Another Kimber Montana 8400 WSM conversion ... this time to 6.5 PRC

[Gtscotty]

I've been messing with this 147gr ELD Match bullet just to get some data but I really intend to get on with the 142gr ABLR load ASAP. I'd be ok with similar results with a 142gr load producing 5 shots under 1 moa and bracketed by loads that aren't terrible and have similar POI.

I may have missed it, but are you going to try any other powders in your rifle? H1000 has a great reputation, but I can't help but wonder if something like RL23 or RL26 might shine in the PRC. I tried both in my .270, both gave great velocities, RL26 was a bit faster, but RL23 gave slightly better groups in my gun and is supposed to be very temp Insensitive.

Do you know anyone that has run one of those 142gr ABLRs into an elk? I wouldn't mind having a slicker bullet for my 6.5 Montana and I've though about giving the 142gr a try. I've heard the ABLRs are soft, but on the other hand they're bonded and have a high SD... The regular 140gr ABs penetrate great, I just wouldn't want to compromise that performance for the BC gain.

Just wanted to follow up on the 143 eld-x's. Im pretty unimpressed, with how they performed.
Not only did they penetrate fairly shallowly, less than a similar 7mm 162 amax with a launch velocity of around 3k, they also didnt cause as much internal damage as i would expect from said Amax, or a Berger VLD.

What game were you shooting? Do you have any pics you could share from the hunt? I'd be interested to hear more about the problems you had with the bullet. I have talked to several guys that have used the 143gr ELDxs out of Creedmoors on Antelope, Muleys and Elk. Performance on the Antelope and Muleys was apparently good, the elk was a bull at 775yds so I'm sure over expansion wasn't the concern on that one...

 

[LoonWulf]

I may have missed it, but are you going to try any other powders in your rifle? H1000 has a great reputation, but I can't help but wonder if something like RL23 or RL26 might shine in the PRC. I tried both in my .270, both gave great velocities, RL26 was a bit faster, but RL23 gave slightly better groups in my gun and is supposed to be very temp Insensitive.

Do you know anyone that has run one of those 142gr ABLRs into an elk? I wouldn't mind having a slicker bullet for my 6.5 Montana and I've though about giving the 142gr a try. I've heard the ABLRs are soft, but on the other hand they're bonded and have a high SD... The regular 140gr ABs penetrate great, I just wouldn't want to compromise that performance for the BC gain.



What game were you shooting? Do you have any pics you could share from the hunt? I'd be interested to hear more about the problems you had with the bullet. I have talked to several guys that have used the 143gr ELDxs out of Creedmoors on Antelope, Muleys and Elk. Performance on the Antelope and Muleys was apparently good, the elk was a bull at 775yds so I'm sure over expansion wasn't the concern on that one...

I've got thread running in hunting. Im chasing kids, and have a pile of meat to cut but I'll update it with pictures this evening, hopefully.
The animal was a 500ish lb bull, range was about 50-75yds, launch velocity was in the 2880 range.
I think it would be a great deer bullet, but I'm pretty sure if I'd hit the front leg the bullet wouldn't have gotten into the vitals deep enough for a quick kill.

 

[Gtscotty]

I've got thread running in hunting. Im chasing kids, and have a pile of meat to cut but I'll update it with pictures this evening, hopefully.
The animal was a 500ish lb bull, range was about 50-75yds, launch velocity was in the 2880 range.
I think it would be a great deer bullet, but I'm pretty sure if I'd hit the front leg the bullet wouldn't have gotten into the vitals deep enough for a quick kill.

I hear ya, no rush, just got the toddler to bed myself, was just curious to hear more about the performance as I've considered using the 143gr for Antelope and Muleys. I'll check out your hunting thread.

 

[mshootnit]

Just wanted to follow up on the 143 eld-x's. Im pretty unimpressed, with how they performed.
Not only did they penetrate fairly shallowly, less than a similar 7mm 162 amax with a launch velocity of around 3k, they also didnt cause as much internal damage as i would expect from said Amax, or a Berger VLD.

Have you seen the promo vid? If you slo mo the video as the eld-x passes through ballistics gel, you can see fragments of bullet coming through like a shotgun pattern. No doubt shot a close range to emphasize the wound cavity but still...

 

[LoonWulf]

Have you seen the promo vid? If you slo mo the video as the eld-x passes through ballistics gel, you can see fragments of bullet coming through like a shotgun pattern. No doubt shot a close range to emphasize the wound cavity but still...

Naw, I bought them about a year and a half ago for my 6.5CM, but hadnt done much research on them. I read they were supposed to be tougher than the Amax, which isnt "ment" for hunting, and just assumed they would perform similarly, but give deeper penetration. Obviously I should have done a bit more research, but considering how well the Amax has done for me i just kinda went with it.

