.416 isn't grouping well!

[Shootist43]

mdwest, I too use a Caldwell Lead Sled on occasion, the most weight I add is a couple of sandbags. No problems so far.

 

[njc110381]

I just double checked the Alliant website and loads for a 400gr bullet are 101gr. The sign in page says reduce all loads 10% for start load, so 90.9gr for a 400gr bullet. I'm loading 410gr. So my load is at the bottom of the chart but not under spec?

I'm using various brass. I think the current batch is Remington but I also have Federal and Norma. The bulk of it is Norma. I think once I've checked that it's not the scope that's the issue I will start upping charges. I can't be bothered to pull the rounds I have made - I don't think they'll shift all that easily in a kinetic hammer so I'll just fire them!

 

[Inline6]

KISS

Keep
It
Simple
Silly

Don't read much into the reloading talk. It's not causing 10" groups.

 

[Patrik D]

Don't read much into the reloading talk. It's not causing 10" groups.

Realy? I have seen it with a .300wm. In summer (25 degree celcius) the groupings were just fine. Even the winter came (below 0 degree celcius) the rifle began to spread all over the target.

The chronograph showed us what was wrong.

 

[bruce moulds]

patrik d,
that rifle had a problem if that happened.
when fclass and benchrest guys talk about accuracy going off with temperature/ pressure etc, thay might mean going from 2/10" to 1/4" for a benchgun, or 1/4 to 1/2 moa for an fclass gun.
usually 1/10 0r 2/10 gn will bring them back.
you would not notice these differences in a hunting rifle.
going to 10" means something is wrong with the gun, or not enough load testing has been done to verify anything, good or bad.
or the load was a really bad one in the first place.
bruce.

 

[Patrik D]

No, with the right case fill with powder that rifle went from randomly 8" groups to steady 1" groups.

The pressure was just too low when fiered when it was that cold outside.

Just avoid min and max loads and start in the middle. Always use premium case brass, primers, powder and bullets when everything fails.

 

[IvW]

I just double checked the Alliant website and loads for a 400gr bullet are 101gr. The sign in page says reduce all loads 10% for start load, so 90.9gr for a 400gr bullet. I'm loading 410gr. So my load is at the bottom of the chart but not under spec?

I'm using various brass. I think the current batch is Remington but I also have Federal and Norma. The bulk of it is Norma. I think once I've checked that it's not the scope that's the issue I will start upping charges. I can't be bothered to pull the rounds I have made - I don't think they'll shift all that easily in a kinetic hammer so I'll just fire them!

So we are loading a cartridge which has a very large case capacity, we have a start or perhaps a below recommended start amount of powder, we are not using the best primer for the job, we are using three different types of cases, we are not shooting them over a chronograph so we have no measure of consistency of the speed of the load.....for me this is a strange way of starting out with a new rifle.
On bigger calibers the closer you can get to 100% load density within pressure limits the better. Start loads or below in such a large case with so many variables cannot give good accuracy. If you are below 90% in such a large case you will be surprised how much that can affect efficiency, consistency and ultimately accuracy...

Different types of cases have different case capacities further leading to different load densities.

RL22 is not the greatest powder for reduced loads in the 416 Rigby to begin with. As an example his powder in the Rigby case with Norma cases performs best with loads 100 to 104 grains which gives 103 to 107% load density, with 400gr bullet. So 90 grains will be very low for this specific powder.

Try some IMR4350 if you can get it...

At least get a chronograph and check the speed, that will give you an idea of consistency. If you have consistent speed, without that you are clutching at straws.

We have a saying in Afrikaans-"om te meet is om te meet" roughly translated "to measure is to know"

KISS

Keep
It
Simple
Silly

Don't read much into the reloading talk. It's not causing 10" groups.

Indeed what should be done keep it simple and start with the basics....

However it seems start loads, 3 different cases, no chronograph etc. etc. are the way to go when sighting in a new rifle....

I suspect at the end of the day there will be more money spent on reloading than what a simple box of factory ammo and following a few simple steps would have cost to start with.

Anyway there is the easy way and the hard way of doing things....

