6mm Crusader

[kombayotch]

Re: 6mm Crusader

Some more results for ya...

Played with Retumbo and H1000 a bit more. H1000 is showing promise at around 51-51.3 gr. with magnum primers. Results with Retumbo are still unsatisfactory. Going to try exploring lighter loads with it...

50.3 gr. of RL-25 is a keeper, I verified it out to 1k today:

300 yards

600 yards

1st groups at 1k

2nd group at 1k


This load is running at around 3100 fps. Bare 115 DTACs seated to 2.945".

 

[steve123]

Re: 6mm Crusader

kombayotch,

Did you adjust the velocity back to 3100fps because of being limited by a velocity cap in tactical matches or is it because that's where the best accuracy came from?

From the little experimentation I've done with my 6x47L(nothing near as sophisticated as yours)It seems like 115 Bergers and 115 DTACS don't like velocities past 3150 fps.

I haven't gone back and reread this thread.I just wondering if that's what you've experienced.

Looks like it's shooting well and pressures must be lower than most cartridges at those speeds.Possibly better throat life too?

Steve

 

[kombayotch]

Re: 6mm Crusader

It's purely for accuracy, the charge was found doing an OCW test. I can run the 115's up to 3250 fps. and they still group just under 1 MOA at 300 yards.

I think pressures are higher than I originally though.

For barrel wear, that has yet to be seen. But, I am very skeptical of statements about barrel life. I think many barrels get tossed before their life is really up.

 

[aqualung]

Re: 6mm Crusader

Any more updates on this project?

 

[Glen Seekins]

Re: 6mm Crusader

I have everything i need now and will get some pictures up tomarow if i can remember my camera...

I got my action from Defiance machine and cant wait to start on it!!

you guys are going to LOVE the stock!!

 

[arnygollott3]

Re: 6mm Crusader

Any other data or news on the 'improved' version of the DTAC as described above by Hazardus? (cleaner, more closed nose)

 

[rc2125]

Re: 6mm Crusader

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: arnygollott3</div><div class="ubbcode-body">Any other data or news on the 'improved' version of the DTAC as described above by Hazardus? (cleaner, more closed nose)

</div></div>


old vs. new: @700yds 3.7mil vs 3.4, @800yds 5.0 vs 4.4, @900yds 6 vs 5.5, @1k 7 vs 6.4

little better in big wind.

 

[kombayotch]

Re: 6mm Crusader

Put the Crusader barrel back on and did a bit more load development. 51.3 gr. H1000 with a magnum primer is giving the same size groups at 300 yards as the 50.3 gr. RL-25 load.

Just need to nail down the Retumbo load and then I'll run a temperature test on all 3 loads.

 

[JRose]

Re: 6mm Crusader

Wow, 50 gr of RL-25!!!

 

[Blackhawk95]

Re: 6mm Crusader

heres a link to some pics i took of the new DTACs when i got a batch. the new ones ar BN coated too.

http://6mmbr.websitetoolbox.com/post?id=3562579

 

[A10XRIFLE]

Re: 6mm Crusader

Try RL 17 with the 105 Scenars, 3400 with no Pressure.

Also got good results with 115 Coated with 4831SC.

My load with Retumbo is 52 grains.

 

[kombayotch]

Re: 6mm Crusader

What velocity is that Retumbo load giving you? Is that with a bare bullet?

 

[kombayotch]

Re: 6mm Crusader

Yep, it looks like the high node for Retumbo is at 52.0 gr. and the lower node is at 50.5 gr. Bare bullets.

 

[arnygollott3]

Re: 6mm Crusader

How much more muzzle velocity does the extra 1.5 grn of Retumbo give you?

 

[kombayotch]

Re: 6mm Crusader

About 70 fps.

 

[A10XRIFLE]

Re: 6mm Crusader

Try the 105 Scenars at about 3300. RL 22

 

[Sendero_Man]

Re: 6mm Crusader

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: heatseekins</div><div class="ubbcode-body">I have everything i need now and will get some pictures up tomarow if i can remember my camera...

I got my action from Defiance machine and cant wait to start on it!!

you guys are going to LOVE the stock!! </div></div>

pics ??

 

[Sumpter Steve]

Re: 6mm Crusader

George. You going to bring this stick out to Oregon in May?

 

[A10XRIFLE]

Re: 6mm Crusader

Yes Sir, it will be there.

 

[A10XRIFLE]

Re: 6mm Crusader

Here is a Pic of my main Comp Beast

 

[NOMAD]

Re: 6mm Crusader

Is that the one you just sent to me in the mail the other day? If so I may not send it back!!

That bad boy does shoot like wild fire!!!

 

[Sendero_Man]

Re: 6mm Crusader

what are all the specs ? sweet looking rig !

 

[BKS]

Re: 6mm Crusader

George, is that molded-in camo on a manners stock?

