I'm helping a friend get into reloading, and we're getting some strange things, with both calibres we're working on, namely 7x57 and 8x57JRS. Both calibres give the same results, but let's take the 7x57 as an example:

The powder manufacturer (Somchem) gives a start load of 37.6gr with a 170gr bullet, at 2277fps. Using a Sierra Matchking 168gr bullet, a load of 38gr put us right around 2250, with slight cratering on the primers around the firing pin indentation, but no serious flattening. 39gr gave us a 100fps velocity increase, with clearly visible flattening of the primers. 39.5gr gave flat primers with sticky extraction. I forget what velocity the first (and only) shot we fired with this load gave. Needless to say, we never got close to the 41.8gr book max!

At first, I suspected the (Lee) scale. When I got home (my friend lives on a game farm a couple of hundred miles from my home), we did a very rough comparison between her Lee and my brand new RCBS 10-10 scale, using some .22LR cartridges I had left on the farm (She couldn't weigh a 168gr bullet, as her scale only goes up to 110gr). My scale gave higher readings, but on an average of 5 cartridges weighed, the difference was only .3gr - definitely not enough to point fingers at the scale.

The rifle in question is a fullstock Mannlicher Mod M, which is a VERY sweet shooter with factory ammo.

My question is - what other variables could be causing this? Powders are fresh, straight from the sealed canister, primers are standard Large Rifle (Remington), cases are FL sized, to only just kiss the shoulder and a Lee Factory crimp was applied, ever-so-lightly. OAL 78mm (3.071") which is well clear of the lands.

Looking forward to some ideas from the wealth of knowledge and experience gathered here!

I would try a slower powder.
What temperature was they shot in?
Has mod M rear locking lugs?

Norma suggest MRP 47-49,4gr(similar to rl22) for a 170gr bullet a much slower powder.

Cratering around the firing pin dimple is not a very reliable sign of pressure but more often the result of a large hole with a small firing pin. However, if the primer is seriously flattened and the bolt hard to operate then you're onto something.
If it is a custom rifle, I'd suggest that you have a minimum dimensions chamber.
I'm not familar with your powder but from your velocities, it doesn't appear that you are getting the yield that you should from the bullet and cartridge. I think I'd try a slower powder. Something in the range of 4350.

Which powder is that you're using? What is the load density measured to the base of the neck? I always look for a powder that nearly fills the case with only a small air space under the bullet or better still, a slightly compressed charged.

Are you using new brass, if used are they trimmed to proper length?

Headspace will flatten primers at low pressure.
Neck size only and try again.

quote:

39.5gr gave flat primers with sticky extraction. I forget what velocity the first (and only) shot we fired with this load gave. Needless to say, we never got close to the 41.8gr book max!

My goodness, that's enoungh to make a fellow think maybe the book makers know what they're talking about when they say, "Start low and slowly work up to max unless pressure signs occur earlier" don't it? Primers aside, case sticking IS a valid overpressure sign.

Lee's scale is very sensitive and very accurate, anyone who seriously knows anything about scales recognises that whether they like using that scale or not. And it's a POWDER scale, it was never intended to weight bullets, cases or rifles so it's limited range is no big surprise is it?

If you are getting high pressure readings with low to moderate charges it generally indicates that the bullet does not start to move down the barrel until excessive pressure occurs. This is usually caused by some restriction such as brass that is too long (like Lucky Ducker said) or the bullet is jammed into the lands.
Make sure your brass are trimmed to less than the max brass length.
To make sure your bullets are not resting against the lands, measure for max overall cartridge length with that particular bullet by doing the following:
Drop one of the bullets down the barrel and hold it against the lands with a pencil or dowel. Now while the bullet is against the lands slide a long dowel or cleaning rod down the barrel from the muzzle until it touches the bullet and make a mark. Then remove the bullet and close the action and slide the dowel in until it contacts the bolt face and make another mark. The distance between the 2 marks is your max overall cartridge length for that bullet in that particular rifle. Make sure your loads are less than this dimension.
If you have already done the above, I would suspect the powder and would try a different lot or different powder.
Also check that you are not over resizing the brass to cause excessive headspace.
Hope that helps.

Also the brand of brass matters. Some are thicker then others, and that can cause increased pressure.

I would definitely recommend you try a slower powder. 39 grains of powder is "lost" rattling around in a case which will hold well over 50 grains. Your "loading density" (percentage of powder space taken up by the powder charge) is less than 80%. When charges leave this much empty space they can act erratically, particularly with heavy-for-caliber bullets like a 170 in the 7mm.

