6.5x55mm Viht N160 overpressure at 44gr - any wisdom?

[Sharpie]

I've never used Sako brass in the 6.5X55mm, but have found it to be both heavy and extremely 'soft' in other common cartridges. I have read several times that Federal makes Sako brass and my experience of the make is that the two are certainly very simple. Many, many years ago, when 308 Win Boxer primed brass was hard to get and good once-fired examples were much sought-after, I soon found that Federal was a poor purchase. Many (genuine) once-fired cases already had slack primer pockets (with CCI-200s, the most widely available primer of that time) after the one firing with the factory load. I and others quickly ditched what we'd been led to believe were premium cases. None of this may apply to today's Fed/SAKO cases, of course, but I have to say I feel suspicious and it is at the least a bit of a coincidence.

If, as you suggest, the Sako/Federal brass is heavy by comparison with other known-good makes, then that must mean that it has a smaller internal volume.

You can measure this easily enough as e.g. "grain weight of water", or calculate the difference between two types of brass by weighing the cases. Knowing the density of brass, (between 8.4 and 8.7 grams/cc) that will give a reasonable estimate of the difference in internal volume.

Vhit. use Lapua brass, but do not specify the primer, used to develop their basic load data.

So it might be as simple as heavy relatively soft brass with small internal volume is producing higher than anticipated pressures.

Possibly someone on here who does use Lapua brass could weigh some cases, so you could compare that with your Sako stuff.

Either way, if intending to change to say Lapua brass in the future, probably better to do it now, otherwise you may have to work your loads up all over again. Which is costly in powder, bullets, barrel wear, and time. Possibly negating any savings made by persisting on using up your Sako cases first. Over a full reloading cycle, the cost of new brass is relatively minor compared with that of the powder, never mind Barnes bullets.

The same applies when starting with a fresh batch of new brass, even of the same make, at least compare the weight of the old and the new cases, and if there is any significant difference (more than say the tiny amount lost during trimming) then be cautious.

Reloading once-fired factory ammo can introduce variability. Factories can adjust powder charge, even precise powder formulation, across large batches, to account for say differences between the cases between batches. Even change brass supplier between batches. You wouldn't know that if they all bear the same head stamp. If you buy your factory ammo a few boxes at a time, maybe from different dealers, there could also be some variation.

I prefer to start with new brass, bought in sufficient quantity to cover say a couple of years of reloading

AFAIK brass manufacturers do not continuously produce brass in every possible case size, they set up their machinery for one, do a run to cover predicted demand, or orders, maybe just once/year, then set it up for a different calibre, run that batch, etc. So even between runs there might be small differences, depending how precisely they set up their machinery each time.

 

[zambezi]

If you buy your factory ammo a few boxes at a time, maybe from different dealers, there could also be some variation.

Yup. Different batches of Sako factory have greater or lesser standard deviation in their CBTO values. And in some batches the shot-to-shot MV differs more than others. To be fair though, accuracy remains at or below 1 MOA in all cases so somewhat academic as I am a hunter, not an F class competitor. Reloading is my opportunity to reduce the cost and standard deviation and to optimise accuracy.

Is there a reason you are persisting with the Barnes nontoxic bullet?

A couple of reasons: After trialling a raft of OTS ammo from Hornady, Winchester, Federal and Nosler I chanced upon the Sako offering and discovered it to be the most accurate round for my rifle. Secondarily to that is the rather obvious legislative march towards banning lead projectiles. It is already an FC stipulation and very likely to become mainstream affecting all UK hunting. Given the time, cost and effort involved in developing loads, I do not want to build the best load possible around a bonded bullet now only to have to re-do the legwork again in 18 months.

 

[cjs66]

18 months, I hope not...

My load for my Swede is Lapua brass, CCI 200 primer, 120grn Nosler B/T and 45.5g of H4350. OAL 2.990. Cracking load with no pressure signs and doing 2800 fps in my R8. Also made a load up with N160 at 46g with very similar results. No pressure. I'll use that load when the H4350 is gone. I might add that I've never crimped for my 6.5x55. I also have a couple of good loads with the Nosler 140g B/T and Hornady SST using N160 and Reloder 22, again no pressure and loaded close to max. I appreciate that these bullets are the polar opposite to the lead-free one that you're trying to recreate but, they work very well for me and I'll worry about the ban when/if it happens.

Good luck. cjs.

 

[zambezi]

Says it all really: 42.2gr of N160 is [often] too much for once-fired 6.5x55mm brass. Which is very difficult to understand given (1) that loading is near the lower end of the Viht suggested loading for that case+bullet combo as well as (2) good experiences of so many on this forum running loads of 46gr or more.

