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470 Nitro Express and IMR 7977 powder-A positive reloading experience
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Greetings AR Colleagues,

This is primarily a reloading post but I felt it better placed in Double Rifle forum…

I have a good supply of 0.474” 500 grain Woodleigh soft points and wanted to work up a load with them for my Krieghoff Classic Big V. Researching the published loading information on the powder manufacturers Web site, Load Data and AmmoGuide, showed that several powders work well in the 470 Nitro Express. I noticed in the published Hodgdon data (which is combined with IMR and Winchester) that they listed the new IMR 7977 powder. This powder shows a lower pressure (37,200 PSI) than some of the more traditional powders which average approximately 40,000 PSI. Released in 2014, IMR 7977 is one of the Enduron, temperature insensitive powders:

From the DuPont Web site:

7977 IMR Enduron 7977 is the slowest burn rate in the Enduron family. Loading density is perfect for magnums, contributing to superb uniformity. This is a true magnum propellant yielding outstanding performance in 300 Winchester Magnum, 7mm Remington Magnum and 338 Lapua, among other cartridges. Loading density is perfect for magnums, nicely filling the case at maximum charges, contributing to superb uniformity and accuracy. The main features of the Enduron series are copper fouling eliminator, insensitivity to temperature changes, ideal loading density and being environmentally friendlier. 7977 performs comparably to Hodgdon H1000 but charge weights are materially different.


I found interest in this new powder and opted to work up a load with the Woodleigh’s starting at 120.0 grains up to a maximum of 123.0 grains in 1.0 grain increments. I loaded 2 rounds at each charge weight and duplicated the set of 8 rounds thereby having two sets. I shot one set on one day at 50 yards from my Lead Sled (total weight about 50 pounds including the sled) and the second set 3 days later as above. The maximum charge of 123.0 grains proved to be exceptionally accurate. On both test firings that charge printed both bullets touching into a group of 0.5” and about 1.5” high which is outstanding accuracy in my opinion for a double rifle. The chronograph showed an average velocity of 2222 feet per second with very low extreme spread and standard deviation This velocity is a bit stouter that factory loadings at 2150 fps. Recoil was attention getting but not overbearing when shot offhand. The gun was regulated by Krieghoff in 2001 with Federal Premium Safari ammunition with 500 grain Woodleigh’s at 50 meters which is 54 yards so it might explain the slightly higher printing. I do also believe that my sight picture was a factor of course in the shot placement. Overall, I am pleased with the load regulation and shot placement. In addition, I shot loads also with IMR 4831 and IMR 7828SSC and in both of those powders found good loads but not at the accuracy level of IMR 7977.

A few other observations of interest in no particular order:

  • IMR 7977 showed very low extreme spreads and standard deviations for all charge weights tested. Average extreme spread = 10 fps and standard deviation = 6 for a total of 16 shots. At the maximum charge of 123.0 grains the average extreme spread was only 6 fps and a average standard deviation of 4 for both sets.

  • IMR 7977 charge density is very good and fills the case just enough for moderate compression of the powder

  • When testing the Krieghoff, the company recommends firing the right then left barrel in a period of 5-8 seconds, which I did.

  • This rifle has the Krieghoff See Through sight worked very well but was still challenging for 63-year-old eyes. I used my eyeglass lens target dot which helped a great deal. This is a small circular peep sight that adheres to the lens of my shooting glasses. Placement takes some experimentation but sight picture is much improved. It is equivalent to “squinting” to see the front red fiber optic sight.

  • Both barrels of the Krieghoff shoot at approximately the same bullet speed averages for any load. A statistical analysis of all shots fired showed an average velocity of the right barrel to be 2196 fps and 2194 for the left barrel for IMR 7977 loads. The barrels seem to be very well matched, one barrel is not faster than the other.

  • Hodgdon also lists IMR 7977 in the 416 Rigby and I plan on trying that in my Ruger Express.


While this experience is a relatively small sample size, in my opinion IMR 7977 is a modern powder with many advantages and gives an updated option for the 110-year-old 470 Nitro Express.