You don't say what the barrel length is, but since it is a Mannlicher I am assuming that it has a carbine-length barrel of around 20" or so. The data you are working with was probably obtained in a 24" or longer barrel, thus you can expect your actual velocities to be 100 fps or more less than that indicated by the book data.

Nonetheless, with a somewhat slower powder you should be able to achieve significantly higher velocities than you list.

You all make good points. Firstly, let's address the powder. We were using Somchem's S335, which is roughly equivalent to IMR 3031, AA 2460, R902. Case is filled 81.1% with the start load, according to QuickLOAD. We should be running pressures of 47631psi against a QL max of 56561. My friend did try S365, which is equivalent to IMR 4350, H205 etc., but also had excessive pressures right near the start load.

Case length (after firing the suspect loads) is 56.8mm, so that shouldn't have been an issue.

I doubt headspace would've been at fault, as I set the sizing die up by my usual method of blackening the case, running it through the die and adjusting for the first sign of contact with the shoulder, then backing off a touch. Call it partial FL sizing if you will.

Given all the above, plus the fact that we're seeing much the same trend with the 8x57JRS Heym combination rifle, I'm still leaning towards a fault on or around the scale. Unfortunately the distance precludes me from popping over with my scale to compare directly, but I think we've got that one covered with our (admittedly rough) long-distance comparison.

What a fascinating hobby!!

To address some of the other issues / questions raised - The rifle is a full stock carbine, with a barrel length in the order of 20-22", with rear locking lugs.

My method of checking max overall length is much more rudimentary than what Blacktailer suggests - I drop a loaded cartridge into the chamber, close the bolt, eject and check carefully for rifling marks, of which there were none.

Cases were twice-fired PMP

Have your friend proof his scale using different weights of match bullets.Actually, most standard bullets are close enough to find any gross errors in the scale.

What was the seating depth? A 174gr bullet should not seat past the neck-shoulder junction. If it doe the powder charge should be reduced accordingly.

Proofing the scale should be easy - use the standard supplied with the scale. There are cheap digital pocket scales out there, send him one in the mail. Make sure it has a 0.01g (.15gr) resolution. Some are 0.1g (1.5gr) - not good enough for a powder measure. They do not replace the beam scale - that is far more accurate and reliable but slow to use and inconvenient for spot checks.

Is PMP south africa military brass? If so Reduce the load by 15% and work up,

quote:

Originally posted by Rikkie:
I'm helping a friend get into reloading, and we're getting some strange things, with both calibres we're working on, namely 7x57 and 8x57JRS. Both calibres give the same results, but let's take the 7x57 as an example:

The powder manufacturer (Somchem) gives a start load of 37.6gr with a 170gr bullet, at 2277fps. Using a Sierra Matchking 168gr bullet, a load of 38gr put us right around 2250, with slight cratering on the primers around the firing pin indentation, but no serious flattening. 39gr gave us a 100fps velocity increase, with clearly visible flattening of the primers. 39.5gr gave flat primers with sticky extraction. I forget what velocity the first (and only) shot we fired with this load gave. Needless to say, we never got close to the 41.8gr book max!

At first, I suspected the (Lee) scale. When I got home (my friend lives on a game farm a couple of hundred miles from my home), we did a very rough comparison between her Lee and my brand new RCBS 10-10 scale, using some .22LR cartridges I had left on the farm (She couldn't weigh a 168gr bullet, as her scale only goes up to 110gr). My scale gave higher readings, but on an average of 5 cartridges weighed, the difference was only .3gr - definitely not enough to point fingers at the scale.

1. Slight primer cratering probably doesn't indicate increased pressure.

2. You will always have some primer flattening. If there is still a little rounded edge to the primer at the edge of the primer pocket, the the primer isn't too flat. Primer pressure signs, by the way, can vary between firearms so what indicates high pressure in one may not be an accurate indicator in another.

3. Sticky extraction in a bolt action rifle means excess pressure irrespective of what the load is provided the chamber is clean and smooth.

4. In my opinion, though it's useful information to have, velocity is a pretty poor indicator of pressure.

5. I would be surprised if inaccuracy in your scale was to blame but it's a good idea to check scales on occasion. Lyman make a little set of weights one can use to check scales. I have an RCBS scale that has been used a lot in the almost 30 years since I bought it that is still exactly on when I check it.