So I am going to drop charge weights even further and will load once-fired Winchester and Hornady brass in parallel.

Building those Hornady cartridges tonight I was struck by how much easier they passed through the neck-sizing process. The Sako brass is much harder. And the primer seating sequence was the exact reverse: seating a CCI 200 large rifle primer into the once-fired Sako cases was a gentle affair whereas the Hornady cases took a bit more encouragement.

If the Hornady and Winchester experiment is successful at charge weights at which the Sako brass fails, then I will try one further permutation with the Sako brass: annealing.

 

[CerebralDistortion]

Nice to see my input generated results in the right direction.

Questions:
Have you weighed and compared case capacity of the Sako cases compared to other brands?
When comparing loads with others, are they also loading for a Blaser?

Have fun annealing, don't burn your fingers.

 

[Blobby159]

'Zambezi'...
That you have noted such resistance to bullet seating AND to the disassembly through use of an inertial hammer in your SAKO brass 6.5Swede reloads definitely says to me that :-
1). the brass in the neck area is waaaaay waaaaay too hard and requires careful annealing to (hopefully) address this function for you - assuming you want to continue reloading said cases once used, now fire-formed factory offering that is(??) . Given this feature alone I for one would think hard and long about continued use of that particular cartridge..
and..
2). again, assuming you still wish to continue with your Sako Brass reloading efforts - and I can see that if you start from 'Factory' and don't want to be wasteful with the empties this is the only obvious way to go - then I would respectfully suggest you also experiment with the neck sizing dies, using one that gives as light a hold as you can get whilst yet giving a 'sensible hold' of the bullet, say 1.0 to 1.5 thou of measured spring-back. By 'sensible hold' I mean a situation whereby firm pressure of thumb on the bullet tip does NOT move the projectile back into the case neck in any way. ALSO, nor does a firm hold on the bullet yet give you the ability to twist it free from the case neck, but the 'feel' during bullet seating is one that suggests the projectile is being held well, but with minimal force just sufficient to do the job required!!

With a properly annealed case-neck area on those Sako cases that minimalistic seating force 'feel' should be attainable and repeatable. If it ISN'T then perhaps try annealing for a second time maybe? I can't say this will make much of a difference if the initial annealing exercise was executed correctly but who knows(?), and I haven't been there so cannot give a true report back on that particular experience....

If this works out as anticipated, and with other assistance you find the internal volume is noticeably lower than other major manufacturers (what you expect here) then perhaps that poor initial experience of yours with this Sako Brass can be turned around and you can produce quality reloads WITHOUT seemingly spurious, unexpected high pressure signs.

Personally I would ditch the use of Sako factory ammunition right from the get-go, and I would do as I am now and START with New Lapua 6.5x55 brass and work up a decent load right from the start. Not with the projectile you are using (I have yet to trial any monolithic bullet in my home loads) but I have found Rel22 to be a reliable performer for me in this cartridge.


ATB ..... and shoot safely

 

[zambezi]

suggest you also experiment with the neck sizing dies, using one that gives as light a hold as you can get whilst yet giving a 'sensible hold' of the bullet, say 1.0 to 1.5 thou of measured spring-back

Both Hornady and Sako factory once-fired brass compress to a 3+ thou smaller internal diameter [0.261"] than the bullet [0.2645"] after being neck-sized in the RCBS die. However there is a marked difference in resistance that those two cases offer during bullet seating. The Hornady is much more accommodating...

...so this looks to be wisdom if I persevere with the Sako brass:

brass in the neck area is waaaaay waaaaay too hard and requires careful annealing to (hopefully) address this function for you

work up a decent load right from the start. Not with the projectile you are using

My bullet selection is based on proven performance in the factory load over 5 years. It is accurate, it drops deer, it is future-proof. That will be the last thing I change. [BTW I also shoot Barnes in my 30.06 and .375]




My next round of testing will reveal whether Hornady brass suffers any over-pressure symptoms at charge values at which the once-fired Sako brass fails. The round of testing after that will involve annealing of all the cases and, thereafter, raising charge weights if all good at a starter load of 42gr N160.

 

[zambezi]

After this coming Wednesday, it may be a while before I can carve out more time for load development, so I have decided to complete what would have been my next step and run those tests immediately after the Hornady vs Sako brass test I had already planned.

