Poor results 6mm arc and 85g nosler partitions

[Shadow9mm]

Was trying to work up some 85g Nosler Partitions in my 6arc. I used my usual load workup process, start to max to make sure I was safe. Work down to find a powder charge with a reasonably good ES/SD, in this case es30, sd9 with an average of 2795fps out of a 20in gas gun. Went to the range today to do seating depth testing to tune for accuracy. Seems I wasted my time and components. upper left was a 6 shot group, rest were 7 shot groups, all at 100yds.

For reference I also shot this rifle with a 75g v-max load today and was able to get a 0.85moa 9 shot group at 100yds with it today. So I am having a hard time blaming the rifle or myself for this performance.

 

[44 AMP]

Looks like your rifle doesn't like that bullet as much as it does some others.

Different rifle might give much different results. No way to know without shooting...

a reasonably good ES/SD, in this case es30, sd9

Seems like this is one of the cases where "good" ES/SD numbers didn't result in stellar accuracy. The barrel is always the final arbiter, and "good" numbers don't ALWAYS result in good accuracy. Often, sure, but not always.

 

[MarkCO]

I have not seen good accuracy in Nosler Partitions below 7mm. But in the larger calibers, some of the most accurate.

 

[FrankenMauser]

I don't think the 85 gr Partition likes velocity.
It couldn't get it to shoot well in my .243s.

It is also the 'hunting' bullet for my 6x45mm, and the accuracy load ended up only running about 2,600 fps. (More like .223 velocities than proper 6x45.)
Beyond that, groups were opening to 2-3x as big.

It isn't the best group that the load has given me, but when I verified the zero last week, it shot about 1.25" at 100 yd. Adequate, but not the little bug hole groups that rifle tends to shoot with varmint bullets.

 

[Shadow9mm]

I don't think the 85 gr Partition likes velocity.
It couldn't get it to shoot well in my .243s.

It is also the 'hunting' bullet for my 6x45mm, and the accuracy load ended up only running about 2,600 fps. (More like .223 velocities than proper 6x45.)
Beyond that, groups were opening to 2-3x as big.

It isn't the best group that the load has given me, but when I verified the zero last week, it shot about 1.25" at 100 yd. Adequate, but not the little bug hole groups that rifle tends to shoot with varmint bullets.

That's good to know. I'm about 0.6g below max at an AVG 2795fps out of my rifle. I still have about 50 bullets left, and I was just gonna let them sit. I may try and down load them a bit and see if I can get them to play nice, just for my sanity sake. Thank you!

 

[603Country]

Nosler Partitions are not what I’d call an accuracy bullet. I think of them as good hunting bullets with acceptable accuracy (for that purpose). If they aren’t shooting the way you want, I’d try a different powder. Over the years, I have noticed that Nosler’s recommended powders for various bullets are good recommendations.

 

[stagpanther]

I agree with two observations here--partitions like being driven fast; and in larger calibers can be very accurate. Put the two together--like in the 300 weatherby magnum--and it can be downright awesome (except to whatever is being hit by it).

 

[gwpercle]

Nosler Partitions were never noted for their accuracy but rather their performance on game .
And it's a fact that some rifles just don't shoot all bullets accurately .
Keep tying different bullets and find something your rifle likes ...
... not much else you can do !
Gary

 

[stagpanther]

And it's a fact that some rifles just don't shoot all bullets accurately .

And some rifles shoot very few--sometimes none--bullets accurately.

 

[Shadow9mm]

Nosler Partitions were never noted for their accuracy but rather their performance on game .
And it's a fact that some rifles just don't shoot all bullets accurately .
Keep tying different bullets and find something your rifle likes ...
... not much else you can do !
Gary

So far I have 75g v-max at at 0.85moa. next up is 107g SMK, then 103 ELD-x, and at some point 95g barnes LRX

 

[603Country]

Nosler says to use IMR 4831 for that bullet for best accuracy. What did you use?

 

[Shadow9mm]

Nosler says to use IMR 4831 for that bullet for best accuracy. What did you use?

I was using Cfe223. I dont have any imr 4831 and even if i did neither Hornady hor Hodgdon have any loads for 6mm arc using imr 4831

 

[FrankenMauser]

Nosler Partitions are not what I’d call an accuracy bullet.

Nosler Partitions were never noted for their accuracy but rather their performance on game

I must disagree.
In my experience, Partitions are some of the most consistent bullets I have ever used - especially up against other hunting bullets. They hold their own against 'match' bullets in pretty much all of my rifles, except the 85 gr 6mm.

They are very good bullets - not even counting performance on game.
Ballistic Tips are right there on the Partition's heels, as well. If your rifle won't shoot Ballistic Tips or Partitions, just throw it away, nothing else will either.


10 years ago, now, I finalized a load that took years to work up. Half a dozen bullets, a dozen powders, with testing from below 0 F to over 100 F.
I'll give you one guess which bullet beat out all of the others (which included Barnes, Berger, and Swift for brands).
Yes, it was a Partition.

