Jump to content


  • Content count

  • Joined

  • Last visited

About mactavish

  • Rank
    Newbie or Infrequent Poster

Profile Information

  • Gender
  • Location
  • Interests
    Long Range Target (particularly ELR)

Recent Profile Visitors

82 profile views
  1. 6.5 Creedmoor; Lapua case capacity & life

    Garbage in, garbage out . If it floats ya boat, do it...!
  2. 6.5 Creedmoor; Lapua case capacity & life

    The main reason we might want to know an accurate figure for case water volume is to help calculate accurate pressure and MV data in load development software like QuickLoad. Also, no reason it should entail too much messing about. At least not beyond taking a few simple measurements.
  3. 6.5 Creedmoor; Lapua case capacity & life

    For reference, interest and what it's worth, I've just cracked a brand new box of Lapua S/R Primer brass and the first one I picked out and weighed was 166.84gr (with a spot of blue-tack up its pocket). With water it was 218.44gr, giving a case volume of 51.60gr. The second out was 167.02gr, going up to 218.46gr, giving 51.44gr. It's probably fair to say virgin Lapua CM case volume is around 51.5gr of your finest H2Os.
  4. 6.5 Creedmoor; Lapua case capacity & life

    Perhaps we've just talked past each other, because it seems you're just bumping the shoulders back as opposed to "Full" Length sizing, which as you say, will bring a case back within SAAMI specs (and it appears well within, if die manufacturer setup instructions are followed to the letter). "...besides which you fire what you size to so that's the only case capacity that matters." No, not really. Load development really needs repeatable baselines and case volume measurement is an important one (as categorically required by QL for example). So, given you're essentially bumping back only 1 thou, I can't imagine why your measured case volumes are coming out so relatively low, considering my findings tie very closely with both Treetop's & Trifid's above when our brass is compared like for like (ie fired case volumes). (Incidentally, my Lapua brass fired case volume of 52.8gr was gleaned from an average of 3 fired cases being measured.) Perhaps it has something to do with your relatively mild loads in such sturdy brass? However, I still don't see that accounting for the large discrepancy between your Lapua results and those of both Trifid and me.
  5. 6.5 Creedmoor; Lapua case capacity & life

