I originally posted this on the Reloading forum and got no response so here goes:

I've started loading for a Ruger .480 as of late and found that my load - somewhat under listed maximum, causes primers to "flatten". Not in the usual rifle sense in that the metal flows to cover the bevelled part of the pocket, but after decapping, they have a sort of "T" look to them, a small ring around the edge of the cup side. I backed off another grain and the ring is still their though not as pronouced. At this point, it is similar in appearance to the factory fired primers. (I am using Large Pistol primers as per the published data). Is it really too much pressure or is part of this the result of using regular Large Pistol primers? Hogdon recommended cutting the load when I quered them.

What say ye?

Thanks,
Telly

Need more info, what brand and number of primer, how much of what powder, and what bullet?

I've loaded and shot nearly 3000 rounds through the 480 and have somewhat of a feel of how the round likes to be loaded. Here is a thread about some of those loads http://www.accuratereloading.com/ubbthreads/showflat.php?Cat=&Board=UBB25&Number=421253&Forum=f25&Words=480&Searchpage=0&Limit=25&Main=421244&Search=true&where=bodysub&Name=1250&daterange=1&newerval=2&newertype=y&olderval=&oldertype=&bodyprev=#Post421253

Initial load was 20.0 grs. of H-110, with 400 gr. Hornady XTP bullet Winchester LP primers (for standard or magnum loads) in Hornady cases. The Hodgdon Manual shows the same load at 20.5 as max. I cut the load to 19.0 for the second go at it. All charges were weighed. I don't care for the 400 gr bullets anyway as the Hornady and Speers in that weight don't expand at all in mud, sand, or any other medium I have shot them in to. Just curious.

As I mentioned in the post I linked, I haven't loaded for any jacketed bullets. Since 21 gr H-110 seems to be a prudent max for the 400 gr cast bullets, I would think the jacketed bullets would take a tad less powder, hence the 20.5 gr load. I have found .5 gr changes in powder charges can have definate effects in accuracy, so try to tune the load for best accuracy.

The 400 gr loads are definately meant for penetration, and not expansion. If your looking for a whitetail load, then the 325 gr would probably be a better choice. You also might want to try some cast bullets, the large meplats are very effective, even if you don't get expansion.

In my SRH 480
H110-20.0gr-1084
" -21.0gr-1137 fps this is not MAX in my gun using a WLP primer.
On the Quickload program H110 20.0gr -27,000 SAAMI pressure
-21.0gr -32,000 "
This is nowhere near MAX.

Sean

Have you tried a different lot of the Winchester primers? If you have not already, you may want to try CCI 350 primers, (Large Pistol Magnums). I use these in my .475 Linebaugh loads with no problems. Otherwise, you may have just reached max for your particular revlover. If you have access to a chronograph, try clocking the velocity of your loads and checking against the published "max" velocities for the .480.

When shooting bullets which are nearly a half inch in diameter to begin with, why do you need additional expansion? The game these cartridges are intended for require more penetration than expansion. I've taken several whitetail deer and an elk with my .475 using the Speer and Hornady bullets with no problem. This year I'll carry the 370 or 405 grain LBTs in it for hunting.

Telly,

My 480 Ruger likes 20.5 gr H-LilGun under the 425 gr hard cast from CPB. Velocity is right at 1150 fps with very tight sub 1" groups at 25 yards. This is a top load but nothing that will be pushing the gun anywhere near its limits.

From the RUgers that have come in my shop, I have found a couple things that may help explain your problem. First off, it seems that there can be a huge variation in chamber finishes from one ruger to another.

Some are very smooth but most have some degree of machining marks left in them. With high pressure loads, most Rugers will get sticky cases before a dangerous situation occurs. If your cases are ejecting smoothly, especially six at a time, I would say your problem is not pressure.

If your cases are sticking a bit, by all means reduce your load until they do not.

What I would suspect more then anything is that your revolver has a bit to large of a headspace measurement. A revolver needs some at least 0.002" headspace to function properly. If it does not the free rotation of the cylinder will be effected.

I would say that your headspace is in the .008" to .012" range. Unfortunately, this is within most manufacturers headspace specs and they will probably not want to fix it.

Let me explain why you are getting the results you are. With excessive headspace measurements, when the firing pin strikes the primer of the round, it will drive it forward until the round is either stopped by its rim or the case as it hits the beginnings of the throat.

As the round comes to a rest, generally the primer ignites and pressure builds up in the primer pocket as the hot gases pass through the flash hole into the powder chamber.

This pressure forces the primer back as far as it will go until it is stopped by the frame of the revolver. With the primer in the rear postition and the case in the forward position, there is a section of primer which is unsupported.

As the powder ignites, the pressure grows and begins to balloon the unsupported primer walls. Also, the increasing pressure is expanding the case to fill the chamber.

When the pressure reaches its peak, it presses the case walls very tight against the chamber walls and they stick in that position.

At that same time, the case head is forced back against the frame just as the primer was. What this does in a revolver with to much headspace is cause case stretching.

As to your problem, when the case head slams back against the frame, it forces that ballooned primer back into a hole that is now smaller then the primer, basically mashing it flat and producing that "T" shape you speak of.

If a revolver like this was sent into me to fix, I would first determine if you do in fact have excessive headspace. I would then ask if you have ever had any primer ruptures? If you had, then I would say that the head space measurement was greater then 0.012" and send it back to the manufacturer after measuring it.

