Long time lurker (since I'll learn more from listening than running my yap) with a kind of an odd occurance. I changed primers for my 700 in .308 from WLR to CCI-BR2, so I thought I'ld reinvent the wheel and work up a Varget / 175SMK. Make up seven different loads in 0.3gr increments, ending with 45.0gr and starting with 43.2gr. OAL 2.270", Lapua cases fired 4-5 times with all the prep work you can think of.

A little background: stock 26" bbl, 100yds, gusts to 10mph, 32.5 degrees, 717ft ASL, BP 30.00 inHg. Chrony refused to work despite my cursing whatever chronograph gods exist. In the words of Richard Marcinko, "doom on me".

To start, I shoot 6 foulers / sighters (I removed my scope and needed to get back on paper). I then proceed to shoot the first group of 1 cartridge at it's own load's target from each of the seven loads. With the 175SMK/45.0 Varget/WLR combo, the load showed very slight extractor marks on the rim.

First group, no major pressure signs (V. slight extractor marks on the 45gr load), couple of WTF's and maybe a poor wind call but POA / POI is pretty close for the majority. Second group goes the same, some potential screamers, some potential shotgun patterns. the second shot of the 7th load (45.0gr Varget) has a little shiney patch on it. Primer's round, no probs extracting. Third group, the shots from the last 3 loads are all getting a sticky bolt. No flatened primers. I notice that ALL the cases from the third round have extractor marks. POA and POI apearently weren't on the same page. I'm a little confused..

When I start to correlate the shots, first group looks good, second group looks better with the 43.5gr, 43.8gr and 44.1gr loads hitting within 0.25", a little bigger in the first group but within 0.4". THIRD group is a barn door: only a called high shot had a similar POI to another round. The rest were scattered mostly low left.

So my question to you learned gentlemen is WTF? Any ideas about the third group? Huge grouping, pressure signs from the LOW charge weight...it could be a dirty bore, but after only ~25 rounds...of Varget?? Maybe crud in the chamber (the MTM boxes had some excess flotsam in them). Time between shots wasn't an issue, nor was bbl temp. I can't see where it could be the bullet seating depth.

TIA,
S.

BTW, most promising trends were seen at 43.5, 43.8 and 44.1 grains, although the 43.2 and 44.7 grain loads shot admirable groupings as well.

[ 03-17-2003, 02:34: Message edited by: echo3mike ]

Can you tell us more about the brass that you used? The trim length, brand, etc.

I've never seen extractor marks and hard bolt lift ahead of flattening primers, but other folks may have seen this. It is true that the CCI BR-2's have hard cups, so they may resist flattening more than other primers. The WLR's are hotter, so the 45 grain load should exhibit less pressure with the CCI's than with the WLR's.

If I understand you correctly, you were shooting the "round robin" OCW method, and on the third pass through the 7 targets, you found hard bolt lift and other pressure signs--even on the low charges? Let me know if I'm understanding you correctly...

Is this rifle new, or is the barrel well broken in? There may be heavy coppering if the factory barrel has fewer than 250 shots or so through it.

Did you throw the charges, or weigh them individually?

Lastly, what seating depth did you use?

Dan

I just saw your OAL. I think 2.270" must be a misprint, or there's something I'm not understanding...

I load the 45 grain Varget/175 SMK recipe to 2.885", but my Savage 10FP will feed that length from the magazine.

I wouldn't go shorter than 2.800", and I'd rather see it at 2.850" or better.

How long can you load, and still feed from the magazine?

Dan

[ 03-08-2003, 09:18: Message edited by: green 788 ]

echo3mike,
Welcome to the site.
I'll tell ya' mike, when a rifle makes up it's mind it doesn't like a load things go to blazes in a hurry. From what you say, I'd forget everything about the third bunch. I'll admit that I'm chicken. When I get pressure indications I quit in a hurry. I guess that's why I have two bullet pullers, too break those loads down with out having high pressures expand the primer pockets. I don't think I'm smart enough to understand tht OCW theory. I have had the best results loading three rounds aith each load. Starting low and working up in half grain increments. The difference a half a grain may make is awsome. The shiny round spots you mentioned on the face of the cartridges may be caused by high pressures. The brass is extruded into the ejecter recess and when the bolt is turned it cuts the brass that is deeper than the bolt face off. The sticking bolt is also a pressure sign. Good luck.

[ 03-08-2003, 09:36: Message edited by: BigBob ]

Lapua cases in good condition, trimmed to 2.005 & chamferred, neck tension at .002 (bushing size .306), flash hole deburred, neck turned... all charges weighed as close as I could get them with a 5-0-5 scale...yeah, OAL was a typo...~2.77X", 3.125 with a Sinclair comporator. I used this OAL during a prior load work up and thought to try it here. The only other OAL I've tried (3.290" with comporator) wasn't mag tolerant, which is what I'm going for here.

