What to do with a short throat?

[tomme boy]

I have a Savage that I replaced the barrel on about 2 years ago. I have about 3000 rounds through this thing and the throat is still very short. About 250 of them rounds were jacketed.

I think that shooting these cast bullets in this thing is why the throat has not moved.

I just received a mold that was supposed to be set for 308 win neck to keep the gas check in the neck. Well that did not happen. I'm thinking about either have the throat lengthened to a factory throat, or just load up about 200 rounds of jacketed and see if it moves forward. Or get some lapping bullets and shoot a few of them. ??????????????????????????????????

GEAR?
Larry?
Run5?
BTROJ?
Goodsteel?

[Bjornb]

Yep waiting to hear what the experts say. My new Savage 10 in 308 has the same issues. Very short throat, all cast bullets end up below the case neck. Drives tacks with jacketed.

[mrbill2]

How short and what is the dia. of the throat?

[btroj]

If you can throat it yourself I would do that. Cut a longer throat with an angle you like. I would then either fire some jacketed to smooth it out of lap it with a few rounds.

Im no expert but that is what I would do.

[45 2.1]

I just received a mold that was supposed to be set for 308 win neck to keep the bullet in the neck. Well that did not happen.

Wrong boolit.............. etc. There is one that does that though.

[bruce drake]

Surprisingly, I'm in agreement with btroj.
Have your smith or yourself move the barrel's throat out a little further. I had a Mauser 98 rebarrelled to 257 Roberts on 2000 when I was getting into collecting and shooting Mausers and I didn't think to tell the smith I was planning to use it for deer hunting versus varmint. He cut the barrel's throat for 87gr varmint bullets...excellent shooting with that size bullet but closing a bolt on 100gr and 117gr factory jacketed loads really was not fun and not to mention the recoil once the bolt had jammed/seated the bullet into the rifling.
Took the rifle to a different smith a couple of years later and less than 2 hours the new proper throat was cut and we had test-fired it on his range behind his house.
It pays dividends to find a gunsmith who will talk to you about your desired endstate and educate you on your options as you build/rebuild a rifle.

Bruce

[btroj]

Why a surprise? I may not see on adding a new forum but it doesn't make me a bad guy or an idiot. Or does it?

45 2.1, what specific bullet would you suggest?

[tomme boy]

This is a Shilen Select Match SS barrel. I do not know what reamer they use. I called them and they would not tell me. When I first put this on, I loaded some 168gr Sierra HPBT match bullets and I had to seat them to 2.75" as I could not close the bolt on 2.8" for what it was called for. I can just now close the bolt on that same bullet seated to 2.8" where it is supposed to be seated. It still leaves rifling marks at this depth but it extracts fine.

Like I said, it is short. I had 45'd mold for this rifle when I first got it. That was seated very deep also. Never could get it to shoot. The mold was sold as it was the worst casting mold I have ever had in my life. The mold was just not made right from what I heard. The design was sound just the maker did not do it right.

[freebullet]

I'm no expert, but I've played with reaming several throats over the summer.

First I had a 45 that kept leading at the sharp start of the rifling. That caused the gun to not go quite into battery. This gun had a very hard ss barrel. I used a Manson throating reamer, it took quite a bit of hand turning to remove the sharp edge at the throat entrance and that did nothing to move the throat. It worked perfectly, it no longer leads at all. There is an excellent write up sticky on doing this, I think it's in the gunsmithing subforum.

The second was a friend's 45. It had a short throat, wouldn't go into battery while some ammo. It was a steel barrel. We used the same reamer on it. It didn't take much with the regular steel barrel to move the throat forward just enough. It worked perfectly.

The third was on a short throated ar barrel. It wouldn't chamber any lead boolit. I was advised here that I would be better off using a standard chamber reamer to make sure it's in spec instead of throating it. I didn't head their advise. I decided to throat it. The steel cut very very easy. Still couldn't get the cast to load. Did a little more, cast were just starting to go in & there was no problems with jacketed accuracy. Well I decided to take it just a bit further, and I learned how far is to far. Now she'll load any cast you try but jacketed groups were now a sweet looking 12" circle around a 8" bull at 100yards, looks almost as if the target were coated in bullet repellent. I really wasn't to concerned over losing that goofy looking little pencil barrel, but wouldn't want to do that to a better barrel.