 

[603Country]

My mistake on the 6mm Arc powder. I looked up 243 Winchester. Duuuh!

And what Frankenmauser said on Ballistic Tips and accuracy, I fully agree with. As for Partitions, well, I’ve never seen them shoot as well as BTs. But that doesn’t mean that a certain rifle won’t do it. I like the Ballistic Tips, and have been shooting them since they were offered by Nosler. Very accurate and very effective on deer, coyote, and hogs. I just wish I could get some 100 gr BTs for my Grendel, but am doing fine with Hornady SSTs.

 

[bamaranger]

6mm ARC

I don't own a 6mm ARC, but bamaboy has an upper so chambered and I expect at some point I will be loading some for his rifle. Looking ahead, the 85 gr bullets were one weight I was considering when the time came.

I've shot 85 gr 6mm bullets from a 20" barreled ..243 Win carbine that I own. The Sierra 85 gr HPBT shoots well and better than the 85 gr Nosler Partition, but I trust the Nosler on deer much more than the HPBT, but have taken deer with both loads, the Partition just does not require as much attention to angles. I use the lighter 85 gr weight in the carbine as I can obtain velocities in the 3000 fps range rather easily, something I cannot do with 100 gr Partitions that I use in my other 24" barreled rifle.

 

[Unclenick]

Assuming your 6 ARC has the standard 7.5" rifling, at 2795 fps, you are spinning the Partition at almost 270,000 rpm, and the JBM calculator puts the stability factor almost at 3, which is the top end of the range Sierra used to recommend for "hunting accuracy." A match bullet may tolerate the extra spin OK, but any bullet with thicker jacket walls is usually at risk of more CG offset than the thin-walled match stuff is, which means faster spin will cause more radial drift away from the mean trajectory than a match bullet would do. Looking only at this one criterion, that 0.95" long bullet at 2795 fps looks like it would be happier with something like a 10" twist.

 

[Shadow9mm]

Assuming your 6 ARC has the standard 7.5" rifling, at 2795 fps, you are spinning the Partition at almost 270,000 rpm, and the JBM calculator puts the stability factor almost at 3, which is the top end of the range Sierra used to recommend for "hunting accuracy." A match bullet may tolerate the extra spin OK, but any bullet with thicker jacket walls is usually at risk of more CG offset than the thin-walled match stuff is, which means faster spin will cause more radial drift away from the mean trajectory than a match bullet would do. Looking only at this one criterion, that 0.95" long bullet at 2795 fps looks like it would be happier with something like a 10" twist.

Its a ballistic advantage barrel running a 1:7 twist. So It looks like I will need to stick with long and heavy for caliber bullets to get this to play nice. I did get the 75g v-max to shoot, but it did not have the forgiveness I am used to with 223. I may bump up to the 87g v-max going forward. Will be loading the 107g smk next.

 

[stagpanther]

Its a ballistic advantage barrel running a 1:7 twist. So It looks like I will need to stick with long and heavy for caliber bullets to get this to play nice. I did get the 75g v-max to shoot, but it did not have the forgiveness I am used to with 223. I may bump up to the 87g v-max going forward. Will be loading the 107g smk next.
__________________
I don't believe in "range fodder" that is why I reload.

I've loaded quite a few of the 6mm partitions in the ARC--here are my observations (for what they are worth). It's got several strikes going against it in the ARC, IMO. It has a pretty wide lead spire point for what are normally zippy pointy things used in the ARC--most ARC dies come with a seating stem meant for high BC bullets --so there's going to be some deformation there possibly. It also has an open base exposing the lead in the lower partition. Because of its' pretty far forward base of ogive--the bullet has to be seated pretty deep, and the already short length makes for a short COL compared to higher BC bullets. In my monster-barreled AR I've found 103 to 107 gr bullets to be the best performing bullet weights, though I have also shot 110 gr bullets.

 

[tangolima]

Start from max and work down. Look for min. ES first. The OP's methodology is interesting.

It is not very rare that I have to stop well below max because of pressure signs. First shot max in those cases I may not even have a chance to regret.

Group size is strong function of powder charge, or MV, and ES/SD is secondary. It would be better to look for hopeful MV first, then try to refine around it, including minimizing ES/SD.

-TL

Sent from my SM-N960U using Tapatalk

 

[Shadow9mm]

Start from max and work down. Look for min. ES first. The OP's methodology is interesting.

It is not very rare that I have to stop well below max because of pressure signs. First shot max in those cases I may not even have a chance to regret.

Group size is strong function of powder charge, or MV, and ES/SD is secondary. It would be better to look for hopeful MV first, then try to refine around it, including minimizing ES/SD.

-TL

Sent from my SM-N960U using Tapatalk

I work up to max, or however far i get looking for pressure signs, then work back down looking for a good es/sd. I do not reccomended or endorse starting at max.