Sierra 6mm 95g MK,s

[onehole]

Well am I really "p*****d off now,,,,,,thought only Hornady could do such a thing!!!!! decided to try some sierra 95g matchkings in my 6BR and begun taking some measurments so I could load up a range of test loads only to find there were "FOUR" different spec,d heads in this particular 100 box/ batch,,,,,,base to ogive mark were clearly either .595,,,,, .600,,,,, . 609 and two heads at .612 !!!!!! That's a spread of 17 thou!!!

I have another box and will go about sorting them as well later today but just giving you lot the" heads up" on what I consider to be a serious quality control issue.

 

I don't know what everone else thinks but for some of you out there that don't check these measurements and are left scratching your head when you get flyers or not happy with the groups you are getting,,,let alone pressure when running close to lands then here is another suspect along with everything else we try to eliminate.

 

Its coming to a point now where I am only trusting some "other" brands and yes they are more expensive,,,,,and I know why,,,,,,,,,

 

What I think Im going to do is make up my own stony point insert on my lathe fior a 6mm head and take the opening closer to actual barrel size to get a reading closer to where actual point of contact would be and see if these measurements are repeated there.??,,,,,

 

 

Sorry have edited and changed one OG to .609,,misquoted as .695 before}

[Davy]

I am not that surprised, bullet manufacturing tolerances can significantly vary from lot to lot and even batch to batch and even those considered to be the 'best' are not so brilliant. The good news is you have started with probably the most important of the three bullet measurements and batching them like this is a good start, are you going to sort by weight and bearing surface as well?

 

Interestingly the #2156s also seem to vary by significant groups however once sorted fully they shoot well and are being used more and more within some F/TR circles.

 

I have just opened a box of the new Lapua type L 155 grain Scenars to measure, Lapua say they are more consistent than previous offerings, time to find out.

 

BTW - More expensive does not always equal better.

[onehole]

Hi Davy thanks for your reply,,,,These errors were in the same box!!! not lot to lot?batch to batch,,,,I can live with the lot to lot batch to batch differences and can understand the reasons why.

I Have started the exercise so will do the rest as well but not today,,,have just opened the other box and found same four sizes in that one as well.

 

I would love to know what actually happens at the factory,,,,I can only guess at least four machines then are making heads and then combined into a huge hopper or somethiong from which they are then packaged into 100 or 500 count boxes.Any other variance would probably come from dies wearing out at the same time. There must of course be more machines than this doing the same thing all day long and night I expect.

 

Not seen problems in "individual" boxes of Berger or Lapua,,,,,,,,,only from lot to lot but as mentioned one can live with that.

[Davy]

Bullets from someone like Sierra will be made on a huge scale with multiple machines and it sounds like either the machines have multiple dies or the output is mixed. My guess is a combination of both however this is not the end of the world, if you are prepared to invest the time in batching them you should end up with sets of very similar bullets and at the end of the day you are trying to remove vertical dispersion by shooting bullets as evenly matched to each other as possible.

 

When I have bullets made for myself I specify single die forming so they *should* be quite similar. In no way is this a comparison of Berger processes however I can see the difference when my supplier was using 4 dies in the early days. I still check them and they still vary however they are a lot closer than they used to be.

 

Berger will vary in weight from box to box and have some local dispersion as well, Berger despite being a well produced bullet still have inconsistencies, just at a lower level than some of the other manufacturers.

 

Out of interest what distance are you shooting at?

[onehole]

Bullets from someone like Sierra will be made on a huge scale with multiple machines and it sounds like either the machines have multiple dies or the output is mixed. My guess is a combination of both however this is not the end of the world, if you are prepared to invest the time in batching them you should end up with sets of very similar bullets and at the end of the day you are trying to remove vertical dispersion by shooting bullets as evenly matched to each other as possible.

 

When I have bullets made for myself I specify single die forming so they *should* be quite similar. In no way is this a comparison of Berger processes however I can see the difference when my supplier was using 4 dies in the early days. I still check them and they still vary however they are a lot closer than they used to be.

 

Berger will vary in weight from box to box and have some local dispersion as well, Berger despite being a well produced bullet still have inconsistencies, just at a lower level than some of the other manufacturers.

 

Out of interest what distance are you shooting at?

 

Hi again sorry for late reply but been working,,,doh!!! Davy I shoot at local range 100m and for final load testing at 200yds. I dont do comps anymore but vermin shoot out to 6/700 yards probably maximum nowadays and more usually from 250 to 450 on a day to day basis with expanding heads.The purpose of playing with these 95,s was to find an economical plinking head for my 8T 6BR,,,,,I,ve yet to try them so early days,,,,regds Onehole.

