Help with a QL run for me please?

[VarmLR]

Would one of you QL users be able to do me a favour please? I've decided to gove the SMK175's an outing before I decide on adopting the TMK (superior bullet but it saves me returning the smks for an exchange).

 

I just need a guide to max safe load, with one seating option looked at to start with based on magazine length and rough indication of MV. Viht data looks way overly conservative for this combination:

 

Factory chamber, bullet seated at 2.8 COL; 175gr SMK; Viht N140; 1/11 twist; 24 inch barrel; Muron KVB-7 Primers.

 

N140 being used solely as I have a kilo of the stuff which I want to use up before switching to RS50.

 

Thanks in anticipation.

[Andrew]

I think that if you want magic from Quikload you'll be waiting a long time. That powder seems a little fast for that combination. A quick look at Hornady's new data doesn't even list this powder with bullets heavier than 150 grains in a 308. There comes a point where powders just aren't optimal with a component combination and this may be one of them.~Andrew

 

(FWIW, I would never put quikload's computer generated data before the manufacturers test data. Even quikload advises against that.)

[blackburnbuccaneer]

This ought to give you a starting point, although Vihtavuori load data is rather conservative, I would imagine working up in increments you might end up over the published max (as always start low and work up in small steps).

http://www.vihtavuori.com/en/reloading-data/rifle-reloading/-308-winchester.html

[VarmLR]

...

[VarmLR]

Thanks gents.

 

I have successfully shot 190 SMKs with 42.8gr N140 for 2500 fps, so know it'd be perfectly fine for 175's but just not ideal. A bit low on MV perhaps and a bit thumpy!

 

N150 is a far better bet, but the question wan't "what's the best propellant" as I'm already switching to RS50 on the recommendation of those who've tried it and rate it, it was whether someone with QL might run the figures for me as it could save some necessary wastage in load development using up my stock of N140

 

This ought to give you a starting point, although Vihtavuori load data is rather conservative, I would imagine working up in increments you might end up over the published max (as always start low and work up in small steps).

http://www.vihtavuori.com/en/reloading-data/rifle-reloading/-308-winchester.html

 

Thanks. Yes, already seen that thanks, but my experience using Viht powders is that their load data is very very conservative!

 

Lyman gives over 43grains but their loads can be a bit hot imho.

.

 

It's a one off and not the best way to go, but I'd like to use up what I have before spending more. This isn't for competition.

[snakeman]

Varm

 

Below is the data for the standard # 2275 ... 175g SMK with N140 applicable to the parameters you've requested (barrel length = 23.622 inches and bullet length = 1.240 and seated at 2.800 ..case trimmed to 2.005)

 

Low pressure (under safe pressure)

 

37.5g = MV 2324fps with a Chamber Pressure of 38,758

 

38.0g = 2351fps & CP = 40,179

 

38.5g = 2378fps & CP = 41,652

 

39.0g = 2404fps & CP = 43,177

 

Normal 'safe' pressure

 

39.5g = 2431fps & CP = 44,758..(with this you hit 'normal' safe chamber pressure)

 

40.0g = 2457fps & CP = 46,396

 

40.5g = 2483fps & CP = 48,092

 

41.0g = 2510fps & CP = 49,850

 

Into the purple 'danger' zone.

 

41.5g = 2535fps + CP = 51,673 ..(entering 'danger'-zone chamber pressure - proceed with caution)

 

42.0g = 2561fps & CP = 53,562...(at 42.1g it becomes a very slightly compressed load)

 

42.5g = 2587fps & CP = 55,522

 

Nearing the top of chamber pressure ..(proceed 'if you must', with extreme caution)

 

43.0g = 2610fps & CP = 57,555 ..

 

43.5g = 2638fps & CP = 59,663

 

 

.5 of a grain higher would be in the 'critical' zone

 

44,0g - (wouldn't go here but for you curiosity = 2663fps & CP = 61,852)

 

 

(Your own standard reloading rules apply)

 

ATB

[VarmLR]

You're a gent Snakeman, many thanks for that.

 

On the basis of the data I've gathered, I'd guesstimated a starting point of 39.5 and was prepared to ladder test up to around 43gr. On the basis of some figures run previously on QL, it appears that the results show that my barrel may result in slightly greater velocities and lower pressures than QL might predict, but I'll play safe and only go up in .2 intervals between 42 and 43 looking for signs of pressure.