 

[njc110381]

I worded that badly. I have various brass but have batched it into specific makes. I've been using the same headstamp since the start (RP). I'm not mixing it.

I can't get IMR powder. In fact I can't get a lot of the popular powders here, it is what it is!

I have Federal 215 primers and will load some rounds at 96, 98 and 100gr charges and let you know the results. Have a little patience with me - I'm taking everything on board but need to get to the range to try it. Nothing is being ignored and I'm merely pointing out where certain things aren't making sense to me. For example if 100gr of RL22 is 103% case fill with a 400gr bullet then 90gr of RL22 isn't below 90% case fill with a 410gr bullet. I'm new to big bores and I say what I'm thinking out loud. That doesn't mean I'm not hearing what I'm being told...

 

[Shootist43]

Njc , some more QuickLoad data for you. 101 gr. of RL - 22 yields a max pressure of 48,174 lbs. On the other hand 90 Gr. of the same powder only yields 34,022 lbs. In short a 30% reduction in pressure. I've read where low powder charges can suffer from "detonation." Can anyone confirm at what pressure levels detonation will occur? I'm assuming that it is expressed as a percentage of the P-max pressure.

 

[Opposite Pole]

Njc , some more QuickLoad data for you. 101 gr. of RL - 22 yields a max pressure of 48,174 lbs. On the other hand 90 Gr. of the same powder only yields 34,022 lbs. In short a 30% reduction in pressure. I've read where low powder charges can suffer from "detonation." Can anyone confirm at what pressure levels detonation will occur? I'm assuming that it is expressed as a percentage of the P-max pressure.

I’ve heard/read of two explanations for low density loads being explosive. Norma reloading guide describes it as SEE - secondary explosion effect. It’s got to do with how too small a charge results in too low a initial pressure causing powder to get partially ignited, move bullet a bit and therefore further drop pressure all the while heating the remaining unignited powder without pressure and heat necessary for deflagration, until eventually volatile secondary combustion occurs. Without pressure smokeless powder burns quite slowly, pour some in a line on the ground and light it up and you might be surprised just how slowly it burns in atmospheric conditions (unlike black powder which is an explosive). Another possible explanation I’ve read about is as powder is seating horizontally in a partially loaded case and primer goes off it instantly ignites a very large amount of powder rather than just the back of fully filled case. What supposingly follows is all of that powder igniting at once in detonation rather than deflagration. While both explanations sound reasonable to some degree there’s no doubt that too light a load can also be very dangerous indeed.

 

[njc110381]

Apparently lab tests have been unable to duplicate detonation conditions in firearms, but it can and does happen. Opposite Pole has covered my understanding of it pretty much.

Load density wise, I've read that you wouldn't have an issue with a 20% charge reduction of the very slowest powders, and can be safe to a 50% reduction with faster powders. I'd say RL22 would be around the 25% area in the burn rate chart, so just over 10% wouldn't be an issue with safety even if it does create a really inconsistent burn.

The main cause is charge density. A third and plausible explanation that I have read aside to those already stated are that when the primer fires, the powder disperses like a dust cloud inside the case and all the kernels can ignite at once. Look into dust explosions in flour mills and coal mines to explain that further - a very effective bomb for use in buildings and confined spaces can be made by placing a fairly small charge under a loose package of mildly flammable powder. When the powder puffs up in a cloud from the initial explosion the dust ignites and causes a secondary, more powerful explosion to occur.

 

[njc110381]

Well it turns out the loads I've made pull ok, so I've done them again. There is one thing that is really bugging me though and that's the mixed data I'm finding for the 400/410gr bullets.

I've loaded up 94 and 96gr charges so far and am still going. What's troubling me is that the lowest book maximum I can find is 96gr, yet I've got Quickload telling me 101gr (Thanks Shootist43) and IvW saying this recipe works best with 100-104gr. I've read elsewhere of loads of up to 110gr giving velocities of 2800fps+ with that weight of bullet! Is the Rigby one of those cartridges where the maximum charge is kept low for older firearms but a modern action can handle more? Like the .45-70 or 6.5x55? As I've said previously I'm a fairly experienced home loader, but this mixture of information really bothers me!

