175 Gr SMK Question

[PharmShooter]

Guys,

I've been reloading for almost a year now and the lot of 175 gr. SMK's for my .308 has finally depleted. With that being said, I just received some new bullets and ran a few rounds set up exactly as before on my Forster Co-Ax press using Redding Competition bushing dies. When I measured using the comparator, the new rounds were .016" longer than the others, but the overall length was just slightly different.

Am I back to the drawing board relative to the seating depth the gun likes? I'm assuming there is a slight difference in the profile of the bullet in this lot...Is this a correct assumption?

How would you proceed????

Thanks!

 

[biner626]

Sorry no help. I need to re measure my new lots...

 

[JeffinTX]

So you are saying that the new rounds were 0.016" longer for the bullet to touch the lands using the comparator from the previous lot of bullets? If so, how many rounds ago was that? 100, 200, 500, more? Its helpful to keep a log for the gun if you shoot a lot to keep track of rounds downrange, and if/when something does real well or poorly. Conditions, light, wind, temp, etc. 0.016" throat erosion wouldn't be surprising if you'd run several hundred rounds through it since you last checked. Then adjust the seating die for the desired jump and move on.

 

[targaflorio]

That's the lot to lot ogive variation in Sierra Matchkings? Wow, that seems like a lot. I would start seating depth like its a whole new bullet.

 

[kansas]

I use a hornady bullet comp and can probably get that much variation if I'm not consistent in the way I attach it to the calipers. I'm saying you did but something to check. SMKs are great bullets and that's mostly what I shoot but I've found Bergers to be more consistent.

 

[TheGerman]

I keep a card on all the rifles I reload for that have the ogive length of the 'master bullet' all of my other measurements are based on. Then I keep what the fired shoulder measurement is, lands dept, etc.

If you keep information like this you can see what's changed. My guess is it may be a few 'bad' bullets in your box. How many have you measured and gotten the same measurement? If they are consistent at the new ogive, simply update the seating depth with the difference from your original ogive depth to the difference in the ones now.

 

[MajorHeadTrauma]

First off, I use a Sinclair comparator. I find it gets closer to the barring surfaces of a bullet.

Second, I found a great deal of inconsistency in Sierra's current bullets. In a single box of the same lot number, I found a .022 inch variation from the bullet base to ogive. The lot appeared to be from at least 4 different dies.

Third, after my frustration with the last lot of 175 SMKs, I switched to Bergers.

 

[ksthomas]

PharmShooter,

Perfectly normal with these bullets, and just something the shooter needs to be aware of. Once a lot is changed, be it different material, an adjustment on the press or a new form die (all of which should cause a lot to be terminated, and a new lot begun) these are simply the sort of variables you get. As far as coming from different dies, no, that doesn't happen. Not unless there was some really (REALLY) major screw-up during polishing or packaging. But it is possible that an operator made some changes during a run, and simply didn't initiate a new lot as he is supposed to when such changes are made.

 

[nuclear_shooter]

I use a hornady bullet comp and can probably get that much variation if I'm not consistent in the way I attach it to the calipers. I'm saying you did but something to check. SMKs are great bullets and that's mostly what I shoot but I've found Bergers to be more consistent.

Are you sure you're doing it right? I use the same tool and get maybe a 0.002" variation worst case. I just stick the bullet in, close the calipers, and make sure the base is square with the caliper.

Edit: I didn't mean to come off as hostile, it just doesn't seem right.

 

[Deerhunter28]

I separate all my SMK's by ogive length.
.020 sounds like a lot but they do vary.
Once I find where it shoots the best off lands I just reset my die to make the same distance from the lands.
This is the only way I have found to make it work with the varying size ogive lengths.

Hope this makes since?


PSE EVO 60 Lbs.
Blacked out

 

[PharmShooter]

In response to a couple of questions, I use the Sinclair comp and I am positive I am measuring correctly. I had shot appx 20 test rounds in between so throat erosion of that magnitude probably isn't the issue. At least I wouldn't think so. Thanks for the comments. Sounds like this has been seen by others.

So, are Bergers that much better?????

 

[jkonzal]

Bergers are that much more expensive!!!!! ;-)

 

[SporterII]

Another thing you might see is receiving a returned batch containing someone's culled bullets. I have a box of 500 here right now. They have been opened. Came from a good supplier. They measure all over the place.
Nice huh?

 

[PharmShooter]

Another thing you might see is receiving a returned batch containing someone's culled bullets. I have a box of 500 here right now. They have been opened. Came from a good supplier. They measure all over the place.
Nice huh?

That would make me a very unhappy customer...Sorry for your situation...

 

[biner626]

You could sort them into same length lots. PITA, but, that would remediate some of the issues you may have.

 

[Monmouth]

Another thing you might see is receiving a returned batch containing someone's culled bullets. I have a box of 500 here right now. They have been opened. Came from a good supplier. They measure all over the place.
Nice huh?

That's just wrong!

 

[SporterII]

I did not want to hijack this thread. I do believe that this is what I have . Third box of 500 and this box clearly contains beyond 'spec' compared to the QC seen in my previous lots. Box seal and plastic bag both clearly opened.
I would reccommend the obvious upon recieving product.

 

[opeagle]

I've seen .010 or so between mine and a buddy's older box of 175's. They all shoot fine.

As we obsess over every detail, and I do it too, it caused me some pause. The targets don't know the difference and I cannot tell you they shoot any differently.

 

[George63]

OK - not many of the responses deal with any "meat" of the situation - and answer the ? how to proceed:

1st shoot some of the new batch, any change? - if not, load and shoot

if yes, first would be to adjust the seating die to get the same base to ogive measurement- shoot these, do they perform the same as the original load? - if so load and shoot

if this does not work I would try to "box" the old load + and - .1 gr ; + and - .005 base to ogive (9 test batches)

if none of these do it, then start a new load - this time get 2000 bullets from the same batch

after 2000 a load will need tweaking anyway

 

[Infinity]

PharmShooter,

Perfectly normal with these bullets, and just something the shooter needs to be aware of. Once a lot is changed, be it different material, an adjustment on the press or a new form die (all of which should cause a lot to be terminated, and a new lot begun) these are simply the sort of variables you get. As far as coming from different dies, no, that doesn't happen. Not unless there was some really (REALLY) major screw-up during polishing or packaging. But it is possible that an operator made some changes during a run, and simply didn't initiate a new lot as he is supposed to when such changes are made.

Saved me so much typing...This...