Looking for a bit of troubleshooting advice...

I have a Ruger RPR, 6.5 CM with a Proof Research 24" Carbon Wrapped barrel.

I've been slogging away to find a bullet powder combination the barrel likes. While just about everything I throw through the rifle is Sub MOA, I was hoping for a bit better.

Two weeks ago I thought I found the load. Berger 140 VLDT over a Lapua case and 41.2 Gr of H4350. The Target analysis software showed it to be a .1 MOA spread at 100 yards, at an indoor range. The load was a little "hot" but there were no signs of excess pressure on the primers and the velocity was only just over the 2700 FPS threshold, and I've been working up to that level over several sessions.

I was shooting three round test groups, at 2726 FPS measured at the muzzle, Each powder load is + or - 1 pellet off the target load, with a slight crimp on the round. Each case is run through a neck sizing done with the body only slightly touched.

I was reloading with a Hornady Ammo Plant progressive, but found the seating consistency was not exact enough. So I picked up a Hornady Iron Press and the seating of the bullets, .020 off the lands, is + -r - 0.0005".

In any event the next time went out I had cleaned the barrel, and ran three 5 shot groups one .1 Gr above and below the target load and one at the target load.

The spread was about .5" to .7"

I'm a bit perplexed in that I can't at least get close to the original group.

Thanks in advance,

Bryan

 

how many groups did you shoot that averaged .1?

 

Why do you feel the need to crimp? I am not sure that anyone here that shoots very small groups competitively, crimps their loads. There is a place for crimped rounds, but generally not done by someone that is trying to shoot bench rest type groups.

 

I also shoot a RPR in 6.5 CM. The RPR isn’t exactly a benchrest rifle, more of a PRS rifle. You may be seeing your groups relate a little more to gun handling and a heavier trigger pull. You might also find the barrel is speeding up as part of break-in. I shoot about the same load at Hornady brass, CCI large primers, Hornady 140 gr. ELD-M and 41.2 gr og H4350. I get 2692 fps and shoot .4 moa .6 moa 5-shot groups at 100 & 200 yards as an average over 10 5-shot groups a session. This is still using the factory barrel with 1986 rounds down the tube. I have a Kreiger 26” barrel sitting in the safe for when I decide to swap it out.

 

The .1 MOA setup was the third in a series of 3 shot groups. Working up in .1 Gr increments. The next set with + and - 1 Gr was to confirm the finding, and was considerably different.

Last night I shot a series of three bullets, 120 Gr ELDx, 147 Gr ELD Match and a Berger VLD Target. Three rounds each, first set with Match Primers, then Bench Rest then 5.56 "Mil" primers. The results were interesting to say the least. I'll post the images when I get home.

The rifle is fired from a cradle so I can't blame myself for the variances. One session it shoots a mind numbingly tight group, the next it a .6 spread.

I'm using a Nikon X1000 Black 6-24x50 scope on a Larue Quick Disconnect mount. But I can't quite blame the scope and mount as it did turn out a .1 MOA, .144" Group at 100 yards. Figure I could not hold the rifle on the "exact" same spot at 100 yards...

I do have a Leupold Mk 4 4.5 - 12 I can mount on the rifle, but again, I'm not thinking it's the scope.

Bryan

 

Good point on the trigger, but I swapped it out a after the third outing with a Tinley, 2 1/2 Lb pull. The Proof barrel has about 300 rounds through it and I thought it was settled in....

The Proof Carbon wrapped barrel cut about a pound off the weight of the rifle. And after shooting 50 round, you can grab the carbon portion of the barrel - and not scorch your hand.

With my M1A and AR I prefer 2 stage Match triggers, set to 4 1/2 Lb total...

My 30-06 has a dual trigger, "set" and "fire". Unset it's 11 Lb. "Set" it's 11 Oz.

I swapped RPR firing pin with a Titanium unit fro Anarchy Outdoors.

Bryan

 

I haven't kept up with the carbon wrapped barrels. Do they generally shoot better than .5 to .7? Honest question.

 

No crimp , no sled , more flags

 

Yeah....DON"T crimp for a bolt gun.

 

I think youre doing well, but something caught my eye- how much are you shooting between PROPER cleaning? You talk about the barrel not scorching your hands but that heat is in there (if its not burning your hands its cooking the inside of the barrel).

 

The Carbon wrapping adds stiffness to the system while substantially cutting weight, I went with it in order to mount my Wind Talker Can on the RPR, the results were abysmal...

The Wind Talker suppressor is just too heavy. And as it's such a pain to transfer I guess I'm stuck with it. I see little hope of the Hearing Protection act passing in the next two months let alone with the makeup of the Next House.

I have shot groups as low as .4" with this barrel. I think it's worth the duckets, and it do make it lighter. But I just need to figure out what load it likes. Having some issues reproducing the results.

- Bryan

 

The carbon wrapping sheds heat a lot faster than the standard SS or CM barrel. But I take the point on heat.

I have never put more than 40 rounds through it at any sitting and they have been slow fire. And I probably need to clean it after every session...

- Bryan

 

Best batch and reshoot...

 

Shooting 3 shot groups is no indication of the rifles true accuracy potential .

Changing the powder charge by 1/10 gr above and below the favored loading would seem to be a waste of time. Unless you have a super, hi tech scale? Most scales are only accurare to +/- 1/10th gr.

Your true accuracy would seem to be 1/2" at best. imo. Sorry.

 

Tagging for interest

 

1. Give that bbl. the best cleaning you can, especially during break in .
2. I agree with @win243xb statements. In small capacity cases like the 223 or 6BR I load in increments of.2-.3 gr. If the cartridge has the capacity to hold 40-50 grs. I make jumps of .4 to .6 gr.
3. Forget the crimp and consentrate on uniform seating pressure.
4. Find your “seat to touch” measurement then establish where your bullet likes to be seated.
5. Although your progress may seem maddeningly long and tedious, keeping good notes will prove to be priceless in the long run.
I hope this helps,

Lloyd

 

Get some wind flags too- thatll help you a lot

 

Carbon fiber transmits heat BUT you can touch the outside easily after many shots , so what happens to the heat ? It can't just evaporate .
It either transmits heat to the air via the exterior or it doesn't .

 

I'm sorry but I agree , your real accuracy is about .5" or more . Try 5 shot groups , flags , no sled and no crimps . Use a good front rest and rear bag for testing .

 

This goes against the laws of thermodynamics as carbon fiber is considered and insulator. It will prevent the barrel from sheading heat unless you know something your not telling.