6. If your cartridges chamber easily and there are no marks on the bullets from the lands, then they should be quite suitable for shooting in a bolt action rifle.

In short, if the 39.0 grain load shoots well, accept it for what it is and use it.

For a scale check simply weigh three or four commonly available coins to see what an average weight is (they likely won't vary by more than single percent, if that much.) Use that average to long-distance check your friend's scale when your friend runs the same test with the same denomination of coin.

I don't know how closely Somchem holds its cannister-grade powders to a certain standard. You could possibly have a "fast" lot of powder, but having used a slower powder with similar results seems to discount this possibility.

Sticky bolt: Describe how the bolt is "sticky". If it exhibits resistance during the lift portion of the cycle, then that indicates excessive pressure from the case head being somewhat swaged to it from internal pressure. If it lifts fairly easily but the rearward motion is impeded, then that is likely not a result of pressure but of some other cause. In which phase of the bolt operation does it exhibit resistance?

Foreign substance in chamber: If oil (or even oily bore cleaner) is present in the chamber it can increase the head thrust against the bolt and the resulting sticky bolt lift can then mimic high pressure. This possibility varies a bit with the shape of the cartridge, but the 7x57 has enough taper that a slickly oiled chamber could result in enough bolt thrust -- particularly with a rear-locking action -- to cause sticky bolt operation.

I'n not disagreeing with Stonecreek, just elaborating.

quote:

If oil (or even oily bore cleaner) is present in the chamber it can increase the head thrust against the bolt and the resulting sticky bolt lift ...

The bolt face thrust might be increased a little if any but it will not cause or contribute to a sticky bolt. On the contrary, it will reduce the sticky bolt.

quote:

... the 7x57 has enough taper that a slickly oiled chamber could result in enough bolt thrust --

The emphasis is on slickly oiled chamber.

PMP cases are thicker walled but that does not seem to have an effect on chamber pressure effects because the cases are stronger. The 7x57 has a SAAMI pressure way below the pressure required to 'swage' or extrude brass so high pressure signs should never be visible. Dry cases fired in dry chambers that are not particularly smooth can exhibit these symptoms by over gripping the cases causing them to actually fail which means, the web area gets overstressed and extrudes, resulting in permanent case elongation. Lube those loaded rounds lightly and those symptoms would probably go away. If anyone is scared of the 'increased bolt face thrust' then don't shoot that gun - no gun should rely on case grip to 'protect' the bolt. Heavily lubed chambers or cartridges are a different matter. It's not the lube as but the presence of foreign material that reduces case volume and quite likely adds to the bolt face thrust. But a lightly lubed case will not. Dry cases and chamber are more of a problem.

quote:

Dry cases fired in dry chambers that are not particularly smooth can exhibit these symptoms by over gripping the cases causing them to actually fail which means, the web area gets overstressed and extrudes, resulting in permanent case elongation. Lube those loaded rounds lightly and those symptoms would probably go away. If anyone is scared of the 'increased bolt face thrust' then don't shoot that gun - no gun should rely on case grip to 'protect' the bolt. Heavily lubed chambers or cartridges are a different matter. It's not the lube as but the presence of foreign material that reduces case volume and quite likely adds to the bolt face thrust. But a lightly lubed case will not. Dry cases and chamber are more of a problem.

Bing, bing, bing, we have a winner!

quote:

Sticky bolt: Describe how the bolt is "sticky". If it exhibits resistance during the lift portion of the cycle, then that indicates excessive pressure from the case head being somewhat swaged to it from internal pressure. If it lifts fairly easily but the rearward motion is impeded, then that is likely not a result of pressure but of some other cause. In which phase of the bolt operation does it exhibit resistance?

Foreign substance in chamber: If oil (or even oily bore cleaner) is present in the chamber it can increase the head thrust against the bolt and the resulting sticky bolt lift can then mimic high pressure. This possibility varies a bit with the shape of the cartridge, but the 7x57 has enough taper that a slickly oiled chamber could result in enough bolt thrust -- particularly with a rear-locking action -- to cause sticky bolt operation.

This is a variation of the P.O Ackley argument that straight cases produce less bolt thrust than tapered. This is bogus. Given that the brass case is always in yield, always stretching, taper does not matter. Pressure does.

