6.5 PRC group size

[OmegaRed]

Where did you get that target, Sir?

Lots of targets, like that one available on this site.

 

[jmkasza]

Shot again yesterday, slowly went through 20 rounds. This has been a helpful thread in getting me to (1) sloooow down at the range and (2) clean the barrel between trips to the range. I typically don't clean as often with my hunting rifles, but this one has made it clear she likes to be clean. And run cool.

The 3-shot groups instead of 5 has been better for data collection and my sanity.

I've landed in an acceptable place for hunting season with the 140gr Elite Hunter, all four groups were under one inch this time. Average size 0.875" and moving 2920 fps. Will continue to tinker as time permits.

-Jake

 

[Gabe22BR]

Today’s match
6.5 PRC with Retumbo & 144Hyb

 

[lawman29]

I'm a bit surprised at getting 3100 fps out of a 24" barrel with H1000. Not that it can't be done as it appears your 59.2 grs is a compressed load and pressure might be just a tad over max. I've done that with RL23 giving me 3100 fps with some decent results (but with a 26" barrel).

No pressure. I loaded a few today with 59.2 & Berger 140 and took a couple photos. COAL 3.065

 

[Straightshooter1]

Where did you get that target, Sir?

I can't recall exactly since it's been a few years, but I think I got it from a link on this website. If you're interested in having it, attached is a PDF file I use to print it out:

 

[Danboyd7]

I’ve read (and heard) lots of opinions on group size. Typically I shoot 5-shot groups for my target rifles and when doing load development. I’m a casual target shooter and avid deer hunter; for the most part I’ve figured out what works for me.

18 months ago I bought a 6.5 PRC (Savage 110 High Country) for a potential mule deer hunt. I haven’t got the tag yet so it hasn’t become a big priority to get load sorted out. Free time has been in short supply too. It started off very promising, but I’ve ran into issues with huge group sizes. Here is the story:

2/25/24 Purchased new and cleaned bore

3/17/24 Shot 5 and gently cleaned. Bore was not very dirty.

Group size not measured, shot Hornady Match 147gr​

3/22/24 Shot 10 total, Hornady Match 147gr

0.749” group with 5 shots​

0.483” group with 3 shots (different group)​

Cleaned bore, rifle sat untouched till August​

8/30/23 Shot 10 – group size exploded!

2.620” group with 5 shots Hornady Match 147gr​

3.259” group with 5 shots Hornady Precision Hunter 143gr​

Cleaned bore​

Checked for loose screws, found none, verified correct torque on all​

12/13/24 Shot 5 again, group size even worse. Was pissed, did not measure.

Hornady Precision Hunter 143gr​

12/21/24 Swapped scope from a Vortex Viper PST 5-25 to a Zeiss 4-16

12/27/24 Shot 16 rounds, Hornady Precision Hunter 143gr

Huge group sizes, did not measure (wish I did, but too frustrated at the time)​

Cleaned bore​

12/28/24 Put the Vortex scope back on, removed the action from stock and reinstalled

Verified torque. Checked and torqued bases and scope rings.​

12/29/24 Shot 8 rounds, Hornady Precision Hunter 143gr

3.259” group with 3 shots​

Cleaned bore​

3/16/25 Tested a batch of handloads and more Hornady PH 143gr

1.256” group with 5 shots Berger 156gr EH​

1.699” group with 5 shots Berger 156gr EH​

1.139” group with 5 shots Berger 135gr CH​

0.506” group with 5 shots Berger 135gr CH (was shocked)​

3.840” group with 5 shots Nosler 129gr ABLR​

Ran bore snake​

5/23/24 Finished testing handloads

1.499” group with 5 shots Hornady PH 143gr​

3.211” group with 5 shots Hornady 143gr ELDX handload. Had a flyer, group would be 1.277” without it​

3.047” group with 5 shots Nosler 129gr ABLR​

1.148” group with 5 shots Berger 140gr EH​

1.355” group with 5 shots Berger 140gr EH​

2.286” group with 5 shots Nosler 140gr AB​

2.568” group with 5 shots Nosler 140gr AB​

Cleaned bore​

Out of all this.. I wish I would have saved targets. The Berger 140gr Elite Hunter showed promise so I loaded up 15 more for tomorrow. The 135gr Classic Hunter had the best group by far, but that’s my Creedmoor bullet I wanted the PRC to shoot heavier bullets. Evidently it does not care for the Nosler bullets I tried. Most of the dispersion has been vertical, on the handloads anyway. On the 3+ inch groups it’s been all over.

I shot next to a guy doing load development for this 6.5 PRC last time and he was doing 3-shot groups. Maybe I need to do this? Maybe I’m not letting it cool enough and it starts to walk.. I don’t know.

Could be me too as I haven’t been shooting much lately. When switching to a different rifle I seem to be just fine. I’ve been conscious of technique and getting setup the same every time. Shooting off bags, front and rear, from a bench.

