Weighing Bullets -- how much difference matters?

[awshoot]

I had a sweet hunting load developed for 6.5mm 140 gn Hornaday SSTs but it sounds like, at least from the place I usually buy my stuff, that those are getting replaced with 143 gn ELD-Xs. So I've been trying to develop a load for those bullets and just having a devil of a time. To give you some idea, I could shoot a 1.5" group at 200 meters with my SST load, but I haven't been able to get under 1.1" with the ELD-X at 100 yards.

So for my next test I've weight sorted the bullets into lots falling into a tenth of a grain band (they range from a low of 142.50 to more than 143.60 (several were over this and I just set those aside). I'm wondering what people feel is a decent weight range to use. Should I keep them all within a tenth of each other (my scale measures to the 100th so I can probably get fairly accurate tenths) or is that a little on the extreme side?

I'm also tempted to change powders (IMR 4831) but I know I should only change one thing at a time. In previous batches, I hadn't weight sorted the bullets. I also found an online supplier of SSTs so picked up several boxes in case they really do go away and I can't get these to work well enough.

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[Steve M]

I don't see anything on the Hornady website or in their 10th edition manual to suggest that the SST is discontinued. Midway is expecting to receive stock in 9 days which is another indicator that it hasn't been discontinued.

Can't help you on the bullet sorting, but a test group of bullets weighing +/- 0.1gr would answer the question of how much does it help.

 

[bsa1917hunter]

The problem is more likely a seating depth or charge wt. issue. How much load development went into the ELD's????

 

[Alexx1401]

I had a sweet hunting load developed for 6.5mm 140 gn Hornaday SSTs but it sounds like, at least from the place I usually buy my stuff, that those are getting replaced with 143 gn ELD-Xs. So I've been trying to develop a load for those bullets and just having a devil of a time. To give you some idea, I could shoot a 1.5" group at 200 meters with my SST load, but I haven't been able to get under 1.1" with the ELD-X at 100 yards.

So for my next test I've weight sorted the bullets into lots falling into a tenth of a grain band (they range from a low of 142.50 to more than 143.60 (several were over this and I just set those aside). I'm wondering what people feel is a decent weight range to use. Should I keep them all within a tenth of each other (my scale measures to the 100th so I can probably get fairly accurate tenths) or is that a little on the extreme side?

I'm also tempted to change powders (IMR 4831) but I know I should only change one thing at a time. In previous batches, I hadn't weight sorted the bullets. I also found an online supplier of SSTs so picked up several boxes in case they really do go away and I can't get these to work well enough.

There are SOOOO many things that can effect this when you get to the kind of accuracy you're after. Yes I would sort them, find a weight that seems most abundant to try. Then different bullets? Of course different powders, and even seating. This is a trial and error thing since the round that is sub MOA in one gun is only groups in another. Even guns made by the same manufacturer will often for some reason like different loads. Of course keep good notes on what each is and play till you find the magic combination. Not really any other way I have ever seen to get the very best out of a load but trial and error.

 

[Member 5605]

Charge + case volume has more effect than bullet weight.

 

[DizzyJ]

I surprised you found that much variance in bullet weights. Even my cheapo Midway Dogtown bullets were within .1 GR each.

 

[james2562]

In my 308 loading I accept a standard deviation of 0.10 grain. With that level of accuracy I have not been able ro corrolate a difference in muzzle velocity to a difference in powder weight. I have not gotten to the point where I evaluated accuracy with the loads yet.

 

[USMC-03]

For hunting purposes, not in the least; worry about other variables.

 

[thorborg]

Bullet shape may change performance. for instance, I don't know the ELD-Xs since it is not in my book but from the online picture it appears one has a cannelure and one has not, it could change barrel harmonics, and possibly exacerbated if barrel is free floated or so I have gleaned from others. I'm hopeful to shoot under 1.5" @ 100 yards putting me in the good enough class instead of the sniper class.

 

[awshoot]

The problem is more likely a seating depth or charge wt. issue. How much load development went into the ELD's????

A fair amount I think. I started doing 7 sets of 7 shots each. First I one of those Hornady depth seating tools to get a measurement to the lands and then backed off a little and made 7 series at different seating depths. I measure with a quality caliper using an anvil and ogive attachment. I loaded it with a minimal load. Then I picked the best seating depth and did another 7 sets of 7 shots at fine grained seating depths above and below that best of the first batch. Out of these batches, I picked the best depth.

Then I started with the powder. My wife had been complaining about how much time I was taking at the range, so I tried to speed things up a little. So I did a batch of 5 sets of 6 shots with varying powder weights, then of those chose the best performer and did another batch of 5 sets/6shots with smaller increments above and below the previous best performer. Out of that my best set produced a six shot group of 1.7" for all six, if I subtract the worst of the group (so 5 shots), it is 1.43", and if I subtract 2 shots (so a 4 shot group) it is 0.67". If I average these three ways of looking at the group, I get 1.27". These were at 100 yds from a bench with sandbags.

