Laurie thoughts on H4831SC in 6.5x47L

[ofrn]

HI

 

looking for laurie and other reloaders thoughts here. I have several hundred 139 scenars coming for my 6.5x47l. My 6.5x47l has a 26 inch barrel and .250 freebore (designed for long 140's) I will be single loading these as long as possible. I have a few questions here in australia basically the only powders we have are ADI.(Hodgdon usa) Most people use H4350 for this bullet. Iam thinking with my very long freebore and very long bullet seating I might try H4831SC instead to get a better case fill (maybe around 42+ grains) I can load 38g of varget with 123 scenar in this gun with no pressure sign at all and there is still so much room i can shake the case and hear powder moving about.

 

One of the other reasons to try this other than better case fill is it seems them is conflicting heat potential information for these powders. The H4831SC is consistently listed as 3870KJ however the H4350 people tell me quickload says 3760KJ but other sources such as the barrel life calculator have this powder at 3990KJ. This makes big different for barrel life. If it is in fact 3990KJ vs 3760KJ for H4350 i would think the slower burning H4831SC might be slightly better for barrel life. Funds are limited and barrels and fitting is extremely exepensive in australia i dont want to be replacing the barrel. Thoughts anyone.

[Catch-22]

Hi ofrn,

 

I guess I'd start by trying to know what kind of shooting you'll be doing and understanding what your expectations are with it.

 

If you're a high volume shooter, or shooting matches with long strings of fire, then using a lower energy rated powder may be good.

If however you're an informal shooter (no comps), aren't shooting rapid fire or long strings (i.e. You shoot maybe 10-30 rounds over several hours, possibly once a month) then I doubt you'll really know much difference between the two in a real world situation. Others may dissagree.

 

The 6.5x47 is a great round. I was pushing 123g Scenars at 2930fps using 38.6g N140. No pressure signs and bloody accurate. I did choose a single base powder because I shot comps and would often fire 150-200rounds per practice session (day long), so maintaining barrel life was important to me and I chose my powder accordingly.

 

Hth

[Laurie]

Well, I've never heard of anybody using H4831 in this cartridge, and it's not one that I'd think of straight away - definitely too slow burning for the relatively small case.

 

Running it through QuickLOAD suggests it wouldn't be necessarily disastrous, but then nor would it be optimal or even close to optimal. Assuming you can use the full CIP COAL of 2.800" with the 139 Scenar with your long freebore chamber, you'd theoretically get around 2,775 fps from a heavily compressed H4831sc load. Pressure should be OK at that, a bit down on a full-house VarGet / H4350 load. The problem is that with the slower burning powder, you won't burn it all - QuickLOAD says 94-95% charge burn in a 26-inch barrel. To be honest, I take that with a bit of a grain of salt - it could very likely be less than that in real life as opposed to a model.

 

With pressures in the high 50,000s psi, top (but I reiterate, heavily compressed) loads would give reasonably consistent pressures / MVs, but at lower levels as you work up, I'd suspect they'll have large variances as peak pressure will be too low for a consistent burn. At a 39gn starting load, the model says only just over 40,000 psi and 90% charge burn; even at 40gn (a full case) it's only 45,000 psi and an estimated 92% charge consumption.

 

Actual COAL makes a large difference. Anything less than 2.800" is pretty hopeless, but if you can go longer without being in the lands so that you're only just seating the bullet into the case-mouth, you have more leeway. Well more leeway in one sense, but very shallow seating limits you in another - if you're running very high compression levels, it becomes difficult to retain consistent COALs because of powder compression pressures on the bullet base. When you get down to less than a tenth inch of bullet shank in the neck, the charge can literally push the bullet out of the case if compression is high enough. The other thing to watch here is that charge compression extending COAL doesn't put the bullet into the lands, more likely some but not all bullets which creates very inconsistent results and usually poor accuracy. (Not to mention a risk of excessive pressures for those that go into the lands if you've managed to stuff enough powder into the case.)

 

So, if your actual COAL off the lands is 2.800" or more, you might be able to try this powder and get reasonable results. The other thing you'd have to consider is making up or getting someone to make up for you, a powder funnel with a very long drop tube - 24 inches or more - and then pour the charge in agonisingly slowly a few kernels at a time to settle them fully. (Don't laugh - there is a UKV member who has just such a set-up for one of his cartridges with a particular powder. Charging cases sees them in the loading tray on the floor and him pouring it in from above waist height. This practice is not unknown too among long-range BPCR shooters too IIRC to get another grain or two of black powder into the 40-65 and 45-70 cartridges.)

 

As to the barrel wear issue, I doubt if you'd get much if any benefit out of this. A slower burning powder may actually increase erosion in that it takes longer for the charge to burn and the bullet travels further in the early stages of the burn - so a longer section of throat and barrel just ahead of the throat is subjected to peak heat and pressure. There is a school of thought that says that the highly erosive nature of a mass of heavily compressed partly burned powder pushed out of the case into the throat accelerates barrel wear and that one wants all the charge burn to take place inside the case. With H4831 in this cartridge that isn't going to happen. If this 'turbulence point' hypothesis is correct (who knows?) the 6.5X47L with sharp shoulders and a long neck is an excellent design keeping the TP within the neck with 'normal' powders. Use H4831 and you'd throw this (hypothetical) benefit away pushing compressed and burning powder kernels up the barrel behind the bullet base. So, the only way you'd get improved barrel life with a too-slow burning powder is if you run at significantly reduced pressures - and then you don't get full value MVs.

