At the last match I attended I had various conversations with a bunch of people about a new project I was into. Most of those in the conversations were interested to the point of asking me to keep them updated with results.
The 6mm Grendel Imp is a 6.5 gGrendel necked down to 6mm with shoulder moved forward and squared to 40 degrees. A relatively short .2 " neck is left. PPC bolt face required.
I'm about half way through load development and am very pleased with the results so far.
I'm shooting 103 grn copperheads (mollied) & am having absolutely no problems running them up to 2970 fps with a case full of 2206H. Accuracy, at this point, appears to be best at about 2930-2950 which with this bullet will get the job done at long range. I have a 26" Rem Varmint profile barrel screwed onto my PPC weighing under 11.5 lbs.
I intend to keep playing with seating depths & other powders but I'm sure this will be a competitive cartridge at 500 meters.
Full length neck bushing die and also a hydro forming die were supplied by the gunsmith. This particular hydro die will neck the case down from 6.5 to 6mm at the time the case is formed.
I guess this post is mainly directed at those short range shooters who might be interested in the 500 Fly. You guys already have the platform in your PPC's. This the low cost solution to long range shooting. Simply get another barrel chambered and you're good to go at 500.
Some time ago I was talking to Luke about a long range PPC. It was then he told me he had a reamer for this cartridge. 8 twist PPC's have been attempted by a few others without great success but this little case allows for a bit more powder.
Luke made the full length/ neck bushing die & also the Hydro case forming die.
He also re chambered the 3 barrels that came with my 2nd hand PPC as 6mm ProCal's. I haven't shot these yet so no comment to make. (Not that I know anything about short range anyway!).
Next outing I'll give 2208 a run but I'm expecting it might be a little slow for mollied projectiles….time will tell…with a compressed load I reckon I can cram up to 32+ grains in!
Nice work belly, keep us informed
if i remember correctly there is a bloke from the US doing the same thing on accurate shooter forum and hes having great success in 600y shoots but i think he is using lighter grain bullets, cant remember as it was a awhile ago i read it
they are saying greatthings about it
going to shoot it at the Nats haha
I was among those interested at the BRT Canberra shoot, and am very enthusiastic to hear of your results. Do you have a the reamer print? Just curious to see it up against what they are calling the "Grinch".
I am hoping it may have accuracy qualities in a slow twist barrel as well, would simplify a precision loading bench. I know they are already having good success in short range in the US (using 80gr bullets in a 12 twist) with this design.
The velocity you are getting with the 103 mollies is fantastic. Are you concerned with chasing the lands at all?
No mate, I'll be shooting the trusty BRX in the light rifle at Little River. The Grendel is basically an experiment at this point.
Stuart & Geoff,
There have been similar cases around for some time now apparently. The 6mm AR Turbo is very close but I think there is a patent on the reamer. There's a 6mm fat rat & now the 6mm Grinch. From what I can tell they are all much of a muchness.
Luke from ProCal ordered a reamer to his specs & he is calling it the 6mm ProCal.
As a short range rifle the "Grinch" is kicking a few goals in the US with Bart's 80 grain dominators, a projectile that is supposedly very similar to Ken Melgaard's 6mm 80 grn flat base.
As a long range rifle it is also showing a lot of promise. Luke Easter (ProCal) shot the small group for the day at Batemans Bay earlier in the year using this case & in the US some people are using it in 6oo yard matches with good results.
Yes Geoff, the velocities are surprising with 103's & 2206H….I was expecting to max out at just over 2900. I'm hoping to find out what 2208 will do some time this week…. I have no idea, at this point about barrel erosion etc..with "mollied" projectiles I've run up in .1 grain increments from 29.5 to 31.1…so….I'm guessing that erosion will be about what 6PPC, 6 Dasher, BRX etc shooters would consider to be normal, given the charge volume. Just a guess though.
Well…..I'm very nearly to the point of calling this little cartridge a winner.
I've given 2208 a go and again had no issues running the mollied 103's up to 2970 fps & again accuracy seems to be best at about 2940 fps.
At this stage I would say that 2206H has the accuracy edge with tighter groups more often.
Below is an example of what I've been experiencing.