Thanks for listening,
Paul



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Posts: 1026 | Location: Southeastern PA, USA | Registered: 14 February 2001Reply With Quote
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Wow, that's nice shooting. I have an 8lb hug of this on my shelf I have yet to try in anything.


Mac

 
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Not necessary to test any other loads ! tu2


Morten


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Paul, did you find it necessary to use a filler, such as backer rod, or was the amount or bulk of this powder sufficient to fill the case close to the bottom of the projectile?
 
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Dutch,

No filler was necessary. The powder filled the case to about 1/4-3/8 inch from the top. Seating the Woodleigh bullet to the crimping groove allowed for mild compression which I believe contributes to the accuracy and low extreme spreads....sort of a 100% load density effect. As I mentioned the whole experience using IMR 7977 was very pleasant and everything a reloader might want from a powder. It is a stick powder and will bridge a bit in the powder measure is about the only negative I can come up with. I will mention also that since I wrote the above I have shot another 50 rounds or so and I do also believe that copper fouling is less in the Krieghoff barrel. That same load of 123.0 grains, which is a maximum load so be sure to start lower and work up, has continued to prove to be accurate and my offhand shooting groups have improved as a result. Give it a try and let us know how you make out.

Thanks
Paul


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I'm wondering if this would be a good powder for my .475 No.2 with a 3 1/2 inch case? I would like to try this powder. I'm currently using 115 grains of IMR 4831 and a 480 grain Woodleigh or 83.5 of 3031 both with backer rod filler.
 
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Paul;

Did you use a "virtual" chamber pressure computer software system(such as QuickLoad) to estimate the pressures of the various loads using this IMR propellant? My version of QuickLoad does not incorporate this propellant.

Regards;
Steve
 
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quote:
Originally posted by Transvaal:
Paul;

Did you use a "virtual" chamber pressure computer software system(such as QuickLoad) to estimate the pressures of the various loads using this IMR propellant? My version of QuickLoad does not incorporate this propellant.

Regards;
Steve


FYI
I just got an update disc on Quickload last week. It shows 52986 PSI with 123.0 of IMR7977 at 2253fps.


Mac

 
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quote:
Originally posted by McKay:
quote:
Originally posted by Transvaal:
Paul;

Did you use a "virtual" chamber pressure computer software system(such as QuickLoad) to estimate the pressures of the various loads using this IMR propellant? My version of QuickLoad does not incorporate this propellant.

Regards;
Steve


FYI
I just got an update disc on Quickload last week. It shows 52986 PSI with 123.0 of IMR7977 at 2253fps.


Hmmm nearly 53K

Could be abit stout for a 35K nominal cartridge
 
Posts: 633 | Location: Texas | Registered: 30 December 2012Reply With Quote
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quote:
Originally posted by Clan_Colla:
quote:
Originally posted by McKay:
quote:
Originally posted by Transvaal:
Paul;

Did you use a "virtual" chamber pressure computer software system(such as QuickLoad) to estimate the pressures of the various loads using this IMR propellant? My version of QuickLoad does not incorporate this propellant.

Regards;
Steve


FYI
I just got an update disc on Quickload last week. It shows 52986 PSI with 123.0 of IMR7977 at 2253fps.


Hmmm nearly 53K

Could be abit stout for a 35K nominal cartridge


Just for fun I looked at a couple loads in Quickload that IMR shows on their website for 7977. In a 300WM load Quickload shows about 3K more pressure than IMR and in a 7RM Quickload shows about 1.5K more pressure. Both similar FPS.

Just wanted to see if Quickload has something goofy in their formulas for 7977. A bit higher for those two cartridges but nothing like it is calculating for the 470.


Mac

 
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Wow!!!!!!!!!! That is a lot of pressure above the max of 39,000 psi.

Thanks for letting me know there is an update for propellants. I am going to order it straight away.

Steve
 
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Transvaal et al,

My data was taken directly from the Hodgdon Web site. I have Quickload but did not run it for this application. Go here and search for 470 Nitro Express in the Rifle section. There is only one bullet weight listed, the 500 grain and if you just select the bullet and select "Get Data" it will return all the powder combinations including IMR 7977 (start at 114.0 gr, max is 123.0 gr)with measured pressures.When you peruse all the charge combinations you will see that IMR 7977 shows a pressure of 37,000 PSI. Retumbo is lower at 34,800 PSI.