    Sounds pretty good to me...
  6. 6.5 Creedmoor; Lapua case capacity & life

    Hi Varm, My Lapua brass are 52.80gr H2O, while Federal (I got 20 factory rounds thrown in very cheap with the rifle) are 53.52gr. Because you're measuring FL sized brass, you're really just making a measurement particular to your dies, and while this makes a comparison across your brass of sorts, the measurement will be relatively meaningless in comparisons with varied brands in various different states. (For instance, QuickLoad stipulates that for all its calculations it requires entry of the H2O volume of your fired cases because it's the only state in which measurements will remain constant across the world's different 6.5 Creedmoor brass and sizing regimes.) Also worth bearing in mind that "Full" FL sizing is pretty brutal. My Redding FL die, set "correctly" as per its instructions, knocks headspace from a fired state of between 1.540 and 1.542 (depending on load stoutness), right back to 1.533. That's a whole 9 thou of brass working, along with corresponding case volume restriction. (My new Lapua brass headspace measured 1.538, incidently.) These are the two reasons I bump my brass back to a whisker over 1.539 (an average of around 1.5 thou)... thereby holding brass work to a minimum while maintaining the highest possible capacity along with case & neck uniformity and ease of chambering. In regard to Lapua's smaller capacity relative to other manufacturers brass, then a grain of so less (0.7 in my case) is two thirds of chuff all (as a quick fiddle with QL quickly reveals) and is more than off-set by its proven strength and pressure tolerance. Glad you mentioned the muzzle thread issue. I never had any problems with my Wildcat Predator, however, when I became aware of the issue (through this forum), I dismantled the mod then fitted and tightened only its front portion to the rifle. On careful inspection I did actually notice a tiny gap and I found I could just squeeze a 2 thou feeler gauge between the mod rear and the barrel front face. I guess it never presented a problem as its already slightly rebated thread allowed as close to true alignment as made any difference. Anyway, I simply rebated the mod thread a further millimetre and the job was a good'n. Like you, I didn't much like GMK's Heath Robinson solution.
  7. This 147gr OCW was shot in virtually no wind (I'd waited nearly two months to shoot this batch that I made up last November, having passed up a number of shooting days due to learning the hard way by twice wasting lead doing OCW in choppy conditions). The real point I made earlier is that with these pretty small groups from a factory rifle on a small tactical bipod, a tiny rear bag and about 10 minutes cooling after each group, I reckon I'm not prepared to believe either rig or I am good enough to resolve POI causes and effects further. We're all fallible (as demonstrated by the big flyer on the last group). If I did try to draw conclusions further from the resulting groups I think I could easily be chasing shadows. (See the pic below where I've just overlaid the whole set in Photoshop. Note that discounting the 2 "flyers" at top & left, that all 16 remaining rounds lie in a 8.5mm x 12mm group. At 100 metres and across a whole grain of powder, you got to be happy with that... ) Anyway... I've just checked back in my Loading/Firing Records and note I actually speed tested 10 of that 46.86gr load last month. They were shot in 5°C conditions (hence slightly lower MVs than indicated by an earlier RS70 and 147gr ELDM speed ladder shot last October) and ranged 2808 - 2823 fps for an ES of 15 and an SD of 4.9. As mentioned, I'm pretty happy with that, especially given the potential for inconsistencies in my batch 2 brass from which this OCW was shot.
  8. You might be right... but then again, from 100 metres out I was more inclined to conclude that I couldn't rule out that what had occurred within the 6mm of 46.8's horizontal aspect and the 6mm of 47.0's vertical aspect, wasn't down to the trigger puller...
  9. Assume that's a typo, VarmLR, but 46.85 grains seems pretty clear to me... Oops! Apologies. That's a typo of my own. I was referring to RS62 throughout. Results for RS60 have been mixed in this rifle. I've found reasonable accuracy, but neither in the same "across the board" manner or specifically excellent nodes as found with RS62 and with RS70.Turns out it's just less forgiving at the higher velocities I was chasing with it and I'll be keeping RS60 for future use in a custom project I'm currently contemplating. And yes, I reckon you're right re bearing length being less on the Scenars v the SSTs. That they're a smidge lighter and I've also found them to be ever so slightly narrower than the SSTs, it's no surprise to see them flying 30-40fps faster for a given charge. I've not done extensive strings on my developed loads to find MV consistency (I've a magnetospeed and I consider every round shot a bit wasted in terms of anything other than for assessing MV), but in the 2 or 3 I speed tested after OCW, I did find ES for both RS62 & 70 to average sub 15 in all the nodes found and that was with no regard to barrel temp controls. I guess for now, these hastily found preliminary ES figures are well within acceptable working limits, but as this season progresses and ranges increase, I might find that revisiting MV consistency and making a few tweaks beneficial. Related to this, I too seem to have found accuracy has incrementally improved over the first 3 firings of this Lapua brass and I reckon ES has probably benefited here too (I'm bumping 2 thou, which is obviously working well also). Unlike you however, I've only ever used Murom S/R Magnum primers (KVB-223M) from the outset, so can't comment on any other primer type, though I do find it odd you're finding