Or if anyone has intimate knowledge of the 110 High Country I’d love to hear it. I really felt it had great potential at first, now with 120 rounds down the tube I’m not so sure.

-Jake

Something is just off..it shot good right out of the get go and then got worse? Is the rifle free floated? Is there anything touching the barrel? stock? (you dont have a magneto speed on the barrel do you?) Do you notice it gets worse as the barrel heats up? Problem is it could be a variety of things?

 

[Straightshooter1]

No pressure. I loaded a few today with 59.2 & Berger 140 and took a couple photos. COAL 3.065

View attachment 1676183View attachment 1676184View attachment 1676185

OK, "no pressure". That's fine! But I take it you mean no pressure signs?

And though there's no pressure signs doesn't mean your not a little over max pressure. I've loaded cartridges that calculated over the max SAAMI pressure and didn't have any pressure signs.

Looking at your pics, it does look to me like you've got a slight (very slight) powder compression, even with a COAL of 3.065". Though, that little compression is not a big deal.

 

[lawman29]

Went out this morning to confirm 59.2 and test 290 vs 289 bushing. Load shoots.

 

[jmkasza]

Something is just off..it shot good right out of the get go and then got worse? Is the rifle free floated? Is there anything touching the barrel? stock? (you dont have a magneto speed on the barrel do you?) Do you notice it gets worse as the barrel heats up? Problem is it could be a variety of things?

At this point I believe it was a combination of a couple things.. letting the barrel get too hot and inadequate cleaning. Never found anything loose and the barrel is free floated. No magneto speed.

More frequent cleaning and longer time between shots/groups has made a significant improvement. I feel like I can get back to load development now as time permits.

 

[ronsatspokane]

I'll relay my experience with 6.5 PRC in a gun setup for F Class. I've tried it twice. The first time I was using H1000, Fed 210M's and the Berger 156 EOL's. I was 20 thousands off the lands and running at 2958. The gun was an absolute hammer for the first half of the string (2 sighters and 20 shots for record per string). Less than 1/2 MOA. As the second half would come around the groups would open up to a little over an MOA. Happened in multiple matches. I was scratching my head. I came to the conclusion that it had to be carbon fowling due to the cartridge being a bit overbore. I didn't see any other viable powders that were readily available so I abandoned the cartridge for competition (still use it in hunting rifles).

Fast forward a couple of years and Berger came out with the 153.5's. Seemed like a great bullet for 6.5 PRC and Vihtavuori powders were more available. Others also had good luck with H4831SC so I cut another barrel and screwed it on the the BAT action. Did load development using 565, 568, 570, 4831 and even tried H1000 again. Thought I had a load nailed with 4831. Had good groups with the other powders as well but I had a lot of 4831. Took it to an F Class match at a range that is known for light winds and targets that are easy to clean when those winds are light. It started out wonderfully. By mid string the groups started opening up. Dejavu to say the least. Got so bad that a friend of mine who was scoring (our Accurate Shooter admin) jokingly said: Ron, try to keep it in the 9 ring.

I tweaked the load and took it to a big 1000 yard match. The day before at the mid range another (well known) F Class guy was testing a 6.5 PRC and he was running into a similar problem. In my mind I was thinking that if mine did that tomorrow at long range I was going to abandon the cartridge for a second time. It was unlimited sighters so I shot 10 sighters and I was thinking that this is very manageable and shooting quite well. Went for record and this time the group started opening up around shot number 5. By shot 15 the bullets were not making it to the target. Guys sitting behind me could see the gray poof as the jacket was stripped with prejudice. That ended my second trial of 6.5 PRC in competition.

So I called Burger and ran the issue by them. I won't name names but the gentleman I talked to was very knowledgeable with decades of experience and was on a first name basis with many of the top national shooters over the years. What he articulated the problem as was exactly what I was seeing. It seems that as heat build up in these overbore cartridges (and it really builds up in a 20 shot string) that the copper jackets get soft. He said that if it gets hot enough the jacket turns to jello. That explains the gradual deterioration in performance and the eventual shedding of the jackets when it gets way to hot. It is simply a problem with smaller calibers and large powder loads. In larger calibers like 7mm and up there is a lot more surface area inside the barrel to dissipate heat. But I'd think that you could even get a 7mm to behave similarly with a large powder load. Say something like a 7mm mag or a 7 PRC with 20 or 30 shots at an F Class pace.

That's my story.

 

[Kracken McGraw]

I'll relay my experience with 6.5 PRC in a gun setup for F Class. I've tried it twice. The first time I was using H1000, Fed 210M's and the Berger 156 EOL's. I was 20 thousands off the lands and running at 2958. The gun was an absolute hammer for the first half of the string (2 sighters and 20 shots for record per string). Less than 1/2 MOA. As the second half would come around the groups would open up to a little over an MOA. Happened in multiple matches. I was scratching my head. I came to the conclusion that it had to be carbon fowling due to the cartridge being a bit overbore. I didn't see any other viable powders that were readily available so I abandoned the cartridge for competition (still use it in hunting rifles).

