6.5x47/R-17 Phenomenon

[/VH]

This past weekend while shooting my rifle, I had an unexpected experience and I am hoping some of the more experienced shooters can give me some insight on what happened.

BACKGROUND INFO:

RIFLE: Atlas Factory 6.5x47 Lapua hunting rifle with a .293 (tapered) nk (basically a tight/no turn). It has a 26” Krieger #4 sporter contour, a 2.5-25x March scope in Kelbly rings on Kelbly bases. It has shot very well for having such a light bbl. with a variety of bullets (123 Scenars, 130 & 140 Berger VLDs, 120 A-MAXs, 130 Scirocco IIs and 129 Accubond Long Ranges) at distances out to 360 yds., using R-15 and H4350. The rifle, hampered by me, has fired some 100 yd/3 shot groups less than .200”, most under .400” with a little development and a few 200 yd./5 shot groups less than .500”.

CRONOGRAPH: Shooting Crony (I know not the best but it’s what I have) set 7’8” from the muzzle.

ME: I have been shooting since the early 60s and handloading for rifles, shotguns and handguns since the early 70s. I have competed in a few NBRSA short range group matches with a 6ppc in a Panda action where I have done all my own brass prep from fire forming through neck turning and feel that I have more experience and therefore knowledge than most average hunter guys in regard to what is required to develop accurate loads, though I have virtually no experience with ranges beyond 400 yds. I also not only own but have read the loading manuals from all of the major domestic bullet and powder brands, along with Lapua and Vita Vouri. Until I shot benchrest, I always “stayed within” a printed manual with power charges. However, I expect most of us know that “within” one manual may be exceeding another by 2 grains or more. In the PPC world, with the guidance of several helpful shooters, I came to learn of the strength of custom actions and that there were no manuals that included data with loads as hot as most group shooters were using. Over time and through my experience, I developed within my own mind a perception (this may be the problem) that with fairly typical rifle loads when one has worked up to a powder charge with a heavier bullet, a lighter bullet (neglecting a substantial increase in bearing surface, change in jacket hardness, increase in diameter, change in seating relative to the lands, etc.) could pretty likely be safely substituted with the same powder charge.

Now to what happened; I had never before loaded any R-17 and wanted to try it. I had worked my way to 37.5 gr with Berger Hunting 140s and 129 Accubond LRs both seated at the lands, shooting 200yds and not being overly impressed. I then continued on with the 129 ABLRs to 38.4 gr. and managed about a ¾” group at just over 2800 fps. I wanted to try some 120 A-MAXs, so I just loaded the same three shells substituting only the bullets with the A-MAXs, seated at the lands. Expecting a slight increase in velocity, upon my first shot, the chrony read 3429! No hard bolt lift, no visible pressure signs on the brass or primer, no excessive recoil and the bullet hit the top edge of the 1” 10 ring. I decided it may have been a fluke reading that possibly the muzzle blast may have caused. (I had previously gotten 9 legitimate looking readings from the crony with the other bullets, with no error messages). So, I decided to fire one more……3407 flashed for a couple seconds on the crony screen and the ERR2. No detectable pressure signs again and cut the bottom right edge of the 10 ring. Well, I only had one more loaded like that so………….3417! The third one cut the bottom left edge of the 10 ring.

Finally the durn question: (Hope no one passed away in the course of reading this but I think details matter in this game) Do you suppose those bullets really went that fast or did I probably blast the crony by having it too close?

Seems like awful consistent readings for a blasted crony or a gross overcharge.

I loaded those same 3 cases again, same load but went back to the 129 ABLRs. No loose primer pockets and the crony went back to the middle 2700s.

I also know that Berger lists R-17 with 130 & 140gr. bullets but not the 120s. Is there something peculiar about this powder that may have caused a 600fps increase with a 9gr decrease in bullet weight.

I’d appreciate the reasonable opinion of anyone that might care to offer one.

Thank you.

If I haven’t exceeded your patience, there is another phenomenon (a good one) with this rifle, custom sizing die, and the great Lapua brass that I’d like to throw out there sometime and see if anyone else has experienced the same.

I LOVE my 6 and a half!

 

[mikecr]

Auspicious,, but no, your chrony sucks.

