Barrel Re-Crowning

[Losing_Sanity]

I recieved a reply fro Ruger Customer Service today, here is thier reply:

"First make sure the front mounting screw (under the floor plate hinge) is torqued to 95 inch pounds, torque the trigger guard center and rear mounting screws, evenly and incrementally, to a final level of 45 - 60 inch lbs. Give the barrel a good cleaning and shoot a 3 shot group at 50yrds to see your results. It should be no more than 1.25" at 50 yards.

If it doesn't improve, contact us at 336-949-5200 with the serial number to have an RMA number issued for return and evaluation.

Our chamber design matches SAAMI specifications. Both specify .124 to .139 inches length of .309 diameter of freebore prior to the rifling leade beginning. Then, for reference, the leade should end approximately 2.426 inches from the breech face. At that point the rifling form is fully developed .

Ruger Customer Service"

I am not real savvy on the definitions of everything, so given the variables from Ruger and compared to my rifle measurements, is there too much freebore? Seems like to me there may be, but I may be reading something wrong.

As I mentioned above in the post, I seated to a length of 2.857 to allow for the magazine area. The overall length to the lands is 3.150 and the bullet was touching the brass, but did not seat into the brass. A jump to the rifling of .293 seems excessive to me. Is this normal? The book calls for an overall length in the 2.840 range.

I used an Hornady Lock and Load OAL gauge for my measurements. So they should be pretty close to accurate. I guess I would need to make a cast to be sure.

I am going to recheck the torque on the screws as recommended, but I would hope there is a better accuracy at 50 yards than 1.25". I will also try the 10 shot meathod of finding the right load.

Thanks again to all that have posted suggestions and that have help me already. I do appreciate it.

 

[Losing_Sanity]

Finally got to go to the range today and shot a 10 shot ladder test with the 300 RCM.

I loaded 59 to 60.8 grains of IMR 4350, 165 grain Hornady SST, *CCI 200 primers, and an overall cartridge length 2.840. The information was obtained from Hornady reloading manual.
(*The manual that I have called for Large Rifle primers. After I loaded them, I realized that Hodgdon Reloading web site called for Magnum primers. So I may need to do the test again.)

Load: FPS:
59 2749
59.2 2795
59.4 2772
59.6 2795
59.8 2807
60 2818
60.2 2836
60.4 2836
60.6 2867
60.8 2879

I'm not real sure what this information is telling me, but looks as though the node is at 60.2 and 60.4. But it also looks like there is one at 59.2, .4, and .6. But I'm thinking I should ignore that one. Based on that, I should load a 5 shot group of 60.3 grain of powder and then adjust the overall length based on that information. There were no pressure signs on the brass.

All suggestions are appreciated!

 

[VikingsGuy]

Finally got to go to the range today and shot a 10 shot ladder test with the 300 RCM.

I loaded 59 to 60.8 grains of IMR 4350, 165 grain Hornady SST, *CCI 200 primers, and an overall cartridge length 2.840. The information was obtained from Hornady reloading manual.
(*The manual that I have called for Large Rifle primers. After I loaded them, I realized that Hodgdon Reloading web site called for Magnum primers. So I may need to do the test again.)

Load: FPS:
59 2749
59.2 2795
59.4 2772
59.6 2795
59.8 2807
60 2818
60.2 2836
60.4 2836
60.6 2867
60.8 2879

I'm not real sure what this information is telling me, but looks as though the node is at 60.2 and 60.4. But it also looks like there is one at 59.2, .4, and .6. But I'm thinking I should ignore that one. Based on that, I should load a 5 shot group of 60.3 grain of powder and then adjust the overall length based on that information. There were no pressure signs on the brass.

All suggestions are appreciated!

FWIW I would redo the velocity ladder with magnum primers.

If you do stick with large primers, I’d do 5x at 59.4 and 5x at 60.3 and see which one gives you better fps ES, SD and smallest groups calculated by mean radius. If you need a tie breaker I would use mean radius unless you regularly shoot over 500y and then I would use fps ES. Not all flat spots shoot the same so it is worth trying both.

 

[Losing_Sanity]

FWIW I would redo the velocity ladder with magnum primers.

If you do stick with large primers, I’d do 5x at 59.4 and 5x at 60.3 and see which one gives you better fps ES, SD and smallest groups calculated by mean radius. If you need a tie breaker I would use mean radius unless you regularly shoot over 500y and then I would use fps ES. Not all flat spots shoot the same so it is worth trying both.

Thanks for helping and breaking it down for me. What are your thoughts on the primer choice? I'm thinking just stay with the large rifle primer and then see if primer change tightens up the groups if needed.

 

[VikingsGuy]

Thanks for helping and breaking it down for me. What are your thoughts on the primer choice? I'm thinking just stay with the large rifle primer and then see if primer change tightens up the groups if needed.

My rule of thumb (and that’s all it is) is magnum primer for anything that comes with magnum in the name, anything with 60gn of powder or more, or any ball powder used below freezing. YMMV.

As for your situation- I handload to chase small numbers just for the engineering fun of it so I would definitely redo the ladder with magnum primers. But again, YMMV.

 

[44hunter45]

My rule of thumb (and that’s all it is) is magnum primer for anything that comes with magnum in the name, anything with 60gn of powder or more, or any ball powder used below freezing. YMMV.

As for your situation- I handload to chase small numbers just for the engineering fun of it so I would definitely redo the ladder with magnum primers. But again, YMMV.

+1

 

[Losing_Sanity]

Went to the range yesterday and attempted another 10 shot test.

