Another 6mm Remington AI "the bug bites again"

[dbduff]

Thanks for the Bullseye starting point. Enthusiasm keeps us all going.

 

[wildcatter]

Well I made a range trip Monday in this major rain event, 3" over a 24 hour period, mainly to get some rounds thru this new barrel and see how it was going to respond to both load pressures and velocity, as well as fouling so I can start some 3 shot groups on Wednesday. Yes I managed to catch enough let ups in the rain to chrono all but one shot.

Started with 47 grains of 7828 with the 108 Berger Elite Hunter, with a WW-LRM primers. First shot took more than I expected to clean, 23 patches, two brushing's with 10 passes each, and two tries with JB to get all the copper. Second was with the same load, cleaning was much better, only 8 patches with one brushing consisting of 10 passes, and no JB. I put that load on the target at 50 yards to zero the scope, cranked the hairs to the shot and was ready to shoot again with 47 grains, this is the max load listed for a 105 grain bullet in 6mm Remington in my old Hodgdon manual.

Well again 8 patches total, but followed up with a JB rubdown just for insurance, I don't think it was needed, but I didn't chance it.

Then I fired the last two rounds I had with me, this was two shots again but moved to 100 yards to make a little scope adjustment and confirm my POI change, as well as check pressure at 47.5 grains, 1/2 grain over a 6mm Rem max load. I am posting the results below with the target of the 5 shots, as well as velocities.

These final shots were followed with a cleaning again, and this time it was 3 wet patches of Butches, 10 strokes with a brush, followed by three more wet patches, and dri patch 5 minutes later,,,, pure white!! This was my cleaning ritual throughout this session with follow ups when needed.

Aftera clean dri patch each time I run a wet parch with TSI-301 through the barrel for prep with a clean shot. never a first shot flyer, and 301 being a lubricant in solvent that allows the lubricant to penetrate the pores of the steel while drying film free,I experienced no first shot flyers as you see, and if storing, the barrel is protected. This is all I use to clean and lube my DW Valor V-Bob for over 10 years, but will be the first rifle I've used this last patch method on,,,, time will tell if I continue or not?

not to exciting in between rains, cold, windy, just plain miserable. But now we can see what can push this load to Tuesday, as this was Mondays sesion. I'll post todays, (Tuesday) later, but trust me, calm and sunny, in the upper 50's Wednesday, will be my first day to teat, all at 200 yards to see if this powder is going to be pursued or not! the picture from Monday tell the story,, pretty miserable.

 

[wildcatter]

Day 2, I had no sign of high pressure Monday so I loaded 48.0, 48.5, and 49.0 grains. I only loaded one each to check for pressure signs, and run each thru the chrony. All seemed ok with the 49.0 grain load showing a slightly stiffer bolt lift, but 49.5 was no different than the others?

But the velocity gains started showing little gain, and if I can't find anything between 47.5 3064 fps, and the 49.5 grain load at 3268 fps, I will back out and start looking for my load with 4831SC? But I hope that 3268 fps load shows some promise tomorrow, that would be right where I was hoping to get with this barrel.


Back in the man cave I loaded all four loads with 3 rounds each 48.0, 48.5, 49.0, 49.5. I also loaded 4 rounds with 47.5 grains for foulers, I intend to shoot each fouler before the 3 shot groups putting all of them on one target, since this is a Varmint barrel, that first shot with a clean barrel is important to me to know what it will do. So tomorrow with light winds, and mostly sunny ski's predicted, the search for an accurate load at 200 yards begins.

 

[wildcatter]

Well that didn't go so well. I was pleased with fouling shot, it seemed to be right there about 1/4" high. then I fired the first two rounds of 48.0 grains and not bad, about 3/4" apart, but the third made those three about 1.5", and the speed took the extreme spread to 72 fps. I wasn't to alarmed expecting everything to tighten up as I started seeing some pressure with this powder.

So after a 15 minute break, I proceeded with the 48.5 grains and the first shot was not at all close to what I had expected, speed seemed legit but after the second shot, a solid 1" apart, and over 70 fps spread from the first slower, I hesitantly shot the 3rd and was not at all happy, just under 2" and now a 84fps ES.