If you had never had a primer rupture with max loads then I would then ask how long your cases are lasting. With a headspace measurement over 0.008", you will likely need new brass every 4th or 5th firing due to case wall thining.

I guess it would depend on how picky the owner was if I did anything to fix the problem or not. It is quite possible to correct a revolver with to much headspace. The cyinder just needs to be modified to move it back closer to the frame. This creates another problem which is excessive cyinder/barrel gap which is corrected by setting the barrel back one thread and refacing and recutting the forcing cone.

IF your not getting ruptured primers and your cases are lasting long enough for you, I would say leave the gun as is. If it bothers you, take it to a good smith and have him measure the head space. If it is over 0.012" send it back to the manufacture. If it is under that and you still want it fixed, it will cost a little bit but it is correctable if thats the problem.

From what you discribe, it sounds like its a mechanical problem and not a load problem. This does not mean you can increase your loads.

A revolver with excessive or even outer limits of spec headspace will not handle the full tilt pressure loads like a properly adjusted revolver will. You will get ruptured primers and stretched cases much sooner.

Just something to look at, it may not be your load at all.

As for wanting your bullets to expand, your starting with a .475" diameter anyway. This is larger then most premium bullet measure after full expansion.

Paul is 100% correct, if you want expansion go with the light 325 gr or even the new 275 gr Gold Dot from speer. In my mind, and I know in Pauls as well, who by the way knows more about the round then anyone else I know, A heavy, non-expanding hard cast will perform the very best in this and most big bore handgun rounds.

Big bores do not kill with expansion and energy transfer. They kill by drilling large permenant wound channels through heavy muscle, bones and vitals. They really need no expasion to work extremely well.

Good Shooting!!!

50

Telly,

What are you shooting?
Does it have a brake? I have seen wierd primer stuff with my cousin's 629 with the power point. They were mild loads and had wierd pressure signs but yet was a mild load. In my unported 629 they were fine. I have had the best luck with my SuperRedhawk and CCI mag primers in my 480.

Hcliff,

Just a plain jane SRH with 7.5" barrel, no brake etc.. I am aware of the penetration issues with a pistol, I just think if it has a hollow point, it should do something besides clog up with whatever it hits. I don't (and probably won't) hunt with it as I don't see as well as I used to. Just a play thing at the moment.

Thanks to all who have responded.

Telly

Here is some more info

375 LBT LFN-GS 23.0 H110 1239fps
425 LBT LFN-GS 18.0 H110 1070fps
390 LBT LFN-PB 21.0 H110 1128fps
390 LBT LFN-PB 20.0 H110 1090fps

These were cast performance bullets

325 gold Dot 27.0 H110 1280fps
325 XTP 25.6 H110 1200fps
325 XTP factory 1310fps
375 LBT GC 23.0 H110 1240fps more recoil than 20.0 gra H110 390 LBT
375 Lbt 24.0 H110 1287fps

370lbt PB 24.0 H110
325 XTP 23.0-27.0 H110
425 LBT 18-18.0 H110
370 LBT PB 9.0 Win 231
390 PB 16.0 2400 Not a good load for me stopped that powder
400 Lee (from BBT bullets) 7.0 - 8.0 Titegroup powder
390 LBT 7.0-8.0 Titegroup

Titgroup is a great fun powder I loaded a box yesterday
375 10.0 Titegroup

400 Lee 19.0-21.0 Lil Gun
390 LBT 21.0 Lil Gun

This is Hornady load data

400 XTP 9 1/24 SRH 1.630 length


1000 1100 1150 1200 1250fps
Vith V110 15.3 16.7 17.3
2400 14.8 16.6 17.5
AA#9 15.2 17.0 18.0
Lil gun 15.30 16.8 17.7 18.6 19.6
H110 17.4 19.2 20.1 21.0
Win 296 17.9 19.7 20.6 21.5

325 XTP 1100 1200 1300 1400 1450fps 1500
Vh N110 17.00 18.6 20.3 21.9
2400 16.6 18.5 20.5 22.5
AA#9 16.4 18.6 20.8 23.0
Lil Gun 16.1 18.6 21.2 23.7 24.9
H 110 19.8 21.7 23.6 25.5 26.4 27.3
Win 296 20.1 22.3 24.4 26.6 27.7
IMR 4227 22.1 23.5 25.4


Kelly Brost from Cast performance gave me this data

390 grain H4227 17.0-19.0 grains 1012fps
370 grain H4227 17.0-20.00 805- 1032fps

findarticles.com http://www.findarticles.com/cf_0/m0BTT/154_25/77824414/p1/article.jhtml?term=480+ruger this is the john taffin article with lots of data

Hope this is helpful

One thing to keep in mind is the jacketed bullets are really designed for the 475 Linebaugh, which pushes a 400 gr to 1400-1500 fps, and will definately expand those bullets.

If you want expansion in a 480, keep to the 270-325 gr bullets, if you want penetration, and reasonable wound channels, a 400 gr cast @ 1200 fps will do the trick.

I agree with Paul statement. My favorite load is a 400 grain cast. I have been shooting lots of Titegroup loads and have cut down on the barnburner loads. This is a fun gun to shoot with "reduced" loads. Still powerful but I can shoot alot more rounds.

Hcliff

Can't really tell what is going on without a chronograph. This is a short, fat case like a 40 S&W on steriods so seating depth is critical.