This a reduced copy of the Wagga 300 meter Fly target which I did on my computer. The 10 ring measures about 33mm.
This 5 shot group measures just under .7" with the first 4 coming in at about .3" I reckon this would be the 15 th time 3 or more shots have gone under the .6" mark & I think I've gone under the 1" mark for 5 shots 8 - 9 times. I should also say that usually the conditions have been quite calm because I'm normally out early morning & that all testing was done at 300 meters.
I can't say it's all beer & skittles though as this rifle seems quite sensitive to powder charge weight & seating depth. However when I get it right it shows extreme accuracy potential.
This barrel seems to like the 103's seated long into the lands & is also ok about 5 thou "out" but when seated in the "just in" zone groups can blow out to 1.5" - 2.0". I also think that .1 of a grain of powder can make a difference leaving me with quite small accuracy windows.
Conclusion: My test rifle weighs in at under 11.5 lbs so it's very light for a Fly rifle. Consequentially it has a bit of bite when shooting the 103's. When I say bite I don't mean Bull Mastiff style rather it's more like an angry Fox Terrier. It won't knock you off the stool but some effort to get technique right is required.
It's likely I could have gone for a stiffer, heavier barrel profile & still maintained rifle balance, which I believe in, but I was attempting to keep it legal for short range.
If I was a PPC shooter looking to get into "Fly" shooting I would definitely consider this case . I would probably like to get it up to at least 15 pounds (balanced) but I think that wouldn't be very difficult.
Just as a matter of interest a fellow over here in WA has been shooting a 6mm Grendel in 500m Fly for at least the last 18month that I know of at our local club meets and has had some good success with it. He shoots the 115gn Bergers I believe, not sure of powder or speed?? The rifle is fairly light, although he has just invested in a HV Kreiger so will see how he goes with a little more weight. He did shoot the smallest group at our 500m Fly State Championships just recently, a 1.3". So the cartridge definitely has potential. Good luck with your experiment..
The Jury is IN,
The 6mm Procal is indeed a very competitive cartridge.
During last weekends Fly Nationals held at Eagle Park Little River, Grant Groves shot this rifle to 3rd place outright scoring 258.04 & in so doing shot a national record single target high score of 60 points. Target attached.
As per testing previously mentioned in this thread, 103 grn copperheads (Mollied) where propelled by Adi 2206H at a velocity of about 2940 fps. CCI 450 primers were also used & the projectile was seated firmly into the lands.
So,..there we have it. There is a new kid on the block & it's very good news.
Here in the US, this cartridge is called the Grinch. You can find lots of info at both accurateshooter.com and on Bart Sauter's website. http://bartsbullets.weebly.com/ Click on the tab named 6mm Grinch.
There are two distinct ways to approach this cartridge. You can run an 8 twist barrel shooting the 103 to 108 grain bullets or you can run a 12 twist barrel shooting the 80 grain bullets. Usually, the 600 yard guys are using the 8 twist barrels and the short range benchresters are utilizing the 12 twist / 80 grain combo.
I have one and it seems to me to be real close to the 6mm BRA cartridge. As stated above, it is a nice way to take a rifle with a PPC boltface and use it for longer range. My rifle is a legal 13.5 lb HV rifle. It does have a bit of recoil but is it is a little less than my 13.5lb 30BR.
It will shoot well at 500 meters. Back in September, I used it to win the Huntsville TX light gun. You can see my best target shot with it over on the best target thread. I was shooting Bart's 103 grain Dominators.
The most used powders here are Varget and H4895.
G'day Shaun & Joe,
As it turns out I do have a bit more to offer on the performance of this case.
I was so encouraged by the results with my PPC converted to Procal that I decided to have a barrel chambered for my light Fly rifle which I have run as a BRX for a number of years.
I was curious to understand how it would perform over the length of a season in the variety of conditions we experience & at the different ranges.
There were quite a few unknowns like case life & barrel life etc, etc, so I committed to shoot the Procal in the light rifle category for the entire season for better or worse.
With this slightly longer, heavier barrel I worked up a load of 2206H (Joe, this is H 4895 in the US) which was very close in performance to the rem var barrel on my PPC platform. I used 103 copperheads for every match but did experiment with other projectiles during practise. In my view the 103's suit this case best ( of the projy's I tested) in an 8 twist barrel.