 

[A10XRIFLE]

Re: 6mm Crusader

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KansasMag</div><div class="ubbcode-body">George, is that molded-in camo on a manners stock?</div></div>

No its Transfer coating. Its then coated with matte clear ceramic so its tough as nails.

 

[AMMOWASTER]

Re: 6mm Crusader

George

Is that built on a short or long action?

 

[A10XRIFLE]

Re: 6mm Crusader

Short Action

mags have room for 2.955 " OAL

 

[kombayotch]

Re: 6mm Crusader

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: A10XRIFLE</div><div class="ubbcode-body">Try the 105 Scenars at about 3300. RL 22 </div></div>

The highest BC for a 105 gr. bullet is the Berger 105 VLD.

The 95 Berger VLD has the same BC as the 105 Scenar (per Litz's book) and QL says RL-25 will get it up to 3500 fps.

1000 yards:
95 VLD @ 3500 fps. MV -198" drop (-5.5 mil) 65" wind (1.8 mil) 1721 fps.
105 Scenar @ 3300 fps. MV -231" drop (-6.4 mil) 72" wind (2.0 mil) 1575 fps.
115 DTAC @ 3125 fps. MV -246" drop (-6.8 mil) 68" wind (1.9 mil) 1595 fps.

 

[mattmcg]

Re: 6mm Crusader

Has anybody posted the H20 case capacity for this yet? I'd love to play along with QL and check out some of these loads.

 

[kombayotch]

Re: 6mm Crusader

60.1 gr. in my chamber with WW brass.

We can also look at 6mm AI loads, it has the same case capacity. Load should be almost identical.
http://www.angelfire.com/sd/6mmackley/index.html

 

[mattmcg]

Re: 6mm Crusader

Interesting..... Thanks kombayotch.

So I've been running this through QL at 2.950" OAL using RL-25 and 105gr Berger VLDs and can see 3250fps at about 64K psi. Compared to the 115gr DTACS at the same psi and OAL, you get about 3125fps.

Drop tables show at that speed (Litz BC data):
Bullet----500yds---1000yds
Berger----2.0mil---6.3mil
DTAC------2.2mil---6.8mil

Another benefit that you get with the Berger 105 VLDs is that they are shorter than the DTACs. Being somewhat OAL constrained with AICS mags, this will help. Seating long may allow for a slightly less compressed load (or a slower powder which I'll have to play around with). I'm showing the DTAC bullets are 1.290" long while the Berger 105gr VLD is 1.235" long. Given a G7 BC difference of .272 for Berger vs .276 for DTAC, aside from a slightly lower BC (negligible), the Berger would seem to outperform on almost all fronts here given the added velocity and OAL benefits........

Comparing the Berger 105gr VLD to the Lapua 105gr Scenar definitely favors the Berger.

BCs---------G7---G1
Berger--.272--.532
Lapua---.248--.484

 

[Blackhawk95]

Re: 6mm Crusader

I would have thought the 6Crusader would have had a little more capacity than 60gr h2o..

 

[steve123]

Re: 6mm Crusader

Food for thought.

I did a small test(inconclusive) and tried driving the 105gr Berger VLD target bullets fast during two separate ladder tests from 3100 fps all the way up to 3345 fps in my 6x47L.

In my gun at just less than 3200fps the results became erratic.Spraying bullets so bad I was just about missing the whole box.

So IMO just because you can drive a bullet fast doesn't mean that it will shoot the best at those velocities.You have to find a speed for a certain bullet that it likes.

I'm not by any means slamming the 6mm Crusader.It's a fine cartridge.

Edit..to say that I'm in agreement with you about your 105 vs 115 opinions.

Steve

 

[DTubb]

Re: 6mm Crusader

The litx BC data for the DTAC 115 is not correct with it's closed nose configuration (only way the DTAC 115 bullet is now available).
Using the G1 drag function the upper end velocity BC is slightly over .590 per Sierra test data.
Note-This is over 30 points better than the older open nose data...

 

[mattmcg]

Re: 6mm Crusader

I just so happened to email Bryan about this very question. Sounds like he used the older version from what you're saying.

That said, can you provide any G7 BC data on the DTAC for comparison purposes?

 

[kombayotch]

Re: 6mm Crusader

http://www.snipershide.com/forum/ubbthre...627#Post1306627

 

[C.K]

Re: 6mm Crusader

any one try bib 108's yet

 

[kombayotch]

Re: 6mm Crusader

Ok, ran some temperature tests tonight.

Got this:

Not sure why the H1000 curve looks the way it does. It was always after Retumbo in the round robin sequence.

I did notice that the first shot at high temperature was lower than the others. If I only use that shot at the high end, I get this:

I got weird results with Varget in 308 Win. when I ran it with RL-17 too. But, it gave a nice linear curve when I tested it alone after cleaning the bore. Lesson learned: don't mix powders in the bore during testing. I should have know better... In any case, this pretty much kills RL-25 for me. I knew it would be unstable, but didn't think it would be that much. For long range loads, that just doesn't cut it for me. And yes, it was over pressure at the high end. PT says somewhere around 70k psi.