 

[MCMXI]

I may have missed it, but are you going to try any other powders in your rifle? H1000 has a great reputation, but I can't help but wonder if something like RL23 or RL26 might shine in the PRC. I tried both in my .270, both gave great velocities, RL26 was a bit faster, but RL23 gave slightly better groups in my gun and is supposed to be very temp Insensitive.

Do you know anyone that has run one of those 142gr ABLRs into an elk? I wouldn't mind having a slicker bullet for my 6.5 Montana and I've though about giving the 142gr a try. I've heard the ABLRs are soft, but on the other hand they're bonded and have a high SD... The regular 140gr ABs penetrate great, I just wouldn't want to compromise that performance for the BC gain.

I'm probably going to stick with H1000 unless I can't find a good load around 3,100 fps for the 142gr ABLR. I know quite a few people up here that have taken elk, deer, bear, moose and more with 7mm versions of the ABLR but not the 6.5mm version. I might be the first.

 

[LoonWulf]

Buddy of mine has shot 3 cows with the .270 and 150 ablrs now. Short ranges only. They seem to do a pretty good job of holding together, haven't put rounds on game...oh he did shoot an axis at 150-200, which went down no problem, still not long range tho.

 

[flyguyskt]

I cannot get any of my rifles to shoot 168 .308 ABLR...best I can do is 2" at 100. same exact load in one rifle swapping to the regular AccuBond produces .5" 100 yard groups. ***... I was pulling my hair out with 3 different rifles thinking it CAN'T be the bullets!!! I've tried different seating depths different powder charge...finally decided to change bullets. all 3 rifles now sub MOA. Maybe I just didnt find the seet spot but 5 loads with .002 difference and were close.

I would love to know your results with the ABLR.

 

[LoonWulf]

I cannot get any of my rifles to shoot 168 .308 ABLR...best I can do is 2" at 100. same exact load in one rifle swapping to the regular AccuBond produces .5" 100 yard groups. ***... I was pulling my hair out with 3 different rifles thinking it CAN'T be the bullets!!! I've tried different seating depths different powder charge...finally decided to change bullets. all 3 rifles now sub MOA. Maybe I just didnt find the seet spot but 5 loads with .002 difference and were close.

I would love to know your results with the ABLR.

You might want to check your bullet run out.
I've found that the long pointy bullets tend to have more issues with alignment than shorter blunter projectiles, especially if seated short.

 

[MCMXI]

Update: It's been a while since I did anything with this rifle, but yesterday afternoon I removed the 24" 6.5 PRC barrel and screwed on a 20" 6.5 PRC barrel with 1/2-28 muzzle threads. I finish reamed the chamber and got "perfect" headspace with some resistance closing the bolt on a GO gage. The rifle is back together and I hope to shoot some factory loads in the coming days. I have lots of velocity data from the 24" barrel so it will be interesting to see if this configuration is significantly slower, and also see if the accuracy/precision results are better. I have a SilencerCo Harvester on the barrel and a Vortex Viper PST 4-16x50mm FFP scope on the receiver that I'll swap out for a lighter 1" Zeiss Conquest if the rifle shoots well. Weight as shown is 8lb 5oz.

 

[MCMXI]

Here's velocity data for the 16 shots from today along with the best target. The 143gr ELD lost about 50 fps compared to the 24" barrel but the 147gr lost a whopping 122 fps!! I did shoot the 147gr last year in May when it was a lot warmer than the 30F of today but I doubt that's the issue.

 

[Nature Boy]

The 143gr ELD lost about 50 fps compared to the 24" barrel but the 147gr lost a whopping 122 fps!!

That’s interesting

I assume different conditions could account for the change, but if that’s the main reason I don’t think I’d want to use a power that sensitive to temps changes.

Is there a big difference in bearing surface between the 143 and 147?

As is usually the case, the root cause is likely the result of a couple of variables,

barrel length + something - something else

 

[MCMXI]

@Nature Boy , I haven't checked to see if there's a big difference in the bearing surface of the two bullets. Here's Hornady's data for the 6.5 CM and 6.5 PRC from a 24" barrel. It's not clear to me why I saw such a big drop with the 147gr load compared to the 143gr load. I didn't get Hornady's numbers when I was using a 24" barrel so I'm not too concerned about their published data. I would think that Hornady would use the same powder for both loads for the same cartridge so I'm scratching my head a bit. Based on how the factory loads shot today I think it's definitely worth working up an ABLR load using H1000 or another suitable powder. I'm looking for temperature stable loads so that's why I started out with H1000.

