A Theory offered by CINDERS

[CINDERS]

For a very long time I have loaded my 303's with 174 SMK's and driven them at or near 2,440FPS which is the velocity the standard Mk VII ball round was.
What I had noticed is that at this velocity it did not match up at all to the sight graduations on the sight ladders of either my Mk III's or No.4's.
As you found that at times it equated to a 100 to perhaps 200yd higher setting on the ladder to get POA/POI and this had me a bit perplexed until I got a light bulb moment.

I was consulting the latest ADI book and reading about the new propellants coming on line and how they are lowering the temp of the flame and also incorporating an additive to reduce copper fouling.
Got to thinking about BC's and this is where I think I have erred all these years and my thoughts are thus;
There is no comparison between the MK VII ballistics and the reloads we have due to better powders, different rates of burn as cordite burned faster & hotter the BC's of the projectiles are streets apart.
So here is what I think if we have an SMK that flies flatter than the MK VII projie at the same velocity then it will hit LOWER on the target at a given range by that simple fact it flies flatter.
So in order to get the POI we raise our sights because we need to be on POA/POI but it defies logic as we have a bullet flying flatter so we have to lift up the sights.

Sooooo what I am going to play with and be a secret squirrel till I get it right is load down the rounds to minimum and go from there (NOTE: Never go under minimum load data)
Will see what happens and I will report back and as we only go back to 600yds in our matches keeping above the tran-sonic will not be a problem.

What do you chaps think is my summation correct it sounds bizarre I know but think about it and you will see I feel the theory has merit.

Information

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[Bruce_in_Oz]

Several thoughts.

"Good old Cordite" burns faster than AR-2206(H) and WAY faster than AR-2208.

The solid-based SMKs being boat-tailed, do not "set up" the same way that the traditional, open-based Mk7 bullets do.

.303 barrels can run out to some horrendous GROOVE diameters, eg. .320" and STILL be in spec.

Furthermore, the FACTORY practice of hand-lapping a strange taper in the barrels lead to BRAND NEW barrels having belled muzzles.

Thus, a boat-tailed, SOLID-based bullet is going to require a SERIOUS boot up the backside, if it is to be "upset" to fully seal the distance between the .312" bullet starting diameter and the potential .320" groove diameter.

Without a complete and CONCENTRIC gas seal, the bullet will be off to a bad start as it gets going. If it is still "off centre" and POSSIBLY NOT perfectly aligned with the bore, when it comes time to exit the muzzle, it will get really weird, moreso if the crowning is not "perfect".

With a less-than-perfectly aligned bullet, as the boat-tail starts to exit the muzzle, the gas bleed will be uneven, causing more "bullet tilt" and thus, precession spiraling, in turn causing randomly enlarged groups.

In the real world, all bullets fired from rifled barrels, precess to some extent. Even good old Mk7 ball does it. Talk to the "old guys" about bullets "going to sleep" (becoming more predictably stable) as they go down range. In Mk7, the design of the bullet, i.e. seriously base-heavy, adds to this phenomenon. FBHPs, like the new "Mk7 equivalent" FBHP from the Bullet Factory, will also do the same.

Interesting little, sort-of related video [URL="https://www.youtube.com/watch?v=7kB__9CteSg"]here.

Hornady have an interesting prospect, here: https://www.hornady.com/bullets/rifle/303-cal-312-150-gr-interlock-sp#!/

Note NOT a 174gn bullet.

One further "interesting" issue is the state of the throat / leade.

ALL .303 rifles made for service ammo have LONG throats, because they had to be able to handle ANY service ammo of that calibre. MAYBE late production N04 and No5 barrels were made with shorter throats, but ALL service SMLEs had long ones, originally designed to handle Mk6 and earlier ammo. SAME overall bullet length, give or take a couple of thou, BUT radically different profiles and thus bearing surfaces.

A hard-worked throat (LOTSA Cordite) will be a somewhat longer than when it left the factory. This unwanted free-bore WILL alter the pressure curve and also PEAK pressure AND muzzle velocity like.

Keep us posted.

[Ovidio]

Wow, this is getting really interesting!
I should check my SMELLY again with flat base, round nose bullets (174 grs) and see if I get closer to the sights settings.
But I guess that, first of all, one should be sure he has the right front blade height.
Or am I wrong?
In any case, if I can hit right on POA at 100 meters with the sights set at 200 or 300 and then keep the POA/POI aligned going to 200, would that be a good way to judge, or ist the height increase in the rear sight not linear enough even at closer ranges that I'm making wrong assumptions?

Ah, love this place!

Attachment 87049Attachment 87048

[us019255]

I had a similar problem with both my SMLE and No. 4 until I realized I was using U S Army targets and aiming procedures. I was shooting at a round bull and holding at the 6 o'clock position. I then found that the British Army uses a bull with only the top half black. You then are holding on the center of the bull. I made some and sun of a gun started hitting really close to right on at 200 yds and the 200 yd setting.

[CINDERS]

I am going to play anyway so it may take a while to get back to you with findings I played with 2208 did not like the recoil forces to sharp so I now use 2209 bit slower and a more subtle recoil you still feel it after say a 60 - 100 round day but you do not get as fatigued by the pounding.

At this point I am not worried about the factors with stabilization and obturation at this point as BIO pointed out there are so many variables in the mix with the barrels, besides I have my hands full digesting 2 books I recently brought by Bryan Litz that coupled with what he contributed to the new Berger Bullets reloading manual is certainly food for thought.
I tried the Bullet factory's 174gn FBHP projie the other day out of my T and was very happy with the results what I may do now is to stop crimping my 303 rounds as I have the AMP annealer now so the brass will be consistent as using a battery drill and gas torch for annealing really was well pretty pointless as far as repeat-ability goes.

