How much weight deviation?

[Will]

When trying for small groups and weighing boolits. How much deviation do you allow as a percent of total weight. Say for a 150gr 30 cal. 1/10 a percent would be .15 gr. How much does it take to open up a group?

[btroj]

Much depends upon the rifle too. If the rifle is capable of 1 inch groups at 100 then 1 percent variation is certainly adequate.
If you have a bench type rifle with a good barrel- and I mean an honest bench type gun here- then you might want to go closer than 1 percent.
It also depends upon how good a shot you are. What are your expectations?

I think trying to get enough bullets that weight within .15 gr of each other is going to drive you crazy. Most jacketed bullets can't even come close to that.

Try going with 1 percent and see how it goes. So many things can affect cast bullet accuracy other than bullet weight. This is part of the challenge with them- controlling all the variables at once.

Good luck

[ku4hx]

When trying for small groups and weighing boolits. How much deviation do you allow as a percent of total weight. Say for a 150gr 30 cal. 1/10 a percent would be .15 gr. How much does it take to open up a group?

+ or - 1/10 a percent sounds good to me; might even find you can even widen that band.

How much it affects group size is likely going to be a gun-specific thing.

[onesonek]

I would have to say there is no set rule. That is entirely up the firearm and it's own wants. They have personalities not unlike people. But like most anything that shoots, the less variation, and more consistency, the better off one is. Powder or other component choice, alloy, etc. could very well could change group size more than minor weight variation also. So many variables for a definitive answer.

[Blammer]

on ten thousandth of a grain. :)

yea, that's the ticket!

usually with in one grain or less

[largom]

When weighing cast boolits I sort them by 1/10 grain. When finished weighing I sort them into groups based upon their weight. If I have 15 or more boolits that weigh the same they go into one group and labeled. The next group will contain boolits that weigh + or - 1/10 gr. and the next one will contain boolits + or - 2/10 gr. and so on. Boolits that do not fall into a spicific group go back into the pot.

You will find that the larger the boolit the greater the variation and also the least effect on target group size. My 22 cal. boolits get sorted by 1/10 gr. period while my 45-70 boolits may go into groups of + or - 3/10 gr.

Does all of this weigh sorting make that much of a difference? I doubt it but I like to do it and at my age I need all of the help I can get on the target. One other point I will add is that most digital scales are accurate to + or - 1/10 gr. so you already have a slight variance built in.

Larry

[darkroommike]

New to reloading but have an education in chemistry and physics.

If your scale is accurate to +/- 0.01 grains that's usually with a deviation of half that. Remember that you weigh your boolits, you weigh your powder charges (and sometimes you slice powder granules into thirds to get that +/- 0.01 per cent accuracy), you weigh your brass (you do weigh your brass, right?). Each piece of brass has the same neck diameter +/- 0.10 %, the same neck thickness +/- 0.10 %, each has been turned down to perfect symmetry +/- 0.10 %, and you have exactly the same tension +/- 0.10 % on each bullet, each bullet has exactly the same lube +/- 0.10 %.

To take advantage of all this painful accuracy and the ten "perfect" rounds you somehow load per week, you have embedded your rifle in 5000 lbs of concrete so that the weight of your rifle is +/- 0.10 % of the the shooting mass, the system is cooled to the same temp +/- 0.10 % for each shot, the muzzle is ported into a vacuum chamber 100 yds long to avoid any wind deflection. And then, during the third shot an 2.0 Richter earthquake spoils your group.

You have to take the system as a whole, if you are already shooting 1/2 MOA groups, then you need to tighten control of what you CAN control, and decide which loading variables are going to affect the size of your groups the most by changing one variable at a time and then testing by shooting it.

I'll draw a final analogy to photography, something I know a lot about. Cameras used to have shutters that were only really accurate at one or two shutter speeds, other speeds could be off by as much as 25%, (you had to test to find).

Films were only approximately the rated sensitivity and that only in the lab with the company equipment (think powder) and the next batch could be different.

If you processed your own film (like loading) you could be sure that your processing time would be different from the recommended time.

And through all of that some very good pictures were made.