Load: FPS:
59 - 2710
59.2 - 2777
59.4 - 2783
59.6 - 2801 *
59.8 - 2807
60 - 2836 **
60.2 - 2801 *
60.4 - 2842
60.6 - 2836 **
60.8 - 2861

I don't understand the nodes on this one. This is with the magnum primers and seated to the books overall length for a starting point. It appears to me that possibly 59.3, 59.7 and 60.3 are where I need to start. Those all seem to be within 10fps change and interestingly enough, they are close to what @VikingsGuy suggested with the CCI 200 primers.

If you do stick with large primers, I’d do 5x at 59.4 and 5x at 60.3 and see which one gives you better fps ES, SD and smallest groups calculated by mean radius.

But, I'm confused with the 2 low points of 2801fps (*) and the 2 of 2836fps (**). It looks like there is a spread of 35fps and 6fps. Am I on the right track? There are no pressure indicators, so maybe try hotter loads?

I do appreciate the help I have received from @VikingsGuy and @std7mag, and all suggestions are welcome.

 

[cahunter805]

Do you have a picture of the target shot showing all the rounds fired?
Also what type of chronograph is it?

 

[Losing_Sanity]

No pictures, grouping really wasn't a concern, at least I don't think so. But all 10 shots were within a 5 inch circle. The chronograph is Prochrono.

 

[VikingsGuy]

Feels like there is some noise in the system. Did you try 5x of a couple like was suggested above to get a sense of not only the loads but your loading process? Or did you try magnum primers, as you may be getting inconsistent ignition with a 60gn load?

 

[Losing_Sanity]

Feels like there is some noise in the system. Did you try 5x of a couple like was suggested above to get a sense of not only the loads but your loading process? Or did you try magnum primers, as you may be getting inconsistent ignition with a 60gn load?

No, based on what you "rule of thumb", I figured just try a set with the magnum primers. But they were seated deeper.

My rule of thumb (and that’s all it is) is magnum primer for anything that comes with magnum in the name, anything with 60gn of powder or more, or any ball powder used below freezing. YMMV.

As for your situation- I handload to chase small numbers just for the engineering fun of it so I would definitely redo the ladder with magnum primers. But again, YMMV.

Did I miss understand? But the similarities are interesting...

I can still try to follow up with 2 test, one magnum and one with large rifle.

 

[VikingsGuy]

There are a lot of moving parts, but if I was getting your data I would do the following:

Until I really trusted my load process and rarely received counterintuitive results I would not do single load test ladders - Until it felt really locked down and consistent I would do my ladder in triplicate. I would also use a magnum primer as this is a magnum cartridge and the top end of your likely range is above 60grn. So, I would to 3x of 59.0 59.3 59.6, 59.9, 60.2, 60.5, 60.8. (and if not above published range 61.1) over a chrono. I would see how the triplicates looked and if that data was tight enough to trust the finding of flat spots. If the replicates were clean enough and I felt good about one or two flat spots I would take 5x of each of those candidate and shot them over a chrono and 100ytarget and compare sd, es and group size. If one of them was both under 1.0MOA and under 15 es I would pick that one and move on - good enough for hunting load. YMMV

ps es is not between different loads, it is between replicates of one load - you may already know that, but I was a little confused by one of your remarks.

 

[Losing_Sanity]

Thanks @VikingsGuy, I got some test to do...

I think I'll also recheck the toque on the stock screws and confirm they are still as recommended by Ruger.

 

[Losing_Sanity]

ps es is not between different loads, it is between replicates of one load - you may already know that, but I was a little confused by one of your remarks.

Been thinking on this. I think maybe my comments about the differences in fps in relationship to 10fps. I really have no idea about reading the data to determine the node, and I am trying to learn it. I read an article in which some guy talked about he looks for a slight deviation of about 10fps to indicate the node. In trying to analyze the data was looking for slight increases or falls in fps. So, maybe that is not correct?

I think I understand that ES comes into play when doing a 5 shot test of one load (determined from the node) to see what it gives you.

 

[johnp]

After a bad tumble after dark that ruined my scope and appeared to also ruin the accuracy of my Rem. 700 , 270. A frustrated gun smith decided to recrown a second time. Worked !

 

[cahunter805]

Losing
Follow the advice of Vikings. Load up those charges and shoot the 3 shot groups recording the velocity of each shot.
I also prefer to shoot the test all on the same target and POA if possible. You would be surprised sometimes to watch the POI change and then settle and then change again.
Use a target like this. You can print them online. Use a few stapled on your target board if needed.

 

[std7mag]

I've always done my ladder tests leaving the chrono at home. I let the target tell me what powder charge the barrel likes.
I do powder charge differences by 0.3gr increments, and look for 3 closest vertically on the target. Middle weight being my powder charge.
Then play with seating depth for group size.
Then i'll pull out the chrono. While i don't want a high ES, i pay more attention to SD.

95 inch lbs for an action screw seems like quite a lot to me.
I got a Choate Ultimate Varminter stock recently. Torque specs from them is 50 inlbs. Seemed like a lot for that.

 

[Losing_Sanity]

95 inch lbs for an action screw seems like quite a lot to me.
I got a Choate Ultimate Varminter stock recently. Torque specs from them is 50 inlbs. Seemed like a lot for that.

Seems like a bunch to me too. I got it to about 80 inlbs before the screwdriver bit gave way. Broke it right off. Probably too much torque, so I guess that's about good right there.

 

[std7mag]

EEK!!!!

 

[Losing_Sanity]

I was kind of hoping that one of HT resident experts would have seen it and advised me if it was too much before I cranked down on it. But, it came from Ruger so it should be right...