How much difference does.4g make in accuracy?

[urbanrifleman]

I have nodes in 6bra and 6xc that shoot in the same hole that are at least .3 grains wide.... if not more.

And, of course, this all relative. If you are shooting a say, a 33xc with Retumbo .4 grains would be tiny at 100 grains of powder verses a 223 with 23 grains of powder...

 

[7br]

Not an F-Class or PRS shooter. Mostly groundhogs and an occasional local SBR match. My personal parameters are +/- .05gr for a .1 spread. 6br, .223 Wylde and .204 Ruger with extruded powders at 100yds delivers consistent 5 shot ragged holes easily covered with a dime.

 

[Pete Wass]

Sorry I lead many of you astray. I was looking for information on hundredths. Ill correct the headline.

 

[searcher]

I'm not knocking the anal folks who must measure to the nth decimal place, as I'm kind of in that category - but when i think back on all the

Just an observation here. I read the posters who scoff at a .04 variation in powder wt. as not making a difference in overall accuracy. Among this same group, they will post how a .005” difference in seating depth was a game changer for their group size. Guess it depends on the shooting discipline ur are competing in!
The powder u are using will often dictate the fidelity of ur powder charge. Each kernel of stick powder will have a different value depending on the powder itself. A kernel of Varget is typically .02 grain, powders like VV140 cut that down to .015 gr. With that difference, ur loading window can now become smaller. At long range where ur taking quality control checks to the extreme ( weighing primers etc.) that smaller powder charge window can matter ( low es & sd).

I mentioned a .004 variation not being much at all - not .04. Having a .004 variation in powder will result in a few feet per second in most calibers, perhaps less in the largest ones. A .005" seating depth variation is HUGE for most tuned rifle loads, often turning a great load into a poor one. Granted, if one is shooting a pistol at a target from 75 feet, one might not see much if the seating is .005" off. I know this from having shot 3-gun bullseye matches for years. But I also know from shooting bench rest for many years, that .005 depth can be like the Grand Canyon. If I were shooting against a peer and both of us were challenged to change to either a .004 powder deviation or a .005" change in depth (in either direction) with all else being the same, I'd jump on the .004 all day long. I know the .005" seating depth change is going to change my velocity one way or the other FAR more than a .004 change in powder - whether stick, ball or whatever. If shooting a rifle, these same facts will apply whether shooting PRS, benchrest or any other discipline. Perhaps we disagree on this....

 

[searcher]

Depending on the tune and the rifle/load...you won't see that.

I agree. 4/10 of a grain will completely change the load in my .17 Hornet. In my .375 H&H, not noticeable at all.

 

[Bob3700]

I'm not knocking the anal folks who must measure to the nth decimal place, as I'm kind of in that category - but when i think back on all the

I mentioned a .004 variation not being much at all - not .04. Having a .004 variation in powder will result in a few feet per second in most calibers, perhaps less in the largest ones. A .005" seating depth variation is HUGE for most tuned rifle loads, often turning a great load into a poor one. Granted, if one is shooting a pistol at a target from 75 feet, one might not see much if the seating is .005" off. I know this from having shot 3-gun bullseye matches for years. But I also know from shooting bench rest for many years, that .005 depth can be like the Grand Canyon. If I were shooting against a peer and both of us were challenged to change to either a .004 powder deviation or a .005" change in depth (in either direction) with all else being the same, I'd jump on the .004 all day long. I know the .005" seating depth change is going to change my velocity one way or the other FAR more than a .004 change in powder - whether stick, ball or whatever. If shooting a rifle, these same facts will apply whether shooting PRS, benchrest or any other discipline. Perhaps we disagree on this....

So I assume that you are chasing the throat in your bbl as the round count climbs to maintain the<.005" variation in seating depth?
If you shoot a discipline where you can seat your bullets long and let the bbl determine the actual depth, then a variation in seating depth of .005" in a loaded round is inconsequential. A variation of .04gr. of powder at 1K may give you just enough vertical to cause issues.
Short range benchrest may be one of the games where that .005" matters. Our experiences may just differ on this one.

 

[DShortt]

I agree. 4/10 of a grain will completely change the load in my .17 Hornet. In my .375 H&H, not noticeable at all.

So.... let's review definitions here.

.4 = 4/10

.04 = 4/100

.004 = 4/1000

I don't think I'm off in the weeds. (?)

And we are talking about divisions of a grain to begin with.....

The OP listed .4 in the thread title, yet .004 in his verbiage. Then began talking about .02.

WTH?

 

[Dufas]

0.4gr @ 100, yup. 0.04 gr @ 100 nope.

 

[hoz53]

So.... let's review definitions here.

.4 = 4/10

.04 = 4/100

.004 = 4/1000

I don't think I'm off in the weeds. (?)

And we are talking about divisions of a grain to begin with.....

The OP listed .4 in the thread title, yet .004 in his verbiage. Then began talking about .02.

WTH?

he did apologize in #43 and said he made a typo and was looking for info in hundredths which would be .04

 

[hoz53]

0.4gr @ 100, yup. 0.04 gr @ 100 nope.

.04 gr @ 1000 yup

 

[DShortt]

he did apologize in #43 and said he made a typo and was looking for info in hundredths which would be .04

OK, well I'm gonna call myself out as a Neanderthal then.

I'll never fret over .00

 

[Larry Koch]

I'd worry about the wind.

 

[DShortt]

I'd worry about the wind.

Bingo!

 

[searcher]

So I assume that you are chasing the throat in your bbl as the round count climbs to maintain the<.005" variation in seating depth?
If you shoot a discipline where you can seat your bullets long and let the bbl determine the actual depth, then a variation in seating depth of .005" in a loaded round is inconsequential. A variation of .04gr. of powder at 1K may give you just enough vertical to cause issues.
Short range benchrest may be one of the games where that .005" matters. Our experiences may just differ on this one.

No - I don't chase the lands in any of my rifles. Some of the barrels on my varmint rifles have well over 6,000 rounds on them and I found better success in re-tuning the load as the barrel wears, rather than chasing lands. When that no longer works, I replace the barrel. Mind you, these are all barrels where I'm shooting off the lands.

What you say here about chasing the lands to maintain under .005" seating deviation if fine if you want a jammed load. But not all loads are jammed and that .005" seating depth variation will bite you. But, maybe you have just never noticed the results by firing thousands of groups on paper?

As you state, it does depend on the discipline. I don't much shoot what some might call long range, has always been point blank bench rest, F-Class (600 yd.) and varmints. What you now post about seating depth, using the "soft-seat" method of allowing the bullet to push back into the case is NOT the same as having .005" variation as you earlier referred to. Doing the "soft seat" method, there is no (or very little) variation - as you know. That said, continuing to use that method over the life of a barrel, due to throat erosion, one has to periodically tweak the load anyway, as when the throat grows, one gradually loses velocity as the bullet is systematically further out of the case over time.

I employ the "soft seat" method on my target rifles with most loads and I know when the barrel is ready for replacement when tune can no longer be achieved. We all do things differently. But - ask any successful benchrest shooter if they would be O.K. with having .005" deviation in seating depth on their loaded ammo. See what they have to say. Then ask them whether .004 powder deviation would have stopped them from setting the world record they shot dumping powder straight from the hopper. And while far more guys are weighing now than 20 years ago, some of those records have yet to be broken. I'm not professing to tell you or anyone else what works - but I know from my own experience what will ruin a load for me - and what hasn't. I know in my small caliber rounds, just pushing the bullet in another .005" can result in a much bigger change in velocity than .004 grains of powder ever would. Not arguing with you here. Just not sure we are on the same page.