I'm wondering if Quickload takes into account the different burning characteristic of the Enduron powders but as McKay states he just got a new update from QL but maybe there is something quirky. I can say that at the max load of 123.0 grain I have fired about 50 rounds. In all experiences the cases fell free from the chamber, primers had a very moderately flat surface with no cratering etc. By all accounts the load does not act over pressure. Also as I stated above in all the loads that I chronographed showed very low extreme spreads and standard deviations. Might be worth a call to Hodgdon to confirm?

Paul


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Paul;

I would have to believe that Hodgdon is correct vs. QuickLoad. As I do not have the update as of yet from QuickLoad, I went to my QuickLoad and entered the data for IMR 4350 and a 500 gr Woodleigh SN projectile a .474" diameter bullet for the .470 NE and I got 2,000 psi more pressure that Hodgdon quotes on its website for this load using 99 grs of 4350; the velocity was 100 fps more than Hodgdon quoted using QuicLoad calculation. To my mind QuickLoad allows us to get in the ball park of chamber pressure, but the load results as tested in the Hodgdon lab in a rifle chamber and its barrel is the real thing to go by.

Steve
 
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quote:
Originally posted by Transvaal:
Paul;

I would have to believe that Hodgdon is correct vs. QuickLoad. As I do not have the update as of yet from QuickLoad, I went to my QuickLoad and entered the data for IMR 4350 and a 500 gr Woodleigh SN projectile a .474" diameter bullet for the .470 NE and I got 2,000 psi more pressure that Hodgdon quotes on its website for this load using 99 grs of 4350; the velocity was 100 fps more than Hodgdon quoted using QuicLoad calculation. To my mind QuickLoad allows us to get in the ball park of chamber pressure, but the load results as tested in the Hodgdon lab in a rifle chamber and its barrel is the real thing to go by.

Steve


You would think so, just seams weird that quickload is close to IMR data on the 7RM and 300WM and it is way high on the 470.


Mac

 
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I just updated my quickLoad. I've found that QL is great except for 45/7. Load that are published else where are off the chart in QL.
When I glanced at loads for mhy 450/400 the pressure curves were mild with IMR 7977. I will check again.


Rusty
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Posts: 9797 | Location: Missouri City, Texas | Registered: 21 June 2000Reply With Quote
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Rusty et al,

Thanks for all the information and feedback. This experience drives home to me even more significantly to always confirm reloading data. As I stated I have and use Quickload and it is a great piece of software, but I think we all know in the back of head to use caution when using the data.

In my case my normal reloading procedure when loading for something new, is to collect at least 3-4, often as many as 8-10 sources of data primarily from the powder/bullet manufacturers, Load Data and Ammo Guide and finally, always with suspicion from the Web. I pull the data into a spreadsheet and run some statistics on it throwing out the outliers of very high or very low charges. I start low and work up of course.

In this case since IMR 7977 is such a new powder there is not much corroborating data to go on. My plan was of course to use the mainstream powders in the 470 NE but when I saw the data for IMR 7977 and the 500 grain bullet in the 470 NE with lower pressure than the other powders, I was intrigued enough to try it. As I described the experience was very positive with outstanding accuracy, better than factory velocity and no obvious signs of excess pressure.

I don't have the latest update form my Quikload software but will do so. If I can speak with someone at QL I will mention this experience.

I am also working up some loads in my 416 Rigby with IMR 7977 based on my experience in the 470 NE.

Good luck, be safe.

Paul


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Forgive me if I've missed something, but does the rifle regulate similarly when fired off-hand or over a standing rest as it does with the Lead-Sled?
 
Posts: 5188 | Location: Melbourne, Australia | Registered: 31 March 2009Reply With Quote
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Greetings sambarman338,

Yes, I believe the rifles shoot the same off the Lead Sled and offhand off sticks (I do not have a standing bench). However to be accurate I can't say that I tried to conclusively test if for accuracy off the sticks or offhand but it shoots to the same point of impact as best as I can tell. I shot 2 or three groups of doubles and they grouped tightly (though not as tight as off the Lead Sled, but probably due to my personal accuracy off sticks).