What I would do with yours is try to identify what is happening. If it's just that the rifling start has a blunt sharp start then I would carefully ream the throat. If the match chamber is tight all around I would use a standard chamber reamer on it, which could open the throat just enough.

[MBTcustom]

Tommy, have you made a pound cast of your chamber? I have a reamer with a good throat on it. Use the NOE XCB boolit with this throat, and you will have a good shooter.
That said, all you need is a boolit that fits properly. That starts with a pound cast.
I have a throat and a matching boolit here, but there is probably a boolit that matches the throat and neck length you now own. But you can't know what it is, unless you measure what you've got. Measure it, match it, shoot it.

[geargnasher]

This is a Shilen Select Match SS barrel. I do not know what reamer they use. I called them and they would not tell me. When I first put this on, I loaded some 168gr Sierra HPBT match bullets and I had to seat them to 2.75" as I could not close the bolt on 2.8" for what it was called for. I can just now close the bolt on that same bullet seated to 2.8" where it is supposed to be seated. It still leaves rifling marks at this depth but it extracts fine.

Like I said, it is short. I had 45'd mold for this rifle when I first got it. That was seated very deep also. Never could get it to shoot. The mold was sold as it was the worst casting mold I have ever had in my life. The mold was just not made right from what I heard. The design was sound just the maker did not do it right.

Pound cast it. I'm betting the throat entrance is about .309" with a long, gentle taper. 45 2.1's bullet as made by Mihec won't do for really tight throats as it must be sized down too much. Put up a picture of the cast with the critical measurements and we'll see.

Gear

[tomme boy]

http://img.photobucket.com/albums/v21/tommeboy/1380241_760989310604174_153254047686658904_n_zps05 ee0e16.jpg (http://smg.photobucket.com/user/tommeboy/media/1380241_760989310604174_153254047686658904_n_zps05 ee0e16.jpg.html)

This is what is going on.

[tomme boy]

This is when I sized to 0.310". I just resized some up at 0.309" and the ridge is almost completely gone. It is more of a scuff.

[tomme boy]

This is NOT the 30 SIL. Never again on that one. It is this one.

http://noebulletmolds.com/smf/index.php/topic,322.0.html

[geargnasher]

Like I thought, tight throat. You just need to size smaller. What would be the berries is one of 45 2.1's .30 Sil moulds like you had (my first one was trash like yours, too) but that cast .310" and had a properly sized gas check shank. Then you could bump them to .309" or so if you needed to. Keep in mind the .30 Sil wasn't designed for those small throat entrances. The nose shape, however, has worked extremely well in a variety of throat tapers.

Gear

[geargnasher]

Oops, I got distracted trolling Midway for a recommendation and missed your last two posts. Yep, size .309. Then you have to decide what you're going to do with all that neck slop so the bullet doesn't bump up to .315" before going through the throat, or go sideways in the neck and rake one side off when fired.

Gear

[tomme boy]

So, it looks like I need to have it opened up a little?? The chamber will take a 0.3105" bullet with Federal brass.

[leadman]

Some may think I'm crazy but I have had some very small groups made with the Lee 200gr RN 30 cal. It even fits in my K31 that has no throat.
For $20 it is not expensive to try one, or PM me for some samples.

[geargnasher]

Why would you open it up? Just make the bullet fit.

Gear

[tomme boy]

With that much clearance in the neck, how would I do that? With it shaving like it is, that has to be shaving an deforming the bullet like crazy. It likes the Lee 200 gr and the RCBS SIL but I can not run them past 2K fps.

I was thinking to have it opened up right at the entrance of the leade so as to not shave. It is still going to swage the bullet down, but it would not leave the bullet un-supported in the neck when fired. I think I can make it fit better this way. The bullet comes out exactly as the print shows. So if I size it with a 0.311" die it should have the right amount of clearance in the neck. Or is it being swaged too much as it passes through the throat?