[captaint]

Just guessing here - but I'm thinking other factors, like what size was each boolit before you sized it?? How good is the base?? I would think one half percent is adequate for really good groups. Then, there are the other factors..... enjoy Mike

[1Shirt]

My rule of thumb is the smaller the blt, the more exact the weight requirement. I want my 22's and 6mm's to be exact weight. Want my 6.5's and 7MMs to be within a quarter of a grain, same for 30's. 32's and 35' a third to a half a grain is ok. 375's, 44's and 45's half to a grain is fine with me. I inspect but don't weigh handgun projectiles. If they look good they get shot. My 22's are picky in what they shoot as are my 243's. Weighing and sorting to exact weights is a pain in the tush, but it is rewarding at the range.
1Shirt!:coffee:

[W.R.Buchanan]

I'm not an expert on this , but it seems according to what I've read that it is more important to segregate your boolits into groups of the same weight, than what that exact weight is, and then shoot each of those groups for your accuracy groupings.

IE: you weigh all your boolits and they will fall into different groups of weights. 150 gr +.1,+.2,+.3,+.4,+.5, etc. You end up with 5 or more boolits of the same weight you shoot those as a group for accuracy. Thus all boolits in that group are exactly the same weight.

You will have several different groups of weights , all within 1/10 gr or so of each other , and all are loaded the same way, so the only difference between the groups is a few tenths of bullet weight, but all the bullets from one group are the same weight. So they should fly the same way, unless they have other problems ???

This is how the BPCS guys load their big boomers for accuracy in long rang Silhoutte and long range target matches. I personally think the BPCS guys and the Scheutzen shooters are probably at the top of the heap as far as Cast Boolit shooters go. So doing what they do is probably as good as you're going to get.

Here's the deal , at the end of the day loading the best ammo you are capible of is going to show up on your targets. It's up to you to learn how to load the best ammo you can.

I know from personal experience that my current process of loading .308 ammo has resulted in my placing much higher in my clubs silhoutte matches, than alot of other guys who are just throwing ammo together. Better ammo makes better shooters, simple as that.

Randy

[cbrick]

Randy,

Thread hijack but are they still shooting handgun silhouette at Rose Valley? What weekend?

Rick

[williamwaco]

I am assuming you are talking about cast bullets.
Weighing commercial jacketed bullets is a complete waste of time unless you are a competitive bench rest shooter and then you are not using commercial bullets anyway.

For years I have weighed my cast bullets into 1 grain groups.
Say 100 bullets will produce. . .

149.0 to 149.9
150.0 to 150.9
151.0 to 151.9
152.0 to 152.9

With a nominal 150 grain .30 caliber rifle bullet there will be 3 or 4 in the first group, 30 or so in the second group, 60 or so in the third group, and 5 or 6 in the heavy group.
I discard the lightest and heavest groups. That leaves me with two groups of bullets that weigh +/- half grain.

After thousands of rounds buried in the 100 yard berm, I can say with no doubt in my mind that the the entire exercise is a complete waste of time. The only positive thing that comes from this procedure is that I always find two or three wrinkled or unfilled bullets I missed on first inspection and an occasional bullet that will be four to five grains under weight.

Testing with loads using bullets from all four weight groups produces 100 yard groups of the same size as loads with bullets in a single grain group.

Yes, I still do it anyway.

[cbrick]

I can say with no doubt in my mind that the the entire exercise is a complete waste of time.

Testing with loads using bullets from all four weight groups produces 100 yard groups of the same size as loads with bullets in a single grain group. Yes, I still do it anyway.

Diddo. Yep. uh huh.

Not even my long range revolver match bullets do I weigh. I used to, years ago. Complete waste of time. Far more important is a perfect base and if used a completely flat, against the bullet base, square GC.

Rick

[williamwaco]

Diddo. Yep. uh huh.

Not even my long range revolver match bullets do I weigh. I used to, years ago. Complete waste of time. Far more important is a perfect base and if used a completely flat, against the bullet base, square GC.

Rick



Again DITTO.

[W.R.Buchanan]

cbrick: It is a Short Range Silhoutte Match and handguns get mixed in too. They also run .22 match at the same time.

3rd Saturday of every month.

We also shoot LR Sil on the 1st Saturday of the month.

Goto www.dock.net/ovgc/ for the club website and there is a monthly caldender posted so you can see what else is going on. 900+ members so there is alot to do.

Love to meet you face to face. where are you located? I'm in Ojai CA. I assume your relatively close by?

Just found out there is a CMP National Match Clinic tomarrow I want to go to. 10/30/2011 Next day,,,, Yes,, I did go. I am now CMP'd and part of the Civilian Militia. :Fire:

Randy