010-09-23

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 11th 2014, 1:00 pm

That doesn't make sense to me either. I guess if it was mine i'd ignore it, and sight in for the 80gr. As long as it's consistent with that load.

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Pete

I'm addicted to black powder.
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FrontierGander
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FrontierGander

Male Number of posts : 16313
Age : 35
Location : Boncarbo,Colorado
Registration date : 2008-05-19

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 11th 2014, 2:13 pm

Shooting flatter due to the higher velocity most likely. Did you recover those patches with the 80gr loads to inspect them for rips and tears?
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hunting savage



Number of posts : 170
Age : 72
Location : southern Mi
Registration date : 2014-05-03

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 11th 2014, 6:03 pm

A patch, a spruce  on ball, powder not seated all the way,or ball.Try 50 gr, an a 100 should be closeThis is my load for small game an deer
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Spitfire



Number of posts : 5314
Age : 53
Location : South Africa
Registration date : 2011-11-20

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 12:33 am

If the groups are good with 80gr just re sight the rifle , like Jon says with the higher velocity the mid range trajectory will be lower hence the balls print lower.
BTW were you using 2F or 3F with the 80gr load  ?  With 3F the ball will be very close to 1600 fps.
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OldMtnMan

OldMtnMan

Male Number of posts : 10394
Age : 76
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Registration date : 2010-09-23

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 8:00 am

You guys aren't thinking this through. With no change to the sights, and shooting the same 50yd distance. There's no way that adding 20gr of powder will make it shoot lower. If any change happens it will shoot higher.

Think about it.

_________________
Pete

I'm addicted to black powder.
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Bwana71



Number of posts : 2
Age : 48
Location : Whip-poor-wil, MO
Registration date : 2014-07-10

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 8:30 am

I was using 3F Goex powder.
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Spitfire



Number of posts : 5314
Age : 53
Location : South Africa
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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 10:27 am

Depends on the distance the rifle is sighted in for in the first place. If sighted for 100 dead on and you decrease the velocity the trajectory in the mid range will increase and if you increase velocity the mrt will decrease and at the midrange the groups will print lower , at 100 it will then shoot higher.
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OldMtnMan

OldMtnMan

Male Number of posts : 10394
Age : 76
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Registration date : 2010-09-23

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 10:36 am

Ok, lets look at this another way.


Lets lock the gun in a vise to take out all human error. Lets also assume we can load the gun without moving the gun from the vice.

Load 60gr, and aim the sights right at the bull at 50yds. The POI is exactly 4" high from the bull.

Now, without changing anything you load 20gr more. Where do you think the POI will be?

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Pete

I'm addicted to black powder.
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Spitfire



Number of posts : 5314
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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 12:06 pm

Ok I see what you mean . According to my calculations the gun will now shoot about 3 1/4" high with 80gr . To get the gun to shoot 4" high at 50 with 60gr it will have to be sighted to 116 yards.
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Randy Johnson



Number of posts : 235
Age : 67
Location : Connersville, IN
Registration date : 2014-03-17

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 12:49 pm

I think you also need to take into account the attitude of the gun/barrel.

If the attitude is perfectly level, a projectile fired from the gun at any velocity over a level surface will hit the ground at the same time as an identical projectile that falls free from the height of the bore at the same time the fired projectile leaves the muzzle. The only result of the extra velocity is that it will hit the ground farther away. If a given powder charge dictates that the projectile will strike the ground at 250 yards, it stands to reason that a lesser charge and velocity will cause it to hit the ground at something less than 250 yards. And if there happens to be a paper target between the points of impact, the holes will be lower with the lesser charge because, although both projectiles are falling at the same rate, the slower one does not cover the same distance.

The thing is though, we seldom if ever shoot with the gun perfectly level. Sight the gun in at a range where you are “benching” it. There is a good chance that the gun will be shooting slightly up hill. You get it zeroed at start shooting offhand. Now, the attitude of the bore in relation to the ground is changed. And so, will the point of impact. It’s why I shaved a wad of hair off the top of deer’s shoulder years ago (about a 70 degree downhill shot) and why shooting uphill on the primitive range at Friendship can take some getting used to.

 
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OldMtnMan

OldMtnMan

Male Number of posts : 10394
Age : 76
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Registration date : 2010-09-23

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 1:08 pm

I know all that Randy, but in this case the POI should be close together if not the same. No way will it drop 6" with more powder.

_________________
Pete

I'm addicted to black powder.
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patocazador

patocazador

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 1:17 pm

The OP says: "I always have shot 60 grains of FFF BP with a .015 patch and Hoppes Patch lube."

That indicates it may not have been shot with that load recently and something changed in the meantime. Either the sights were bumped, or a change was made that has been forgotten but something had to change.

Anymore, I have to write down every load in a notebook so I can remember it the next day, otherwise I can easily make a mistake.

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Bob

"My reading of history convinces me that most bad government results from too much government." -Thomas Jefferson
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Randy Johnson



Number of posts : 235
Age : 67
Location : Connersville, IN
Registration date : 2014-03-17

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 1:24 pm

Guess I didn't explain it the way I had hoped, but I am agreeing with you Muley.
Twenty grains of powder in a .54 shouldn't show that much difference. For sure, it should not cause the POI to be lower.
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Randy Johnson



Number of posts : 235
Age : 67
Location : Connersville, IN
Registration date : 2014-03-17

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 1:27 pm

@patocazador wrote:


Anymore, I have to write down every load in a notebook so I can remember it the next day, otherwise I can easily make a mistake.
I am lazy.
I just make a non-adjustable powder measure. Very Happy
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OldMtnMan

OldMtnMan

Male Number of posts : 10394
Age : 76
Location : Buena Vista, Colorado
Registration date : 2010-09-23

POI question on different BP loads?  Empty
PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 1:28 pm

@patocazador wrote:
The OP says: "I always have shot 60 grains of FFF BP with a .015 patch and Hoppes Patch lube."

That indicates it may not have been shot with that load recently and something changed in the meantime. Either the sights were bumped, or a change was made that has been forgotten but something had to change.

Anymore, I have to write down every load in a notebook so I can remember it the next day, otherwise I can easily make a mistake.

I agree that something had to change. You can't fool the law of physics. Faster bullets/balls don't shoot lower at 50 yds when everything else is equal.

_________________
Pete

I'm addicted to black powder.
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Spitfire



Number of posts : 5314
Age : 53
Location : South Africa
Registration date : 2011-11-20

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 1:37 pm

The calculator showed a difference of 3/4" lower , but the gun had to be sighted to 116 yards to get it to shoot 4" high at 50 yards.
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OldMtnMan

OldMtnMan

Male Number of posts : 10394
Age : 76
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Registration date : 2010-09-23

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 1:46 pm

The gun wasn't re-sighted. What it does at longer ranges has nothing to do with what's going on here.

_________________
Pete

I'm addicted to black powder.
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Spitfire



Number of posts : 5314
Age : 53
Location : South Africa
Registration date : 2011-11-20

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 1:54 pm

What I meant was that for the gun to be high 4" at 50 it had to zeroed at 116.
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OldMtnMan

OldMtnMan

Male Number of posts : 10394
Age : 76
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Registration date : 2010-09-23

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PostSubject: Re: POI question on different BP loads?    POI question on different BP loads?  EmptyJuly 12th 2014, 2:09 pm

I know what you meant.  clown 

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Pete

I'm addicted to black powder.
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