 

It would appear that I'll be through transonic and into subsonic at 2600 fps (G7 BC of .243 gives 900 yds @ 1215fps & 1000yds at approx 1103 fps). Hope they're stable through transonic or I'll be peppering the target!

 

Ideally, I'd need closer to 2800fps to make them work well, and I'll not get that from N140 in my barrel. If they shoot anywhere near as well as the 190's I'll be happy.

 

Ought to get a little better than that using RS50 with them.

[VarmLR]

Update after some load dev.

 

Actual resulst to compare with Quickload.

 

All rounds loaded at 2.800" COAL.

 

Load (gr) Ave. Velocity (fps) Pressure signs

(un-corrected for chrony distance from muzzle)

 

41 2464 None

41.5 2501 None

42 2539 Primers fine, very slight mark on head, light bolt lift (freshly cleaned chamber)

42.2 2554 As above

42.4 2559 As Above

42.6 2582 Some very slight flattening on the primer edges, nothing significant. Bolt lift fine

42.8 2596 As above

43 2621 Recoil heavier, slight flattening of primer, slight extractor marks on case head. Bolt lift fine.

43.2 2620 As above, and bolt fractionally stiffer to lift.

43.4 2614 Heavy recoil, ejector marks on case head. primers still ok, haven't flowed to edges or flattened and slightly harder bolt lift.

 

It is obvious from the above that pressure has spiked by 43 grains N140 and increased loads are starting to give reduced benefit by 42.6 grains. Anything above 43 grains is raising pressure unnecessarily (and perhaps dangerously) high with no lee-way for temperature sensitivity which could cause dangerous spikes with higher temperatures.

 

Velocities are too low much below 42.4, and still only marginal for 1000 yards even at 43 grains/2621 fps. Really, MV needs to be closer to 2760 fps to stay above transonic.

 

We can add around 5fps to the above velocities to account for the several metres away that the chronograph was measuring, so around 2587 fps is more likely actual MV at around 42.6gr. This gives around 1104fps at 1000 yds and just under supersonic at 900m (984yds) which is the target distance for the load development.

 

As long as the 175's are tolerant of the transonic region, they may work, but I will be trying RS50 when it comes back in stock locally as results from that ought to be better (I do not want to use hotter burning double base powders).

 

Corresponding 5-shot group sizes below:

 

Load Group (inches)

 

42.2 .444

42.4 .483

42.6 .553

42.8 .643

43 1.175

 

However, the above does not tell the whole story, since the lowest horizontal spread BUT the highest ES was at 42.6gr with a spread of just 0.138" and an ES of 35 compared with a horizontal spread of 0.321" for 42.2gr and an ES of 15.

 

Had the 42.6 group had the same ES, the calculated vertical dispersion would have been about .24".

 

Group pattern shows a very even about-axis touching hole group at 42.4, and a touching group with a tiny horizontal spread for the 42.6 node, so I reckon that loading to 42.5gr allows a little to play with on pressure with temperature sensitivity whilst being very darned close to a decent node, hence I'll try them at that. Interpolating the above, that gives a true MV of around 2565fps at 22 degrees C.

 

Not earth shattering but may be enough.

 

Comparison with Quickload:

 

42.5gr estimated an MV of 2576, so really very VERY impressively close!

 

43gr estimated an MV of 2610, compared with closer to 2626, so as loads climb (in my barrel, I'm getting slightly higher if I add on 5fps for the chrony distance or within 11fps if I don't! Splitting hairs as QL seems remarkably close.

[snakeman]

Varm

 

Such close outcomes and it reads as though Quickload has done itself proud this time. I wonder how accurate it is with different criteria in other calibres?

 

I use N150 with the 175g but there'd be hardly any difference in real-time outcomes (MV) than you achieved with N140 I should think? - good luck with the RS50 and keep us posted

 

Top write-up Varm and glad I could assist with QL criteria

 

ATB

[VarmLR]

Thanks snakeman, and thank you for taking the time and trouble to put the loads through QL. Great help, and it demonstrates the value of Quickload very well.

[stu47]

I used to use N140 with SMK175's and achieved good sub .6 MOA accuracy out to 600 yds with BR2's.