I decided to clean and check screws both action and scope, and was shocked when everything seemed good, and the cleaning was a simple 3 wet patches, followed by 6-8 passes with the brush, then two more wet patches and the second was pretty clean, but I pushed a third thru, and spotless. So I gave it five minutes and pushed a dri patch thru and no sign of copper?? This barrel is a dream to clean!

But then it happened! When I went back to put the rifle in the front and rear rest, WTF? I find this little black donut laying on the bench top. I mean little steel blued donut with what looked like a sprocket on it's inside circumference inside??? After a brief moment it dawned on me, it was a countersunk screw head, with torx drive. Then after closer inspection, yep, the front screw on the front base was just a threaded post with the head missing.


Well I new this was a waste as far as seeing any accuracy, but was relieved to see why everything opened up. But I still was wondering if this 7828 powder was going to ever start showing any pressure signs at all, and would start getting any consistency in the Extreme Spread dept? So what the heck, I had 49.0 and 49.5 grains left, so I decided to just aim center of targets and record the speed.

Glad I did as the 49.0 was an improvement, 42 fps and an average at 3204 fps. But finally the 49,5 grain load, now with primers not as rounded, but no heavy bolt lift, showed more what I was looking for, 3262, 3242, and 3257. for a 20 fps ES. Now I have a starting spot, and will when I get a new scope mount and screw, instead of using whatever was on it when I bought the rifle used for this build. Who knows what the previous owner did, were they stressed to begin with, were they just cheap nock of bases and hardware?

When I get this last issue taken care of, a cheap screw up on my part, taking such an inexpensive but important part for granted. I also am not going back out till Vortex get's the Golden Eagle back to me. which expect before the weekend. I will be starting with the 49.5 grain load, and will try 50.0, that was what I was hoping to be able to get to, as 50.0 grains puts the powder right at the bottom of the neck. If need be I may be able to compress 51.0 if pressure allows, but it would be great to see 49.5 or 50.0 be THE LOAD! But for now, it is set and wait.

With rain till Saturday everyday I now will wait after getting everything set back up to start final work with this powder. It would be nice if that 49.5 grain worked or even better if 50.0 or 50.5 was what it liked, but if not, it's it will be time to open the 4831sc, I now regular 4831 is making the factory barrel hap hap happy, using 80 grain bergers, 100 grain Sierra, 85grain HPBT Sierra. all easily under 1/2" at 100 yards for 3 shot groups. But would like the velocity that comes with the 7828 in this case for the Varmint setup.

 

[Plumsask]

Well that didn't go so well. I was pleased with fouling shot, it seemed to be right there about 1/4" high. then I fired the first two rounds of 48.0 grains and not bad, about 3/4" apart, but the third made those three about 1.5", and the speed took the extreme spread to 72 fps. I wasn't to alarmed expecting everything to tighten up as I started seeing some pressure with this powder.

So after a 15 minute break, I proceeded with the 48.5 grains and the first shot was not at all close to what I had expected, speed seemed legit but after the second shot, a solid 1" apart, and over 70 fps spread from the first slower, I hesitantly shot the 3rd and was not at all happy, just under 2" and now a 84fps ES.

I decided to clean and check screws both action and scope, and was shocked when everything seemed good, and the cleaning was a simple 3 wet patches, followed by 6-8 passes with the brush, then two more wet patches and the second was pretty clean, but I pushed a third thru, and spotless. So I gave it five minutes and pushed a dri patch thru and no sign of copper?? This barrel is a dream to clean!

But then it happened! When I went back to put the rifle in the front and rear rest, WTF? I find this little black donut laying on the bench top. I mean little steel blued donut with what looked like a sprocket on it's inside circumference inside??? After a brief moment it dawned on me, it was a countersunk screw head, with torx drive. Then after closer inspection, yep, the front screw on the front base was just a threaded post with the head missing.
View attachment 1289066

Well I new this was a waste as far as seeing any accuracy, but was relieved to see why everything opened up. But I still was wondering if this 7828 powder was going to ever start showing any pressure signs at all, and would start getting any consistency in the Extreme Spread dept? So what the heck, I had 49.0 and 49.5 grains left, so I decided to just aim center of targets and record the speed.

