6mm RAT powders for NRA HP

[bpm990d]

What is the reason for the CCI 450s? Better groups, harder cups?

I just checked my cases I shot yesterday with a magnifying glass. The cases that I shot the Hornady's out of had a clear ridge around the firing pin indent, where as the cases that fired the Sierras did not. I think I'm going to drop it to 27.8 gr. for both bullets and call it good.

B

 

[Rtheurer]

What is the reason for the CCI 450s? Better groups, harder cups?
[/quot

No more reason than I have a BUNCH of them from my 6BR and 223 loadings. I also have a Bunch of Russian primers as well. Ill be testing those sometime down the road as well.

Have you ever had the chance to read German's amazing article on primer studies.... Very good read on the subject I thought.

http://riflemansjournal.blogspot.com/2009/06/primers-small-rifle-primer-study.html

Russ T

 

[dfry]

Russ, Russian's under Wolf are all I have been using. I know Gary Yuen uses 7 1/2s which I still have a lot of also and need to shoot some of those.

On another note, I was having failure on bolt lock back like some others in slow prone. Replaced the buffer spring but it didn't help. Started to have failure in rapids also. Well finally started examining the mag bolt catch relationship and found that the arm that the mag follower pushes up on to catch the bolt wasn't long enough any longer. Tried a Colt, it was to short also. So broke out the wire welder and extended it a little and then shaped with the dremel tool and cold blue, and seems to be working like a champ again, Dave

 

[infantrytrophy]

... Well finally started examining the mag bolt catch relationship and found that the arm that the mag follower pushes up on to catch the bolt wasn't long enough any longer. Tried a Colt, it was to short also. So broke out the wire welder and extended it a little and then shaped with the dremel tool and cold blue, and seems to be working like a champ again, Dave

Dave,

Any chance you could post pictures of what you did?

Randy

 

[rcw3]

Here's the same type of welded add on I had to do on mine because of the same issue (i.e. where the tip of the bolt stop that is pushed up by the magazine follower was not long enough for .223 Rem or other magazines). We also put a chamfer on the side of the bolt stop because it was sometimes being hit there by the bolt/carrier assembly and slowing down the cycling of the rifle.

These rifles are supposed to be just "put the parts together and go" but that's not how it works out some times.

Robert
www.6mmAR.com

 

[infantrytrophy]

...

I just checked my cases I shot yesterday with a magnifying glass. The cases that I shot the Hornady's out of had a clear ridge around the firing pin indent, where as the cases that fired the Sierras did not. I think I'm going to drop it to 27.8 gr. for both bullets and call it good.

B

The ridge around the firing pin indent may not necessarily be due to high pressure. It could be due to a large firing pin hole, even with "normal" pressure.

I have a 6BR bolt gun (real tack driver) that shoots perfectly with no pressure signs on the brass, and the primer edges have a nice radius, almost like unfired primers. Initially there was a ridge around the firing pin indent, like you described. I sent the bolt to Greg Tannel, and he "bushed" the firing pin hole in the bolt face, plus turned down the firing pin (Rem 700-type) to a smaller diameter. Now there is no ridge in the primer, even with higher loads than before.

Greg explained that the problem was simply the size of the firing pin hole in the bolt face, even though there might be a good fit with the firing pin, and even though the powder loads are not excessive.

Others have said that mild "cratering" or a ridge around the firing pin indent is not a problem, absent other pressure signs.

Randy

 

[dfry]

Thanks Robert, nice pic! The radius is a good idea! Yeah funny how the all parts should work doens't always. Have guite a few rounds on this lower and nver had a problem with it, so if this is my only issue issue, then I'm happy! Dave

 

[bpm990d]

Thanks Randy,

Good point. I wish I had a set of pin gauges to be able to measure the FP hole. I know about guys bushing Rem. & Win. bolt faces, and I even remember hearing about David Tubb doing it to his AR10. I just got back from the range and got some numbers on a ladder test. It's right where I guessed it would be and in accordance with some numbers that have been posted by Dfry.

B

 

[spclark]

These rifles are supposed to be just "put the parts together and go" but that's not how it works out some times.

Clever mods Dave & Robert! Thanks for the pic too.

That might very well have been an effective fix when I was having 'issues' with a couple of 6.5 Grendel uppers a few years back. The cartridge itself eventually failed to win me over but frustration with bolt lock-back and FTF were what turned my head early on.

 

[bpm990d]

Just got back from CC in North Carolina. Gun shot great at 600 yards and I could not be happier. Waterline elevation and sub X ring sized groups. Only thing different is that I weighed my charges on a beam scale and seated them .095 thou further out. I got a modified Hornady OAL case from Accurate and Reliable rifles and found out that I was nowhere near the lands.

