Discussion in 'Big Stuff--7mm, 30 Cal, .338+' started by Quickoz, Jan 18, 2018.
Contact Doug Boyer, He ran them at the 2018 Berger SW Nationals.
AB tested bc for the bullet 0.349 G7 or 0.682 G1
Tested various OAL from touching to .040" jump in 1:9" twist 30" Brux 308 Win barrel, 2013 FTR Reamer with 42.20gr Varget, Lapua Palma brass, CCI-450 SRP here in South Florida at 600 yards. I used my LabRadar and ran the data through RSI Shooting Software. I'll be doing more testing.
How did they print on paper? Encouraging?
What was vertical like at 1k yards with 2 and 20 shots.
Haven't shot at 1K yet. No decent range near me.
Still need group testing. Had ammo issues with brass case mouths being trimmed improperly causing some head spacing issues. With the small number of shots, I feel there will be some merit to them. After speaking with others with more experience than me, I think I'll need to sort & batch.
Yes I'm running 308 Win long action, detachable mag with 50.8 gr of pp2000mr with Sierra 2231 200 gr. Bullet With a muzzle velocity of 2860 fps. 30" Bartlein 1-8 twist 3.175 COAL about .005 off lands. G7 around .360...just finished it about a month ago. Tried lots of powders like all the usual with the usual accuracy and velocity. Even Hybrid 100V and RL 26...but pp2000mr gave the highest velocity, so far...and accuracy and s/d is good. 50.3 gr might be the best.
2860 fps from a 30" 8-twist barrel? Are both those numbers correct? That's a pretty aggressive twist rate when Sierra indicates a 9-twist should be sufficient. The reason I ask is that the biggest issue with this bullet among F-TR (.308 Win) shooters has been the fair number of gross outliers from groups that have been observed. As far as I know, this was from no faster than 9-twist barrels. I have had the exact same experience from a 9-twist barrel with a bullet having similar very dimensions and BC as the 200 SMK from a different manufacturer. It's possible that early results of unexplained fliers with the 200 SMK may have been in part due to the much slower velocities most F-TR shooters obtain (~2650 fps from a 30" barrel) combined with slower twist rate (9-twist) barrels. I'd imagine if a 9-twist is only marginally sufficient for stability, an 8-twist barrel and an extra 200 fps velocity might noticeably improve performance.
Curious why this powder? I literally know zero people using this for F class competition. Just interested why you chose this powder.
@Tempest you need to look back about 5 yrs, a lot of us tried it.
As XTR is alluding to, there is a good reason for that. Powders such as PP2000MR and Re17 can generate almost unbelievable velocities as compared to the extruded single base powders we commonly use in F-Class, but that may come at a cost. Such powders tend to be very touchy and unpredictable near the upper end of the useful charge weight range. Further, it is not at all uncommon for that to be exactly where an F-Class load tunes in during load development.
If you shoot loads with those powders where 30 to 40 degree temperature swings are not uncommon throughout the course of a single day's match, combined with the long strings of fire we shoot in F-Class, don't be surprised if the load goes out of tune, and you might even start popping primers in the afternoon. I personally know few F-TR shooters that were lured into using these powders by the extreme velocities they offered, only to switch back to more typical powders after suddenly blowing several primers in the afternoon match and not being able to finish.
Even here in the British Isles where we rarely if ever see such temperature variations (more likely over seasons rather than hours!), such super-performance powders have rarely worked out for people, especially in 308 Win. Major deterioration during the course of a match / pressure rising too high isn't so much an issue, rather inconsistent performance between matches or outings for no obvious reason.
Interestingly, most additions to powder line-ups are double-based / 'high-energy' these days - the IMR 'Endurons', all new Alliant marketed Bofors or Nitrochemie (continuing the Hercules / Alliant 'tradition' of no single-based products), and of course all 'ball' types. Viht has added two new 500 series (N565 and yet to arrive N555) 'high-energies', but no new 100s for years now, not that there's much room in such as crowded range. In the early days of F/TR before we discovered how to achieve suitably high MVs without super-hot powders, a number of us in GB F/TR discovered just how quickly Viht N540 would burn a barrel out even with 155s. However, used sensibly, N550 seems to be more flexible and less hard on the barrel. With the 185/200gn loads being run over here now with single-based N150 in SRP brass, I'm not convinced that this version of itself delivers longer barrel life than its 550 'high-energy' variant at similar MVs. I'm looking forward to seeing how N555 works out although suspect it'll be rather slower burning and much closer to the 4350s for use in the smaller to middle size 6.5s and suchlike, maybe too slow burning therefore for 308.
Trying to push MVs up too far / too quickly beyond current technology boundaries always seems to produces these problems. We have a Nitrochemie 'high-energy' 'EI' grade here called Reload Swiss RS40. It's really a 223 Rem grade, believed to be a canister version of that used in the Swiss GP90 service rifle cartridge in fact, but had a brief exciting ride as the 308 F/TR 155gn bullet wonder-powder. Hardly anybody uses it for this nowadays, partly because of the move to heavier bullets, partly because it proved so inconsistent when loaded to its full potential. Temperature may have been one factor, but people also got very different results between days where temperatures were close. When you push a cartridge (or more accurately powder) so far, any number of minor variances seem to combine to produce such undesirable outcomes.
A final thought. With new much more temperature stable grades appearing, I wonder if they also behave more consistently in all conditions, not just across temperature differences. We can but hope.
My data for the bullet was; 1.580" length of bullet in my batch, 2667.3 AVG MV, 84 deg F, 30.01mmHg, 65.9% Hum. 44.20gr Varget (Can't seem to find BTO/COAL measurements now), -.040" Jump, es:22, sd: 8.2 with Labradar. G7BC says: 0.331(Seems a bit low). I wasn't very impressed with the groupings, shelved them for the 200.20x. I'll work on them more in the coming months. I think after reading a lot on here that I need to experiment with seating depth more.
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