Seems pushing the 90 over 3k in a 7 twist would create unusually high bullet rpm and cause excessive barrel wear. I'm not much for worrying about barrel wear but within reason. I'm thinking the 90s are better suited for 223 velocity guns and a bit faster twist barrels where getting over 1000 Rds of barrel life is possible.
Who's shooting 90 VLD's with a 1:6 twist barrel?
- Thread starter Mozella
- Start date
Yes, back in June 2011 shooting with / against the visiting US FTR team at Blair Atholl in Scotland. We had a practice / fun day before a long weekend three-day series of comps (two days of individual 800/900/1,000 yard matches in the Scottish Rifle Association annual Long-Range meeting) followed on the Monday by an unofficial 4-shooter / 6-person international teams Scotland v USA team match shot with 15-round 900/1,000/1,100 yards stages.) Blair has a 1,200 yard facility (actually a true 1,225 yards) for 'Match Rifle' competitions and the US visitors were very keen to try it never having shot at this distance (nor had I at that time). It was an ideal day for a test / fun shoot with good light, little mirage and hardly any wind. I fired 10 shots for a score in the low 40s, (ex 50 HPS our 'Bull' counting 5) all in the four ring with good elevation bar one low outlier (the curse of 223 and 90s IMO). So 9 out of 10 were in something under 1.5-MOA, most inside 1-MOA with around half-MOA elevation consistency bar the one flier.
In the serious stuff, I took a 'gold' in a 1,000 yard individual match against the Blair 'locals' shooting 308 with 210s and the American visitors shooting 155.5s at unspecified but very high MVs. In the coached teams matches where I had a top Scottish 'Target Rifle' shooter and expert wind reader do the hard work for me, the 223 was in the top two or three individual scores throughout including 1,100 yards despite several of the 'locals' being of the view that the 223 can't hack it beyond 800 yards. (The Scottish top TR and FTR shooters have long experimented with heavy-bullet 223 and gained a great deal of experience / expertise.) It was a hot day though (by Scottish Highlands standards) and the Re15 load of 25.2gn started to give pressure problems as the day went on and became hotter despite the cartridges having been well cooled overnight, kept in an insulated sandwich bag throughout the morning and exposed to the sun as little as possible. My final shot in the 1,100 yard team match stage around midday blanked the primer so I just got away with it. Hot North American conditions would have seen that load too hot for the non-bushed Savage bolt anyway.
That (True-Flite) barrel really performed, a subsequent one wasn't nearly as good. The same Savage 12 PTA based rifle is being revamped as a fun F-Open rifle for club shoots with a very heavy profile Benchmark 1 in 7 barrel and a barrel-tuner fitted to see what the little cartridge can do with modern powders. We have a Swiss Nitrochemie 'Reload Swiss' powder here, RS52, a high-energy propellant with a similar burning speed to H. Varget and Re15 that also has Nitrochemie's advanced EI deterrent distribution technology to reduce pressures longer in the early stage of the charge burn. It works superbly wherever VarGet works, but usually gives around 30-50 fps higher MVs in typical applications. (Think a faster burning version of Alliant Re17 which Nitrochemie also manufactures for Alliant ATK and which we get under the Reload Swiss brand as RS60.)
Tests last year in another Savage based 223 with a 28-inch barrel gave very good results with the 90gn Berger target BT (barrel didn't take to the VLD) at ~2,850 fps, so I'm hoping that the new heavier rifle with the Benchmark 31-inch job will perform with both BT and VLDs at 2,900 or so next year. I'll ahve to see, but it'll be fun finding out.
I must add though that although that set up gave me 7th place in the GB FTR league championship in 2011, my first selection to shoot in both Scotland and GB FTR teams, as well as these Blair Atholl results, 223 has really plateaued since, a few new powders aside, whilst the 308 as an FTR cartridge has seen major advances in bullet designs and with the adoption of the Lapua Palma case. In correspondence with Bryan Litz, I know that he has always had reservations about the 90s being too long a bullet for the calibre. He did say a few years back in the ballistics section on this forum that a heavy 224 Hybrid was a possibility at some time, but that it would almost certainly be in the low to mid 80s grain weight bracket, not 90gn should it ever come to pass.
The OPTIMUM TWIST RATES we now have listed for our bullets is based in a worst case scenario of 59 degrees at sea level. Altitude is your friend on this. Run your data over our TWIST RATE CALCULATOR and enter the altitude(s) you will be shooting at. Base your twist rate choice on the lowest altitude.
Using a 1:7 twist barrel at 2650fps in my winter shooting conditions of 40 degrees and 10 foot altitude, the SG is only 1.3. In summer time at 90 degrees it increases to 1.43, still below the SG recommendation of 1.5.
No problems with SG under any conditions with a 1:6 twist barrel except that to stay below the 300,000 RPM recommended limit, I would have to shoot no faster than 2500fps.
Using the calculator once again and plugging in various numbers, the obvious answer is to stick with my 1:7 twist barrel and move to Denver.
Ned Ludd
Silver $$ Contributor
Using a 1:7 twist barrel at 2650fps in my winter shooting conditions of 40 degrees and 10 foot altitude, the SG is only 1.3. In summer time at 90 degrees it increases to 1.43, still below the SG recommendation of 1.5.
No problems with SG under any conditions with a 1:6 twist barrel except that to stay below the 300,000 RPM recommended limit, I would have to shoot no faster than 2500fps.
