Sierra .243 bullets #1530 really inconsistant length?

[Bart B.]

From Redding's FAQ referenced:

You must use a bullet comparator, like our Instant Indicator, to compare bullet seating depths. A comparator contacts the bullet at the bore diameter contact point. This is important, as bullets can vary slightly in overall length.

What 24 caliber bore diameter fo they use? There's a couple thousandths spread across all of them. Same spread allowed for 24 caliber bullets

The lands first touch the bullet at a diameter larger than bore diameter. At the very small leade angles used and the average small angle the bullet ogive has there, several thousandths spread on the bullet ogive touch point happens for .001" spread in diameters and a 30 MOA spread in leade angle

What diameter does Redding use?

Another thing they mention:

Our Competition Seating Die features a bullet guide that is only .0005-.001" larger than bullet diameter.

I've seen a spread of .002" spread in 30 caliber bullets. No idea what the spread is for 24 caliber ones. What guide diameter do they use?

 

[K22]

I've used this bullet extensively for many years. I have encounter the same kind of ogive variations in this bullet. In many rifles brands this bullet requires seating a lot shorter than the book values. The one exception I found is with the Rem factory barrels which have a long free bore.

For example and can seat to 2.675 COL in my Rem 700 (factory barrel) and still be no where near the lands. Whereas in my Tikka 3, my COL is 2.610 with a .010" jump. In my Browning X bolt it's 2.620 with a .010" jump. My model 7 Rem, re barrel with a Hart barrel it's 2.590 with a .010 jump.

If you measure the distance to the lands for each rifle with this bullet and set it back .020" you should be fine. This bullet likes a little bit of jump in my experience.

This is an excellent hunting bullet and is my all around go to bullet for the 243 Win. I wouldn't let the ogive variation kept me from using it.

 

[Bart B.]

Berger has this article on CBTO that leads me to think they believe the bullet first touches the lands at bullet diameter; the place where the curved ogive starts from bullet diameter.

http://www.bergerbullets.com/effect...coal-and-cartridge-base-to-ogive-cbto-part-2/

This is a good article on ogive shapes.

http://www.accurateshooter.com/ballistics/tangent-vs-secant-vs-hybrid-ogive-bullets/

 

[Dusty Stevens]

It is not a match bullet and is mass produced on multiple dies. Cant believe some are as close as they are

 

[Ironworker]

How do they shoot ?

 

[Bart B.]

It is not a match bullet and is mass produced on multiple dies. Cant believe some are as close as they are

I doubt any retail lot of Sierra bullets comes from several machines' set of forming dies. If they adjust any one of several dies in a given machine, a new lot number is assigned to all bullets from it thereafter.

If you don't believe me, ask them. If you don't believe them, so be it.

 

[KevinThomas]

They're all coming off the same die, if we're talking about a single lot of bullets. This "multiple die/multiple machines" nonsense gets repeated from time to time and has no basis in fact. They aren't mixed, and are segregated by their lot numbers all the way from production to packaging.

 

[Bart B.]

This "multiple die/multiple machines" nonsense gets repeated from time to time and has no basis in fact.

Frankfort and Lake City arsenals often mixed 30 caliber bullets from different machines (and therefore dies) in both service and match versions' lots of ammo. So says the government ballistics engineers affiliated with them.

Commercial bullet lots are single machine/dies produced.

 

[KevinThomas]

Actually, Sierra used to mix lots of 168 SMKs as well; they did it for a single customer, at the insistence of the customer themselves. That customer was Lake City Army Ammunition Plant. They (LCAAP) didn't want to bother with trying to keep the lots separated during loading, and so had us mix them (or "composite lots" as they called it) during production. Different machines, different form dies, different everything, all into the same orders. It seriously went against the grain, but it was what the customer wanted. In the literally hundreds of runs that I shot and certified over the years, I don't recall a single one, ever, that failed to meet accuracy specs and was subsequently rejected. That said, I'll add that with the creation of the M118LR and the (then) new 175 gr SMK, they discontinued the practice of mixing lots, and began to take the additional pains to ensure that bullets remained separated by lot, and were loaded with bullets all coming from the same lot.

In the case of Berger, everything within a given lot is literally coming off the same draw punches and run through the same forming die, no exceptions, and they're NEVER mixed. Lapua runs theirs in a similar fashion, and again, NEVER mixes lots. I can't vouch for Hornady, Nosler or Speer from personal observation, but I very seriously doubt that any of them mix lots either. It's an obvious point for trouble to be created, and something that is very easy to prevent by simply not mixing lots.

 

[Dusty Stevens]

I guess i should have taken pictures at sierra last year. They had concrete mixers full of bullets and barrels full of cores. Those cores came off 8 squirt dies

 

[Bart B.]