[tomme boy]

I'm about ready to just make this thing into a jacketed bullet barrel only.

[tomme boy]

Just thinking, you think maybe reforming some 06 brass may fill the neck up to help center the bullet better? Same as you guys are doing in the XCB?

[5Shot]

Choke a lot?

[tomme boy]

?????????????

[prsman23]

Think he was making a joke about having a short throat. Not rifle related :)

[btroj]

Just thinking, you think maybe reforming some 06 brass may fill the neck up to help center the bullet better? Same as you guys are doing in the XCB?

Give it a shot and see. You can also use a bit more belong on the case mouth and don't reove it to help center the neck better.

What a thicker neck does that belling won't is fill the neck area with either bullet or brass. This helps prevent the base from expanding under pressure which results in more deformation as it must be sized back down by the throat.

[tomme boy]

Well I went to the range a few minutes ago and shot some bullets that I sized to 0.309" I have not checked the bore yet to see if there is any leading or not.

I loaded them up with H4895 with no filler. I went from 31 gr to 35 gr in 1 gr lots. I only loaded 4 each as I only cast a few bullets last night. They are checked with Hornady checks and lubed with Tac-X. They were seated to have the check just on the bottom edge of the neck but still in it.

31 shot the best but I think I am going to try some at 34 grs and work some on each side of it. I don't have a chrono today so I have no idea on the speed. All shot at 100 yds of a bipod and my hand for a rear rest.

http://img.photobucket.com/albums/v21/tommeboy/101_0410_zps02636837.jpg (http://smg.photobucket.com/user/tommeboy/media/101_0410_zps02636837.jpg.html)

[btroj]

How does that compare to the larger bullets ?

[geargnasher]

Pound cast. Need to know what the chamber neck is before speculating on brass.

Things I do know: Most production "match" .308 necks go from .344" to .342" ish at the case mouth end. Most .308 brass will have .0135-.0140" necks at the thickest after turning off the high point, so even with .311" bullets there will be at least .003" loaded clearance, more likely .004-5" clearance. You need thicker necks anyway, so go ahead and make some cases out of '06 and they should give you enough meat to get under .002" with .309" bullets.

Gear

[Hang Fire]

I have a Savage that I replaced the barrel on about 2 years ago. I have about 3000 rounds through this thing and the throat is still very short. About 250 of them rounds were jacketed.

I think that shooting these cast bullets in this thing is why the throat has not moved.

I just received a mold that was supposed to be set for 308 win neck to keep the gas check in the neck. Well that did not happen. I'm thinking about either have the throat lengthened to a factory throat, or just load up about 200 rounds of jacketed and see if it moves forward. Or get some lapping bullets and shoot a few of them. ??????????????????????????????????

GEAR?
Larry?
Run5?
BTROJ?
Goodsteel?


Or, one can order a custom push through die from Lee (about $34.00) that is correct diameter to size the boolit nose down to desired bore rider diameter. Set depth of engagement, then from the top of die with wood rod manually push boolit back out.

I size down the too fat nose of the Lee 6.5 Cruise Missile in .257" die for my short throated Swede M39.

[MBTcustom]

I hate to sound like a broken record Tommy, but this is all just grabbing at straws and feeling around in the dark till you do the pound cast. Once you have it, you have something to measure against, and draw conclusions from.
One thing that you need to be thinking about is that you change a lot about your boolit when you size it to a smaller diameter. The material is not shaved off, it is displaced. Which means it doesn't leave. Which means it has to go somewhere.
Your boolit will get longer and the contact angles may change slightly. Good? Bad? Indifferent? You have to have something to compare to in order to make that call.
Typically, I want to take a measurement of the pound cast, right where the 30 or so degree angle leaves the neck portion of the chamber and joins the leadin/throat of your rifle. There will often be a radius in the corner there, which I disregard as it will give you a larger diameter than you really can use, but I put the edges of my micrometer on there and hold the pound cast up to the light so that I can see where the boolit will definitely get full purchase of the lead when it contacts that acute angle.
Whatever that diameter is, I do not go over it at all, but I do try to match it.
In your case, if you do this and find that the only reasonable diameter that will easily enter your lead is .309, then you know that running a .310 diameter boolit is asking for trouble. Also, if it seems that the design of your boolit is such that the damage of engraving is exacerbated beyond a reasonable ammount, then you can wisely choose a boolit design that will work better. Another reason you might choose a different boolit design is if your boolits are dropping .313 and you are sizing them down to .309. I'm not saying that you can't get good results that way, but you seem like you want to push past 2000fps with this setup, and a badly deformed boolit is not going to do you any favors in that department.

