Help - bullet seating depth 303 br

[RonR]

Having trouble determining bullet seating length for a new to us 303br.

Method: adjusting collet die to provide enough neck tension so when the dummy round is inserted and the bolt closed, then opened to extract the round, the result is bullet seating depth. Measure, repeat 5 plus times to prove and that’s it. This has worked very well for factory rifles but of course milsurps are a different animal.

Pardon any ignorance…does this indicate that the lands are “worn” out from usage?

Test bullet was a Sierra 180 gr prohunter. Are there longer/heavier bullets available to try to hit the lands?

From those experienced 303br guys…how difficult is it going to be to achieve 2 moa accuracy? What’s the road going to be like going forward so to speak…

I was hoping that this would/could be a shooter for my son to enjoy but I’m a little disheartened after this.

Regards
Ronr

 

[Tinman204]

Since you didn't mention what the intended use for said 303 is and which gun you're loading for I can only try and answer your questions in general terms.

Here it goes.

Crowding the lead on a 303 is pretty hard to do with most as the rifling on many will have some throat wear. That doesn't mean that you won't get good repeatable accuracy with your reloads.


When you say is 2 moa possible with a 303 do you mean the cartridge or a specific gun? A good and I mean really good Lee Enfield will do 1.5 moa on a good day. At least that's been my experience after thousands of rounds of Lee Enfield shooting.

Now if you're talking a Ross mk2, mine will do about 1.5" groups at 100 but I think it can do better. My mk3 Ross can do 1/2 moa on a good day or better if I feed it what it wants and I do my part.

I have a pattern 14 here that I built from parts. The barrel, receiver and bolt are all from different guns. The headspace is bang on and I bedded the action and did a trigger job. It looks like a normal run of the mill p14..that gun will stack em 1 on top of the other with good hand loads.

So long story short, 303 British is a fine cartridge capable of amazing accuracy at sane ranges. The limiting factor other then shooter ability is what gun you're loading for and it's condition.

 

[RonR]

Since you didn't mention what the intended use for said 303 is and which gun you're loading for I can only try and answer your questions in general terms.

Here it goes.

Crowding the lead on a 303 is pretty hard to do with most as the rifling on many will have some throat wear. That doesn't mean that you won't get good repeatable accuracy with your reloads.


When you say is 2 moa possible with a 303 do you mean the cartridge or a specific gun? A good and I mean really good Lee Enfield will do 1.5 moa on a good day. At least that's been my experience after thousands of rounds of Lee Enfield shooting.

Now if you're talking a Ross mk2, mine will do about 1.5" groups at 100 but I think it can do better. My mk3 Ross can do 1/2 moa on a good day or better if I feed it what it wants and I do my part.

I have a pattern 14 here that I built from parts. The barrel, receiver and bolt are all from different guns. The headspace is bang on and I bedded the action and did a trigger job. It looks like a normal run of the mill p14..that gun will stack em 1 on top of the other with good hand loads.

So long story short, 303 British is a fine cartridge capable of amazing accuracy at sane ranges. The limiting factor other then shooter ability is what gun you're loading for and it's condition.

Thanks Tinman, this response is what I was hoping for. Apologies for not being clearer. Purpose is target shooting.

- ok...perhaps repeatable results possible. got it.
- 2 moa for this specific rifle. Thanks for the experience on what may be realistic. I have another "bubba"'d 303 that I haven't investigated to this extent but IIRC it would shoot around 2 moa with factory offerings but it has a scope. Right now my son's No 4 is more interesting and he wants to bang away with it.
- I caught your post about your build, I believe on a related thread on 303. I know you know what you are talking about, thanks for taking time to provide some knowledge. Ganderite also is respected regarding 303 subject matter and I follow closely his posts.

Here's a picture of range results of the first time shooting with this rifle by my son. The objective at that time was to fire rounds to learn more about the rifle and the headspace amount. In short, from a rest, 22 of 35 landed on the paper at 100 yds. I shot 5 at another target and landed two of five. The target aim points were almost undiscernible for myself so I think he did pretty good. Recipe on the target, charge was 39.3gr of IMR 4064.

Again thanks for taking time.