You do bring up an important underlying point that I believe does have some effect and that is the way rifles shoot off a Lead Sled versus off standard sandbags. I do believe there is some difference and I have noticed it shooting my other smaller caliber rifles. My lead sled weighs a total 50 pounds including the sled and a sand bag. I've weighed it and I won't increase the bag weight for fear of damaging the stock which I do believe can happen with too much weight. In my opinion the examples where that has occurred there is too much weight on the sled and all of the energy is transferred to the rifle. In my case my Lead sled still "recoils" on the bench and will slide backwards but certainly the recoil is mitigated by it. I have always planned to take a couple of my accurate rifles and a known accurate load and shoot them off the lead sled, regular sandbags and perhaps a bipod to test the effects.

I'm still playing with IMR 7977 in other big bore rifles and will report my results. I know I got pretty lucky with this load behind the 500 grain Woodleighs in my 470 NE Krieghoff but I'll take that luck any day. The load was good enough for me to place 3rd at the recent Vintagers Double rifle stopping competition...it is always tough to beat Josh and Mal!
Good luck,
Paul


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Posts: 1026 | Location: Southeastern PA, USA | Registered: 14 February 2001Reply With Quote
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quote:
Originally posted by McKay:
quote:
Originally posted by Transvaal:
Paul;

Did you use a "virtual" chamber pressure computer software system(such as QuickLoad) to estimate the pressures of the various loads using this IMR propellant? My version of QuickLoad does not incorporate this propellant.

Regards;
Steve


FYI
I just got an update disc on Quickload last week. It shows 52986 PSI with 123.0 of IMR7977 at 2253fps.


............................................................... Eeker


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Posts: 14634 | Location: TEXAS | Registered: 08 June 2000Reply With Quote
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quote:
Originally posted by Dutch44:
I'm wondering if this would be a good powder for my .475 No.2 with a 3 1/2 inch case? I would like to try this powder. I'm currently using 115 grains of IMR 4831 and a 480 grain Woodleigh or 83.5 of 3031 both with backer rod filler.


Dutch...what kind of rifle is your .475 No. 2..?

Pics..?



 
Posts: 3974 | Location: Vell, I yust dont know.. | Registered: 27 March 2005Reply With Quote
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IMR 7977 in a 450/400. Does anyone have any
information or starting loads yet. Sounds like
it may work well. Any feedback appreciated.
Thanks

Tetonka
DRSS 450/400 K-Gun
 
Posts: 295 | Location: Willow City, Texas & Polebridge, Montana | Registered: 12 June 2009Reply With Quote
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Paul Reed,

Superb!
Have you considered high "operating" temperatures of 100 degrees plus and how this would effect the reliable functioning of your load/rifle combo?

Enjoy and good hunting!
Leon
 
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Tetonka,

Hodgdon does not list the 450/400 in their loading data but you might try to use the contact form on the Web site to see if they can give you some guidance. I have emailed them on other questions and always had good customer service.



Leon,

I did some of my first testing in late August and temps were 90 degrees or so. I am in the Philadelphia area so we do get some warm temperatures with high humidity. The maximum load of IMR 7977 (123.0 grains) showed no signs of excess pressure including flattened primers, sticky extraction etc. In fact, one of the main features of the Enduron powders is temperature stability across a broad range. But to directly answer your question, no I have not tested it at very high temperatures that you might experience in Africa in the late seasons. I normally don't operate my handloads at maximum charges but this load was so accurate that it makes it hard to not use it. If you duplicate my testing make sure to back off and work up slowly watching for excess pressure signs.


Thanks
Paul


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Thanks Paul, somehow I seem to have missed your answer and the subsequent posts.

I have only used a Lead Sled once and it worked very well with a 22RF, because we had no other provision, giving excellent groups.

But, yes, things like that can wreck rifles. I've seen an ersatz version, which looked like a steel skateboard, split the stock on a Zastava .300 magnum - without even having a bag of lead added.
 