Glad I did as the 49.0 was an improvement, 42 fps and an average at 3204 fps. But finally the 49,5 grain load, now with primers not as rounded, but no heavy bolt lift, showed more what I was looking for, 3262, 3242, and 3257. for a 20 fps ES. Now I have a starting spot, and will when I get a new scope mount and screw, instead of using whatever was on it when I bought the rifle used for this build. Who knows what the previous owner did, were they stressed to begin with, were they just cheap nock of bases and hardware?

When I get this last issue taken care of, a cheap screw up on my part, taking such an inexpensive but important part for granted. I also am not going back out till Vortex get's the Golden Eagle back to me. which expect before the weekend. I will be starting with the 49.5 grain load, and will try 50.0, that was what I was hoping to be able to get to, as 50.0 grains puts the powder right at the bottom of the neck. If need be I may be able to compress 51.0 if pressure allows, but it would be great to see 49.5 or 50.0 be THE LOAD! But for now, it is set and wait.

With rain till Saturday everyday I now will wait after getting everything set back up to start final work with this powder. It would be nice if that 49.5 grain worked or even better if 50.0 or 50.5 was what it liked, but if not, it's it will be time to open the 4831sc, I now regular 4831 is making the factory barrel hap hap happy, using 80 grain bergers, 100 grain Sierra, 85grain HPBT Sierra. all easily under 1/2" at 100 yards for 3 shot groups. But would like the velocity that comes with the 7828 in this case for the Varmint setup.

For what it's worth, my 6mm AI, Shilen 1-8 26" shoots very well with H4831SC, with low es and sd. I'd say it's worth a look.

 

[wildcatter]

For what it's worth, my 6mm AI, Shilen 1-8 26" shoots very well with H4831SC, with low es and sd. I'd say it's worth a look.

I shot H4831 in my last 6mm AI as well as my 257 AI, both shot great with it, 1/4 moa was the norm. But this one I want to try the slower 7828, lower pressure, better velocity is my goal. So far at 49.5 with only 22 ES and 3268 fps using the 108 grain Elite Hunters I'm very happy.

Thats up there with the 6-284, and as good as you'll see with a 240 Weatherby, and looks like 50.0 may be better yet? But until I get the 15x60 GE back and see what it groups like, I'm sticking with the 7828, maybe better than 3300 fps?

But I have 4 fresh pounds of the 4831sc in the batter's box waiting if it's needed, but I already know itb will cost me some velocity if I have to go with it. The 4831 is doing great in the 22" factory barrel, better than was expecting from it on the blued action with 3 different loads,

80 grain Berger MEF's - 1/4 moa at 3291 fps


100 grain Sierra SP -1/2moa @ 3050 fps


Then just this week 85 grain Sierra HPBT Gameking 2 solid 3 shot groups under 1/2 moa, boyh 48.0 and 49.5 grains, and if that isn't good enough I loaded 3 cartridges with the 80 grain SPBT Varminter also with 48.0 grains, all with 4831 and it shot right at 1/2 moa as well.


So seeing all this in a punched out factory sporter barrel, I'm sure the premium Kieger barrel will give the accuracy with the 108's I want, under 1/4 moa with the 4831, I'm just hoping to get that accuracy and the velocity gain with the 7828 powder,,, but gotta go thru the test to see.

 

[wildcatter]

Well I made a range trip today after all the rain stopped and the temps bounced back up from the 40's to 65 today, just chrono graphing, and very frustrated. the best ES with either 7828 or 4831sc were not to my liking, my best 3 shot string came 4831sc at 47.5 grains with the 108's @ 36fps.

I did get the scope rezero'd with the new base and hardware. I also set up the rings to give me about 12-15 MOA more elevation with a -10 in the front ring and +10 under the rear. This should be plenty when I go to the 6x47 or 6BR later for 1000 yard shots.

only shot 2 groups of 3 with each powder, and just over 1/2" was the best, not at all what I am hoping for. But I decided to start over and instead of loading just to touch I am going to a .020 jam. I'll clock these same loads again and see if this helps the ES before I try going up. I am doing this because that almost 1/2" group that was best was the one with 78fps ES.