The season started pretty well with good results in the first 3 matches. Then I stumbled a little with a few poor performances upon which I couldn't blame the rifle.
Turning up crook (self induced) on the odd occasion, bad calls on some targets mid match both contributed to some self doubt through the seasons middle.
Then...a chance phone call from Will Greer, a very talented short range benchrest shooter from Gladstone who was interested in discussing this case. He had an 8 twist barrel chambered for his PPC & was interested in shooting longer range.
The discussion went something like this.....What bullet are you using Will?..(.he told me). What powder & charge are you using? I'm using BM2 & up to 31 grains! Are you Molly coating your bullets with these loads?... No! .... Holy Crap! What do your cases look like after shooting an uncoated 105 with 31 grains of BM2?? Well...I blew a few primers out with the max load but it shot OK!.......Why did you use BM2? ... Well, I'm a short range shooter & I've got heaps of it!
At this point I should say I was using 30.7 grains of 2206H with "molly" coated 103's so I was way behind Will on the pressure curve as 2206H is a slower burning powder than BM2 & "molly" coating takes the equivalent of up to a full grain of pressure off the charge!
All this said I was (in the back of my mind) having a think about trying 8208 (faster than 06H) in my rifle & this conversation with Will provided an arse kick causing me to immediately purchase some 8208 & test it against BM2 (which I already had some of) and 06H.
Out I went early one morning with enough loaded ammo to do a good comparison. I really had no idea what to expect so I very tentatively pulled the trigger on the 1st BM2 load & was quite surprised at the result.
Without going into all the nuts & bolts I can say that all 3 powders, in the 6 Procal case with 103 copperheads, are a lot closer in burn rate than I had anticipated. BM2 is the fastest & 06H is the slowest but only about half a grain seperate the three, and BM2 is only faster than 8208 by about .1-.2 of a grain.
I also think that both the faster powders shot with less verticle than 06H.
I decided to finish the season with the faster powders & went to Brisbane with a load of BM2 delivering very close to 3000 fps.
I was very happy with the way it shot so I went to Melbourne with the same load & again it performed very well in typical Little River weather.
By the time I got around to testing these faster powders my barrel had about 850 rounds on it. The cases had been fired probably about 10 times each and were just starting to get a little "clicky" at the back end. Whether the faster powders contributed to this or whether my custom die doesn't quite size the case base sufficiently I can't say.
What I can say is that my 850 round barrel shot like a new one with the faster powders &, as yet, I haven't lost a single case to split necks nor to I have any loose primer pockets.
As I type this out I have another barrel being chambered by Luke Easter from Procal so that I can find out how a "new" barrel will go with either BM2 or 8208.
Can't wait for next year!!
Thanks for your info. I think I will end up doing one. All my mates have BRAs or BRX so Id like to try something different. Im a F/TR shooter first and foremost so my 6mm is going to be a play gun for short range and Fly. 308 is a tad big for 300 to 500m work. Haha.
interesting on the bench mark 8208 there belly.. in my 6BRA with 103gr copperheads i also found this to be best powder out of 2206H and 2208...
i haven't found a final load yet as i put the 6BRX back on
as I mentioned before, H4895 and Varget are probably the two most used powders. But, the 4895 can behave a little erratically at times.
Two other powders I have tried are IMR 8208XBR and Alliant AR-Comp. They will both shoot very well and I believe the edge goes to AR-Comp. It seems to shoot a little better over a wide range of temperatures. It does seem to burn a little dirty and leaves lots of black in the barrel. However, it held up over the entire match for me. I do need to shoot a few more matches with it.
Is my IMR 8208XBR the same as the 8208 yall have mentioned?
Same powder, made in Australia at Mulwala, a small town about 100 kilometres ( 60 miles) from where I live in Albury.
Many of the Hodgson powders are made in Australia by ADI and rebranded for the US market.
Our AR 2206H is sold as H 4895 in the US.
Our AR 2208 is sold as Varget in the US.
Our Bench Mark 8208 is sold as IMR 8208 XBR in the US
Our Bench Mark 2 (BM2) is sold as Benchmark in the US.
There are quite a few others as well.