any pressure signs with RS62. I wasn't even seeing pressure with Scenars on 44gr of RS60 pushing them at 2915 fps...!! (Though I did see pressure with Berger HTs from 43.7gr+ RS60 at 2850fps+.) Incidently, I have 5 batches of 100 cases ranging from 1x unfired to batches 1& 2 being 4x fired. A problem I considered from early on (and another reason for limiting MV analysis) was because I was running various different powders and bullets (from mild to pretty hot) within batches 1 and 2, I knew load to load consistency within these batches could be affected and I now no longer use them for ultimate precision (as an aside; finding the ES values noted above is something of a bonus). My aim is to anneal, trim and re-batch all batches after 5 firings. Again, as this year progresses and I undertake more longer range precision work with single bullets & charges now identified, I will be able to use case batches 3, 4, 5 and a re-batched 1 & 2 to provide more consistent precision MV analysis and tweaking.
  10. When you found the SST needed more powder than the Scenar, was this to hold the same MV, or did you find 44gr doesn't hold quite so accurately for them? I ask, because I found (without getting down to scientific levels of measurement) that 44gr RS60 proved equally accurate across every 139/140 bullet tried to date. I also found Berger HT & Hornady ELDM & SST all consistently average 2640 fps, while Scenars average 2670. To be fair, however, I have not invested "scientific levels of measurement" into the Scenars, SSTs and 140 ELDMs because my focus for ultimate precision in this rifle turned to the Berger 140gr HT for short/medium range and Hornady 147gr for long range. This is why they were the only bullets afforded full OCW and subsequent seating depth analysis. (The Scenars and 140 ELDMs were acquired early doors while awaiting the arrival of 147 ELDMs to the UK and I'm now running down my last few, while I found some SSTs really cheap a few months ago and couldn't pass up the opportunity... that I found them to hold well under 1 MOA in practice/plinking (with zero time invested) was a great bonus. ) Anyway, good results yesterday... these A1s really ain't too bad... OCW: Hornady 147gr ELDM at 2800fps+ ...
  11. Hi VarmLR, It's great to see your OCW experiences written up in such detail. Very interesting. Given your experiences to date, you might be interested to learn that on doing 140gr Berger Hybrid Target OCW in my own A1 last July... I happened upon the exactly the same figures as you quoted above. The self-same powder, cases & also including Murom S/R magnum primers from the outset. Our respective results appear identical even down to finding that 42.4gr of RS62 is marginally the more accurate, being a remarkably consistent 1 hole maker at 100m. I also found that the same charges of RS62 work exactly the same across a number of 139/140gr bullets I've tried from Hornady & Lapua, with only relatively minor MV shifts between each. Subsequently, I've mucked around with various bullets from 95gr to 147gr and the four RS powders (52, 60, 62 & 70) that lend well across the 6.5mm Creedmoor spectrum. The upshot has been [mostly] positive results and to summarise, I've found the Creedmoor is a fantastically versatile round. That said however, I think I did find a real darling in this rifle... a combination the rifle might have been built for. Finally getting my hands on some 147 gr ELDMs last October, I'm now running them at 2825fps with RS70 and it shoots repeatable 6mm groups at 100 meters. Such a slippery little specimen at over 2800 with this level of precision is proving to be an absolute blast.
  12. Many thanks for this, Laurie. There is some very useful info and no doubt a great deal of experience here for me to ponder. Especially in regard to the 28 Nosler perhaps not lending itself so well to F-Open. While this won’t make or break choosing it, it does bring bearings I need to consider. The barrel heating/cooling issue for one. I’ll certainly look at ways this might be controlled/mitigated, but those loading manual comments make for bleak reading in that regard. If the concept barrel can shoot careful strings and push up and over 800 rounds, then F-Open dabbles remain feasible. Significantly sub 500; not so much. Also, to be honest, I hadn’t considered the 28 Nosler would be quite that brutal without a brake… those figures are hefty!! Still, all this has made me now wonder if as new developments in cartridges, powders, bullets, barrels etc. come online, revisiting past concepts such as Pete Wilson’s once winning formula, with the odd modern tweak might once again find something viable in the class. Others’ ideas, as you suggest, might be very interesting to hear on this. Anyway, I guess ultimately whether ELR and F-Open in the one platform is a viable proposition will depend most on how honest I am with myself over how serious I might want to take F-Open once dabbled. I’m now beginning to fear such a proposition might prove itself compromised by the need for yet another project at some point. In regard to taking on the likes of the.375+ in such as the Ko2M; that’s not where I see my goals with this. I’m just interested in pushing some way towards what they can achieve within a reasonable budget and within the natural constraints we find on ELR shooting here in the UK. Your (and Bartlein Barrels’) comments re the overbore bearing on barrel life are very interesting and in conjunction with the interesting reading in Catch-22’s earlier link (showing a relatively successful attempt to mitigate big 7mm throat erosion) suggest a strong confirmation of what we’ve already started to establish. With an overbore index of 1522, the 28 Nosler’s significantly in excess of anything on that list. So, unless it’s blessed with something approaching alchemical qualities, then barrel life for anything approaching competitive shot strings, will be dire. I can imagine looking out for lots more of those early adopter anecdotes across the pond will keep me quite busy in the next few months. Thanks again.