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Paul Reed,

Not long after you started this thread I was made an offer on a Searcy .470NE that I simply could not turn down. This is my first double. While I've been hand loading for a number of years now, that was all obviously for single barreled rifles.

I actually took possession of the rifle in late November, but due to work/family life, I only recently had a chance to shoot a few of my own loads. I first saw this thread in November, but came back to it to use IMR 7977 as a start.

I loaded 2 each at 119gr up to 123gr in 1gr increments. I did not shoot these over a chronograph so I don't know the speeds.

There are a number of variables at play here. I'm new to DRs as mentioned and still tweaking a bit with my shooting form. I haven't shot open sights regularly since I was a kid shooting my BB gun. As such I only shot at 25 yards, not the customary 50. And I was shooting off sticks versus the more solid rest a bench offers.

But in the end I was quite pleased with my initial results. There is still work to do to ensure repeatability, but I feel confident that this powder will work well with my rifle.

You can see a report with pictures here if you'd like: https://www.africahunting.com/...e.42607/#post-433390

Just wanted to say thank you for taking time to post this thread, it helped this new DR guy get off to a good start.
 
Posts: 584 | Location: Phoenix, AZ | Registered: 13 August 2004Reply With Quote
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Phil,

I looked at your results and I think the proof is in the shooting as they say. I suspect there would be some variation from shooting off sticks versus a bench but in either case, the groups are perfectly respectable for DG hunting. I’m glad to hear that you had good results with that powder also.

I’ve got some 416 Rigby loads with IMR 7977 sitting on the loading bench just waiting for that bitch of a Mother Nature to get the nor’easter snow out of her system here in the east. Had 14” overnight which makes it hard to go to the range.

I would be interested to hear of your velocities when you get a chance to chronograph them. Is there a buffalo in your future?

Thanks for the update on your results.

Paul


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Posts: 1026 | Location: Southeastern PA, USA | Registered: 14 February 2001Reply With Quote
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quote:
Originally posted by Paul Reed:
Phil,

I looked at your results and I think the proof is in the shooting as they say. I suspect there would be some variation from shooting off sticks versus a bench but in either case, the groups are perfectly respectable for DG hunting. I’m glad to hear that you had good results with that powder also.

I’ve got some 416 Rigby loads with IMR 7977 sitting on the loading bench just waiting for that bitch of a Mother Nature to get the nor’easter snow out of her system here in the east. Had 14” overnight which makes it hard to go to the range.

I would be interested to hear of your velocities when you get a chance to chronograph them. Is there a buffalo in your future?

Thanks for the update on your results.

Paul


I hope there's more than one buffalo in the future! Yeah somehow my chrono got up and walked away from my garage, a bloody miracle.

Will be borrowing a friends however hopefully soon.
 
Posts: 584 | Location: Phoenix, AZ | Registered: 13 August 2004Reply With Quote
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Thank you for letting us know of your experience with 7977,it's great that you are trying this,but I have hunted Africa six times with Rx15 in the barrels,it has not let me down yet & I will stick to it,I would love to hear more when you hunt with this combo in the high temps Smiler
 
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BTW I would rather see a group of maybe 2"@ 50,in the same hole means nothing if you are shooting DR's.


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quote:
Originally posted by Bill73:
Thank you for letting us know of your experience with 7977,it's great that you are trying this,but I have hunted Africa six times with Rx15 in the barrels,it has not let me down yet & I will stick to it,I would love to hear more when you hunt with this combo in the high temps Smiler


I won't be hunting in high temps anytime soon. But it will be hell on earth in Phoenix soon enough. I will shoot it sometime in the 105-110 degree range and let you know how it goes.
 
Posts: 584 | Location: Phoenix, AZ | Registered: 13 August 2004Reply With Quote
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quote:
Originally posted by Bill73:
Thank you for letting us know of your experience with 7977,it's great that you are trying this,but I have hunted Africa six times with Rx15 in the barrels,it has not let me down yet & I will stick to it,I would love to hear more when you hunt with this combo in the high temps Smiler


Chrono'd loads at 121, 122 and 123gr of IMR 7977 today. Results were a bit surprising. 121gr was fastest, with a low dip at 122gr and then coming up at 123gr but still below the 121gr load.