But I need to wait as I have doctor visits tomorrow and then the temps here ore going back to 30's and 40's for highs. I should just back off now and wait for spring, but we will see, after Thanksgiving I will be to busy hunting then I know I will wait till spring.

 

[wildcatter]

Well I changed my mind, and decided to try the 7828 going on up to 51.0 grains. I got a little better ES, not much but 42 fps for the 5 shots. I was grouping them at 200 yards. I just aint happy, to much spread and groups are nearly moa. with the best 5 shots running 1.75" at 200.

So I am going to do what I mentioned, I here a lot of advice saying go at least .015" in, or back off at least .015". Many say there is no middle ground with these big VLD's. So I'm all ears, I'm setup to load .015" in the lands. This going to go again starting a grain below the 6mm Rem starting loads.

I also should say everything has been north of 3100fps, up to just over 3300 fps. this is another concern with this .236" tight groove barrel. Randy Robinett cautioned me running his 104's this fast in this twist worried about the ability to stay together at the rpm we were looking at. So now I'm thinking maybe this to hard on these jackets.

If this were not enough to think about, now Fred brought up another possibility, 4 groove! With 4 instead of 5 or 6 groove, am I putting more torque on the drive bands using instead of 6 that would breakup the force on the jacket more? Is it more than the jackets like getting those cores up to that increased rpm, maybe not enough for them to come apart, but possibly enough to create some instability with the core and jacket???

This barrel is not fouling, the easiest barrel to clean I own, and only around 70 rounds thru it now. I have considered shortening it to 26 and rechambering to the 6x47 or 6mm BR instead of buying another 8 twist this winter for that setup. Buying a 10 twist which is what I always ran on the 6mm AI in the past, but then I built this for over 600 yards, and from 600 on out the gain I would get using a lighter faster round would become a wash with the heavier VLD's gaining beyond that?

Now with these cooler temps and winter closing, it gives me a lot to think about before I make any rash decisions. Anyone pushing these 108's and 105's over 3200 fps, some sound advice is welcome!

 

[wildcatter]

Well I have regrouped and might get to do some test next week, with some 60* temps in the forecast, and talking with the guy's that know their bullets, I'll start again .015" off and work back to see if I can get anything to show some possibly acceptable Extreme Spreads.

But if this don't work, before I waste this barrel, it will be my last attempt to make these heavy bullets take the speeds and RPM's that no one else put's them thru. If It wants stay with the high spreads for spead, I have decided to take 1.75" of the back end, and rechamber it to the 6BR either Dasher or Akley. But everyone that uses these heavy bullets with success are keeping them well below 3200 fps, and I don't need a 6MM AI to do that!

Hoping for some satisfying results, with this extreme weather were suffering next week, we'll see.

 

[wildcatter]

Well I finally got to do some testing with temps in the upper 50, overcast so no numbers, but in light winds without flags, pretty happy if it will hold this accuracy out to 800 or a bit further. If it will hold these MOA's out there it should give me some pretty consistent kill's on the groundhogs, and if any Yote's get that close it should be money.

I'm not getting the speed I would like with just over Max loads for the standard 6mm Remington, but I'm willing to take it. With 47.0, 47.3, and 47.5 grains of IMR 7828 driving the 108 Berger Elite Hunters, it seems to be pretty happy, so next warm up we get I'll have a dozen or so loaded to 47.3 and stretch it out.


I think it's time to switch over to H 4831SC and see if I can find some speed with accuracy. I know even though I couldn't chronograph yesterday, these are only in the 3050 fps range from clocking some loads doing the barrel break in.

I will also mention this is the second barrel I have had Kathi at Cryo-Plus freeze a barrel before smithing it. In both cases I ended up with barrels that have proven to clean 10X easier than any other barrels that I have ever built on rifles. It is almost unbelievable how little they foul, and never need more than a total of 7 patches, and 5 or 6 passes with a bronze brush to be completely back to as spotless as new! I thank Mrs. Kathi, and hope her recovery and health are back where it should be 100%!