  13. Hi stephentri, Long story short(ish:) … my CM is 24in (actually a Tikka TAC A1). I got the rifle last July and after initial successes with 140gr bullets (Berger Hybrid Target & ELDMs) using RS62 at around 2650 fps, I found stepping up speed using RS60 more of a challenge. Accuracy was relatively poor in OCW (compared to repeatable 5mm @ 100m groups with the 140s/RS62) and while ladder testing I started to see pressure signs (ejector ring) in the Lapua S/R brass earlier than I might have imagined at around 2850fps (Though tbf, these only showed in the Bergers and not in the ELDMs). When I finally got my hands on 147 ELDMs in October, I already had RS70 here waiting and have never looked back. QL guided a start at 45gr and an overall excellent bout of OCW ended up giving 46.8gr with the above mentioned accuracy node at 2825fps. It's in bump sized brass. S/R magnum primers. COAL is 2.890 (=.045 jump). (Incidentally, there were no pressure signs right up to the 47.4gr max tested. Coincidently, compression is occasionally heard/felt on bullet seating at 46.8gr, indicating around 100% fill.) Usual caveats apply. Obviously these figures work a treat in my rifle, but they are pretty hot CM loads. Work up your own loads carefully & observe for pressure. Cheers.
  14. Hi @Catch-22 and thanks for the considered response. In regards to bullet price comparisons, like for like, .338 Hornady ELD-M (ELDM chosen as they happen to have highest [conventional bullet] BC in either calibre) are getting on for twice the price of the 7mm. But yes, you're right, of course. A big 7 and a .338 Magnum are broadly comparable across a number of criteria and where they do differ, they're broadly and reasonably arguable in terms of the various compromises they need to accommodate. Also, thanks for the reference to the 7mm Practical. I'm off to work shortly and I'll make a point of reading it during my break. I drew up some fairly basic ELR Tables/Charts a few months ago (based on QL & Strelok Pro outputs) to help me visualise what I'm trying to achieve across this ELR project. I've added them here to show some of the data across the discussion. Cheers. Ballistics - Various ELR Tables.xlsx
  15. Thanks for the useful comments on the 28 Nosler, Laurie. The method in considering this cartridge hinges around building a low round count ELR platform (given UK ELR opportunities being relatively few and far between) that is good for testing limits of precision repeatability at 2500+ metres. A secondary consideration is that it might still show a good account in the odd F-Open foray when the opportunity arises (given a hefty all-up weight and a premium recoil pad). Final build details for this are still fluid, but 28 Nosler, with its (granted, mostly anecdotal) big new reputation for speed* and (perhaps gravy train inspired ) reports of stellar accuracy, have put it to the top of my list if I decide to go BIG on my 7mm idea. (*QuickLoad indicates that with RS80, a 180gr ELDM with its huge .401 G7 BC has a max MV well over 3300fps out of a 30in barrel. Therefore, thinking goes something like; in terms of available MVs & BCs, this big 7 far out-classes even the Lapua Magnum in elevation and does so similar where wind is concerned out to around 3000m. I could even be tempted to consider this a [not so] poor man’s .338 Lapua Magnum LR project, but only evidence produced in practical application will confirm or deny this.) As you pointed out however, that the brass currently costs over 30% more than that of even Lapua Magnum, and ran relatively hot will have high brass and very high barrel wear, are serious considerations. As is the veracity of the early adopter reports out of the US, of course. Though to counter, this rifle will only shoot around 300-400 rounds per year (my Creedmoor will do the donkey work in LR practice) and brass, once acquired, will render the 7 significantly cheaper to feed in terms of powder and premium LR bullets than would be for feeding a Lapua Mag. Also (albeit anecdotally again), there are murmurings of higher than anticipated adoption rates, “Creedmoor like” real-life cartridge efficiencies & accuracy, and short timescales until we have other, including Norma branded, cases (not to mention the ability to neck up/down 26 & 30 Nosler brass). As I mentioned in the earlier post, this 7mm project will either be in the form of 7SAUM (perhaps as a stepping stone to a .338 LM) or it'll be one of the biggest 7s, which as just discussed, by measures comparable to the .338 will likely suffice in its own right in terms of ELR in the UK. Decisions… decisions… In this game, the journey is often as much fun as the arriving. Incidentally, time is on my side here, as none of this will happen until I’ve fully stretched the legs on my 6.5CM and now that I have 147 gr ELDMs running at 2825fps and shooting repeatable 6mm groups at 100 meters, it’s barely scratched the surface in terms of LR (at a little over 600m so far). This means I have plenty of time to further research and mull before I make that decision. However, if this spring goes to any kind of plan, the CM should be out to a mile (hopefully with some precision) by summer and then a hankering to go further than its realistic capabilities, will, I’m afraid, very likely arise… Anyway, I’d be interested if you’d like to share your ideas on my mission brief and tell me how and why you might do anything differently? Edited to add: Ooops, thread hijack alert!! Apology to meles meles for interrupting your convo...

Important Information

By using this site, you agree to our Terms of Use and Privacy Policy