 

[Shootist43]

Njc, from my observations there are a lot of loads in Modern reloading manuals that have been downwardly adjusted as the result of input by the legal profession to avoid the possibility of law suits. Do a google search and you will find questions from older reloaders about the charges they've been using for years. See if you can talk to someone that has published reloading data from the 1980s & 1990s. See what the loads and pressures were back in the day. I think that will help answer some of your questions. You may have to save up your "quid" or what ever is equivalent to our "pennies" and buy a chronograph. Measuring velocity is about the only way a handloader can see what is really going on.

 

[njc110381]

That would make sense. I guess the best thing I can do is not worry about it and proceed with caution. There are more than enough telltale signs that a load is getting too stout, so I should really just go for it and stop/back off when those little hints arise.

A chronograph isn't an issue, I have access to one at the range I use. I just want to get used to the gun and avoid that until a little later on when I know I'm not going to accidentally shoot it! Initially I am hoping I can just play with a few things in a sequence and solve the issue without the chrono, factory ammunition etc. My first steps will still be to pull the scope off and try some different loads. The stock screws have already been fastened to the recommended specs so I'm one stage in so far. I have loads of 94, 96 and 98gr to try, I'm hoping that will do as I really don't want to run it flat out this soon!

 

[Shootist43]

BTW njc, if you give me your load data and actual velocity I can modify the inputs to QuickLoad and we'll be able to see to some extent what kind of pressures are "theoretically" being developed.

 

[fourfive8]

If you are still chasing minutia of load tweaking trying to solve a 10" group problem I still think you are chasing the wrong gremlin. Just load 94-96 gr of Reloader 22, seat the 400-410 gr bullet to suggested cartridge OAL, load one at a time to eliminate potential of recoil induced bullet set back and go shoot. You can shoot at 50 yards. 50 yards will certainly separate good from bad accuracy, its easier to see target clearly and easier to change targets. Leave the 100 yard or longer stuff for fine tuning sight-in later or for testosterone moments if needed. If you are certain you are holding steady with good sight picture and good trigger, it is going to be the rifle or the scope/mount. If the rifle, it will be either the chamber or the barrel or both. Two rifle ailments I've seen that really wreck accuracy are a chamber cut off axis to the bore line or a bent barrel. There would have to be some really weird, excessive stock stress on the barreled action or a huge and obvious bedding issue to cause that type inaccuracy. If not the rifle it is going to be the scope and/or mounts. I have never seen ammo, loaded to within reasonable specs, cause such accuracy problems in normal/average/common/off the shelf rifles/scopes that are not somehow otherwise out of kilter. Such inaccuracy problems are by far most commonly tracked to gun or scope or scope mount problems. Use some system or process of elimination to solve your problem.

The answer to your internal ballistics data questions/anomalies probably has to do with the fact that the grossly oversized cartridge was designed in 1911 to keep pressures low in high temperatures using a very temperature sensitive powder developed in 1890.

 

[njc110381]

My gut feeling is that it's the scope but I can't be sure yet. The fact that I was hitting the base of a 2l drinks bottle fairly centrally and consistently off hand with the iron sights at 50m, which then turned to a 10" group off of sticks at 100m when the scope was added, kind of points in that direction. I do have the issue that I took the rifle out of the stock at the same time as scoping it to sort out the horrific trigger pull - that didn't help my confidence as it's another possible variable.

I want to get the load somewhere handy. My low charge weights have caused enough of a fuss with a few members that I feel I need to address that at the same time. It's a shame my range visits are only monthly and it's a long way from home. I kind of have one stab at fixing it before having to wait another month which is pretty annoying. The closer to home ranges aren't cleared to use rifles with this much muzzle energy.

 

[fourfive8]

Understood! We here in the US have it pretty good, so far, when it comes to guns and loading and shooting.

All the reliable pressure data I see for the 416 Rigby show a normal charge range for the 400-410 bullet of about 90-103 gr. of Reloader 22. I do see some data from some sources that gets a little "ragged" on the edges which likely has to do with both a normal expected variation of different test guns and equipment coupled with the necessity of using relatively slow powder in such a voluminous case in an attempt to duplicate the original intent of low pressure in high temperature using Cordite powder. All the while maintaining the original goal of the 400-410 gr bullet at 2350-2400 fps muz. vel while having no sticky extraction with the oversized and fairly straight walled case.

