Bore diameter

[Bloodman14]

It seems to me that there is some confusion (maybe on my part) about bore diameter(s).:confused::I measure across the lands (caliber) vs. across the grooves (bore), e.g. my Lee-Enfield (.303 ( lands )x .316 ( grooves ) ). If the current school of thought is to cast .001 over, do I cast / size to .304 or .317? I would love to be set straight. Thanks!

gunnerd

Lead Forever! :lovebooli

[Calamity Jake]

.317 or .318 if chamber will allow.

[mag_01]

Agreed otherwise gases would be escaping around the boolit big time.:castmine:

[docone31]

Wow, you got a big one.
I went to paper patching form my Enfield.
That really works.

[Bloodman14]

docone31, a big what? question or bore? Just to inform, I've been shooting Lee's C309-200-R as cast (.309), and I get M.O.A. at 100 yds. Should I leave as is? How can I tell if I'm losing gases from 'blow-by'? And how does paper patching actually work?

gunnerd

Lead Forever!

[docone31]

Gunnerd,
If you are successfully using the C309-200R in your Enfield, I suspect your measurements might be off. Especially if you are getting MOA at anything! .311 minimum groove is the spec for the rifle.
I slugged my bore and got .304 for bore, .314 for groove. Even though it is a five land rifleing and a little hard to measure, at least for my brain, a .309 if there is blow by, or gas cutting, you would not get MOA on anything.
I had sized my castings using the C312-185R sized at .311 and got 20 minutes of berm, maybe.
I suspect, the casting you use the nose is around .301, or .302.
What paper patching does, is to substitute copper for paper on a jacketed bullet.
The Enfield was originally a black powder cartridge. It is very paper patch friendly. I am more accurate with paper than with .312 commercial bullets.
I have a few threads in the paper patching section on my trials and errrors with my Smelly. I also paper patch my .30s, especially my Ishapore 7.62. What a fantastic combination with these rifles.
Essentially, I wrap two wraps of computer paper, the 8 X 11 size found in dollar stores, or Office Depot. I cut the strips 1" X 2 3/16" with 45* angles on each end. I size my castings at .308 using dish soap for lube, then wrap the WET patch using a cigarette roller. I let dry, cut the tails, use a small amount of JPW, or car wax on the patch, size to .314.
In my opinion, anyone who has a Smelly, or Ishy, paper patching is very satisfying. I run full tilt loads in the cartridge.
I did a three point bedding, competition style, scoped it, I made my scope mount aka the original variety. It came with a factory cheek piece.
The patch is cut by the rifleing, and seperates from the casting on firing.
I had severe hammer marks in the barrel. I patched slightly small, smeared some Clover on the patch and fired 18 rds through the barrel. In other words, instead of .314, I sized using three wraps of Meade Traceing Paper producing .3135. Adding the Clover gave my final paper patch dimensions at .314, which I wrap now. The "fire lap" cleaned out the hammer marks and gave the bore a mirror finish. I now only have the slight wax on the patches as any lube. Essentially they are dry.
I have perhaps fired 500rds using this technique through my Smelly. I am still using the original cases I started with! Very easy on the shoulder, cleans as it shoots, and hits what it is aimed at.
My Smelly gets real hot after firing 40 consecutive rds. The barrel at that point acts like a piece of spaghetti! The three point bedding makes a serious difference. Still gets hot, but, the POI does not move.
Go to the paper patching section. I have a bunch of threads there.
I definately enjoy the benifits of paper patching.
Much easier to clean after firing.

[Bloodman14]

Hmmmmmmmmmmmmmmmm............

[Bloodman14]

docone31, I just mic'ed my boolits; .301 on the nose x .3115 on the bands. Does this help?

gunnerd

Lead Forever!