Rifle's got 800+ rounds through the bore and doesn't usually foul bad enough to cause this type of reaction, even after 40+ shots.

Yes, was shooting "round robin", 6 sighters / foulers and the 21 test shots. Loads were as follows:
1) 43.2gr
2) 43.5gr
3) 43.8gr
4) 44.1gr
5) 44.4gr
6) 44.7gr
7) 45.0gr

First group, only slight -> very slight ejector marks on the 1st shot of the 45.0gr load. No sticky bolts. Second group has slight ->very slight ejector marks on the 44.4gr, 44.7gr and 45.0 gr loads. No sticky bolts. Third group has slight -> significant ejector marks on every load and sticky bolts in the 44.4gr, 44.7gr and 45.0 gr loads. Third group groupings also displayed a signifcant deviation in POA / POI difference relative to groups 1 and 2.

Upon closer inspection, primers from the 3rd group look slightly flatter than those in the 1st group. This occurred both within the same load and across groups, with the heavier charge weights showing a more pronounced difference both within their respective loads and in relation to the lower charge loads, (third shot of 45.0gr load flatter than 1st shot of 45.0gr load, shots 1-3 of 43.2gr load). There seems to be a flattening from the first to second shot of the 43.2gr load as well; this difference is difficult to notice without close inspection. Case body expansion was measured at .469" in both fired (45.0gr) and unfired cases.

Looking at groupings, second group is smaller than either 1st or 3rd group, with better POA / POI correlation. In groups 1 and 2, the 43.5gr, 43.8gr and 44.1gr loads have POI within .31" and .24" respectively. No noticable similarities were noted in the third group.

I switched to the CCI primers since I've read about the WLR primers being hot and less consistant. My prior groups can attest to the less-consistant part. This latest soire' has me a little flummoxed. I can't think of anything that would have caused the ejector marks or (now) the flattening.(Flattening from the first to the second group of LOW loads??? It's slight, but it's there.) Fouled bore / throat? Schmutz in the chamber / bore? (Bore and chamber cleaned up without any noticable difference between these loads and others, incl. factory stuff).

Like I said, I'm a little confused. Since I'll have to chrony the loads at some point, I may just do the whole thing over. Some items to possibly change are
A) seat the bullet out to the longer depth I've used before or to 2.8XX" for a mag tolerant cartridge;
B) clean the bore between groups and shoot foulers prior to shooting groups (...would this affect the overall reliability of the testing paradigm?);
C) use fresh cases;
D) take up golf instead (who am I kidding...)

Any other suggestions or input is welcome. Let me know if I'm still not making sense.

Thanks,
S.

With the 45.0 grain Varget load, which used the WLR primers (and did not show pressure signs)... What was the OAL then?

It may simply be that the bullet is seated a bit too deep. I believe that I would go with the longest length that the magazine will allow, and that should get the pressure down some.

An effect called "nail-heading" can occur when a long bullet is seated too far into the case. The bullet's base obturates (bulges) when the powder charge fires, and enlarges as it tries to squeeze through the case neck. Naturally, pressures spike noteably. With the seating depth you were using, this effect may have come into play--at least to some degree. Exactly how the warming and fouling barrel may have exacerbated this I don't know, but it's my best guess at this point.

The 26" barrel length will cause pressure to rise a little, but not that much. The rifle will probably shoot its best groups at or very near 45 grains. If you don't want to repeat the whole test, try loading a half dozen or so shots with the 44.7 grain charge, with the bullet seated out farther. Then, if you get no pressure signs there, shoot a group charged with 45.0 grains.

Let us know how it goes...

Dan

You asked for helpful ideas, so here are a few more questions:

Were the unfired cartridges laying in the sun? Did some form of case lube, grease, or gun oil get into the chamber from earlier rounds fired? Could some moly have gotten into your chamber?

Did you shoot the rounds in the same order as they were loaded? I have accidentally moved the weight hanger on my 505 scale before, and upset the supposed weights by accident, before I upgraded to a 10-0-10 model that has a locked down feature on it.

Did you measure all OALs for each setting before shooting? Could a magazine full of loosely held charges result in compression of powder due to recoil from the previous shots?

My money is on the charges sitting in the sun and proving that even varget is temperature sensitive.

mean to help.

Jameister

With the WLR primers, the bullets were seated to the 3.290 (comporator) measurement. Cartridges were under cover and loaded one at a time, and were shot in the order they were loaded (sorry, Jameister).