Oil in the chamber, oil on the cartridge, the increase in bolt thrust is so small it is a philosophical argument rather than a real argument. Action loading is calculated ignoring any theoretical , philosophical or doctrinal ideas about friction between the case and chamber. It is assumed to be zero. If a bolt sticks, lubed case, dry case, the pressures are too high.

One issue with rear lugged actions, they are springy as heck. You can look up the calculations in Otteson’s book, but assume that rear lugs bolt flex 0.001” per inch. You have four inches of flex in the thing and that entire structure is now a virtual compressed leaf spring with an over pressure load.

quote:

You have four inches of flex in the thing and that entire structure is now a virtual compressed leaf spring with an over pressure load.

Which is why a Rem 788 will show pressure before a Rem 700....

To answer Stonecreek's question - this is undoubtedly the 'bad' sticky bolt syndrome, where the bolt handle won't lift without undue force (Thumb on scope, forefinger on bolt handle type of stuff). Once primary extraction has been effected, the bolt slides back and forth slicker than spit. No - definitely not something one would want to live with, especially when one's target bites, scratches or has a gun.

On the lube issue. We use Molyslip Copa Slip as a case lube. For those not familiar with the product, it's used in machine shops to provide lubrication when press-fitting components together. This is then cleaned off with a clean rag. So one can assume that there is always a miniscule coating of Copaslip on the case, and it actually feels that way. Enough to constitute foreign matter? No way.

Then we mustn't forget the fact that we're seeing the same thing happen with the 8x57JRS, which is a top-break combination, and a tight one at that. No spring there.

Looks like I have a reason to go hunting again, and take my RCBS test weights, my scale and a new can of S335 along. How bad can that be?

quote:

which is a top-break combination, and a tight one at that. No spring there.

Actually yes. The length of the receiver under load is measured from the breech face to the hinge pin. The longer it is the more it will spring. The larger the receiver cross section area the less it will spring.

I would check the scale with a check weight or a 50 grain bullet.

Just another thought.
Lot to lot variances in powder burn rate can cause what you have experienced.
Again as Jim C.<>< said "start low and slowly work up to max unless pressure signs occur earlier"

muck

Rikkie, it would take a lot of lube to constitute 'foreign matter'. It sounds like you have enough lube there to prevent excess case grip. That kinda rules out that idea. And the seating depth? The fact the same thing happens in the 8x57 would seem to me to rule that out too. It still seems strange that two powders have the same effect on two rifles of different calibre. That leaves the scale as a common denominator. The idea of using coins as a test sounds good, especially if several are used together and are of the same design/year.

Could it be the batch of brass? Both calibres could be made from the same brass (I'm not sure they would be drawn on the same machine though). Could a softer brass cause the symptoms of bolt sticking?

Please keep us posted on what you find.

If you guys doubt that case shape has anything to do with bolt thrust then you should experience the enjoyment that S&W did with their .22 Jet revolver, the Model 53(?) I believe it was. The funky taper of the Jet (necked down from .357 brass with a long radius shoulder) would shove the head of the case so hard against the pressure plate of the revolver as to lock up the cylinder -- even when pressures were relatively mild. They could never overcome this problem and quickly discontinued this model. Now, this is (was) not so much an instance of greater "bolt thrust" per se, but of the tapered shape of the case tending to hold the case head in its most rearward position, thus locking up the action. The more tapered a case, the more significant this phenomenon. Although tapered cases don't necessarily create more actual pressure against the bolt face, their shape may very well keep the case head pressed more tightly against the bolt face (or pressure plate) than would a straight or less-tapered case. Hence, a tapered case, particularly one "assisted" by a lubricated chamber, might well exhibit sticky bolt lift when a less-tapered case in a dry chamber would not.

And no, I don't entirely buy many of the "bolt thrust" theories that float around; however, it is worth checking to make sure that the chamber is clean and dry.

There is one more possibility, although a distant one. The brass could be defectively soft in the head. "Apparent" pressure is, after all, mostly a function of how much deformation is caused to the brass case. If a lot of cases is unusually soft, they will deform at lower pressure. Softer cases also have less spring back, so they continue to bear against the bolt face after the pressure is relieved when, due to a harder case's spring back, it might not. You can theoretically get the same amount of bolt lift stiffness from soft brass at 40K PSI as from hard brass at 70K psi. Trying a different lot/brand of brass might yield a different result.