Actually, Sierra used to mix lots of 168 SMKs as well; they did it for a single customer, at the insistence of the customer themselves. That customer was Lake City Army Ammunition Plant. They (LCAAP) didn't want to bother with trying to keep the lots separated during loading, and so had us mix them (or "composite lots" as they called it) during production. Different machines, different form dies, different everything, all into the same orders. It seriously went against the grain, but it was what the customer wanted. In the literally hundreds of runs that I shot and certified over the years, I don't recall a single one, ever, that failed to meet accuracy specs and was subsequently rejected

LCAAP did that for the M852 match ammo. Arsenal M852 accuracy spec was 3.5" mean radius ar 600 yards for a couple hundred shots in a bolt actioned test barrel in a Mann rest. One group about 12" diameter on average.

 

[Bart B.]

I guess i should have taken pictures at sierra last year. They had concrete mixers full of bullets and barrels full of cores. Those cores came off 8 squirt dies

I now think Sierra has not been mixing core lots for a given lot of hollow point bullets. Each lot of bullets has the same core lot. They're the least critical part of the bullet. They upset quite uniformly in jackets.

Thanks to Kevin's post. Must be confused them with FMJ bullet cores. I'll accept 2 demerits.

 

[Lefty Trigger]

Years ago i had a box of 1530 bullets that produced 3" groups @ 100 yards out of my Rem 40X when the norm was 3/4" or smaller.
I now give every component a lot number and record it. When accuracy goes bad, i have a place to start.

Sierra sells seconds, maybe you got a box? https://www.sierrabullets.com/about-us/factory-outlet/

That's possible, I bought them off the shelf from a store I have never been to before.

 

[Lefty Trigger]

How do they shoot ?

Actually,... not worth a damn in my gun. Not bad but not awesome either. The gun really likes the 87gr V-max and the 95gr SST. 1:10 twist barrel.

 

[KevinThomas]

That's possible, I bought them off the shelf from a store I have never been to before.

No, not possible. They only sell seconds at the factory outlet, and they're sold by the pound in bags, never boxed. If you got them in a sealed green box, they were factory firsts that went through the normal channels.

 

[Richard Coody]

Sierra game kings are.exellent bullets on game of all types. They are not a match king. the ogive will not be as consistent therefore seating will not be as consistent. you could sort them by base to ogive and get more consistency but is that really necessary for your intended use?

 

[Dusty Stevens]

Sierra game kings are.exellent bullets on game of all types. They are not a match king. the ogive will not be as consistent therefore seating will not be as consistent. you could sort them by base to ogive and get more consistency but is that really necessary for your intended use?

Ojive consistency (which is what people use to sort) is a product of the lead core consistency. Every different die that squirts the cores will make a different bullet.

 

[Bart B.]

Sierra game kings are.exellent bullets on game of all types. They are not a match king. the ogive will not be as consistent therefore seating will not be as consistent.

Back in the '50's and '60's, people pulled the 174 grain match bullet from M72 30-06 match ammo then replaced it with a Sierra 180 grain SBT hunting bullet. Shot more accurate than the original load and often as good as Sierra's 180 FMJBT Match King bullet.

The 165 grain AP bullet in military 30-06 ammo was often replaced with Sierra's 165 grain SBT hunting bullet and it typically shot more accurate than M72 match ammo

 

[Richard Coody]

Back in the '50's and '60's, people pulled the 174 grain match bullet from M72 30-06 match ammo then replaced it with a Sierra 180 grain SBT hunting bullet. Shot more accurate than the original load and often as good as Sierra's 180 FMJBT Match King bullet.

The 165 grain AP bullet in military 30-06 ammo was often replaced with Sierra's 165 grain SBT hunting bullet and it typically shot more accurate than M72 match ammo

i have shot them in my 6br and 6mm turbo 40 and they shot very well . not up to berger hybrid standards but very acceptable for varmints.

you certainly need to check seating depth.

 

[Bart B.]

Ojive consistency (which is what people use to sort) is a product of the lead core consistency. Every different die that squirts the cores will make a different bullet.

Jacket copper quality is more important than that of the lead core, in my opinion. Had several chats with Sierra's first ballistics tech about that part of the bullet.

Coin, cup and draw stages starting with a sheet of copper into longer jacket lengths for a given caliber bullet keeps jacket thickness more uniform when the sheet of copper is more uniform in quality. Sierra's first big problem with this was their first prototype runs of 7mm 168 grain HPMK bullets. One small lot of jacket copper made those long 28 caliber bullets test as accurate as their 30 caliber 190 grain HPMK's.

That's the ones my friend used in 1970 when he broke the Wimbledon Match 1000 yard record set in 1935. Few subsequent lots of that bullet were made that shot that well for almost 15 years. In the 1980's, Sierra was able to get better jacket copper quite regular. That was a breakthrough in finally getting 26 and 24 caliber HPMK bullets heavier and longer.

Sierra keeps a few hundred of super accurate bullets of each caliber and weights to qualify test barrels. They're in boxes labeled "Standards" and typically test about 1/8 MOA or better through 200 yards. They used to sell them in plain brown cardboard boxes of 1000.