Brass came out easily with the extractors not having to work hard. Temperature was over 90 degrees.

My plan is to back off the 121gr load. Groups were about the same.
 
Posts: 584 | Location: Phoenix, AZ | Registered: 13 August 2004Reply With Quote
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Thanks very much for the info. Although I load for the 450NE 3 1/4", I'm wondering if this will work. I currently use H-4831 exclusively and I had very poor results with RL-15 and filler.


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Posts: 7149 | Location: Orange Park, Florida. USA | Registered: 22 March 2001Reply With Quote
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I didn't mention the speeds recorded.

121gr: 2265fps / 2243fps
122gr: 2216fps / 2223fps
123gr; 2224fps / 2232fps
 
Posts: 584 | Location: Phoenix, AZ | Registered: 13 August 2004Reply With Quote
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Thanks for the info, Phil. It is a bit strange that the velocities were a bit inverted but burning that much powder nothing surprises me. One thought and a question-this could be due to crimp pressure variation. What types of dies do you use and how heavy do you think your crimp was applied. In my case, using RCBS dies, I seated and crimped in separate operations and crimped into the cannelure of the Woodleighs very heavily. I usually measure my crimp closure with a micrometer but I am not in front of my loading data and don't remember what I did for this load.

Either way, you have found a suitable minute of buffalo load for your gun.

I've got some 416 Rigby loads worked up with IMR 7977 and a 400-grain Hornady DGX to test will keep you posted.

Thanks
Paul


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I always crimp hunting loads but frequently I don't bother when just developing loads. And this was the case this time.

This isn't the first time I've seen speeds drop with increased load. I can't say for sure what it was due to. Perhaps heating of the barrels? Perhaps just a fair amount of unused powder and normal speed variation?

My plan is still to back off and hopefully find an accurate/regulated load no faster than 2200fps. Other loads in the box that came with the rifle chino'd at 2150fps and recoil was noticeably less at that speed making the rifle a little more easy to handle and get ready for a second shot.
 
Posts: 584 | Location: Phoenix, AZ | Registered: 13 August 2004Reply With Quote
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well so much for the "minute of grapefruit"..Ive always owned accurate doubles as I might need to pop some old buff or elephant in the eyeball under severe circumstances and never wanted to shoot around the POI..as opposed to into it..

Your combination would serve that purpose quite well..

My only question strictly out of curiosity would be, is this a fluke or will it do that or come close every time..

My .470 won the world class double rifle shoot ( shot by Butch Searcy who borrowed it for the shoot) and he later traded me out of it for a 450-400 that shot almost as well..Neither of which would shoot like yours..congrats you got a winner there...


Ray Atkinson
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Posts: 42312 | Location: Twin Falls, Idaho | Registered: 04 June 2000Reply With Quote
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quote:
Originally posted by Atkinson:
well so much for the "minute of grapefruit"..Ive always owned accurate doubles as I might need to pop some old buff or elephant in the eyeball under severe circumstances and never wanted to shoot around the POI..as opposed to into it..

Your combination would serve that purpose quite well..

My only question strictly out of curiosity would be, is this a fluke or will it do that or come close every time..

My .470 won the world class double rifle shoot ( shot by Butch Searcy who borrowed it for the shoot) and he later traded me out of it for a 450-400 that shot almost as well..Neither of which would shoot like yours..congrats you got a winner there...


Every time at this stage may be a bit bold to claim, but of the 16 rounds I've fired using this powder, I do believe minute of grapefruit could be claimed.

I'm a total newbie to DRs and as such you should view my results in that light. I won't make any strong claims, just don't have the experience to do that. Hadn't shot open sights since BB gun days as kid some 40 years ago.

Hopefully with attaching a red dot sight I'll be able to zero in on a load a little better.
 
Posts: 584 | Location: Phoenix, AZ | Registered: 13 August 2004Reply With Quote
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Just a note on charge weights...

The first L/R I did with 7977 was today - 118gr with a 500gr A-Frame.