[docone31]

If you wanted to patch that load, I would
Size to .308, two wraps of Meade Traceing Paper available at WalMart. That will give I believe, .312.
IF you are getting good results with .3115, you will get good results paper patching with the Meade.
I suspect your groove measurement is a little off. Those five land barrels are hard for me to measure also.
IF your groove is what you originally stated, with the unsized casting at .3115, you would have a lead mine in your bore, tumbling, whistling castings with little accuracy.
I suspect, if you tried the Lee C312-185R Sized .312, you would get good casting results also. However, if it ain't broke, don fix it!
It sounds like you have one of the tight bores rather than the loose bore like I have.
The grain on the Meade Traceing Paper is across the paper, rather than down the sheet. Wrap so the stretch goes with the wrap so when it shrinks it shrinks hard down on the lands. You can see them bulging the patch when it is dry.
I use fingenail clippers to snip the tails, leaving a nub so when it is sized it acts like a check on the base. No exposed lead on the base. I use water quenched wheel weight for my alloy.
I do wax the exposed paper after the patched load is finished. I just wipe a little wax on the paper, mostly to keep it dry.
Which Enfield do you have, the #1 or the #4?

[Bloodman14]

docone31, I have 2 Lee's, a No. 4 Mk 1* 2 groove ( the one we're discussing ), and a Mk 2 5 groove ( .3075 x .314 ). I just reslugged the bore of the Mk 1, and confirmed .303 x .316.
I'll have to do some more shooting, and send pics of the target. You won't believe the accurracy! Leading does not seem to be an issue. I'll keep you posted. Thanks!

gunnerd

Lead Forever!

[montana_charlie]

Gunnerd,
From your descriptions, it appears you should be getting leading in your barrel(s).

Perhaps your alloy is so hard it thinks it is copper...
or
Maybe your bullets bump up to fill the groove diameter...sealing the bore from gas cutting, with it's accompanying bore leading. Only a recovered bullet could really answer that question.

If you really are shooting a bullet that is supposed to lead your barrel...and it is not doing so...you should file a complaint, in triplicate, sent to the management using Registered Mail requiring a signature upon receipt.

I really hope you get what's coming to you...

CM

[Char-Gar]

Gunnerd... The proper size for a cast bullet is a little more complex than many think. There are three dimensions in your rifle barrel that are import and not just two. The best accuracy is found when the bullet is a good fit for all three. Of course powder, charge weight , and bullet temper are also very important, but we are talking bullet sizing here correct? Let's talk about those three dimensions.

1. groove diameter - The old advise of having cast bullets .001 or .002 over this dimension is a good one. The notion of course is to seal the bullet from hot gas erosion. However, it will do no harm it the bullets is larger than these numbers. Sometimes you need to go larger to meet the other critical dimensions.

2. land diamter - This becomes important if you have a bullet designed for the nose to ride the lands. Such long nose bullets need to have the bullet supported by the lands. Exact land diamter or several thousands over is what you need. It is always nice to have the bullet engrave on the rifling, but if the bullet nose is too large, or the temper is to hard, you can have trouble chambering the round or push the bullet back into the case.

A fat nose bullet is not a bad thing. You can get nose sizing dies to make that nose a perfect fit.

3. throat diamter - The bullet body needs to as close to be throat diamter or even .0005 larger if possible. When the bullet fits the throat, it will enter the barrel straight and straight is a critical component of cast bullet accuracy. A bullet that does not fit the throat has a good chance of hitting the rifling off center and that is not a good thing.

Throat diamters do vary and can change with with use. Some well worn military rifles have eroded throats that are quite large.

Size your bullets to fit the throat if possible, and if that makes them larger than the holy .001 - .002 over groove diamter than so be it.

The fly in the ointment is that sometimes a bullet that will fit the throat will make the neck of the loaded round to large to chamber or not have enough clearance for the neck to expand to avoid really high pressure. If you run into this, it is time to turn the necks of your cases to reduce their thickness to provide proper clearance for the loaded round.

Now a couple of notes on sizing..

