Starting to reload for 100 yd match

fshfindr · July 28, 2016, 06:51 PM

I'm reloading for my Ruger M77 357. I will be shooting in a 100 yd match and I'd like to know just how accurate I need to be with my powder. Will 1 or 2 tenths of a grain of H110 make much of a difference. I'm loading 16g into 158g XTP's.

Thanks,

Jimro · July 29, 2016, 02:31 AM

Hogdon lists 15gr starting for 1,619fps and 16.7gr max for 1,757fps.

That's 1.7gr difference causing 138fps difference. 138 fps/1.7gr gives 81fps/gr of powder. 2 tenths of a powder would be 16 fps difference.

So if your charges were +/- 0.1gr of powder you should have a very low extreme deviation for velocity, about 16 fps. If your powder charges are +/- 0.2gr then your extreme deviation should be around 32 fps. THIS IS WITH ALL ELSE BEING EQUAL such as bullet mass, frictional resistance, case capacity and primer energy, you won't get numbers that tight just from powder charge consistency.

You can get an idea of how much dispersion two different velocities will give you with a standard 10mph crosswind. 1619fps with a 158gr FP XTP bullet has 3.5 MOA of wind correction at 100, and 1757fps with the same bullet has 3.2 MOA wind correction at 100. That's a difference of 0.3 inches drift for the two velocities, which is less than the diameter of the bullet. So I personally wouldn't worry too much about a +/- 0.2gr charge as long as that range is safe in my firearm.

Jimro

std7mag · July 29, 2016, 04:48 PM

To add to Jimro,
Don't forget that with any powder your going to have some degree of standard deviation, and an extreme spread with your loads to contend with also. Which would exaborate any difference in point of impact from your charge variance.

Shimpy · July 29, 2016, 05:24 PM

I found out years ago while shooting bench rest that volume was more important than weight of powder. I never weighed my charges and had no idea what they were. My drop tube settings on a Belding and Mall drop tube were what I recorded for reference.

buck460XVR · August 1, 2016, 10:28 AM

One or two grains will make a difference if you are one side or the other of the sweetspot of your accuracy load. Otherwise, the difference of a few fps will not be worth worrying about. I've found that with H110 in .357, that the highest velocity loads are not the most accurate.

TimSr · August 1, 2016, 10:38 AM

Quote:

Will 1 or 2 tenths of a grain of H110 make much of a difference. I'm loading 16g into 158g XTP's.

1 or 2 tenths is insignificant and will probably be undetectable. With 110 I work in .5gr increments and even then see little effect.

nhyrum · August 2, 2016, 10:04 PM

When I do my ocw loads, I do .2 grn. Increments. There is a DEFINITE difference in. 2 grains at 100. If I were you, I'd go down to the smallest division you can repeatedly, consistent and efficiently get. If that's .1 grain, go that way, if it's .01 do that(although a HELL of a lot more development needed there) but doing efficiency is key

I'm working with more powder as I reload 6.5cm so I'm in the 42 grn ballpark

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July 28, 2016, 06:51 PM	#1
fshfindr Senior Member Join Date: February 19, 2013 Location: South Jersey Posts: 188	Starting to reload for 100 yd match I'm reloading for my Ruger M77 357. I will be shooting in a 100 yd match and I'd like to know just how accurate I need to be with my powder. Will 1 or 2 tenths of a grain of H110 make much of a difference. I'm loading 16g into 158g XTP's. Thanks, __________________ Richard L.

July 29, 2016, 02:31 AM	#2
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	Hogdon lists 15gr starting for 1,619fps and 16.7gr max for 1,757fps. That's 1.7gr difference causing 138fps difference. 138 fps/1.7gr gives 81fps/gr of powder. 2 tenths of a powder would be 16 fps difference. So if your charges were +/- 0.1gr of powder you should have a very low extreme deviation for velocity, about 16 fps. If your powder charges are +/- 0.2gr then your extreme deviation should be around 32 fps. THIS IS WITH ALL ELSE BEING EQUAL such as bullet mass, frictional resistance, case capacity and primer energy, you won't get numbers that tight just from powder charge consistency. You can get an idea of how much dispersion two different velocities will give you with a standard 10mph crosswind. 1619fps with a 158gr FP XTP bullet has 3.5 MOA of wind correction at 100, and 1757fps with the same bullet has 3.2 MOA wind correction at 100. That's a difference of 0.3 inches drift for the two velocities, which is less than the diameter of the bullet. So I personally wouldn't worry too much about a +/- 0.2gr charge as long as that range is safe in my firearm. Jimro __________________ Machine guns are awesome until you have to carry one.

July 29, 2016, 05:24 PM	#4
Shimpy Senior Member Join Date: August 27, 2015 Posts: 153	I found out years ago while shooting bench rest that volume was more important than weight of powder. I never weighed my charges and had no idea what they were. My drop tube settings on a Belding and Mall drop tube were what I recorded for reference. __________________ The Villages, Florida.

July 29, 2016, 04:48 PM	#3
std7mag Senior Member Join Date: June 23, 2013 Location: Central Taxylvania.. Posts: 3,609	To add to Jimro, Don't forget that with any powder your going to have some degree of standard deviation, and an extreme spread with your loads to contend with also. Which would exaborate any difference in point of impact from your charge variance.

August 1, 2016, 10:28 AM	#5
buck460XVR Senior Member Join Date: December 28, 2006 Posts: 4,342	One or two grains will make a difference if you are one side or the other of the sweetspot of your accuracy load. Otherwise, the difference of a few fps will not be worth worrying about. I've found that with H110 in .357, that the highest velocity loads are not the most accurate.

August 2, 2016, 10:04 PM	#7
nhyrum Senior Member Join Date: March 9, 2016 Posts: 588	When I do my ocw loads, I do .2 grn. Increments. There is a DEFINITE difference in. 2 grains at 100. If I were you, I'd go down to the smallest division you can repeatedly, consistent and efficiently get. If that's .1 grain, go that way, if it's .01 do that(although a HELL of a lot more development needed there) but doing efficiency is key I'm working with more powder as I reload 6.5cm so I'm in the 42 grn ballpark Sent from my SM-G920V using Tapatalk