Berger bullet question

[rebs]

I have the Berger 80.5 gr full bore in 223 cal.
When I weighed them the spread was 80.4 to 80.6
Base to ogive was .597 to 602
Is this about normal or average for these bullets ?
Will the weight spread and ogive spread show up on your target in slightly bigger groups at 300 yds ?

 

[Zero333]

The weight spread is fine but I would segregate the base to ogive into 3 groups... .
.597"-.598"
.599"-.600"
.601"-.602"

I've not come across Berger bullets with that much base to ogive spread. But segregating them will fix the problem.

I had some 107 smk made back in 1996 and the base to ogive variance was 0.009" (almost 10 thousands !).

Once I sorted them as mentioned above, they were the best shooting 107 smk's I've ever shot.

 

[rebs]

The weight spread is fine but I would segregate the base to ogive into 3 groups... .
.597"-.598"
.599"-.600"
.601"-.602"

I've not come across Berger bullets with that much base to ogive spread. But segregating them will fix the problem.

I had some 107 smk made back in 1996 and the base to ogive variance was 0.009" (almost 10 thousands !).

Once I sorted them as mentioned above, they were the best shooting 107 smk's I've ever shot.

Thank you for the advice, I'll do it

 

[rebs]

Is it normal for Bergers to have this much variance ?

 

[Ledd Slinger]

Is it normal for Bergers to have this much variance ?

If there's only a couple bullets at the extremes on either end and the rest of the bullets are very close, then yeah. Every box will have a few culls. Also depends on where you are measuring the ogive. You should be making contact right at the front of the bearing surface where the rifling lands first touches the bullet as it goes down the bore. If you are contacting higher on the ogive then you can get more variance

I make a short dummy chamber piece with my reamer to measure base to ogive so I know it's the exact same contact point and angle of the lands in my chamber. Also good for measuring headspace on brass

 

[Tesoro]

Without having a custom tool like in the pics above there is no way, imo, you can measure bto of a vld bullet accurately and consistently using dial calipers and a comparator, and especially so on small bullets.

 

[ACard]

This comparator/gauge set up is all formed from reamers as well.

Area 419 ZERO Headspace and Ogive Measurement Gauge Kit

NEED CALIPERS? ORDER MITUTOYO CALIPERS HERE.

www.area419.com

 

[Tesoro]

This comparator/gauge set up is all formed from reamers as well.

Area 419 ZERO Headspace and Ogive Measurement Gauge Kit

NEED CALIPERS? ORDER MITUTOYO CALIPERS HERE.

www.area419.com

Might be able to swallow if didnt have to buy an entire kit. They should sell piecemeal Hornady style. The cheapo hornady comparator works just fine for bumping but bullet measuring is a diff story. Next time I have a bbl made I will have the smith make me what Ledd Slinger has - thx for the idea.!

 

[Bill Norris]

Might be able to swallow if didnt have to buy an entire kit. They should sell piecemeal Hornady style. The cheapo hornady comparator works just fine for bumping but bullet measuring is a diff story. Next time I have a bbl made I will have the smith make me what Ledd Slinger has - thx for the idea.!

I find a chamber copy very valuable in the measuring process.

 

[Ledd Slinger]

This comparator/gauge set up is all formed from reamers as well.

Area 419 ZERO Headspace and Ogive Measurement Gauge Kit

NEED CALIPERS? ORDER MITUTOYO CALIPERS HERE.

www.area419.com

No, that wont be completely accurate. It's so easy to make a chamber copy for measuring. If you don't have the means of doing it yourself, any gunsmith can whip one up on a lathe or mill pretty fast. Even if its made with a SAAMI reamer for a factory rifle, it will be better. Also much more affordable than the 419 kit. I use aluminum round bar so it doesn't scratch the bullet jackets.

 

[rwj]

I find a chamber copy very valuable in the measuring process.

Agreed at the beginning of the barrel’s life. But throat erosion can’t be replicated…

 

[Bill Norris]

Agreed at the beginning of the barrel’s life. But throat erosion can’t be replicated…

It's good while it does work though.

 

[wkdickinson]

I've measured 100's of 105 Hybrids, the base-to-ogive is anything but consistant (sorry I don't have the data at hand), in fact it was shocking how inconstant they were. I don't shoot them anymore.

 

[barefooter56]

I have the Berger 80.5 gr full bore in 223 cal.
When I weighed them the spread was 80.4 to 80.6
Base to ogive was .597 to 602
Is this about normal or average for these bullets ?
Will the weight spread and ogive spread show up on your target in slightly bigger groups at 300 yds ?

Berger bullet specs can be found here : https://bergerbullets.com/information/why-berger/
Keep in mind that your bullet base to ogive variance MAY also be due to variations in pressure used on the caliper. Its an issue we all have with the tools we have to use as optical comparators like we use in production that are very expensive!

 

[RegionRat]

I will add just two more concepts.

First concept is about gaging on curvatures. A hybrid means that two different ogive curvatures are used. A tangent where the rifling is engaged, and a secant or VLD profile above it.

If you try to inspect, try to insure that your tooling doesn't go near the transition. This will lead to very noisy data. Try to gage slightly away from the blend between the two different curvatures, either firmly in the tangent part or up in the secant part if you think that is important. In theory, your rifle only touches the tangent part so think about the inspection "anvil" formed by your tooling. Sorting on the transition between the two different curvatures typically requires profilometry or an optical comparator that is complex and expensive.

(In my opinion, it is easier to just test the rifle's performance with these bullets than it is to gage the bullet's dimensions and then back into a correlation on the target.)

Second concept is about your sorting and testing to determine if you can shoot the difference.
Once you settle on your gaging process and think you have enough samples of the two extreme sort bins, it is time for a side-by-side test to determine if your extra work was valuable or if you can skip it. I will add it takes a pretty healthy sample size to prove to yourself you can shoot the difference between subtle dimensions. It also takes some good shooting to get the signal out of the noise.

Culling what are clearly QC escapes is not the same as normal or common sorting. I hope you don't find wonky ones in the batch but it can and does happen.

Culling the rare escape defect is certainly going to prevent a flyer, but it is up to the user to decide how much effort to put into that task. It takes some disciplined shooting/loading to be able to demonstrate the difference between raw bullets and sorted ones. With experience and progress, you will know when you will benefit. YMMV

 

[DaveTooley]

Just a bit of data. Back when I was testing the affects of meplat shape and diameter over an Oehler 43 I took some 6MM bullets, out of the same box mind you, that had a .020" difference in BTO. Shot them and measured BC's at 300 yds. The difference was negligible. The difference would have gotten lost in the noise even at 1K. Now pick and choose meplat shapes is another matter but that will only show up on the target past 600 yds. YMMV

 

[D-4297]

Just a thought about all of this . Last year ; I bought a thousand rounds of "Spun" 185gr Berger Target bullets from someone who was quitting the sport . These were done on a Bullet Genie , and I had good confidence in them being done correctly . About six months later ; I purchased 2,000 of the same Lot number , strictly by chance , and there was less than a two point difference in over twenty strings shot with the factory bullets , as compared to the Spun rounds used on in Competition . The 1.6 point per string can make a difference , but what I'm trying to say here is , "Sometimes ; we just Over-think things a little bit".