1. If you are after ultimate accuracy, you will need a custom mold that will throw a bullet the exact size in all three areas for your rifle, so it will require no sizing. Off the shelf molds are not likley to be a perfect match in all areas.

2. However, outstanding accuracy can still be had with sized bullets.

3. The old saw, was you could not size bullets more than say .003 without destroying the accuracy. Well, that may be true, if your are using a traditional machine that forces the bullet into the dies base first with pressure on the nose.

4.. But if you use nose first sizing you can reduce the bullet body diamters much more than the above number and still get excellent accuracy. It is a good idea to lube the bullet first so the lube grooves don't get lost in the gross sizing process.

I cannot emphasize too strongly the advantage of nose first sizing for rifle bullets.

I am sorry to muddy the waters and add complexity to an issue, we all wish was simple, but that is just the way of the cast bullet craft. Best of luck and good shooting! Charles

[Shuz]

Charles--Very well said--Shuz

[docone31]

My personal thanks to all here. Charles, MC, Pdawg, Beemer, and the others.
You all helped me take a beautiful rifle from being a wall hanger to a shooter!
Information on this site, WOW!
Can't explain why I love what I do, I do not even hunt and I am absolutely not in the class of some of the BP shooters who come to the range. That is for sure. I love watching those guys! Talk about focus.
Some good stuff here.

[Bloodman14]

I'm going to buy some Cerro-safe. Any cheap recipes / options?
Thanks to all!
Not after Minute of Nailhead, but the more, the merrier. I usually think combat accurracy( ex-Army).

gunnerd

[Forestar]

don't "fix" it. IMO, if you're getting MOA results what's the problem?

[Bloodman14]

No real problem, just trying to understand the whole bore / land dia. question in relation to boolit dia. It seems that my rifle / boolit combo is breaking the rules! I hate being confused with too much info or opinion. Like you said 'If it ain't broke.......'

gunnerd

Lead Forever!

[Larry Gibson]

By definition (it is written in numerous books so please, we know who, don't come back and criticise me) "bore" and "caliber" is from the top of the lands to to top of the lands measurement. This does not account for "groove depth" or the actual diameter of the bullet.

In many posts and writings (including a few of my own) the term "bore" and "caliber" are inaccurately refered to with a meanimg that includes the groove depth or caliber.

Thus to answer the question; "If the current school of thought is to cast .001 over, do I cast / size to .304 or .317? I would love to be set straight." the answer is to size .317" because that is "groove depth" + the additional .001" of which you want the "caliber" of the bullet to be.

Larry Gibson

[leftiye]

Good heck Larry! In the last fiasco I realized that nothing mattered, that I wasn't supposed to post at all. That is - that your returning vituperative would be forth coming if I posted at all. Now you're attacking me before I post!

[Bloodman14]

I wasn't trying to start a fight!

[docone31]

Heheheheh.
Now the big boys are coming in.
Pay attention to them, they sure helped me.

[montana_charlie]

I wasn't trying to start a fight!
You didn't...

[Bloodman14]

OK, I feel better. Seriously, when all this snow melts off, I will be doing some testing of boolit size and all that, see if I can put this all together. I will let you know. Thanks.

gunnerd

Lead Forever!

[leftiye]

Sorry guys. Larry and others have this right - bore diameter is what you can measure with a pin gauge. Groove diameter is best slugged. Charger is also right that freebore or throat diameter is the thing to fill up for best accuracy. A boolit that expands to fill the freebore or throat and is then sized down again by the barrel has twice the opportunity for deformation.

[Bloodman14]

leftiye, wouldn't 'a boolit that expands to fill the freebore or throat and is then sized down again by the barrel has twice the opportunity for deformation' also have twice the chance at bad accurracy? It seems the less a boolit is sized, the better, or have I missed something basic?

Lead Forever!

[Mk42gunner]

While I belong to the "If it works, don't mess with it" school of thought; and have never really played with a two groove barrel, is it possible the 2 large lands are displacing enough metal to seal the bore?


