Varying bullet weight, how much difference?

[Bloke]

I have been reloading .357 mag for a couple of years now, without any serious problems. I was shooting my Phoenix comp targets last week, when I noticed the shot group increasing considerably. When I got home I checked the boxes and found I that on the worse scores I had used bullets from a new box I had bought.

I spent a couple of hours weighing all the bullets (500 !) and found that despite the box being labelled 158grain, the great majority of the bullets weighed between 178-180grain, an average error of 20+ grains! I won't say who the supplier was, because I have complained and they are contacting the company who cast the bullets. This may be a genuine one-off mistake, but it does seem quite a significant variance, partly because the powder I was using had no load data for such heavy bullets, so if these are going to be consistent, I may have to change powders. Some home cast loads that a friend makes for me only vary by about 0.5-1.0 grain at the most.

My question is: has anyone else found this much variance in commercial cast bullets? Also, would this difference in weight alone be responsible for nearly doubling my group size on a 25metre range?

[bullbarrel]

I found quite a bit of weight variance is PPU bullets I was reloading. Stopped using them and went Sierra.

It definitely will change your POI. Different ballistics, different barrel harmonics.

Make sure they refund not only the ammo but also your entry fee.

[Bloke]

I found quite a bit of weight variance is PPU bullets I was reloading. Stopped using them and went Sierra.

It definitely will change your POI. Different ballistics, different barrel harmonics.

Make sure they refund not only the ammo but also your entry fee.

I am waiting to see what the manufacturer's reply is, and the shop I bought them from has already gracefully offered to refund my fees without asking (It was the postal Phoenix league - only a fiver, so I'll just drop it in their Help for Heroes box), I use them frequently and they are good guys.

Part of the problem seems to be the very limited range of cast bullets here in Lincs, The majority of the shooters I know cast their own, reducing the demand, so most shops seem to stock heads by this local maker only. If I then have to order cast bullets for delivery, the postage costs almost make it cheaper to buy jacketed bullets locally ! having said that, if this is a common problem, I will just ask the shop to order from another supplier, if the order is big enough, they will be fine with that.

[bullbarrel]

You could start weighing and putting them into batches and rezero for each batch. The variance could be quite large compared with long range shooting and you'd probably have to work out how large the batch can be.

PITA but a plan.

[enfield2band]

I think the 178 grain bullet is a bit of an odd-ball. There is little or no loading data for it that I can find.
Someone gave me 50+ 178 grain RN FMJ copper jacketed bullets that I thought I would try. I came to the conclusion they are more trouble than they are worth.

[amc577]

If you are shooting comps, you might consider the H & N copper plated bullets, (soft lead core with copper plate, plus HS coating) which are very consistent in weight. Shooting Supplies in Luxembourg will supply them. About the same price as cast bullets, depending on the exchange rate of course.

amc577

[Parabuteo]

You could start weighing and putting them into batches and rezero for each batch. The variance could be quite large compared with long range shooting and you'd probably have to work out how large the batch can be.

PITA but a plan.

That is how we used to deal with the problem shooting FTR Andy. But then we had sighters and each shot indicated.

I used to do it with Bergers and SMKs but dont really need to bother much with HBCs (although I probably should....)

There can be some really wild differences or the occasional bad bullet which is worth weeding out. I used to keep the baddies for fouling shots.

[Bloke]

I have sorted them into batches, and I will try and load up a few, but may end up throwing them at my mate to recast. I just have to pop them back to the shop for them to check and for refund if that is what I decide.

[old_n07]

Hopefully it was just a packaging error at the manufacturers as a 20gr difference is a hell of a lot, as has been said above I found PPU to be very inconsistent compared to SMK's but they are quite a bit cheaper in the first place

Neil

[Daryll]

I found a similar (but smaller) variance with my current batch of 158gn TC lead bullets. I've never weighed them before, but my club ran a precision comp so i wanted some super accurate ammo.

I used a box of virgin Lapua brass, and started weighing the bullets.... and found they varied between 154 and 190gn.
I eventually found a batch of 100, (enough for the comp), which were +/- 1gn.

I may have unrealistic expectations, but i would have expected the whole box of 500 to be maybe +/- 1 or 2 gn...??

[Parabuteo]

Hopefully it was just a packaging error at the manufacturers as a 20gr difference is a hell of a lot, as has been said above I found PPU to be very inconsistent compared to SMK's but they are quite a bit cheaper in the first place

Neil

Some time back I weighed a 500 batch of optimus HBCs.

There was not more than .5 grain across the 500 and that came down to 10 or so rogues.

[sidesy]

i think you'd be surpised by the varation in most bullets. Especially if your after consistency

[amc577]

Weighed 30 of the H and N HS plated bullets 165 gn....all weighed 166.7 gns...no variation. The lead centres are swaged, not cast, before electroplating with 6 thou of copper, then given a "high speed coating" to prevent any barrel fouling.

amc577

[Bloke]

Must have been a one-off batch, my money has been refunded with an apology, and I can keep the duff ones - (time to pop to my mate's and fire the smelter up), the new box are all fine, sorted.