6.5 CM
143gr ELD-X > 2,700 fps
147gr ELD Match > 2,695 fps

6.5 PRC
143gr ELD-X > 2,960 fps
147gr ELD Match > 2,910 fps

The rifle is really fun to shoot with the Harvester attached. I felt good about every shot today but I'm going to adjust the trigger pull. I thought it was very heavy and my trusty trigger gauge shows an average pull weight of 4lb 8oz which is 50% more than I like.

 

[MCMXI]

Is there a big difference in bearing surface between the 143 and 147?

143gr ELD-X on left, 147gr ELD Match on right. Hornady claims a G1 of .625 for the 143gr and .697 for the 147gr … seems like a huge difference.

 

[horsey300]

Hodgdon online now has some data for the prc, I'd email them about imr4451 as well for temp insensitive powder, it's useful almost everywhere that h1000 is, or......I think you have QL? (Still waiting for the coffee to kick in) I usually get good results with the 4451, and I'm a huge h1000 preacher, but the 4451 does merit a look......just a thought for you, good luck and keep us updated, I'm really enjoying this one!

 

[Gtscotty]

I wonder if Reloder 23 and 26 would be good fits for the PRC as well. Both give great velocities in similar cartridges like the 7 WSM and are temp stable (perhaps 23 moreso than 26).

 

[MCMXI]

@horsey300 & @Gtscotty , thanks for the info. I do have QL but my version doesn't list IMR 4451 but maybe I can download an update. I have H1000 for my .338 Lapua Mag and it works great in that application. Here's some load data for the 6.5 PRC. Of the powders listed I have Reloder 22, IMR 7828 and H1000. I don't have Reloder 23, 25 or 26 but I would certainly be up for buying a couple of pounds to try. Our local Murdoch's often has a good selection of powder, and their prices are decent if you're only buying a pound or two. I really like VihtaVuori powders but given the numbers shown below it wouldn't be my first choice. H1000 should be a good choice but I'll look for some Reloder 25 and 26 this week.

 

[horsey300]

@horsey300 & @Gtscotty , thanks for the info. I do have QL but my version doesn't list IMR 4451 but maybe I can download an update. I have H1000 for my .338 Lapua Mag and it works great in that application. Here's some load data for the 6.5 PRC. Of the powders listed I have Reloder 22, IMR 7828 and H1000. I don't have Reloder 23, 25 or 26 but I would certainly be up for buying a couple of pounds to try. Our local Murdoch's often has a good selection of powder, and their prices are decent if you're only buying a pound or two. I really like VihtaVuori powders but given the numbers shown below it wouldn't be my first choice. H1000 should be a good choice but I'll look for some Reloder 25 and 26 this week.

View attachment 827064

View attachment 827065

I checked something else out, there's another enduron powder listed for the prc (should match h1000 temp insensitive) hodgdon online lists load data for imr 8133 (the enduron answer to retumbo) to gain a Lil velocity over h1000 (very little according to hodgdon on the 147 and 143s). I still lead with h1000 every chance I get, but every now and then, the enduron powders get the nod, imr4955 is the h1000 "twin" so I haven't found a need to play with it yet.

 

[MCMXI]

Short version: Explain the first round issue given that the barrel doesn't heat up much at all, even after five shots.

I've started to work up a 147gr load for the Kimber 6.5 PRC 20" simply to see what the rifle/suppressor are capable of. Since Hornady refers to the bullet as "match" I'm assuming that it should fly a little better than the 143gr ELD-X and Nosler 142gr ABLR. After shooting a few groups the results are promising but a little bit odd. Two days ago I shot five rounds of the Hornady factory 147gr load and got a typical group for that load of 1.087", an ES of 49 fps and an average velocity of 2,715 fps with the third and fourth shots being the fastest. Basically I'm getting around 2,720 fps for the 147gr factory load that shot at around 2,856 fps from the 24" barrel which is a huge loss of 136 fps. I don't plan on shooting factory loads so it's not a deal breaker but it is a bit disappointing.

So now on to the weird stuff. Yesterday I put together 5 rounds using once fired Hornady brass, 58.0gr of H1000, GM210M primers and a COAL of 3.000" (.020" off the lands). It was cold yesterday (20F) and so the rifle and suppressor were cold at the start. The barrel hadn't been cleaned from the previous day shooting Hornady factory ammo so when the first shot impacted 1" high on the target compared to the rest of the shots I figured it was due to the change in powder, a somewhat well-established phenomenon. Even when I saw that the velocity was higher compared to the other four shots I put it down to not cleaning the barrel for the new powder. It was a bit windy yesterday so the shot to the right could have been shooter error, wind, mirage etc., but the elevation on the target is the same as the three shots to the left so I need to shoot that load again to see if it's a good one.