Regards
Ronr

 

[cosmic]

Well - You're shooting with iron sights, at a sub-optimal target. Most folks don't practice much with iron sights these days, so I would think that this is the controlling factor in accuracy at 100 y. You might want to try a better target (think 6 inch black circle that is sighted to "rest" on the front post, or shoot a group at 50 yards - easier on the eyes.)
If you determine that the rifle is still shooting poorly, then try to measure the bore. Many Lee's have an oversize bore from the factory, which will limit accuracy. I made myself some plug gages (.303/.306/.309 in dia)...
My 50+ year old eyes don't facilitate shooting 100 yards with iron sights. Way back when, when I used a well tuned 303 (not necessarily a Lee Enfield), I could manage 2-3 inch groups with reasonable regularity. The same rifle, armed with a scope, would cut the group size in half...

 

[bigedp51]

RonR

The .303 British was loaded with cordite powder that had more nitroglycerin than many pistol powders have today. Meaning a used Enfield rifle will have cordite throat erosion and you will not find the lands even if you seat the bullet backwards. Creating a false shoulder from my experience over works the case neck. This is why I started using and promote the o-ring method of fire forming as the best method.

NOTE: Aircraft and ground machine guns were only to shoot ammunition loaded with single base powder due to the double base Cordite bore erosion.

Which model are you shooting, fore stock bedding has a great deal to do with group size and accuracy. If I remember correctly the Enfield was to shoot six inches high at 100 yards so I used a large 12 inch bull and aimed at the 6:00 or bottom of the bull. Minimum acceptable 100 yard military accuracy was a group one inch wide by three inches tall.

I'm like cosmic and have chronologically gifted eyesight and now use scoped rifles and sit closer to the target.

 

[grouch]

In my limited experience, seat as long as will reliably feed through the magazine.
Grouch

 

[RonR]

Well - You're shooting with iron sights, at a sub-optimal target. Most folks don't practice much with iron sights these days, so I would think that this is the controlling factor in accuracy at 100 y. You might want to try a better target (think 6 inch black circle that is sighted to "rest" on the front post, or shoot a group at 50 yards - easier on the eyes.)
If you determine that the rifle is still shooting poorly, then try to measure the bore. Many Lee's have an oversize bore from the factory, which will limit accuracy. I made myself some plug gages (.303/.306/.309 in dia)...
My 50+ year old eyes don't facilitate shooting 100 yards with iron sights. Way back when, when I used a well tuned 303 (not necessarily a Lee Enfield), I could manage 2-3 inch groups with reasonable regularity. The same rifle, armed with a scope, would cut the group size in half...

In retrospect I wasn't prepared regarding a larger target. Big faux pas on my part. True, shooting iron sights is not the norm but that's why we like the idea. It's a challenge and personally, I enjoy when discussion starts at the range when shooting these rifles. I appreciate the wisdom of those like yourself when you share.

RonR ...Meaning a used Enfield rifle will have cordite throat erosion and you will not find the lands even if you seat the bullet backwards.

Excellent image. I get it and it made me chuckle for a second.

Creating a false shoulder from my experience over works the case neck. This is why I started using and promote the o-ring method of fire forming as the best method. .

Noted. My other 303 has headspace issues. This was the first time shooting this other one so I didn't try it for this operation. Measuring with the Hornady system there is an increase of .030. Pardon my ignorance, could you offer insight into whether this amount, for this type of rifle, is extremely excessive or just "normal" and expected? O ring fire forming of benefit here Ed? <<< perhaps it's an obvious "YES" but for clarity...(PRVI headstamp for this particular rifle.)

Which model are you shooting, fore stock bedding has a great deal to do with group size and accuracy. If I remember correctly the Enfield was to shoot six inches high at 100 yards so I used a large 12 inch bull and aimed at the 6:00 or bottom of the bull. Minimum acceptable 100 yard military accuracy was a group one inch wide by three inches tall.

I'll try to post some pictures for reference. The bolded information is golden for us here. Sincerely appreciate those tidbits.

I'm like cosmic and have chronologically gifted eyesight and now use scoped rifles and sit closer to the target.

As stated earlier, when a shooter that's senior to myself makes the effort to strike up conversation over these rifles, the next minutes are going to be special. I sponge it up.

In my limited experience, seat as long as will reliably feed through the magazine. Grouch

Yeah...that's what I deduced last night. Mag length is the limiting factor here. Thanks Grouch.

Regards
Ronr

 

[Tinman204]

Ron, try shooting at a black square target of about 6 to 10".

If that target is set on a large white background you can use the tricks that Smellie on here tough me several years ago.