Today I experimented with annealing techniques using the finger-tip-ouch method of establishing when the neck had reached 700°C+ mark. It took 13s in the center of a blowtorch flame to become uncomfortable to hold by the head. Immediately thereafter I arrested the annealing process using a bucket of cold water. Four cases now annealed. All weighed to be within a few grains of each other, neck brass thickness a uniform 0.155". Ease of neck-sizing and bullet-seating later tonight will further inform whether annealing has conferred a detectable benefit, even before range tests.

So these four annealed Sako cases will now be loaded to 43gr, [2x] 44gr and 45gr N160 respectively [those loads previously provoked over-pressure events in Sako once-fired brass that had not been annealed] . The firing sequence will be as follows, with abort called if there are any over-pressure events in the sequence:

1. Fire the 42gr N160 Sako [not annealed] cartridges first and check MV and grouping plus case status [Not expecting over-pressure. Should get a mean MV of 2690fps. Grouping should be tidy]
2. Fire Hornady brass loaded to 43gr N160 to see if it suffers over-pressure in same way as Sako brass did
3. Fire Sako [annealed] brass loaded to 43gr, 2x44gr and 45gr N160 respectively

 

[zambezi]

42gr N160 in both Sako and Hornady once-fired brass looks to have some pressure issues:

At 42gr N160 Sako once-fired brass [annealed or not] always shows primer pin strike "cratering" and one in 5 shots dislodges its primer:



The once-fired Hornady brass loaded to 42gr N160 delivered excellent accuracy at 100m, but close inspection also showed flattened primers with some cratering. Mean MV over three shots was 2700fps.





So I am pretty much at a loss as to how I am going to get a 2700-2800fps MV from N160. Lots of folk are suggesting I switch primers or powder. Since the CCI #200 large rifle primers are pretty universally successful, I think I will buy a tub of RL-15 and see what numbers and groups that throws up.

 

[User00040]

Try Lapua brass, it could be a loose primer pocket giving you a false positive on the primers.

Was the bolt lift sticky or difficult?

I think the Hornady cases look acceptable.

Another thing to note is that the SAKO headstamp on your brass is an older type.

 

[zambezi]

Try Lapua brass, it could be a loose primer pocket giving you a false positive on the primers.

Agree. Obturation measurements do not suggest excessive case distension. And, during reloading, seating primers into the Sako brass is [subjectively] easier than same action on Hornady brass.

Was the bolt lift sticky or difficult?

Nope. All cases extracted easily.

I think the Hornady cases look acceptable.

Tend to agree

Another thing to note is that the SAKO headstamp on your brass is an older type.

Not sure why that might be. I would have purchased the Sako factory ammo in the last 18 months. It is once-fired in my rifle. It may well have been older stock in the RFD store...

 

[zambezi]

Every day is a school day...

Early on I realised that pushing bullets into once-fired Sako brass was way tougher than same operation on Remington, Hornady or Winchester brass. I.e. Sako brass at the mouth of the case is harder than other makers. How much harder? Well...hard enough to shave Barnes ttsx bullets as they are being seated! This is the build up of fine swarf in the seater die. It is unmistakeably the redder colour of the copper-alloy bullet rather than the gold of the Sako brass.



Referring back to YT for wisdom, I chanced on an AMP annealer bench test where a single rifle case was reloaded TWENTY times back-to-back. It was an advert for the benefits of annealing, but at minute 1:08 into the clip, I see the reloader applying "moly" to the inside of the case neck. Is that to reduce bullet friction during seating? Anyone else do this?

 

[Border]

Every day is a school day...

Early on I realised that pushing bullets into once-fired Sako brass was way tougher than same operation on Remington, Hornady or Winchester brass. I.e. Sako brass at the mouth of the case is harder than other makers. How much harder? Well...hard enough to shave Barnes ttsx bullets as they are being seated! This is the build up of fine swarf in the seater die. It is unmistakeably the redder colour of the copper-alloy bullet rather than the gold of the Sako brass.

View attachment 151642

Referring back to YT for wisdom, I chanced on an AMP annealer bench test where a single rifle case was reloaded TWENTY times back-to-back. It was an advert for the benefits of annealing, but at minute 1:08 into the clip, I see the reloader applying "moly" to the inside of the case neck. Is that to reduce bullet friction during seating? Anyone else do this?

Yep. Probably to lubricate the neck before sizing. I haven't watched the clip but I use a graphite mix. Just dip the neck into the ceramic media coated with graphite. Less friction om the sizing ball and no powder contamination with wet lubes.

 

[User00040]

@zambezi, glad you have found the probable cause.

Personally, I would not choose Sako brass for reloads.