The 118gr load chronographed 2,243 at 15 feet instrumental. Ambient 85F in Jamison case with Fed 215 and moderate crimp.

I cannot imagine what 123gr would do in this rifle! I won't be finding out! Heck, maybe like Phil the velocities will go down as charges increase.

Next I am going to see what 116 and 117gr do...I don't really need that much power for a Buffalo!

My Searcy did put the two A-Frames 2" above point of aim and exactly 0.5" center to center. If the slightly slower loads are materially less well regulated I will stick with the thumper load.

Thanks to you trailblazers for reporting on your early success with this powder in the 470! I was set to use IMR 4831 but I have to give 7977 a workout based on these results I'm seeing.


Tim


0351 USMC
 
Posts: 1537 | Location: Romance, Missouri | Registered: 04 March 2002Reply With Quote
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quote:
Originally posted by 7MMNut:
quote:
Originally posted by Bill73:
Thank you for letting us know of your experience with 7977,it's great that you are trying this,but I have hunted Africa six times with Rx15 in the barrels,it has not let me down yet & I will stick to it,I would love to hear more when you hunt with this combo in the high temps Smiler


Chrono'd loads at 121, 122 and 123gr of IMR 7977 today. Results were a bit surprising. 121gr was fastest, with a low dip at 122gr and then coming up at 123gr but still below the 121gr load.

Brass came out easily with the extractors not having to work hard. Temperature was over 90 degrees.

My plan is to back off the 121gr load. Groups were about the same.



Phil

I still have 121gr and 122gr loads to test, but I have enough data to suggest that the non-linear velocity changes you were seeing are not isolated!

Here is what I have so far (all powder, primers, bullets and cases are same brand/lots and all powder charges weighed):

115gr 2,164
116gr 2,149
117gr 2,159
118gr 2,156
119gr 2,172
120gr 2,176

I would never expect a 4% increase in powder to yield a half-percent velocity increase.

I have written to Hodgdon to let them know that at least a handful of us are seeing this, and would they care to comment?

I will share any reply I may get.

EDIT: FYI - the 118gr load mentioned in the post above was from Cody...different primer, different lot of 7977, different brass, and different nut standing at the bench...so no comparisons can be made between that 118gr load and mine here).


Tim


0351 USMC
 
Posts: 1537 | Location: Romance, Missouri | Registered: 04 March 2002Reply With Quote
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posted Hide Post
quote:
Originally posted by tarbe:
quote:
Originally posted by 7MMNut:
quote:
Originally posted by Bill73:
Thank you for letting us know of your experience with 7977,it's great that you are trying this,but I have hunted Africa six times with Rx15 in the barrels,it has not let me down yet & I will stick to it,I would love to hear more when you hunt with this combo in the high temps Smiler


Chrono'd loads at 121, 122 and 123gr of IMR 7977 today. Results were a bit surprising. 121gr was fastest, with a low dip at 122gr and then coming up at 123gr but still below the 121gr load.

Brass came out easily with the extractors not having to work hard. Temperature was over 90 degrees.

My plan is to back off the 121gr load. Groups were about the same.



Phil

I still have 121gr and 122gr loads to test, but I have enough data to suggest that the non-linear velocity changes you were seeing are not isolated!

Here is what I have so far (all powder, primers, bullets and cases are same brand/lots and all powder charges weighed):

115gr 2,164
116gr 2,149
117gr 2,159
118gr 2,156
119gr 2,172
120gr 2,176

I would never expect a 4% increase in powder to yield a half-percent velocity increase.

I have written to Hodgdon to let them know that at least a handful of us are seeing this, and would they care to comment?

I will share any reply I may get.

EDIT: FYI - the 118gr load mentioned in the post above was from Cody...different primer, different lot of 7977, different brass, and different nut standing at the bench...so no comparisons can be made between that 118gr load and mine here).


Tim


Between work travel and the wonderful heat of a Phoenix summer, I've not even thought much about loading lately. I did get my rifle back from Butch and need to get out soon to check out the RMR. But August will be another month of travel.
 
Posts: 584 | Location: Phoenix, AZ | Registered: 13 August 2004Reply With Quote
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