Using the calculator once again and plugging in various numbers, the obvious answer is to stick with my 1:7 twist barrel and move to Denver.
If you like wide open spaces, Raton wouldn't be too bad an alternative, either
.This whole business with the 90s is starting to become irritating. There is no reason they shouldn't be run at velocities capable of getting at least close to an Sg of 1.4-1.5 in a 7-twist to 6.5-twist barrel. Berger sells plenty of small caliber bullets capable of running without issue at velocities far higher than any .223 Rem is pushing the 90s, and with comparable twist rates. Limiting the velocity to some ridiculously low value in order to prevent jacket failure isn't the correct approach. The correct approach is to fix the problem with the jacket. Clearly Berger makes jackets fully capable of withstanding fast twists/high velocities.
Berger stopped doing runs of the 90s for better than a year to fix some production/machining issue that was jacket-related (at least, that is my understanding of what happened). Now, two of the early (if not first) runs they did after the long break are showing signs, however infrequent, of jacket failure. Are the two events related? I have no idea. What I do know is that limiting the velocity to a ridiculously low value that gives up any ballistic advantage you might have had using the bullet is not the answer. Plenty of people are pushing 80 gr bullets in 7-twist barrels at 3000 fps (or faster) without issue, so I suspect if there is some kind of design deficiency or flaw in the jackets as used on the 90s, there ought to be a way to improve the jacket rather than simply loading the bullet light.
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If you like wide open spaces, Raton wouldn't be too bad an alternative, either
This whole business with the 90s is starting to become irritating. There is no reason they shouldn't be run at velocities capable of getting at least close to an Sg of 1.4-1.5 in a 7-twist to 6.5-twist barrel. Berger sells plenty of small caliber bullets capable of running without issue at velocities far higher than any .223 Rem is pushing the 90s, and with comparable twist rates. Limiting the velocity to some ridiculously low value in order to prevent jacket failure isn't the correct approach. The correct approach is to fix the problem with the jacket. Clearly Berger makes jackets fully capable of withstanding fast twists/high velocities.
Berger stopped doing runs of the 90s for better than a year to fix some production/machining issue that was jacket-related (at least, that is my understanding of what happened). Now, two of the early (if not first) runs they did after the long break are showing signs, however infrequent, of jacket failure. Are the two events related? I have no idea. What I do know is that limiting the velocity to a ridiculously low value that gives up any ballistic advantage you might have had using the bullet is not the answer. Plenty of people are pushing 80 gr bullets in 7-twist barrels at 3000 fps (or faster) without issue, so I suspect if there is some kind of design deficiency or flaw in the jackets as used on the 90s, there ought to be a way to improve the jacket rather than simply loading the bullet light.
DITTO.....
If you like wide open spaces, Raton wouldn't be too bad an alternative, either
I was joking about moving to a higher altitude. I'm not about to leave South Alabama.
As Jimmy Buffett says:
Salt air it ain't thin,
It can stick right to your skin,
And make you feel fine.
It makes you feel fine.
Twitchy
Brass Junky
If you like wide open spaces, Raton wouldn't be too bad an alternative, either
This whole business with the 90s is starting to become irritating. There is no reason they shouldn't be run at velocities capable of getting at least close to an Sg of 1.4-1.5 in a 7-twist to 6.5-twist barrel. Berger sells plenty of small caliber bullets capable of running without issue at velocities far higher than any .223 Rem is pushing the 90s, and with comparable twist rates. Limiting the velocity to some ridiculously low value in order to prevent jacket failure isn't the correct approach. The correct approach is to fix the problem with the jacket. Clearly Berger makes jackets fully capable of withstanding fast twists/high velocities.
Berger stopped doing runs of the 90s for better than a year to fix some production/machining issue that was jacket-related (at least, that is my understanding of what happened). Now, two of the early (if not first) runs they did after the long break are showing signs, however infrequent, of jacket failure. Are the two events related? I have no idea. What I do know is that limiting the velocity to a ridiculously low value that gives up any ballistic advantage you might have had using the bullet is not the answer. Plenty of people are pushing 80 gr bullets in 7-twist barrels at 3000 fps (or faster) without issue, so I suspect if there is some kind of design deficiency or flaw in the jackets as used on the 90s, there ought to be a way to improve the jacket rather than simply loading the bullet light.
I bought the older 90s from a LGS that apparently has holdover/old stock. I didn't realize they were old when I started load development. No issues with exploding/jack separation. But now I start load development again with new stock I ordered online.
I only pushed the old stock to 2785 without issue, but I did measure a difference in OAL and if my caliper is correct, a .0005" difference in diameter. I was told it's due to the newer thicker jackets.Different part # but same name, and of course the twist rate requirements and BC are different.
The last thing I need to be thinking about is a jacket failure when shooting against the 308's who have a wind advantage and no issues.
No Issues? Hardly.
I'm quite sure the F/TR guys who feel the need to shoot a "great big gun" have .......... um......... for purposes of polite company let's say they have "size envy issues" when they look over and see us manly-men shooting our .223's comfortable in our ability not only to compete at the rifle range, but later in the evening too. It ain't the size of your pencil, it's all about how you sign your name.
Not reliably, no. Even at 3400+ fps (in a 22/6mm Rem IMP) , the 8" twist barrel was no good with 90gn pills except occasionally when I used it in warm weather and a bit of altitude.
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