Get your son to simply aim at the bottom left corner of the black square target with the top right corner of the front sight.

Break the shot precisely when the bottom point of the left corner touches the right corner of the sight blade. That's the old aim small miss small way of thinking. It gives you a very precise aiming point which means less room for error. I've shot groups back to back with the same rifle but with small square targets vs large round targets many times. My small square targets always yield the smallest groups by a long shot.

The other thing I do is measure the actual amount a front blade subtends at 100 yards by aiming at known sized targets.

That way if your sight say subtends at 6 moa you simply use a 6" wide square to aim at and then line up your sight bang on with the bottom and sides. Break the shot exactly when the top of the blade lines up with the bottom of the square. The white background really helps me to see the exact point when I'm aiming at the bottom of the square.

I love shooting with irons and to be honest I only own 1 scoped rifle which is a 22 used around the yard here.

Now back to 303 loads. I use Sierra 180 grain pro hunters with imr4895 if I'm looking for pure accuracy. My load is always around 38.5 grains of imr4895 in any Lee Enfield. If a Lee won't shoot that I usually won't shoot anything and I start looking for damage in the draws or improper barrel bedding.

 

[RonR]

Ron, try shooting at a black square target of about 6 to 10".

If that target is set on a large white background you can use the tricks that Smellie on here tough me several years ago.

Get your son to simply aim at the bottom left corner of the black square target with the top right corner of the front sight.

Break the shot precisely when the bottom point of the left corner touches the right corner of the sight blade. That's the old aim small miss small way of thinking. It gives you a very precise aiming point which means less room for error. I've shot groups back to back with the same rifle but with small square targets vs large round targets many times. My small square targets always yield the smallest groups by a long shot.

The other thing I do is measure the actual amount a front blade subtends at 100 yards by aiming at known sized targets.

That way if your sight say subtends at 6 moa you simply use a 6" wide square to aim at and then line up your sight bang on with the bottom and sides. Break the shot exactly when the top of the blade lines up with the bottom of the square. The white background really helps me to see the exact point when I'm aiming at the bottom of the square.

I love shooting with irons and to be honest I only own 1 scoped rifle which is a 22 used around the yard here.

Now back to 303 loads. I use Sierra 180 grain pro hunters with imr4895 if I'm looking for pure accuracy. My load is always around 38.5 grains of imr4895 in any Lee Enfield. If a Lee won't shoot that I usually won't shoot anything and I start looking for damage in the draws or improper barrel bedding.

Thanks for this post! I had to read a few times to fully comprehend, but I grasp it. You explained the aim small miss small principle very well and it will be applied going forward with all the shooting we do going forward.

"front blade sub tends" truthfully is over my head but once we're out there applying I'll try putting that together in my head. I realize the concept is related to the size of the target.

I've loaded some 180 prohunters purchased from a supporting vendor and loaded so we'll see what becomes of that. Flat base seems to be common thinking with these gals and I'm starting to experience why. Just tried IMR 4064 so far but the next batch is W760 with half in large rifle and the other half with large rifle magnum to see if I can notice any difference with ball powders. I've got Re15, Varget, and IMR4166 to try as well. I'll use your recommendation of IMR4895 when I come across it. I'll tell you one thing, my son won't mind testing all these combinations. At this rate we'll be 3x loading over our hunting rigs!

My son and I are into this open sight thing and your post is really valuable in this regard. Your time and effort is sincerely appreciated. Much obliged Tinman.

Regards
Ron

 

[Tinman204]

Thanks for this post! I had to read a few times to fully comprehend, but I grasp it. You explained the aim small miss small principle very well and it will be applied going forward with all the shooting we do going forward.

"front blade sub tends" truthfully is over my head but once we're out there applying I'll try putting that together in my head. I realize the concept is related to the size of the target.

I've loaded some 180 prohunters purchased from a supporting vendor and loaded so we'll see what becomes of that. Flat base seems to be common thinking with these gals and I'm starting to experience why. Just tried IMR 4064 so far but the next batch is W760 with half in large rifle and the other half with large rifle magnum to see if I can notice any difference with ball powders. I've got Re15, Varget, and IMR4166 to try as well. I'll use your recommendation of IMR4895 when I come across it. I'll tell you one thing, my son won't mind testing all these combinations. At this rate we'll be 3x loading over our hunting rigs!