 

[zambezi]

More range testing today. Principle difference is that I have upgraded my Chronograph: I am now running a Magnetospeed V3. It declares higher MVs for same loads as compared to Chrony F1 readings of previous weeks. I believe the Magnetospeed to be more accurate. If correct, I now see that I can drop charge quantities further and still make target MV.

Project target was to emulate expensive but effective manufactured ammo: Sako Factory 120gr TTSX ammo declared by Magnetospeed to be doing 2680fps.

42gr N160 in a variety of once-fired brass pushes a Barnes 120gr TTSX projectile at an average speed of 2900fps [see below] with fair accuracy. The downside is some headstamping, infrequent primer gas leakage.

But...since I only really need around 2600fps MV to deliver full monolith performance to 200m, I now know I can drop powder weights further.I will experiment using N160 charges in the high 30s at next time of asking.

 

[User00040]

Good to see your results, came good in the end. N160 is a nice powder for my .270 with 110 ttsx. Have tried Ramshot Magnum which was OK but hard to get up here, Viht is obtainable but seeing people based down south selling off 1kg tubs for £40 on here when I am paying more than double that does sting a bit!

Not sure why you preserved with the Sako brass, I would have binned it but each to their own.

Regards

 

[Alantoo]

Every day is a school day...

Early on I realised that pushing bullets into once-fired Sako brass was way tougher than same operation on Remington, Hornady or Winchester brass. I.e. Sako brass at the mouth of the case is harder than other makers. How much harder? Well...hard enough to shave Barnes ttsx bullets as they are being seated! This is the build up of fine swarf in the seater die. It is unmistakeably the redder colour of the copper-alloy bullet rather than the gold of the Sako brass.

View attachment 151642

Referring back to YT for wisdom, I chanced on an AMP annealer bench test where a single rifle case was reloaded TWENTY times back-to-back. It was an advert for the benefits of annealing, but at minute 1:08 into the clip, I see the reloader applying "moly" to the inside of the case neck. Is that to reduce bullet friction during seating? Anyone else do this?

It is more likely to be a sharp edge than the hardness of the case mouth. Think of the rubbing action from a rounded surface as opposed to a scraping one from a sharp edge.

What sort of chamfering tool do you use? I had a basic Lee one which threw up a burr rather than removed the one left from the trimming cutter...defeating the object.

I now use a Lyman case prep multi tool which has a VDL internal chamfer tool, which helps.

When loading flat bottom bullets I discovered the the Lee Universal Expander die which can be set to give a minimal flare to the case mouth which enables the bullets to seat smoothly with no chance of shaving. I then use a Lee FCD to push it back and lightly crimp.

I now use the expander die as a matter of course on every bullet I load, flat bottom or boat tail it makes the initial push into the case mouth so much smoother.

Alan

 

[zambezi]

It is more likely to be a sharp edge than the hardness of the case mouth. Think of the rubbing action from a rounded surface as opposed to a scraping one from a sharp edge.

What sort of chamfering tool do you use?

I suspect it is a bit of both.

I use a Lee Precision tool to size the cases and whilst the case is chucked up in the drill, I also offer up the RCBS chamfer tool to deburr


What I discovered is that if you offer the deburrer up to the case mouth of an un-annealed piece of brass, you can get cutting edge chatter which renders a rough edge to the chamfer. Even at higher rpm.

Later trials have born out my theory: if I anneal first, the same set up gives me a smooth chamfer. And almost nil bullet swarf.

 

[Rutland lad]

I wish you well with this quest.
I personally have just drawn a line under any more load development on my 120 g Barnes TSX in my 6.5 x 55. Using RS60 I’ve been chasing groups for some time before I tried a box of Norma 130 and Sako Gamehead Pro. Both of the factory types grouped into a ragged hole at 100m, and the Sako were purchased on the basis of being £14 a box cheaper.
I will revisit the TSX again, but in 130 grain next time, as it seems the rifle/barrel like that weight.
So frustrating and expensive in both time and money for no real result.
I’ll have 20 left over TSX in 120 which I’ll offer to anyone who wants to try them.
A very different experience from that with Barnes 180 grain TSX in my 300 win mag. That was an easy development!

 

[zambezi]

I personally have just drawn a line under any more load development on my 120 g Barnes TSX in my 6.5 x 55...I will revisit the TSX again, but in 130 grain next time, as it seems the rifle/barrel like that weight.
So frustrating and expensive in both time and money for no real result.

Frustrating, yes. But there have been glimmers of progress. I won't give up just yet...

A very different experience from that with Barnes 180 grain TSX in my 300 win mag. That was an easy development!

Ditto my experience with Barnes 180gr in my 30.06. And Barnes 270gr in my .375. Development of both have been far more linear and predictable.