6MM GRINCH Defeats entire Field of 6PPCs

[birdog]

Hey Guys, as far as making good Dasher cases, Do you think hydro-forming would minimize the
issue?

No one answered moondog's question. Would hydro-forming help the consistent Dasher case issue???

 

[DJSBRS]

Hey Guys, as far as making good Dasher cases, Do you think hydro-forming would minimize the
issue?

IMO, quality factory Dasher would be utopia.

Precision hydro-forming (one impact at 55,000 psi) would be more consistent with inside case capacity due to less case stretch. Less case stretch is due to forming the case with high piston pressure going in reverse (pushing pressure down the neck) of fire forming process (out the neck). This process causes shorter cases due to minimum case wall stretching. Case failure with this process has been less than 2% with the last few lot#'s from Lapua. Hydro-forming case failure is always at the at the shoulder fold joint from the parent case 6 BR.

Fire forming is merely pushing and stretching the case forward and depending on the where the case grabs the chamber wall during the firing process, will stretch the side walls in different areas causing variations thickness of the case walls. There are more case failures with fire-form due to thinner walls from stretching the case forward. If the case AOL length is going to be longer, it has to come from the case wall. if it were to come from the necks, the neck wall thickness would constantly change.

Just my 2¢

DJ
DJ's Brass Service
205-461-4680

 

[johara1]

IMO, quality factory Dasher would be utopia.

Precision hydro-forming (one impact at 55,000 psi) would be more consistent with inside case capacity due to less case stretch. Less case stretch is due to forming the case with high piston pressure going in reverse (pushing pressure down the neck) of fire forming process (out the neck). This process causes shorter cases due to minimum case wall stretching. Case failure with this process has been less than 2% with the last few lot#'s from Lapua. Hydro-forming case failure is always at the at the shoulder fold joint from the parent case 6 BR.

Fire forming is merely pushing and stretching the case forward and depending on the where the case grabs the chamber wall during the firing process, will stretch the side walls in different areas causing variations thickness of the case walls. There are more case failures with fire-form due to thinner walls from stretching the case forward. If the case AOL length is going to be longer, it has to come from the case wall. if it were to come from the necks, the neck wall thickness would constantly change.

Just my 2¢

DJ
DJ's Brass Service
205-461-4680

I never seen them get longer unless you induce head space while fire forming. Now they do get shorter but you need a way to make them the same length. The other condition is having them end super short ...... 1.530's in a 1.570 chamber ?? Jim

 

[DJSBRS]

I never seen them get longer unless you induce head space while fire forming. Now they do get shorter but you need a way to make them the same length. The other condition is having them end super short ...... 1.530's in a 1.570 chamber ?? Jim

I concur Jim, however, 1.570 oal chamber is old school for a standard 6 BR Lapua. At that time, most did not realize that it would draw back significantly forming a Dasher. Thus, they kept the 1.570 oal.The Lapua 6 BR brass to be made into a Dasher is only 1.555 from the factory. As you know, it will draw backwards making Dasher brass by both either fire-forming or hydro-forming.

Those that are meticulous and savvy are ordering 1.560 oal Dasher reamers for Lapua brass.

Best,

DJ
DJ's Brass Service
205-461-4680

 

[johara1]

I concur Jim, however, 1.570 oal chamber is old school for a standard 6 BR Lapua. At that time, most did not realize that it would draw back significantly forming a Dasher. Thus, they kept the 1.570 oal.The Lapua 6 BR brass to be made into a Dasher is only 1.555 from the factory. As you know, it will draw backwards making Dasher brass by both either fire-forming or hydro-forming.

Those that are meticulous and savvy are ordering 1.560 oal Dasher reamers for Lapua brass.

Best,

DJ
DJ's Brass Service
205-461-4680

Yes, on the 1.560 chamber that I have went to in 2011. I trim to 1.550 in the the Dasher and now the 6 BR Imp....... The IMP. makes better cases easier than the Dasher at it's best. plus shoots in a .1 doing it most of the time..... Jim

 

[Mastershot]

What reamer with what free bore? Was he using. I would like to build a grinch bolt gun. I have several fat rats, should i just stick with that reamer.

 

[gunsandgunsmithing]

What reamer with what free bore? Was he using. I would like to build a grinch bolt gun. I have several fat rats, should i just stick with that reamer.

I'm really liking what I'm seeing from my 6 Grendel. It's simple and doesn't require custom sizer dies or fire forming.

My reamer is a .271 neck, for a light turn and has .070 freebore, which works well with 68-80 grain bullets.