My son and I are into this open sight thing and your post is really valuable in this regard. Your time and effort is sincerely appreciated. Much obliged Tinman.

Regards
Ron

You're very welcome.

I try and pass on the things that others have shown me over the years. Also being that I live on a decent sized property where I can shoot any time I want I tend to try a lot of different techniques.

If you don't have 4895 I'd try Varget next. I load Varget at 1 grain higher then 4895 for all of my military cartridges. Seems to duplicate 4895 loads exactly. So 39.5 grains is the ticket for Varget in 303 with pro hunters.

Basically the whole sub tend thing is your front sight is always the same size so you can measure targets with it once you know how many moa it covers. You can use the front sight to correct windage without being able to physically dial it in like most guys are used to. It's a quick and easy way to adjust for windage.

For instance a buddy and I were shooting in high wind last year at 550 yards. Once he let me know how many moa the wind was moving my bullet over I then used how wide my front sight blade was compared to the 20" plate I was aiming at.

So for instance if my front sight was as wide as the 20" plate at 500 yards and I know that 1 moa is approx 1 inch for every hundred yards then that would make my front sight 4 moa wide. (1 moa @ 500 yards = 5". 5"×4=20" or 4 moa)

So when he called my shot "elevation good, windage 2 moa right" I then simply used the same hold but aimed 1/2 of my front sight post width to the left. I was able to make a hit on that shot. It's funny but I find this technique is so simple but most guys I know think I'm just some kind of guru even after I explain it to them.

 

[Ganderite]

For iron sights a black square or rectangle is the best aiming mark. I cut a wear centre in half to get two such aiming marks. I staple the squares onto plain paper and then make notes on the paper. The black squares can be reused many times.

Here is what it looks like in action.

 

[RonR]

You're very welcome.

I try and pass on the things that others have shown me over the years....

If you don't have 4895 I'd try Varget next. I load Varget at 1 grain higher then 4895 for all of my military cartridges. Seems to duplicate 4895 loads exactly. So 39.5 grains is the ticket for Varget in 303 with pro hunters.

Basically the whole sub tend thing is your front sight is always the same size so you can measure targets with it once you know how many moa it covers. You can use the front sight to correct windage without being able to physically dial it in like most guys are used to. It's a quick and easy way to adjust for windage.

For instance a buddy and I were shooting in high wind last year at 550 yards. Once he let me know how many moa the wind was moving my bullet over I then used how wide my front sight blade was compared to the 20" plate I was aiming at.

So for instance if my front sight was as wide as the 20" plate at 500 yards and I know that 1 moa is approx 1 inch for every hundred yards then that would make my front sight 4 moa wide. (1 moa @ 500 yards = 5". 5"×4=20" or 4 moa)

So when he called my shot "elevation good, windage 2 moa right" I then simply used the same hold but aimed 1/2 of my front sight post width to the left. I was able to make a hit on that shot. It's funny but I find this technique is so simple but most guys I know think I'm just some kind of guru even after I explain it to them.

Thanks for sharing more. Always welcome.

Noted on the Varget, we'll give that a go.

The sub tend thing...I had to read it over a couple of times but I get it. The bullet drop reticle on our rifle scope is supposed to work on the same principle of range estimation. It never would have occurred to me to use the front site in the same manner... and I mean never. I hope to get this rifle and my son to hit the gong at 300 with myself making the call for adjustment just like your buddy. When a person thinks about it, the principle is somewhat easy to understand but likely harder to apply. "Guru's" have a way of explaining what appears complicated to most folk very easily...so yeah I'd call you that.

Man am I jacked to get our loads down. (now I need a spotting scope...)

Much appreciated again Tinman!

Best regards,
Ron

 

[RonR]

For iron sights a black square or rectangle is the best aiming mark. I cut a wear centre in half to get two such aiming marks. I staple the squares onto plain paper and then make notes on the paper. The black squares can be reused many times.

Here is what it looks like in action.

Thanks for sharing Ganderite. I'll put something like that together.

(Pardon my ignorance).. there must be some optical reason why black is used...is it simply the black shape on a white background offering the best contrast for a shooter's eye to register? Or is there more to it?

Regards
Ron

 

[Tinman204]

Thanks for sharing Ganderite. I'll put something like that together.

(Pardon my ignorance).. there must be some optical reason why black is used...is it simply the black shape on a white background offering the best contrast for a shooter's eye to register? Or is there more to it?