 

It is a truism of handloading that goes back a long, long way - but that doesn't diminish its truths - that one shouldn't use ballistically sub-optimal powder grades for non internal ballistics reasons. The usual one is having lots of a particular grade and wanting to use it up, or being able to buy it very cheap, but the same principle applies here. The very first book I read on handloading was by Major George C Nonte Jnr an ex US Army weapons expert and gave an example of something very close to what you're contemplating. He had a friend in the 1950s with a semi-auto 8mm Mauser rifle who loaded heavy gas-checked cast lead bullets over an exceedingly heavily compressed charge and with a heavy case-mouth crimp applied to keep the bullet in. With B E Hodgdon's original dirt cheap slow burning surplus 4831, the friend got good results and it even cycled the action reliably. Then one day the bullet went down the barrel with the case-neck and half the case shoulder still attached to it doing the barrel no good at all. It was surmised that because the load involved a too slow burning powder allied to an excessively heavy charge compression that a compressed mass of unburned powder kernels was forced forward against the case shoulders as the burn started further back and pressures rose. Eventually, the internal pressures on the front end of the case exceeded the brass strength causing a separation behind the bullet. An extreme example, but an illustration of the unforeseen risks of using non-recommended powders.

[ofrn]

WOW what a reply Laurie mate you would make a very good detective. Thanks so much you raised several points that I hadn't even thought of about H4831SC. I will stick to H4350 after this response thanks so much and thanks catch 22 as well for your response as well

[Leeman]

Ofrn,

 

2213 is far too slow, 2209 is just about perfect with the 140 class bullets. I used the Scenars in two barrels, first coal was 2.790 to touch the lands, next was a bit shorter 2.740. The second also shot well with N550 Vit. 2209 was using between 41 & 42 gns after working up from 39gns, but still not compressed, especially with the longer throat.

 

Give me a shout in you need anything further.

 

Used to shoot a bit at Belmont & Ipswich.

 

Richard.

[DaveM]

Ofrn,

 

2213 is far too slow, 2209 is just about perfect with the 140 class bullets. I used the Scenars in two barrels, first coal was 2.790 to touch the lands, next was a bit shorter 2.740. The second also shot well with N550 Vit. 2209 was using between 41 & 42 gns after working up from 39gns, but still not compressed, especially with the longer throat.

 

Give me a shout in you need anything further.

 

Used to shoot a bit at Belmont & Ipswich.

 

Richard.

Agree that 2213 is far too slow. I am also in the same boat only having ADI powders but don't see that as a real problem in the 6.5x47. I have settled on Berger 130 VLD for the range ( limited to 500 yds) . Seems to be bullet weight that suits my rifle in this calibre. 2208 (Varget) and 2209 have been very good performers. Doing more precise tests of the two powders soon.

The Berger handload book was very helpful as ADI don't provide any load data. Powders giving best performance according to Berger author were Reloader 15, Varget and N550 vit.

Good luck with your loads

[ofrn]

So to follow up on this my 139 scenars arrived. I measure them base to ogive with my 6.5mm comparator to find they measure .717 which I was hoping they would measure longer so I could get more bullet in the neck, my 123 scenar base to ogive is .689 so these are only 35 thou longer base to ogive which still leaves not all that much bullet in the case. I had read peoples measurements on the net who obviously used a smaller comparator as the numbers I saw for the 139 scenar were .795 base to ogive. Anyway this is what I have to work with. Does anyone know the longest base to ogive 140 match class bullets out there when measured properly with a 6.5 comparator??

 

So in my rifle to the lands with the 139 scenars measures 2.842. I'm guessing I can fit a whole truckload of H4350 in there seated 10 thou off the lands or so. Thinking of running a 300m ladder from 39-41++ what do you guys think??

[treetop]

What about a faster powder ...

Like IMR 4166 or even 8208 XBR ?

[ofrn]

Hey mate how the only powders that I have access too are adi powders. I have 2208 (varget) which works well with the 123 scenar. My gut feeling is that with 139 scenars that using 2208 will leave a lot of airspace in the case due to the long length I want to run with. I think even using 2209 (H4350) won't even fill the case properly to 100% which is what I would prefer with a coal of 2.832.

[Leeman]

ofrn,

 

If you can get hold of them in OZ, Norma 130's are a long bullet and the newer Hornady 147 ELD Match may need to be seated deeper than the Scenars. I can check the Norma or Berger 140VLD with the Sinclair 'nut' comparator if it's any use, also have some 123 AMAX and 100 grain scenar to help calibrate to whatever comparator your using if it helps.

[ofrn]

Thanks mate for your offer but I have 500 139 scenars to work through before I think about changing bullets if they work well I May leave as is. We do have the 130 Norma gt here and I looked into them they have an excellent form factor. Reports I read on them were patchy though with quite a few people suggesting they were very fussy to load for?!

[treetop]

8208 XBR is an ADI powder