As to the 8x57 on a break-open action: Those are among the worst stretchers. The asymmetrical thrust caused by the hinge pin being below the axis of the bore, coupled with the distance of the hinge pin from the bolt face, makes this type of action very stretchy and is why the ammunition for double rifles is usually limited to lower pressures than that for bolts.

Stonecreek

I had to read your post twice to get the jist of it, but I believe you might be onto something. I like PMP brass specifically because it is so malleable and consequently gives me optimal mileage from a case. Having said that, I'm a confirmed Mauser '98 freak myself, so I could well be dealing here with the relatively unknown factor of an admittedly springy action, combined with (or compounded by) the malleability of the PMP brass, which might not be creating an overpressure situation per se, but rather a 'crush fit' of the now-elongated fired case in the chamber when the bolt returns to 'zero', facilitated by the residue of lube on the case.

What does the forum think? Could this be it, or should I just pack away a lifetime's worth of reloading gear and take up tiddlywinks and factory ammo? Maybe speak to a good shrink??

I belive that anytime you are working with anything other then a Modern, front locking, bolt action rifle, you must accept that you may have to work at reduced pressures, and load accordingly.

Has that brass been left in the sun for any time period perhaps? That would soften it.

I have a batch of PMP cases and apart from being thicker walled, are pretty strong.

I doubt the residual lube would contribute to the problem. The effect the lube has is to allow the case to stretch over its full length in the chamber which keeps the brass away from its yield point. That's why lubing produces virtually indefinite case life. But if the batch of brass is too soft then a dry chamber and brass will make it worse. If you are going to load to lower velocity then you may as well use a way slower powder that fills the case and produces lower pressure rise and peak pressure.

Here's one;

quote:

175 GR. NOS PART Hodgdon Hybrid 100V .284" 3.025" 38.0 2163 34,800 CUP 41.0C 2300 40,800 CUP

That velocity is higher than any other load with that bullet.

quote:

175 GR. NOS PART Hodgdon H4350 .284" 3.025" 35.0 2066 39,700 CUP 37.0 2159 43,400 CUP

Have a look here http://data.hodgdon.com

Can you get imported powders in your parts?

Another consideration is your ambient temperatures. There are powders that are less temperature sensitive. I'm don't know whether Hybrid 100V is one of them. Varget and H4350 are.

7x57 SAAMI pressure is already a 'lower pressure'.

This is a relatively modern Steyr-Mannlicher Model M, correct? I'm not all that familiar with this rifle (or in this case, carbine), but I doubt that the action stretch is what is causing the problem. After all, according to a 1970's Shooter's Bible I just referenced, this model was chambered in virtually all of the belted magnums of the day, so it should take 7x57 pressures in a walk.

I know of no simple way to field-check the hardness of brass, but if you can find some other brand of brass to try the same loads in that might (or might not) shed some light on the problem. That still wouldn't explain the similarly sticky problem with the 8x57 since it is presumably using brass of a different lot, although perhaps the same brand.

Good luck with solving the problem, and keep us posted as to your results!

quote:

That still wouldn't explain the similarly sticky problem with the 8x57 since it is presumably using brass of a different lot, although perhaps the same brand.

It could be of the same batch of brass stock but why would drawn and swaged brass be soft? Heat on the other hand would be a common denominator and it gets hot enough out there to fry an egg on a rock - or the hood of a car. Although that may not be a likely cause. It doesn't take all that much heat to soften brass over a long time period though as I found out when I oven dried washed brass and forgot it there over night! It's still worth ruling out the possibility though.

Primers really aren't a good indication of pressure. I've seen factory loads from numerous manufacturers in both rifles and handguns that produced flat primers.. Just how it is. Lot of variables, difference in hardness between primers, chamber dimensions, throat length, how tight the bore is, etc. I've just come to accept that flat primers happen and as long as my extraction is fine and primer pockets aren't loosening up my loads are fine.

Just a quick update - we checked Hanne's scale against mine, using various coins of the same denomination and mintage, after I had confirmed my scale with RCBS test weights. Hanne's readings are coming out consistently 1.00-something percent lower than mine, so that's not going to be our issue.

She did mention that, during her brief experimentation with S365 (slower-burning powder, equivalent to IMR4350) she did have a complete head separation. However, this was a load based on some rather reckless (IMHO) advice from the local gun dealer to use S365, splitting the difference between book minimum and maximum. I hope said dealer isn't on AR, but if he is, it might not be SUCH a bad thing.....