Anyway guys thats it for a bit on this endeavor will keep you posted.

[Ovidio]

Do you notice any real difference when crimping?
I've never done that on no caliber, so I really wouldn't know if that could help, but I have never had any trouble with bolt-actions or with my Garand without crimping.
And the ammo seems more consistent than the shooter.

[CINDERS]

The only real reason I crimped the rounds Ovidio was to get an even neck tension its the only rifle I used to crimp as it involved a light crimping (not pushing the press lever all the way) then rotate 180 degrees then the final crimp but even then there may be inconsistencies which may upset bullet run out though the bog standard 303 was not an MOA performer.
So I will see what comes out in the wash and get back to you chaps.

[Bruce_in_Oz]

Bullet "crimping" is done for a couple of reasons.

First and foremost, to hold the bullet in the neck of the case even during the most "vigorous" feeding. This is of particular importance with machine guns, for obvious reasons.

I have used the Lee brand "Factory Crimp" dies since they were introduced. I started with a .223Rem job, back in the fun days of AR-25 shooting. My pet load at the time involved the Hornady 60gn FB Hollow Point, which has no cannelure.

It shot pretty well from my bog standard SP-1 and Valmet 71, but rare misfeeds could get a bit ugly. So, being an inveterate tinkerer, I lashed out, bought a Lee die and played around.

The first thing I noticed was a reduction in "fliers". I was using "random" brass; mostly "surplus" stuff, so, even with "batching", some variations were to be expected. Cases were all trimmed to the same length, for pressure/safety reasons, so, internal capacity and neck tension remained as likely suspects.

Gave the crimp die a whirl on a batch of rounds and the groups shrunk. The record one, which is still around here somewhere, was .65"-ish at 100yds Close enough for me and my SP-1, (topped with a 2-7x Leupold). My good wife was very good at head-shooting running wild pigs with that combination.

Feed problems also disappeared. (Mag "culling" probably also helped).

Still use that load in a re-barreled Remington 788. That bullet, though only 2 grains lighter than the SS-109 / M855 etc., WILL happily stabilize in a 1:12" twist, because it is somewhat shorter than the "mil-spec" projectile.

I also use the FC dies on .308Win and 7.5 x 55 Swiss. These dies will cheerfully form a cannelure where none existed before, so if you "stuff up" and have to pull a lot of ammo, the "plastic hammer" tools will be bloody hard work. Get a decent bullet puller like the RCBS; a lot faster, less "mess" and MUCH quieter.

The only question remaining is whether the necks will fail before their time because of the extra "working".

Neck-anneal your cases!

[CINDERS]

Neck tensions the key BIO I said in another thread somewhere about the AMP annealer the fact some of my F Open 6.5 x 284 brass plus my wifes 308 brass is 5 years old and was work hardened after constant reloads I was getting fliers that whilst the conditions were constant were way outside the MPI of the group at all ranges.
That was the primary reason I spent a good sum of cash getting the AMP annealer and pilots for all our rifles its first outings over a few days it got a very good work out doing a 1123 cases of the different calibers we shoot on the first outings with the annealed brass in my 6.5 x 284 I dropped only 1 point.
Then at a comp not 2 weeks ago over 6-7-800m I shot 178.16/180.30 with a 60.09 at 700M so the proof is there about work hardened brass and how it can affect the neck tension I never used to crimp my 303 brass I do not run hot loads the load I have at present is 2 grains under max for the 2209 so I am heading back to that train for this episode to see what gives I may try 5 crimped ones at the end as a base to see the difference.

Anyway I am in disusions with another member here in Aus who is doing something similar and we are going to correlate what we find.

The kicker is the data is going to be what we found with our rifles and can be freely used by shooters as a guide only because the condition of their rifle may vary to ours, their location, their loading habits thats why we are stipulating the data gained is a GUIDE only, no responsibility accepted by its use.
Because I know there a people out there who like to throw spanners through spokes just to try and de-rail someones honest intentions and efforts to try and get something that will work as that's what they do I call it preening the ego that I know more than you well good on ya pity you did not try and do something similar! (Sorry for the angst but I have come across this type in life before a PKFA = Professor know F*** Alls and classify them as air thieves.).
As I said to the member it is far easier to adjust the powder load than change front sights tapping it a gnats whisker this way & that way to centralize then mucking with it to see if you are getting POA/POI with your pet load.

[Bruce_in_Oz]

And, we must remember, the trusty old Lee Enfield family was NEVER intended to be "MOA"; just "rounds for effect". It's primary job seemed to be as an extension handle for the bayonet of the day; just look at the shape of the butt, especially at the wrist..

The SMLE acceptance target was shot at 100 FEET, not yards, metres or ashins.

As per para 42 of the general specifications:

"42. Rifle, testing of, - Every rifle will be fired at a paper target, with full sight, leaf and slide down, at a range of 100 feet, from a mechanical rest. trial shots will be fired, if necessary, and the foresight will be adjusted for lateral deviation, or will be replaced by another foresight to correct vertical deviation. Then five rounds will be fired from the magazine; if the rifle fails to put four shots out of the five into a rectangle 1- inch broad and 1 1/2- inch high, or if the blade, foresight, requires to be set more than .03-inch to one side of its normal position, the rifle will be returned to the manufacturer. The foresight of accepted rifles to be fixed by centre punching."

Roughly 3 MOA; good enough for "government work".