So anyway, last night I was weighing bullets and thinking to myself "is it even worth it -- should I just switch powders now?"

 

[awshoot]

I don't see anything on the Hornady website or in their 10th edition manual to suggest that the SST is discontinued. Midway is expecting to receive stock in 9 days which is another indicator that it hasn't been discontinued.

Can't help you on the bullet sorting, but a test group of bullets weighing +/- 0.1gr would answer the question of how much does it help.

Well that is great news. I'll have to talk to the guy at my shop, the SST is a great proven hunting bullet.

 

[awshoot]

Charge + case volume has more effect than bullet weight.

So maybe I should be weight sorting the brass too. I'm using Lapua and I was sort of hoping that the expense would let me do a little bit of a shortcut.

 

[P7M13]

If I read correctly, you've already toyed with seating depth. It was a fluke discovery on my 308, farther off the lands for some ogive shapes works better than touching or 10 mils off. No idea why.
Also, is the shape of the metplat uniform on all the ELD-X bullets?

 

[P7M13]

So maybe I should be weight sorting the brass too. I'm using Lapua and I was sort of hoping that the expense would let me do a little bit of a shortcut.

Just my opinion, but I think that's going too far....

 

[awshoot]

Bullet shape may change performance. for instance, I don't know the ELD-Xs since it is not in my book but from the online picture it appears one has a cannelure and one has not, it could change barrel harmonics, and possibly exacerbated if barrel is free floated or so I have gleaned from others. I'm hopeful to shoot under 1.5" @ 100 yards putting me in the good enough class instead of the sniper class.

Interesting. I had never thought of the cannelure as anything other than a rough surface that would interfere with airflow. I just started googling on this issue though and Barnes has this bit -- maybe it is marketing, maybe true -- I'm definitely going to keep googling on this though:

An exclusive feature of the Triple-Shock X Bullet is multiple, precisely engineered rings cut into the bullet shank. These grooved rings act as relief valves as bullet metal flows under pressure while traveling down the bore. Instead of flowing from the front to the base of the bullet, the copper material expands into the grooves. This results in reduced pressures and less copper fouling. Reduced pressures mean the bullet can be safely loaded to higher velocities. The rings also alter barrel harmonics, greatly improving accuracy.

FAQ | Barnes Bullets​

 

[awshoot]

If I read correctly, you've already toyed with seating depth. It was a fluke discovery on my 308, farther off the lands for some ogive shapes works better than touching or 10 mils off. No idea why.
Also, is the shape of the metplat uniform on all the ELD-X bullets?

These all have a plastic tip and they appear quite uniform to my eye. The plastic tip is supposed to be improved because their previous tips (like the ones on the SST) would deform in flight (at least at long distance) due to heat from air friction. <broken link removed>

 

[awshoot]

I surprised you found that much variance in bullet weights. Even my cheapo Midway Dogtown bullets were within .1 GR each.

Agreed. I wonder if the plastic tip is the culprit.

 

[awshoot]

I don't see anything on the Hornady website or in their 10th edition manual to suggest that the SST is discontinued. Midway is expecting to receive stock in 9 days which is another indicator that it hasn't been discontinued.

Can't help you on the bullet sorting, but a test group of bullets weighing +/- 0.1gr would answer the question of how much does it help.

That's a good point. The more I think about this, the more it interests me.

 

[thorborg]

Interesting. I had never thought of the cannelure as anything other than a rough surface that would interfere with airflow. I just started googling on this issue though and Barnes has this bit -- maybe it is marketing, maybe true -- I'm definitely going to keep googling on this though:

An exclusive feature of the Triple-Shock X Bullet is multiple, precisely engineered rings cut into the bullet shank. These grooved rings act as relief valves as bullet metal flows under pressure while traveling down the bore. Instead of flowing from the front to the base of the bullet, the copper material expands into the grooves. This results in reduced pressures and less copper fouling. Reduced pressures mean the bullet can be safely loaded to higher velocities. The rings also alter barrel harmonics, greatly improving accuracy.

FAQ | Barnes Bullets​

Well there you have it, messing with the surface of the bullet can alter barrel harmonics, per Barns.
Ignoring any disparity over bullet shape differences; different shape bullets usually require their own set of "tweaks" for optimum performance (not good enough performance) in a particular gun. Though less than radical, a cannelure, is "altering".
All in all, I wouldn't give up on the projectile if it didn't perform Identical when using my best load for different bullet. I would work up a new load like you should when any different component is substituted and let the round speak for itself.

 

[DizzyJ]

Agreed. I wonder if the plastic tip is the culprit.

Still seems odd to me.