Regards
Ron

That's exactly why I use black. I find orange and yellow make my eyes do weird things and I have a tough time getting them to focus. ,

 

[Al-Sway]

Two thoughts came to mind as I read this thread. The second was already mentioned- use a larger target sheet, and a more useful aiming mark. Typing paper sized targets are fine if you are shooting teeny tiny groups. Almost everyone would be better off with larger bedsheet so that you know where your shots are going.
The first thought is that you are obsessing too much over seating depth for a military surplus rifle with unknown rounds through it. If the Sierra bullet has a cannelure, I would seat it to that depth as a first principle. Otherwise I would seat the base of the bullet to the base of the neck. Then see if they will feed through the magazine. You are not shooting the latest 6.5 Whatever with ultra low drag match bullets in a 20 pound chassis rifle with a lunar observation scope on top.
Enjoy, and shooting will tight up the groups more than worrying about seating depth.

 

[RonR]

Two thoughts came to mind as I read this thread. The second was already mentioned- use a larger target sheet, and a more useful aiming mark. Typing paper sized targets are fine if you are shooting teeny tiny groups. Almost everyone would be better off with larger bed she so that you know where your shots are going.
The first thought is that you are obsessing too much over seating depth for a million surplus rifle with unknown rounds through it. If the Sierra bullet has a cannelure, I would seat it to that depth as a first principle. Otherwise I would seat the base of the bullet to the base of the neck. Then see if they will feed through the magazine. You are not shooting the latest 6.5 Whatever with ultra low drag match bullets in a 20 pound chassis rifle with a lunar observation scope on top.
Enjoy, and shooting will tight up the groups more than worrying about seating depth.

Hey Al, you're correct.

The finish of the barrel is different on this rifle than the rest of action...thoughts were at the time that this may be something unique or different than a typical service rifle. I needed to confirm what was happening. That's it. As stated earlier this purely a fun rifle for us to shoot and improve our skills.

However, without this thread and the posts from others I wouldn't have learned about "sub tends" and for tips like that it's worth it.

We will enjoy this rifle Al and we'll get better with this gal that's for sure. It's too cool not to shoot.

Regards
Ronr

 

[Tinman204]

Hey Al, you're correct.

The finish of the barrel is different on this rifle than the rest of action...thoughts were at the time that this may be something unique or different than a typical service rifle. I needed to confirm what was happening. That's it. As stated earlier this purely a fun rifle for us to shoot and improve our skills.

However, without this thread and the posts from others I wouldn't have learned about "sub tends" and for tips like that it's worth it.

We will enjoy this rifle Al and we'll get better with this gal that's for sure. It's too cool not to shoot.

Regards
Ronr

It's funny but I used to think like Al above. Then I got a Ross mk3 and learned that some antique 303 chambered guns can shoot tiny little groups. My Ross can hang with my modern savage 110 actioned target rifle up to 300 yards. After that the 303 bullets lack the BC of the 308s.

Also I have a bedded and match prepped but yet 100% military looking pattern 14 that I built. Last year at the range shooting at 300m I out shot my buddies fancy 6.5 creedmoor. His gun held 3mla and mine around 2.

No joke but some 303s are that good.

 

[Ganderite]

Thanks for sharing Ganderite. I'll put something like that together.

(Pardon my ignorance).. there must be some optical reason why black is used...is it simply the black shape on a white background offering the best contrast for a shooter's eye to register? Or is there more to it?

Regards
Ron

Several factors. Black on white gives you maximum contrast.

A flat bottom matches the flat top of your front sight. And if you use a scope, aim at the corners of the black square. The cross hairs line up perfectly with the sides and corner of the aiming mark.

When shooting with irons, don't let the front sight touch the black. You will lose control of elevation, black on/in black. Leave a band of white between the sight and the target. A rifle/ammo is no better than the sights.

 

[kawicrash]

Tagged

 

[RonR]

It's funny but I used to think like Al above. Then I got a Ross mk3 and learned that some antique 303 chambered guns can shoot tiny little groups. My Ross can hang with my modern savage 110 actioned target rifle up to 300 yards. After that the 303 bullets lack the BC of the 308s.

No joke but some 303s are that good.

That's the hope here but I am also a realist...

I've heard a few good stories. Ganderite has already responded regarding target optics...however if you would Ganderite...care to share a couple of your accuracy stories on this chambering? I find them very interesting.

Regards
Ronr