Bullet weight variances

In reloading when talking about the powders we talk in terms of 1/10 grain,  and how changes in powder weight may effect the accuracy of the bullet.

What about the bullet weight.

How much does the weight of a bullet need to change before we need to adjust the weight of the powder used to maintain a given accuracy.

From the below chart, what adjustments, if any, would you make in loading this batch of bullets for target shooting.

Sorry that the pic is so small and hard to read. Sample size was 712 bullets with weights ranging from 146.2 to 150.2 grains or 4.4 grains. So is the answer to use anything below xxx grains for plinking and load everything else with the same amount of powder and use for target matches.

@ 25 yards no issue @ 50 ?? the only way to know for that bullet and your gun is to chrono and ransom rest the lowest and the highest weight bullets.  Also if you increased powder on the lower weight bullet to increase speed, well unfortunately that is no guaranty of improved accuracy.   2% variation is acceptable to many rifle shooters.

You have a lot of light bullets in that batch.  Find a new bullet mfg. or if you made them recast them.

Everything below 148.2 I'd use for practice or the short line.

Personally I wouldn't worry about it until you are a High Master. 

FYI* - If you zeroed @25yards then at 50yards the difference in POI @ 900fps verses 700 fps is 2" and I doubt your variation will come even close to 200fps, probably less than 1/2 that.  So if it was 200fps and you centered your group 1/2" high the 700fps would still be in the 10 ring.
- Dave

* Sight height from barrel center will change these #'s.  I used an average optic mount height.

This may be hard to believe if your coming from a rifle background but what you need to do with a 4gr difference in bullet weights is ignore it. It will make less then 1/4" difference in POI at 50yds. That .1 gr of powder makes more difference at 50 yds then the bullet weight and that is still less then 1/2" at 50. There are a lot of different ballistic tables you can access to verify those numbers. Shooting the pistol out of hand you will never see the difference. I know that is hard for some shooters to wrap their heads around but if you want to test it then load a bunch of the lightest and the heaviest and see if you can tell the difference on the target. One more bit of info to think about while crunching numbers. A lighter bullet should come out of the barrel faster with the same powder charge and shoot higher then a heavier bullet right? But the heavier bullet creates more chamber pressure and burns the powder better so it should come out faster right? Or....

Went through sorting bullets by weight years ago like most. In the end found it really didnt matter much like Len stated.

All i really look for when loading today is a well formed base with no holes on cast bullets.

LenV has it.  Don't waste your time.  We are shooting very short distances with pistols.  If you really want to know the exact effect.  Get a ballistic calculator and input the information and the variance in bullet weight and it will tell you exactly the difference in POI

Look at it this way

A +/- 2 grain variance on a 148 grain bullet is 3%

A +/- .1 grain variance on 2.8 grains of powder is 7%.  

You readily accept 7% but want to clamp down on 3%?

The target won’t know the difference.

Greetings,

The 4 grain variation is not good.

It suggests that the moulds are not filling out consistently.

Once greased, inspection becomes moot.

A typical downside to buying commercial cast bullets.

Some vendors will sell you "as cast" bullets. Here you can inspect them as if you cast them yourself.

Cheers,

Dave

Thanks to all for the replies. I have learned a lot from you sharing your knowledge and experience. I appreciate it very much.

Wayne

LenV wrote:This may be hard to believe if your coming from a rifle background but what you need to do with a 4gr difference in bullet weights is ignore it. It will make less then 1/4" difference in POI at 50yds. That .1 gr of powder makes more difference at 50 yds then the bullet weight and that is still less then 1/2" at 50. There are a lot of different ballistic tables you can access to verify those numbers. Shooting the pistol out of hand you will never see the difference. I know that is hard for some shooters to wrap their heads around but if you want to test it then load a bunch of the lightest and the heaviest and see if you can tell the difference on the target. One more bit of info to think about while crunching numbers. A lighter bullet should come out of the barrel faster with the same powder charge and shoot higher then a heavier bullet right? But the heavier bullet creates more chamber pressure and burns the powder better so it should come out faster right? Or....