[garyw]

Onehole-i shoot the 95,s in my 6x47 -use them for short range f class and practice- they shoot 1/2 m.o.a out to 400yd .they are not the best out there but for the price they are hard to beat.

[onehole]

Onehole-i shoot the 95,s in my 6x47 -use them for short range f class and practice- they shoot 1/2 m.o.a out to 400yd .they are not the best out there but for the price they are hard to beat.

Thanks ,,mmmm not too bad then in your rifle then,,,,,,I dont mind tightish round groups its flyers that do my head in ,,,still get this with 105 Amax but have to put up with it for expansion factor when live shooting,,,,,I love the bergers to be honest ,,,VLD,s when you find the elusive sweet spot but those 105 boat tails are the most accurate I have ever shot and keep disappearing down holes that wouldn,t disgrace PPC performance.

I,ve batched em up now,,,,weight is good across all sizes so no issue there,,,bit of a stretch to the lands but still enough in the neck,,,will be benching on Tuesday hopefully,cheers.Onehole.

[onehole]

<p>Update for anyone interested?,,,,Have given these heads fair chance but side by side to 90g bt bergers ,,no contest! Worked my way through five loads ,,,no sweet spot anywhere? groups ok ish but nothing touching,,,90 bergers gave tight touching at 30.5 vit140 and again at 31.5 vit 140,,,,suspect these loads were close to a medium and hot accuracy node,,,primers starting to flat on the 31.5 but could go quite a bit more I think with this rifle but wont be chasing more speed for purpose.</p>

<p> </p>

<p>Said rifle in fairness is probaly half shot out and getting variance in finding true jam lengths consistently for the 95 MKings which have quite a VLD shape to them unlike the 90 Bergers which still hit lands abruptly.Will try the 95 MKings again one day in a newer rifle and throat.</p>

<p> </p>

<p>Will pay up and look big I guess for the remainder of this rifles barrel life,,,,your days are numbered I guess,,,,bought this rifle with a need to rebarrel soon so not too bothered and will do local range work where touching is well good enough and burn it out this summer/autumn. Dasherman can have it to bring it back to life then

[garyw]

viht 160 is the best powder i found for the 95gn a good case fill with no pressure signs.

[onehole]

viht 160 is the best powder i found for the 95gn a good case fill with no pressure signs.

Not in 6BR though surely??

[garyw]

Not in 6BR though surely??

NO!I should have mentioned that-have you tried varget and n135 in the 6br?

[onehole]

NO!I should have mentioned that-have you tried varget and n135 in the 6br?

Yes mate ,,,I use 135 for lighter heads,,,,,,,have a ton of 140 and stumps up tight ones with other heads but pretty much think these 95,s dont like my older barrel,,,no worries just ordered up some more 90bergers to see the barrel out,,,Onehole.

[onehole]

With this particular 6br the chamber is a standard min spec no turn and I had been using a standard 6BR modified case to determine seating depths?jam etc well I was wondering why the 95,s didn,t go that well so decided to drill and tap out a fired case to be more precise,,,,don,t know why I didn,t do it in the first place as I usually have to with my tight necked rifles,,,,,,,I have now rechecked where the real contact to land point is and low and behold I,m 16 thou adrift on all heads measured with the standard modified case which incidentally was quite a tight fit?. This could well be the problem,,,,,I got away with the bergers being so far away from the lands but not the 95,s perhaps.

I will now try these heads again in and just out of lands.

 

I really think that if your chosen method to find lands is a modified case then it has to be done on one of your own fired and modified cases,,,,,your friendly smithy,s on here can do it for you for a small fee,,,,,sorry Baldie you might have a ton of brass coming your way now!!!

[onehole]

"I have now[with a threaded fired case] rechecked where the real contact to land point is and low and behold I,m 16 thou adrift on all bullets measured with the standard modified case which incidentally was quite a tight fit?. This could well be the problem,,,,,I got away with the bergers being so far away from the lands but not the 95,s perhaps."

 

Did the whole test again today with all loads truly 5 thou off,,,,,bingo!!! at 31/140 the 95,s being as tight as the 90 berger groupings,,no flyers,,,job done.

 

May get some more 95 SMk,s now as my confidence in them has now been restored as regard their potential once they have been batched up and I pay more attention to taking true and accurate seating measurements in future.There are probably other "off land" sweetspots for this head and my rifle but wont risk anymore playing around and precious barrel life trying to find out.Onehole,