I've been thinking about something that while a little far fetched, seems to explain alot of the symptoms. I noticed that the fouling on the muzzle was caked when I got home...not just the usual light layer, but caked thick after only 20- some odd rounds. So it got me to thinking: could condensation inside the barrel occur?

The shooting benches at the range are kind of enclosed (like shooting out of a garage) and a few degrees cooler than the target. Lots of snow on the ground, and the temp outside the firing line was probably a few degrees warmer than where we shoot. So there was alot of humidity from the melting / sublimation. Hot barrel cooling down in a 32.5 degree F / ~0 degree C very humid environment. Could it make the powder fouling "damp" and along with moisture in the bore, increase the pressure to levels that would cause the results I got?

It's a little far fetched. I've shot in very humid weather, but it's usually been fairly warm along with that. I haven't shot in temps this cold before, so I don't know if it could be a cause. As Doyle was so fond of saying, "once you've exhausted all logical possibilities, the remaining conclusion, however illogical, must be true".

At any rate, I'll try loading a little further out and shoot on a dryer / warmer day. Will post results.

Thanks again,
S.

The condensation idea may have merit. Let us know how the next batch goes... I hadn't thought of that.

Though it may not have been the case here, I've seen several range sessions spoiled due to sun-heated cartridges, so Jameister's words are worth considering for any who may be reading this thread...

Dan

ABSTRACT: OCW loading tests were repeated for a 700VS in .308 with load weights ranging from 43.5gr to 45.0gr. Cartidge OAL changes and different bore cleaning methods were employed to eliminate the excessive fouling found within the initial trial. Most satisfactory POI's were seen with the 44.1, 44.4, and 44.7gr loads. Sources for error include unaccounted for MET / ENV conditions, equipment, less than optimal number of test shots, loader / shooter techique.

Got out to try some of the suggestions posted here regarding the 175 SMK / Varget loads listed above. And with a little help from whatever higher power that looks after guys trying to use a chrony, got some MV data to boot.

First, the rounds were loaded to 3.155" using a Sinclair Intl. comporator, low 2.8" without. Dropped the 43.2gr load, since I'm looking for a load closer to the 45.0gr load suggested elsewhere. Varget loadings were

1) 43.5gr
2) 43.8gr
3) 44.1gr
4) 44.4gr
5) 44.7gr
6) 45.0gr

I also gave more thought to the "condensation" issue. While that might have been a little far fetched, the idea of a residue from the cleaning solvent wasn't (long story short, new marketing co. for MPro7 may have changed the formula). So I gave the bbl an alcohol wash prior to firing.

MET / ENV conditions were 54 degrees F, 30.20 inHG, 29% Hum, winds from 6:00 to 10mph.

RESULTS

The most consistant loads across the 3 three shot round-robin groups were the 44.1, 44.4 and 44.7gr loads, with the 44.4gr and 44.7gr loads hitting in all three group "groupings". Again, the 45.0gr load produced a POA / POI variance not seen in other loads. The most notable grouping was the first, with loads 1, 3, 4, and 5 producing a POI within .304". The second group was delayed 25 min due to a rapidly changing shadow and desire for chronographic data. Average MV was as follows: chrony distance from muzzle at 21 feet / 6.4m.

1) 2688fps (2701 @ muzzle)
2) 2684fps (2697 " " ")
3) 2699fps (2712 " " ")
4) 2695fps (2708 " " ")
5) 2700fps (2713 " " ")
6) 2715fps (2728 " " ")

The first 2 shots of the second group produced an "ERROR" message in the chrony, which necessitated the delay.

The most notable difference was the complete lack of consistant signs of high pressure. There were some "flattened" primers, but there were some primers that were more "rounded" interspersed within each of the groups. As such, these "signs" were ignored. Since different cases (from the same lot) were utilized in this second test group, further case inspection is warranted especially in regard to loose primer pockets.

The results suggest loads 3, 4, and 5 represent a tolerant and accurate load weight of Varget for this 700VS. Loads 1 and 2 also displayed a high intergroup POI correlation; this may be an important factor regarding future bore life, but more uniform MV's within loads 3-5 are consistant with Newberry's OCW test paradigm and acceptable results.

S.

It looks like you did it ...

I believe you're there with the load. I can't decide if the 26" tube, or the deeper seating of the bullet moved the usual 45 grain charge down a bit, but it really doesn't matter: You've got the load for that rifle. The chronograph data looks great, and it sounds like the group sizes are very good as well.

Thanks for keeping us informed, and sharing your data and experience.

Dan