Robert

[Buckshot]

leftiye, wouldn't 'a boolit that expands to fill the freebore or throat and is then sized down again by the barrel has twice the opportunity for deformation' also have twice the chance at bad accurracy? It seems the less a boolit is sized, the better, or have I missed something basic?

Lead Forever!

..............Sizing before shooting serves one purpose. That is to make an oversized boolit fit. If you have to size, the best way to do it is through a push through die, where the nose enters first and you're pushing on the base. I suppose you could do this a couple ways. You could lube the boolit in an oversized (by about a thousandth) die in your lube-sizer then send it up through the REAL sizing die. Or pan lube and then send it though the push through, or pad lube then push through and THEN send it into the oversized lube die.

Boolit deformation in the lube-sizing operation is a real possibility. The press itself can be worn and may cause the boolit to slant upon it's entry into the die. Depending upon how much sizing is to be done, the boolit's alloy, and the presses condition you can actually bend the boolit. First time I ever had this happen (that I realized) was in sizing some Lyman 311284's. A 220gr 30 cal design that has what's called a 'Dirt scraper' groove in front of the top driveband.

Due to the effort and this groove's position, plus the wear on the ram's guide allowed the ram to place side pressure on the nose, and subsequently would bend the slug. Just enough bend for your eye to pick it out, which is way more then anyone would want.

The firing of a correctly sized boolit has no detrimental effect as the boolit is captive. If it's started straight, with it's axis co-incident with the barrel's all will be well. It cannot deform outside it's steel confines.

................Buckshot

[leftiye]

Gunnerd, Yup, that's what I meant. Correctly sized for your freebore, then the boolit only is sized down as it is shot. If it bumps up to freebore size, and then is sized into the barrel, it's not as likely to be accurate.

Mark42 has a good idea there. Your undersized boolits may be displacing to the sides in your 2 groove barrel as they are engraved making a gas seal, and good accuracy. If you had blowby, you'd also have leading, and bad accuracy.

[Bloodman14]

That makes sense. I'm using a bought-for-the-purpose Lee reloader (the small 'C' type). What would be the best way to capture a boolit intact, so I can measure the 'end result'? Or would the 'slug' tell me all I need to know?

Lead Forever!

[Larry Gibson]

Agree with leftiye and buckshot, they are correct.

Larry Gibson

[NSP64]

Gunnerd, use some pure lead cast a boolit then smash it into the barrel. resulting boolit will give you the measurements you need, Also if you tap it from the breech end you can tell if the bore has any tight/loose spots.

[NSP64]

Also, think of the barrel as having a hole bored in it(bore) Then they cut grooves. The lands are whats left.:drinks:


Now adays they bore the hole then hammer the barrel around a mandrel to give the rifling.

[Bloodman14]

is there a 'standard' depth the rifling should cut to?

[Bloodman14]

in other words how will i know if i have enough?

[NSP64]

Use pure lead and pound it through. Lube it up slightly will help. When you get the slug out the other end, you should see the groove and land area cut into the slug. at the base of the slug, you should see lead pulled down below the base of the boolit in the lands and grooves. this will make sure the boolit was bigger than the groove diameter for an accurate reading.



WW slugs have some springback and shouldn't be used to slug a barrel.

[NSP64]

What alloy are you using to cast boolits?

[Bloodman14]

WW mostly, some pure. No real 'recipe'. I use .36 Hornady BP round ball for slugging. I get exactly what you say.

[leftiye]

Re: Height of lands - grooves ideally should be .004 to .005" deep. Some are cut or swaged (button rifled) deeper still. Marlin (and H&R/NEF - Marlin makes these barrels) has a mental problem and likes to make .002 to .003" deep grooves. Often this is not enough for cast boolits (often it is fine though too). These shallower grooves probly work fine with jacketed, but who shoots jacketed?