This stuff is not hard at all. It would be hard if it weren't for the tools that have been developed to make it easy, and the teaching that makes it even easier still. If you want to shoot really fast, then there is a lot of debate about what is required to do that, and I will leave it to those who claim to have done it to explain how. What I know from personal experience, and feel confident in saying, is that if you match the boolit to your throat, keep the check just inside the neck, and keep the nose short and stubby but as pointed as you can get away with and match the lead angle precisely (preslumped Morse taper fit design) and load your cartridges concentrically, there is no reason you should not be able to shoot your rifle to 2100fps with excellent accuracy. Like, load it and shoot it. No funny business.
That gets you shooting good groups right out of the gait without a lot of fancy footwork.
If you want easy, then throw some jacketed bullets in there and you've got it. It's way easier but expensive. Just depends on your time vs. money ratio. If you have tons of free time, but you carry mothballs in your wallet, then this is the way to go.
If you have a few hours a week, but regularly find an extra $40 or so in your billfold, then just load jacketed and call it a day. If you can barely find a spare hour in each week, but keep an extra $100 on you "just in case" then you'd best stash the reloading press and buy factory ammo in bulk and make the spare time you have "trigger time" rather than laboring over a press.
I've had a bunch of shooters in my shop from the poorest of the poor to the comfortably wealthy, and this is what I have observed is usually true.

[geargnasher]

The bullet he's using is spec'ed at .311" per the GB page. Two thousandths isn't going to ruin the bullet. There are several ways to get excellent accuracy (sub-moa) at up to at least 2400 fps in an adequately put-together .308 Winchester, several of us have explained how we have done it in great detail here on this forum, some several times over, and some even do it out to several hundred yards. If all that qualifies only as is a "claim", I wonder why we bother telling about it and posting our targets and chronograph data. Evidently not very many people were paying attention when they should have been.

Gear

[tomme boy]

I know Gear. I figured with over 3000 rounds on this thing that the throat would have opened up a little and it would have been a good fit. I just don't understand what they were thinking with the chamber reamer they were using. To have that big of a neck for even jacketed is just ridiculous. Then to have such a short throat on top of the neck?????????

Gear, what does the Bisley chamber look like on that new barrel? Tim, I am going to do a impact cast, I just have to get out the pure lead to do it. I have over 2K 168 AMAX's and 1.5K 168 MK's sitting on the shelf for the last 5 years. They may be calling my name.

Tim, shoot me a PM to set back this thing back and re-chamber it would you? With the 10 twist I don't know if it will be worth it or not.

[tomme boy]

Here is the pound cast. It looks like it is not short but just a tight abrupt entrance. The neck measures 0.3465" and the throat is at 0.308" before the rifling even starts.

Tim, I am sending this your way. But what do you see before it gets there? Gear?


http://img.photobucket.com/albums/v21/tommeboy/IMG_0097_zps7a6ea677.jpg (http://smg.photobucket.com/user/tommeboy/media/IMG_0097_zps7a6ea677.jpg.html)

http://img.photobucket.com/albums/v21/tommeboy/IMG_0096_zpsfd853000.jpg (http://smg.photobucket.com/user/tommeboy/media/IMG_0096_zpsfd853000.jpg.html)

[45 2.1]

The bullet he's using is spec'ed at .311" per the GB page. Two thousandths isn't going to ruin the bullet. There are several ways to get excellent accuracy (sub-moa) at up to at least 2400 fps in an adequately put-together .308 Winchester, several of us have explained how we have done it in great detail here on this forum, some several times over, and some even do it out to several hundred yards. If all that qualifies only as is a "claim", I wonder why we bother telling about it and posting our targets and chronograph data. Evidently not very many people were paying attention when they should have been. Gear

A very good synopsis.............. Too bad folks don't pay attention.