 

[mattmcg]

Re: 6mm Crusader

Kombayotch, can you explain the x-axis here? I understand this is temp but how did you perform the test? Was this simply ambient testing or were all components at the same temp. I'm very interested in the details.

Good data BTW......

 

[mattmcg]

Re: 6mm Crusader

Also, as I'm playing around with the data, Vihtavuori N570 looks to be a good powder for this application as well. Less compressed than both Retumbo and H1000 and is supposedly comparatively stable with varying temps. It also displays as faster than Retumbo and H1000.

For that matter, Hodgdon 870 looks interesting as well. A bit more compressed but less pressure at velocities. I'm thinking the extra capacity with the Berger 105gr VLD may be an interesting combination.

 

[kombayotch]

Re: 6mm Crusader

N570 isn't available here yet. Also, it is a double based powder, so it is probably pretty temperature sensitive.

The x-axis is the ammo temperature in degrees F. The way the tests works is that you soak 3 batches of ammo at hot, cold and room temperature for several hours (5 rounds of each). I use a cooler with a heating pad and the freezer in the clubhouse for this. Then, you fire them one round at a time in a round robin sequence. You let the barrel cool in between each shot. When you fire each round, you just transfer it from the hot/room/cold storage to the chamber and fire it through the chrono as quickly as possible. You don't want to give the rounds any time to change temperature in the chamber. I set the scope on the lowest magnification and just make sure I'm sending the round through the sweet spot of the chrono (no groups here).

 

[mattmcg]

Re: 6mm Crusader

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: A10XRIFLE</div><div class="ubbcode-body">Here is a Pic of my main Comp Beast

</div></div>

George,

Is that a Badger Thruster brake you have on that bad boy? What barrel contour?

Looks very good. Sounds like you are happy with the Thruster in that configuration.

Matt

 

[kombayotch]

Re: 6mm Crusader

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: heatseekins</div><div class="ubbcode-body">"Working on getting George's spare reamer to Giraud so that a few case holders can be made for the trimmer"

Replied to your email just a few minuets ago..

Im still waiting for my action to arrive!!
</div></div>

Has the reamer been sent to Giraud?

 

[Jedi]

Re: 6mm Crusader

Whats diff tween this an 244 mashburn?

 

[One-Eyed Jack]

Re: 6mm Crusader

The QuickLoad/QuickTarget comparisons of the 115DTAC and Berger VLDs are interesting, but has anyone actually shot both bullets seated to magazine-length COALs?

The VLDs are supposed to be seated so they touch the lands. I'm wondering whether that is possible in most rifles if the rounds are fed from a magazine? On the other hand, the Sierra-made 115DTACs are not fussy about jump length.

Finally, does Berger make a moly/BN 6mm VLD? I hate cleaning rifle barrels and the moly/BN 115DTACs let me avoid that chore for a very long time.

 

[A10XRIFLE]

Re: 6mm Crusader

The 115 Dtac is really the only bullet worth shooting , the Reamer is set up so that when loaded to 2.950 its .010 in the lands. The 105 Berger VLD is worth trying but im afraid it may come apart. For now Im sticking with 52.5 Retumbo and the 115. shooting a flat 6.0 mils to 1000 28" barrel.Not getting any high pressure signs at all.Twist is a Bartlein Gain 1-9 to 1-8
5R with a 237x243 boresize. 236 bores seem to spike pressure and not really getting a vel gain.

 

[mattmcg]

Re: 6mm Crusader

Great info George. I was wondering about the reamer setup for this and how that might remove the Berger dimensionally from consideration.

One other thing to note about a 6mm Crusader build is that the new USO Morta mags won't cause folks to have to modify their AI mags with welds to take the extra seating length. The Morta mags will allow this loaded to recommended length.

 

[mattmcg]

Re: 6mm Crusader

Looks like I stand corrected in my last post. The Morta mags accommodate a 2.920" and George was mentioning 2.950". Doesn't look like that will help with this setup.

George, are you guys modifying mags if sent in with a rebarrel job?

 

[A10XRIFLE]

Re: 6mm Crusader

I have had Accurate Mag Make me mags that are already set up for the longer length. AI AM mags work with a little modification to the bullet guide in the mag.

 

[JRose]

Re: 6mm Crusader

.020 off the lands should be fine (using Morta mags). Until I removed the blinder plate, my .243 at mag length was .050" off the lands and shot fine. Never really noticed a difference in accuracy between having the bullet .050", of .015" off after I removed the plate and started seating it longer.

 

[mdesign]

Re: 6mm Crusader

The more I shoot and read on these 6mm the better I like them.

Can someone explain why sharp shoulders and a long neck give better throat life? I heard this before on AI cartridges but hot gases and pressure should be the same.