I then switched to RS50 with Murom Primers and am able to get sub .8 MOA at 1000 yds regularly.

TMK175 with RS50 and Murom in Lapua Brass (annealed every firing) and group size reduced at 100 yds (.4 MOA), at 1000 yds (.7 MOA) and gave an average of 50fps increase over a similar N140 powder charge.

I had to adjust the RS50 burn rate in QL to get the true MV with the TMK's (2675 fps).

I've now switched to Palma Brass with CCI450's but so far have not seen the reduced ES/ SD I was hoping for but I'm still adjusting the jump to find the sweetspot (currently 15 thou) - more to follow if successful.

Tried N150 in Palma Brass but just cannot find a combination nearly as good as RS50.

Finally, the TMK's produced far less batches when measuring Bearing Surface and weight than SMK's.

I thought about buying a bullet pointing system for the SMK's but even when pointed won't result in a BC increase on par with the TMK's.

These are just my findings, in my rifle, with my loading/ shooting skills/ techniques - you may well get different results.

Good to share though.

[VarmLR]

Thanks Stu. All good information. I'm switching to RS50 and TMKs in due course but have a few hundred SMKs left and a fair bit of N140, so will persevere. What velocities were you getting out of the N140/smk combo out of interest? I'm guessing that the RS50 gave slightly higher velocities?

 

When you mention that TMK's produced "far less batches" are you saying that they had more variance in their bearing wall length and mass than the older SMK design? I've found with the 190 smks, they vary a lot in base to Ogive, by up to 20 thou. Haven't measured the 175's to compare yet.

[stu47]

I was getting 2625 fps +/- 10 fps with N140.

 

My RS50 load at 1675 fps is +/- 4 fps.

 

I bought around 1500 SMK's, though not all at the same time so the batch numbers differed - I always measure bearing surface, base to ogive and weight which gave me over 20 different batches of bullets. The powder charge remained constant, I adjusted the seating depth specific to each batch. Some advised me to maintain the jump and and allow seating depth to differ from batch to batch but, for me, didn't give as good results as adjusting the seating depth. The SMK175 is a very jump tolerant bullet. I would have no problem going back to SMK's if TMK's became unavailable.

[VarmLR]

My velocities aren't as high as that. As you can see, from a 24 inch barrel, I'm getting around 2585fps at the muzzle with 42.6gr N140. Most of the SMK's seem to be very jump tolerant. All I've ever done with any weight of SMK was to load to magazine length and vary the load to get on a node. If I can squeeze in more RS50 without getting pressure signs, I may load for single shot, nearer to the lands.

[ejg223]

This ought to give you a starting point, although Vihtavuori load data is rather conservative, I would imagine working up in increments you might end up over the published max (as always start low and work up in small steps).

 

http://www.vihtavuori.com/en/reloading-data/rifle-reloading/-308-winchester.html

 

 

According to that list you should use a 190gr Sierra instead of a 175....you get slightly higher speed and can safely put more powder in.

 

Vit load data is often confusing.

edi

[VarmLR]

 

 

According to that list you should use a 190gr Sierra instead of a 175....you get slightly higher speed and can safely put more powder in.

 

Vit load data is often confusing.

edi

 

 

Yes. I think that the data for 175's is plain wrong in the Viht data.

Viht Data:

 

 

175gr HPBT: 41.4gr N140 for 2501 fps

190gr HPBT: 42.9gr N140 for 2508fps

 

 

It's as if they mixed up the two, or more likely that their 175 data simply is not correct.

 

From my own load development:

 

175gr: Pressure signs start at 42.8gr to 43gr, velocity 2596fps

190gr: Pressure signs start at 42.6gr. Velocity 2510fps

 

Similar but clearly, higher velocities are generated using the 175's, so Viht data is a bit suspect for these bullets. Demonstrates why you should always start low and work up!

 

By contrast, Lyman's manual gives 43.4gr N140 witrh the 175s. I was getting clear pressure signs by that load which is too hot. I've generally found Lyman's data to be on the "hot" side, which makes me wonder about the chambers and rifles they used.

 

The Lee reloading manual simply seems to re-regurgitate Viht's data, so I suspect that Lee didn't use Viht powders, just replicated what the Viht load data presents.