303Guy - you got the part about frying an egg on a rock or hood of a car right. I've often thought I could fry one up on my bald patch on that farm (15-20 miles south of the Limpopo River). However, our session was bang in the middle of a cold spell in the dead of winter. Must have been in the low twenties Centigrade. i know, I know....

The rifle would have been bought new in Germany circa 1994 when Hanne and her late husband moved out here. It is still in immaculate condition. I'm aware of the same rifle being offered in some serious calibres - I have often dreamt of owning the .375H&H version, before I had my Mauser built in that calibre. However, I get the idea that reloading is not big in Germany (heavily legislated), so maybe they put all their chips on one (factory loaded) shot per case. Fair enough, I guess. Glad I got the Mauser after all!

Unfortunately, we don't seem to get imported powders here at all. I suppose that's our reward for having a President who believes that a post-coital shower is adequate protection against HIV and a past-president of the ruling party's Youth League who seeks advice on land redistribution from Robert Mugabe. SOS.

I'm in the middle of getting everything ready for an Eland hunt this coming week, So I'm going to put this one on the back-burner for a short while. Hopefully the crystal-clear bushveld night sky, the cry of Jackals and a particularly good single malt will help clear my mind. Come to think of it, wouldn't a medium-rare Eland fillet complement that single malt just grandly? Oh, Man - life can be so good.

Complete head separation! Wow. Theoretically a middle load should be safe. Minimum loads are called minimum because it may be unsafe to go lower. Starting loads on the other hand are where one is supposed to start! So the question is, why would a middle load separate the case head? I've had it with the 303 Brit but that was without excess pressure. That was before I discovered about lubing my loaded rounds. Front locking actions can separate case heads just as easily. It could be that the cases themselves are on the small side, i.e. a little short and being of the same manufacturer would explain both rifles showing pressure signs. But not if those are reloads with no shoulder set-back on resizing.

By the way, I've had cases that are tight to chamber and need considerable closing force on the bolt, loosen up on firing if the case is lubed. (The tight closing is from a case fired in a different chamber where the body is bigger at the shoulder body junction).

By the way, Somchem powders are about as good as they get. I used to use MR200 in my 303 and 223 and the velocity spread was like one or two meters per second! Accuracy was as good as it gets too. The ball powders didn't work for me.

Rikkie,
Don't know if you have tried this and realize you are trying to trouble shoot (no pun intended) loading techniques but it may be worthwhile to buy some factory cartridges for both of these rifles so you can eliminate the possibility of problems from the rifles/actions from the equation. At least it would give you a control group to work with.
You don't happen to have a case length gage for these rounds do you?

I've had a case head seperation with an out of the box store bought. The other 19 fired perfectly.

I doubt whether store bought ammo with the same cases can be had. It's PMP cases and they don't load all that many chamberings. They did load 303 Brit (or someone did using PMP cases) but that was a military cartridge.

PMP does manufacture a range of ammunition, among which the 7x57 is well catered for, and it works well in this rifle if one overlooks the lousy bullet. The 8x57 though, is a non-starter. One would be hard put to find ANY ammo for the rifle, by ANY manufacturer in RSA. We are using brass which Hanne has hoarded over the years from the ammo stock she moved over with (RWS). I was incredibly fortunate to find some 8x57 JRS Norma brass stuck away on the back of a dealer's shelf, and bought the lot (80 pcs). We haven't worked with these yet.

Case gauges (I presume we're talking about Go and No-go headspace gauges?) No, I don't have. I could loan a set from a gunsmith for the 7mm, but once again, mention of 8x57JRS will only get you puzzled looks and raised eyebrows around here.

Interesting. You may find the PMP factory loads are quite mild - I could be wrong about that. If factory loads work with the same cases then it makes it all the more puzzling.

Some extracts I found;

quote:

168 GR. SIE HPBT IMR IMR 3031 .284" 3.000" 33.8 2227 41,400 CUP 36.0 2318 45,500 CUP

quote:

S335 IMR3031

quote:

S365 IMR4350

quote:

I tested S355 with the Claw 215 Gr bullet and read off the
tables for IMR 4320 are similar and this weight of bullet off a Canadian
website and find good correlation between the IMR 4320
load/velocity and the S355.

You've already stated the equivalents but check out the difference in load data between the S335 and IMR 3031. Starting velocities are about the same but not the charge mass. Interesting that S355 and IMR 4320 are similar so I wonder why S335 should be that different and yet behave the same as IMR 3031?