2,887 fps
2,842 fps
2,855 fps
2,860 fps
2,862 fps

Discounting the first shot the ES is 20 fps, not great but not terrible given the limited prep, and still less than half of the factory stuff.

147gr ELD-Match, once fired Hornady brass, 58.0gr H1000, GM210M, COAL of 3.000",



So this morning I put together five rounds using more of the once fired Hornady brass, 58.3gr of H1000, GM210M primers and a COAL of 3.000" (.020" off the lands). It was 28F today, the barrel wasn't cleaned after yesterday's group and once again the first shot landed in virtually the same spot as the target above, followed by four shots in a small group in a similar location to the three shots in the center of the target above. All five shots felt very good, I was holding 1/4 moa or better, and had the first shot gone where I was aiming that would have been a 0.5 moa group. Looking at the LabRadar data, the first shot was significantly faster than the last four (I'll update numbers tonight). My working theory at the moment is that the SilencerCo Harvester suppressor is boosting the velocity of the first round due to more oxygen inside the suppressor which is somehow allowing a bit more powder to burn. According to QuickLoad the 20" barrel is burning about 98% of the powder. I can't explain why I don't see this phenomena with the factory 147gr ammunition which is much slower. So what are your thoughts? Am I way out in left field? I am pleased though with the 58.0gr and 58.3gr loads. Velocity is about what I was getting with factory 147gr loads from the 24" barrel and if I can resolve the first round issue accuracy/precision is excellent.

Added in Edit: Here are the velocities for the five shots shown below. ES discounting the first shot is 16 fps.

2,897 fps
2,875 fps
2,859 fps
2,868 fps
2,866 fps

147gr ELD-Match, once fired Hornady brass, 58.3gr H1000, GM210M, COAL of 3.000"

 

[Nature Boy]

That’s looking very promising.

I really enjoy the little problems like this and the learning that comes from solving them.

It will be interesting to see if the problem follows the supressor when you shoot without it.

Could also be an anomaly when shooting with a cold bore

I also wonder if the pattern repeats with a clean bore

It’s certainly got me curious

 

[MCMXI]

@Nature Boy , you're supposed to solve the problem I described, not pile on a bunch more questions! Seriously though, very good points. It would be interesting to see if the loads go to crap once the suppressor is off or if I try a different suppressor. I'll try the Omega 300 with the 6.5 mm caliber front cap because it's not that much heavier than the Harvester and I have a 1/2-28 direct thread adapter for it. Also, it doesn't have the fixed integral brake of the Harvester which I don't like. I have a bunch of others that either won't work due to the interface or are too heavy. The first thing I'm going to do is to load up five each of 57.7gr, 58.0gr and 58.3gr and retest. I'll most likely load up 6 of the 57.7gr so that I can shoot the first round into a different target to see if it's high again and then shoot three groups of five.

 

[MCMXI]

I'm in the process of trying to get 6.5 PRC brass annealed and the shoulder bumped back and shot three groups this past weekend. Accuracy/precision was so/so and ES was terrible which means either the anneal wasn't consistent or the shoulder bump wasn't right, or both. Once again the first shot out of two different and cold suppressors resulted in significant velocity bumps for the first shots.

57.7gr, fouled bore, cold Harvester

2,894 fps
2,842 fps
2,864 fps
2,869 fps
2,846 fps

58.3gr, fouled bore, cold Omega 300

2,931 fps
2,907 fps
2,912 fps
2,860 fps
2,916 fps

 

[horsemen61]

Hey OP any updates on this?

 

[Nature Boy]

He’s been busy building shelves and shopping for stools

 

[MCMXI]

He’s been busy building shelves and shopping for stools

Yes, very true ... and shooting other stuff too along with home projects completely unrelated to shooting. I'm hoping to buy a used gas-powered concrete mixer this weekend and then there'll be more projects.

Hey OP any updates on this?

You must have some kind of "spidey sense" because I was at Proof Research yesterday afternoon discussing my 6.5 PRC project. Kelly told me that the current "best" twist rate is 1:7.5 which is what they use and yet I had barrels made with a 1:8 twist based on Horndady's recommendation. She also mentioned that a tight chamber with "lots" of freebore helps. I don't think that the twist difference would be a deal breaker but I still haven't managed to get consistently good results. I was thinking about trying different torque values at the barrel receiver interface to see if it makes a difference. Overall this project hasn't gone that well and I really don't know why. I was expecting greatness from this rifle/cartridge combination but so far all I see is mediocrity.