I've found Lyman data to be as good and consistent as any. Their data shows:
Test rifle 23" barrel
Cartridge OAL 3.625",
Barnes 400 gr solid round nose bullet (probably old style cup and core solid so will be similar to your Woodleigh SP for purposes of comparable internal ballistics)
Magnum rifle primer- Fed
Reloader 22-- 93 gr.-- 2275 fps
Reloader 22-- 99 gr.-- 2394 fps

Once you've solve the inaccuracy issue-
Use a chronograph so you have a baseline from which to work. If for example you get reasonable accuracy for load X but it is only 2090 fps and your cases show no pressure signs and the velocity SD is reasonably low at around 20 +/-, add a grain or two and shoot another test. Check results... and so.

 

[njc110381]

Ok, range day done. I'm none the wiser but now it shoots quite well. I can only suspect that either the mounts were fitted badly (I moved them to the centre of the dovetails rather than one end) or I'd put the action back in the stock badly (I redid that after the poor groupings were experienced so could have fixed something). With the markings on the scope and mounts, nothing was moving.

A repeat of the process with me and a friend shooting the scoped rifle revealed inch groups at 50m with my 90gr loads. The 94 and 96gr loads both produced a ragged hole in very nearly the same place on their targets. I ran out of shoulder at that point so stopped before I started pulling shots. I'm not sure if the 96gr was as stout as I can handle or just as stout as I could handle after the previous rounds fired? I will continue the 96, 98 and 100gr next month at 100m and through a chrono as that will give me a better idea of grouping and which load to settle on. I suspect with the recoil I experienced today that if the 94 and 96 offer the same trend at 100 I will most likely use the 94 for now and work up a bit more later when I'm more used to the gun. It should, given the 50m groups, come up with something around 1" at 100m which is fine by me.

Now would be a good time to thank everyone for their input. I'm sorry I couldn't offer a precise solution to the problems I was having due to me making multiple possible fixes at once, but all suggestions have been gratefully received. Now I just need to spend a bit of time conditioning my shoulder and getting the hang of the rifle. I suspect a 100+gr load may be a little much for me at the moment so I will hold back from that for a while. I'd rather not rush and develop a flinch as currently I can handle the lower loads quite comfortably as long as I don't fire too many at once.

 

[One Day...]

Super happy for you njc110381 and not surprised in the least

As previously stated, I never believed for a second that a 10" group could be ammo related considering your reloading experience ; I doubted that the scope died (it is actually somewhat rare); and I suspected that the issue was mechanically related (post p. 3) and would be in retrospect very simple .

Since the chances of you not re-assembling the rifle correctly are low: you could not tighten the bolts (they are not long enough) if the action was not nested correctly in the aluminum bedding block of the Kevlar stock, it leaves us with - surprise! - the location of the front scope ring (the rear ring is generally out of contention since it has a lug nested in the rear bridge cut off). Looks like you experienced EXACTLY the same issue I had experienced, and I am happy if sharing the experience helped you...

Proper scope mounting on big bore CZ 550

• One Day...
• May 7, 2019

2) The front edge of the front ring is well clear of front bridge dovetail radius:
The bottom...

I am not sure why CZ did not just mill through the front square bridge entire length (maybe to create a recoil "shoulder" for the ring?), but what I am quite sure of is that resting the square edge of the ring on the radius of the milling clearly does not work, as we both verified

Congratulations for not loosing you mind on the proliferation of so many diverging advises and for trusting your shooting, your loads and your common sense enough to see it through.

Double check the torque on both rings halves screws (they will likely have settled a little and may take another 1/16th turn); keep checking the nail polish drops on the scope/rings junction for a few more shooting sessions; and, enjoy your Rigby. You have BOTH a great rifle and a great caliber...

FYI, there is nothing wrong with wearing a shoulder pad during load developing sessions. The PAST Super Mag Plus Recoil Pad Shield works pretty well