 

[johara1]

What reamer with what free bore? Was he using. I would like to build a grinch bolt gun. I have several fat rats, should i just stick with that reamer.

The Dasher and the 6BR imp. are a different case..... Jim

 

[moondog]

Thanks for the info. I did get hydro-formed brass for my dasher about a year ago from D.J. it's been good.
I jumped into the BRA pool and am have just done 300 pieces fire-forming. Every one ended up at 1.550"
Now, if I can just get it to shoot into the .0000001" groups like everyone else is getting.
so far, 2" at 500 yards is best so far. 31.8 Varget, 105 Hybrid BR4 primer es--2.

 

[johara1]

you using flags? and how many? without them you are guessing........ Jim

 

[moondog]

I'm a "belly flopper" as you guys call us. So, no wind flags for us. look at mirage, grass, trees, and yes, guess. I am just looking at vertical at this point.
funny thing is the fire forming loads with 105 VLDs shot almost 0 vertical at 500. 2855 RPMs. same powder although a bit less, 30.1 Gunna keep working on it.

 

[johara1]

I'm a "belly flopper" as you guys call us. So, no wind flags for us. look at mirage, grass, trees, and yes, guess. I am just looking at vertical at this point.
funny thing is the fire forming loads with 105 VLDs shot almost 0 vertical at 500. 2855 RPMs. same powder although a bit less, 30.1 Gunna keep working on it.

When did they quit using range flags? I was down that road in the 60's we used range flags and mirage...... Jim

 

[moondog]

I was at a range in Wyoming. The wind flags they used are somewhere in Nebraska now.

 

[johara1]

if that is the case the targets would have been gone well before the range flags........ Jim

 

[jbhotrod]

What's a belly flopper? NRA Prone?

 

[moondog]

Tactical matches or, PMS (as I call it) style shooting at steel mostly. I'll go prone even if there is a perfectly good bench next to me

 

[Weim79]

80 gr Bart dominator boat tail

What seating depth does the 80 prefer and what powder ?

 

[JamesnTN]

What seating depth does the 80 prefer and what powder ?

It’s not what the Bullets prefer it’s what your barrel prefers.
Start at + .015 and work back from there

 

[JEFFPPC]

The Grinch took the 2 Gun this weekend at St Louis Missouri. Greg King piloted his 6MM Grinch for the win! Conditions were fairly light on Saturday but were a bit rougher at 200 on Sunday! It's way too early to trumpet the demise of the 6PPC, however it looks like the Grinch can hold its own. Actually 3 of the top 10 were were shooting the Grinch ( Greg King, Brett Stroud and myself Bart Sauter)

Congratulations to Greg King for his fine win!

Yes, the Grinch held its own and congratulations to those who used it. But what is always lost in these conversations is that the new or slightly modified cartridges are usually being used by the top shooters. Give Bart a straight 6BR or even a .222 in the same match and I bet he is right there at the top. There is never enough credit given to those few who master the art of shooting versus the latest and greatest cartridge craze. When you give the new round to the shooters who are normally in the lower third and they move into the upper third then you will have something.

 

[gunsandgunsmithing]

Yes, the Grinch held its own and congratulations to those who used it. But what is always lost in these conversations is that the new or slightly modified cartridges are usually being used by the top shooters. Give Bart a straight 6BR or even a .222 in the same match and I bet he is right there at the top. There is never enough credit given to those few who master the art of shooting versus the latest and greatest cartridge craze. When you give the new round to the shooters who are normally in the lower third and they move into the upper third then you will have something.

True, there's not much earth shattering left on the table but all else being equal, it has a significant edge in bc with 80's vs 68 gr bullets.

I plan to shoot my 6 Grendel in a match this weekend. The long range forecast is for 15-17 mph sustained winds and 35 mph gusts. It won't be a day to proclaim it better than a ppc or anything else, overall, but it's shooting very well with 80 gr fb bullets at about 3,300 fps.

What little I've shot it in conditions, it's like cheating at 200 yards. It just feels like I can get by with things that I'm not supposed to be able to get by with. I need all the help I can get and if the forecast holds true, it should have a worthwhile edge, particularly at 200.

I may even switch barrels between 100 and 200. My 30 Major(Grendel) is shooting extremely well. I was lucky enough to win with it last weekend. If conditions are decent, I may shoot it, at least at 100. I've said it many times before but, I've been shooting my 30 based on a Grendel since 2007. While the difference may not be earth shattering, I could be shooting a 30 BR before dark, but I don't. I shoot what I feel like gives me the best chance to win. Right now, I still feel like it's the 30 Major. I can only hope, the 6 is even close to as good.