 

[Laurie]

Probably the Chrono. I've got one somewhere in the loft that used to do similar things. I shot some 8X57 Mauser handloads over it one day that were really consistent, only the military 196gn FMJBTs were going so fast that Remington had wasted its time developing the 8mm Rem Magnum!

I think that was the final straw - I never trusted it after that.

 

[xswanted]

I'm loading R17 in a 25-06 behind 100gr SMK's

I'm getting consistent velocity at 3550fps.

I wrote a thread on it about 7 months ago or so and everyone told me it was too much pressure, too much this too much that, dangerous, chory didn't work.

One or two people had similar experiences.

Just today I was shooting that particular rifle, reloads with R17 and got the same peformance as last fall. 3550 average and after 9 reloads I lost two cases today. Shot the gun to 800 yards and it works pretty darn good at that range/velocity.

I'm not sure what it is, but R17 works REALLY well for velocity gains in the 25-06, I'm guessing you're seeing somehting similar to what I did in your gun.

 

[/VH]

Thanks for the responses guys. XS, how much powder are you poking in that 25-06?

 

[xswanted]

I don't have my data in front of me.

I'm pretty sure its either 55 or 56 grains. I don't recall....could be 53 grains :-\

Either way, the case isn't very full. I'd have to guess load density is in the 80-85% range tops. The case doesn't look very full.

By all accounts it shouldn't shoot very well. But it does. It's a factory Ruger I put a trigger in and laid it in a HS stock. Shoots this load about 3/4" at 100 yards.

I hit my 10 inch gong at 800 today 4/5 times. The miss was my lack of wind reading skills lol.

I don't kwno exactly what makes it work, but I'm not complaining.

 

[Laurie]

I'm not sure what it is, but R17 works REALLY well for velocity gains in the 25-06, I'm guessing you're seeing somehting similar to what I did in your gun. [xswanted]

Yes, well maybe re Re17. But not a 600 + fps increase simply by changing to a 9gn lighter bullet! And .... 38.4gn Re17 isn't even a maximum load for 120s in this cartridge. Running the load through QuickLOAD, the prediction is 2,828 fps at a little under 50,000 psi max peak pressure. This is about what I'd expect in the cartridge and is in line with the OP's recorded MVs for the same load with a different bullet.

 

[Frankr]

I have used ,and used several shooting chrony's and use one now most of the time. I have found them to be as accurate as any thing same speeds across a few more expensive rigs. I always set it 10 feet from the muzzle as its where it should be. and allways measure to it so you get accurate info. I have experienced the ultra high velocity before. your bullet is not going over the sensors straight. maybe hit one sensor, why you got the err reading. its best to make sure the bullet goes over both sensors straight to get accurate reading.as for RL 17 I shoot it in the 6.5 creedmoore. I have found that it likes heavy neck tension to shoot consistant velocitys and sub 1/2 moa groups.

 

[Larryh128]

I would agree with FJIM as to why the error. RL-17 will achieve some fantastic velocitys with certain weight bullets. I have a 270 load for 110gr Barnes TTSX that hits 3550 consistantly. I'm sure that there are more than a few doubters but I sight in 1" high at 100 and hit 1" low at 300 with the same point of aim on med rings. Pretty flat, in fact, flatter than my 22-250. Check point of aim at 100 & 300 with your 6.5 and that will pretty much tell the story from bullet drop.

 

[schumi]

Tag

 

[/VH]

Thanks for your thoughts, guys.

My take on them is:

Mikecr, you said my chrony sucks, it must suck hard to pull a bullet 600 fps faster.

Laurie, your first post seemed to agree with Mikecr but your second post seemed to somewhat validate my chrony's readings when you stated "This is about what I'd expect in the cartridge and is in line with the OP's recorded MVs for the same load with a different bullet." More importantly, Laurie, your second post also seems to validate my assumption that the bullet substitution that I made should be well within the pressure capabilities of the cartridge and I thank you for running and sharing the QuickLOAD data.

FJIM, you pointed out that I did not set up the chrony as I should have, I had her pretty straight but not at the correct distance. One of those "details that matter".

xswanted & Larryh128, you both seem to indicate that further experimentation with R-17 might be worthwhile.