28 gr. ARCOMP, AA Grendel brass - fireformed; Rem 7 1/2; Sierra 107s .015 from the lands.

Prone Slow #1.....198-12X
Prone Slow #2.....198-8X
Prone Slow #3.....198-14X

B

 

[dfry]

so what was your length to ogive now? I shoot 28.2 grs. and would think that the 7 1/2s being much hotter than the Wolf SRM, that the pressure would be about the same as yours, I have been shoot at 1.790" with 107s, I am at the lands at 1.810", Dave

 

[bpm990d]

1.815 from the base of the case to the ogive with a stony point tool. I was shooting them at 1.800 which is about 2.343 OAL (.015 off the lands).

B

 

[dfry]

BPM990d, wanted to see what you had the Hornady 105 BTHPs off the lands. I shot some this weekend in a 500 yd prone. Shot them in the second string behind my 107s. First string with 107s, 28.2 grs. ARComp, WSRM primers, seated .020 off for the 107s and .015 off for the 105s, shot 198-10X, second string with the 105s was 197-5X. Very strong winds, with severe and sudden let offs. So happy with the load, but the 105s did not shoot as tight. I think Eliseo was shooting them .030 off and getting good results. I will say that the 105s must be seated rather deep in the case compared to the 107s, but they were right at or a little higher striking than the 107s. Last string was with F205M primers, they sucked as I thought they probably would, pierced 5 primers, they just can't take the large firing pin hole in the AR bolt. Need to work with 7 1/2s and BR4s to see how they do, and probably 450s. I did pick up some CFE223 to try, just haven't had the time yet. and need to test H4895 some more, jeez, to many powders! Dave

 

[bpm990d]

It was a lot. Probably 60 thou. I just loaded up some for a match this weekend and they are going to be jumping .015. Some tools like the Stony Point just make things easier.

B

 

[dfry]

Thx, it will be interesting to see how they compare, dave

 

[bpm990d]

Shot a 100 shot RMC today in the rain today.

6mm RAT
105 Hdy HPBT with 28.1 gr ARCOMP - .015 from the lands
Rem 7 1/2
AA Lapua cases

1st 600....200 - 11X
2nd 600....198 - 10X

Seems like a wash between the Sierras and Hornady HPBTs. Next thing up for consideration is the Nosler 107s. I just purchased 2000 of them, so they better shoot.

B

 

[dfry]

Nice shooting, yeah, they were a wash on score for me but not X count, but that could just have been me! I want to work with them some more to see what happens with different seating depths and dropping to 28.1 grs.

I could not get the Nosler's to shoot in the 6 WOA, never tried them in the RAT. I never had any problems getting the Nosler's to shoot in 223, or 308, but had no luck with the 6MM 107s. But I didn't put a huge amount of work into trying to get them to shoot since the Sierra's just hammered, Dave

 

[bpm990d]

I could not get the Nosler's to shoot...

Don't tell me that! Yikes....LoL.... ;D

B

 

[dfry]

HA! I won't!!! No really, I'm sure you can get them to shoot, in my initial testing, I was starting to think jambed, but never tried them that way. Next time I'm testing I may test from the ones I have left from jambed to at least .030 off, but the 107s, 108s, and Hornady 105s all shoot well.

Also, how was your virticle with the 7 1/2s? Dave

 

[Rtheurer]

UPDATE
Ididnt get a chance to go to Camp Perry this year because of work. So i gave my rifle to another shooter on the team to shoot it during the NRA championships.
I was gone for this whole thing so my firend Doug got the rifle set up and loaded all the ammo to hand off to my team mate. ( thanks Doug)
I would say that the loads and powder choices worked very well looking at his scores. The short line load turned out to be a hammer. he never dropped a point at the 300 yard line with it. 200-9x 200-11X and 200-13X all at 300 yards. Not to mention the apreciation cup 200-16X sitting rapid for second place.
So the short line load is...... drum roll please...
CCI 450, 87gr Berger VLD hunting bullet, and 31.3gr of CFE 223.
I would say this combo is way out of the normal for HighPower shooters as it shoots a hunting bullet and a new powder. but boy does it shoot.

Long line showed just as good with great X count here too. 198-13X 199-14X and 199-10X shooting the new Berger 105gr Hybrid and Varget. Thats a good amount of X's and I think display's a quality load.

You might want to give CFE223 a try in the 6 Rat case.

RT

Edit to show 31.3gr of CFE.... Thanks Randy good catch.