Fast forward a couple of years and Berger came out with the 153.5's. Seemed like a great bullet for 6.5 PRC and Vihtavuori powders were more available. Others also had good luck with H4831SC so I cut another barrel and screwed it on the the BAT action. Did load development using 565, 568, 570, 4831 and even tried H1000 again. Thought I had a load nailed with 4831. Had good groups with the other powders as well but I had a lot of 4831. Took it to an F Class match at a range that is known for light winds and targets that are easy to clean when those winds are light. It started out wonderfully. By mid string the groups started opening up. Dejavu to say the least. Got so bad that a friend of mine who was scoring (our Accurate Shooter admin) jokingly said: Ron, try to keep it in the 9 ring.

I tweaked the load and took it to a big 1000 yard match. The day before at the mid range another (well known) F Class guy was testing a 6.5 PRC and he was running into a similar problem. In my mind I was thinking that if mine did that tomorrow at long range I was going to abandon the cartridge for a second time. It was unlimited sighters so I shot 10 sighters and I was thinking that this is very manageable and shooting quite well. Went for record and this time the group started opening up around shot number 5. By shot 15 the bullets were not making it to the target. Guys sitting behind me could see the gray poof as the jacket was stripped with prejudice. That ended my second trial of 6.5 PRC in competition.

So I called Burger and ran the issue by them. I won't name names but the gentleman I talked to was very knowledgeable with decades of experience and was on a first name basis with many of the top national shooters over the years. What he articulated the problem as was exactly what I was seeing. It seems that as heat build up in these overbore cartridges (and it really builds up in a 20 shot string) that the copper jackets get soft. He said that if it gets hot enough the jacket turns to jello. That explains the gradual deterioration in performance and the eventual shedding of the jackets when it gets way to hot. It is simply a problem with smaller calibers and large powder loads. In larger calibers like 7mm and up there is a lot more surface area inside the barrel to dissipate heat. But I'd think that you could even get a 7mm to behave similarly with a large powder load. Say something like a 7mm mag or a 7 PRC with 20 or 30 shots at an F Class pace.

That's my story.

That was very enlightening, Thanks.

 

[jmkasza]

I'll relay my experience with 6.5 PRC in a gun setup for F Class. I've tried it twice. The first time I was using H1000, Fed 210M's and the Berger 156 EOL's. I was 20 thousands off the lands and running at 2958. The gun was an absolute hammer for the first half of the string (2 sighters and 20 shots for record per string). Less than 1/2 MOA. As the second half would come around the groups would open up to a little over an MOA. Happened in multiple matches. I was scratching my head. I came to the conclusion that it had to be carbon fowling due to the cartridge being a bit overbore. I didn't see any other viable powders that were readily available so I abandoned the cartridge for competition (still use it in hunting rifles).

Fast forward a couple of years and Berger came out with the 153.5's. Seemed like a great bullet for 6.5 PRC and Vihtavuori powders were more available. Others also had good luck with H4831SC so I cut another barrel and screwed it on the the BAT action. Did load development using 565, 568, 570, 4831 and even tried H1000 again. Thought I had a load nailed with 4831. Had good groups with the other powders as well but I had a lot of 4831. Took it to an F Class match at a range that is known for light winds and targets that are easy to clean when those winds are light. It started out wonderfully. By mid string the groups started opening up. Dejavu to say the least. Got so bad that a friend of mine who was scoring (our Accurate Shooter admin) jokingly said: Ron, try to keep it in the 9 ring.

I tweaked the load and took it to a big 1000 yard match. The day before at the mid range another (well known) F Class guy was testing a 6.5 PRC and he was running into a similar problem. In my mind I was thinking that if mine did that tomorrow at long range I was going to abandon the cartridge for a second time. It was unlimited sighters so I shot 10 sighters and I was thinking that this is very manageable and shooting quite well. Went for record and this time the group started opening up around shot number 5. By shot 15 the bullets were not making it to the target. Guys sitting behind me could see the gray poof as the jacket was stripped with prejudice. That ended my second trial of 6.5 PRC in competition.

So I called Burger and ran the issue by them. I won't name names but the gentleman I talked to was very knowledgeable with decades of experience and was on a first name basis with many of the top national shooters over the years. What he articulated the problem as was exactly what I was seeing. It seems that as heat build up in these overbore cartridges (and it really builds up in a 20 shot string) that the copper jackets get soft. He said that if it gets hot enough the jacket turns to jello. That explains the gradual deterioration in performance and the eventual shedding of the jackets when it gets way to hot. It is simply a problem with smaller calibers and large powder loads. In larger calibers like 7mm and up there is a lot more surface area inside the barrel to dissipate heat. But I'd think that you could even get a 7mm to behave similarly with a large powder load. Say something like a 7mm mag or a 7 PRC with 20 or 30 shots at an F Class pace.

That's my story.

Thank you for the detailed post