I am now thinking that I should probably set my chrony up per the instructions and work with the powder a little more, not that I think my chrony is all that accurate but I really don't think any of them are perfect and I don't have a good idea of just what the actual tolerances are on any brand of them. Had I not been using the chrony, the other day, or if I had taken the time to move it out the other 2' and then gotten readings more in line with my expectations, I would have no doubt felt like I could have increased the powder charge.

 

[wyoming .260]

Its probably the Chrony , I once had a 3 shot run of 4479,4438and 4482, with a 160 gr. bullet out of a 7x57 ! I laughed and sent it back to the manufacturer.

 

[mikecr]

Mikecr, you said my chrony sucks, it must suck hard to pull a bullet 600 fps faster.

Ok, it sucks hard.

This is what Laurie said and I believe him:

But not a 600 + fps increase simply by changing to a 9gn lighter bullet! And .... 38.4gn Re17 isn't even a maximum load for 120s in this cartridge. Running the load through QuickLOAD, the prediction is 2,828 fps at a little under 50,000 psi max peak pressure.

With a 129gr bullet you had ~2800fps, and with the same load and a 120gr bullet your velocity likely went up to ~2828fps.
It didn't go up 600fps.
And yes your load is "well within the pressure capabilities of the cartridge", but it won't EVER climb 600fps from where you are.
Sorry man

 

[civil82]

I would agree with FJIM as to why the error. RL-17 will achieve some fantastic velocitys with certain weight bullets. I have a 270 load for 110gr Barnes TTSX that hits 3550 consistantly. I'm sure that there are more than a few doubters but I sight in 1" high at 100 and hit 1" low at 300 with the same point of aim on med rings. Pretty flat, in fact, flatter than my 22-250. Check point of aim at 100 & 300 with your 6.5 and that will pretty much tell the story from bullet drop.

I don't doubt your velocity. I do doubt the trajectory, though.

 

[Frankr]

/HV you said you had it pretty straight, there are two sensors I guess about one inch wide if the bullet hits one sensor and is on an angle enough to just hit the corner of the other sensor you will get a err and who knows what it may read I have seen it read 3,600 fps for a 2,900 fps load to no read at all.
I have seen my buddy say it looks good to me. well it was not straight enough.
I have been shooting over a chrony since 1996 was our first one, still have it . it was sent back once for repair,had to sodder the battery wires on. have a new one now with the remote ect. they work as good as any thing out there if you set them up right. some times the lighting conditions will screw with them some. but all in all I like mine and see no reason to spen more money on another one as I have shot over a few high dollar ones same readings. I have made a lot of range cards from the velocitys I have got for quite a few different rifles and they are mostly right on. so they seem to work good enough.

 

[/VH]

FJIM,

I believe you pegged it. Sure enough, when I got those readings, I was shooting at the very top right target on my backer and was probably right at the edge of one sensor. All other shots appeared to give legit readings. I too have seen the chrony give obviously wrong readings (over 6000 fps, on one occasion) and have seen it mess up when shooting at the edges of the sensors or too high above them. I guess what threw me off that day was three consecutive erroneous readings that were very close on velocity along with all other shots appearing to give "good" readings.

Thanks for everyone's thoughts on this.

I have been reading Erik Cortina's thread on long range load development at 100 yds and find it very interesting and educational. That and the willingness of site members to help each other will make a contributor out of me.

I have one little tip that I'd like to offer that might be useful for some new shooters, I know it would be for some at the public range that I shoot at. When setting up a chronograph by your self, remove the bolt from your rifle, get your rifle in the firing position, pointed at the center of the target area and then, looking back through the screens, align your eye with the bore as you set your chrono. For initial set up, this works especially well with a white background behind your rifle, then it should only take minimal adjustment to get it where you want it. In my case; where, I thought I wanted it. Watch out for the edges!

 

[GSPV]

A sheet of paper and a laser bore sighter is great for setting a Chrony up, too.

I like my Magnetospeed for most things, but they have their drawbacks.

 

[FN in MT]

One of the best mistakes I ever made was allowing a friend to shoot over my old Crony. He SHOT the crony, destroyed it and gave me the hundred bucks.

I bought an Oehler 35 and couldn't be happier. The crony wasted more components with ERR readings as well as both overly High and occasional LOW readings that simply couldn't be valid.

For me the crony cost me time and money....You get what You pay for in certain fields....electronics is in my opinion one of them.