I too went through the time consuming exercise of weighing bullets. I also understand that the conversation in this thread is centered around cast bullets, however, I am using Winchester 230 FMJ bullets for matches in my hardball gun as I'm old school. Any bullet with a deviation of 2 +/- grains was put in the short line box. Almost without exception, out of each 100 bullets weighted, only 20+/- made it. Now, after reading your post Len and other posters that agree and add other sound reasons to not be concerned with weighing bullets and some suggesting it is a waste of time, I'm wishing that the time spent at the bench weighing bullets I had used for actual loading and I'd be all set with enough loaded ammo for the 2019 shooting season! I also have a grasp of the fact that ammunition for the short line deserves less QC as sustained fire gun control fundamentals are much more critical than ammunition used.
Accepting bullet weight deviation as almost a non-factor, how about bullet seating depth? I use Redding micro-adjust seating & crimping dies, so would a thousandth or two varation make a difference of significant concern or in other words, how critical to long line accuracy is bullet seating depth?
As some final comments, I also use Remington 230FMJs and I was surprised by the number of cull bullets premier brands like Remington & Winchester would have in each package. I was equally surprised at the deviation in the bullet lengths of those same bullets.

Greetings Brassmaster,

The Winchester 230 RNFMJ bullets, are they jacketed (exposed Lead at base) or plated bullets (Copper all over)?

The old RNFMJ bullets with the exposed Lead were extremely uniform in weight.

Pleased to see you are doing Quality Control on your bullets!!!

Cheers,

Dave

fc60 wrote:Greetings Brassmaster,

The Winchester 230 RNFMJ bullets, are they jacketed (exposed Lead at base) or plated bullets (Copper all over)?

The old RNFMJ bullets with the exposed Lead were extremely uniform in weight.

Pleased to see you are doing Quality Control on your bullets!!!

Cheers,

Dave

Thanks for the reply Dave. The Winchester bullets are jacketed. The weight variations described in my previous post was only matched by my surprise of the length variations of those same bullets. Even though I purchased a large quantity of the Winchester bullets at reduced prices because they have been discontinued by most dealers, (and maybe Winchester) I expected better from Winchester. I haven't weighed or measured the Remington 230 FMJs because I use them for practice, which by the way, are also discontinued. An aside which speaks to previous posts that underscores that QC of powder makes for better results on accuracy than bullet weight varations, I found through RR testing my Les Baer ball gun with both Winchester & Remington 230 FMJs that the Remington bullets required a full grain more of powder to approximate the same accuracy as the Winchesters.

Greetings Brassmaster,

Interesting reply, the plot thickens...

Are the two bullets the same diameter?

I trust the weight was the same 230 grain nominal?

Stimulates the little grey cells as to why one needs a bit more powder.

Do they chronograph the same speed when loaded for best accuracy?

What size groups at 50 yards were you getting?

Perhaps mention the powder and charge you used?

Cheers,

Dave

Wayneinky wrote:Sorry that the pic is so small and hard to read. Sample size was 712 bullets with weights ranging from 146.2 to 150.2 grains or 4.4 grains. So is the answer to use anything below xxx grains for plinking and load everything else with the same amount of powder and use for target matches.

Wayne:
Very interesting chart & SPC work. The C/L of the majority of the bullets probably verifies what others have posted regarding your mold cavities not totally filling. If you did not have the low weight outliers you would probably end up with a variation of only about maybe? 2 grains. And a sample size of 712 is an exceptional large sample size. Using a smaller sample size would have probably showed the same results and saved some charting time until you got closer to your goal/ideal total variation. As I am old & half blind if you ever "blow" that chart up I would sure like to see it.

fc60 wrote:Greetings Brassmaster,

Interesting reply, the plot thickens...

Are the two bullets the same diameter?

I trust the weight was the same 230 grain nominal?

Stimulates the little grey cells as to why one needs a bit more powder.

Do they chronograph the same speed when loaded for best accuracy?

What size groups at 50 yards were you getting?

Perhaps mention the powder and charge you used?

Cheers,

Dave

Dave: First, I have not miked the Remington FMJs as I use them for practice. Secondly, I have not crono'd any of the test loads used in the RR testing. The Winchester bullets were yielding 3-3.5'' @ 50 yards out of the RR. Remington's yielded about the same having used the same QC as with the Winchesters: virgin Starline Brass, resized, Winchester LP primers, 4.2 & 4.3 grains of Bullseye respectively and I'd have to verify bullet seating depth & crimp.  
So, I understand that crimp is a critical component to accuracy, but is bullet seating depth critical to accuracy. The benefit of your and other's thinking will be appreciated.
Thanks!
-Jim

Greetings,

Many thanks for the details.

Personally, I do not crimp jacketed bullets. I merely remove the case flare with the taper crimp die backed off.

I did find some test targets from my archives...

Cheers,

Dave