Here is the pound cast. It looks like it is not short but just a tight abrupt entrance. The neck measures 0.3465" and the throat is at 0.308" before the rifling even starts.

Not much to work with with those dimensions. loosey goosey neck and much to tight a throat. No simple cure. The set back idea is a good one IF the reamer to be used has proper dimensions.

[detox]

Tommy, have you made a pound cast of your chamber? I have a reamer with a good throat on it. Use the NOE XCB boolit with this throat, and you will have a good shooter.
That said, all you need is a boolit that fits properly. That starts with a pound cast.
I have a throat and a matching boolit here, but there is probably a boolit that matches the throat and neck length you now own. But you can't know what it is, unless you measure what you've got. Measure it, match it, shoot it.

.308 freebore after 2000 rounds? You have zero erosion. Measure free bore with micrometer, it should be about .3085 or greater.

I would take goodsteel's advice and use his reamer. It will work with both the NOE X and Hunter design. "IF" free bore of reamer design is slightly longer (.150") and larger .310 diameter. The hunter bullet requires a long free bore when sized smaller... especially when used in 308.

I would not use reformed 30-06 brass... been there done that. I would use new unfired 7mm-08 brass trimmed to 2.025" it will shrink to 2.020" length when fired.

[detox]

Here are Hunter bullet measurements. So far this bullet has performed worse than the 314299 or the RCBS 165 Sil in my rifles.



I received my mold and casted a few to check dimensions. Alloy used is lower shrink linotype. Softer Lyman #2 shrinks about .005 more.
Bore ride section: .3027 (very snug)
Bands: .3134
Front Band length (area before taper section) when sized smaller: .195" length @ .3095 band diameter, .150" length @ .3114 band diameter.
This bullet fits my Remington VS rifle best because of it's NATO chamber with long .150 free bore (worn throat). Rifles with shorter free bore and tighter bore will require trimming of brass and crimping to prevent bullet from moving back when chambering . Especially when using Linotype

[tomme boy]

My 311-188 mold measures exactly as the print shows DETOX. It was made for the use of WW's that is why you are getting the bigger measurements. It was also made to shoot to about 2300 fps. Try slowing it down a little bit and see what happens.

I pulled the barrel last night. It will be heading to Tim shortly. Waiting to hear from Shilen first about the huge neck and the tight freebore. Shilen sent me the print of the reamer and Tim called PTG to get the print. So it is no where near where it is supposed to be.

[detox]

My 311-188 mold measures exactly as the print shows DETOX. It was made for the use of WW's that is why you are getting the bigger measurements. It was also made to shoot to about 2300 fps. Try slowing it down a little bit and see what happens.



I know WW alloy will cast smaller.

I tested bullet at around 1900fps using 30grs of V140 powder. It may do better with my 4759 powder.

I have a 308 cal Brownells short chambered Shilen barrel. I also purchased a minimum SAMMI reamer to set head space and finish ream the small throat. It only required about .015 deep cut so that bolt would close on GO gauge. The SAMMI chamber reamer matches the HUNTER bullet pourly. The .090 length Freebore is too short. I think I will purchase PTG's Uni-Throater to cut throat deeper (.150" @.3100 diameter). Throat taper should be? You will get a lot of different opinions what taper should be.

You could cut the throat with custom Uni Throater. to use for cast bullets. Your other tight, short throat barrel could be used for jacketed only.

[tomme boy]

Well someone at Shilen sent me the wrong print # so the one I have and the one Tim has is wrong. The dimensions I am coming up with from the pound cast are within 0.0005" So that means the reamer they use is just way too big.

DETOX, that 34 gr load above should be at about 2300 fps so it can go faster than what you are getting.

[detox]

My Shilen barrel chamber resembled the 308 Fullbore reamer with very short .050 freebore. Click on Green reamer print button to view.

http://www.bullets.com/products/308-2011-Fullbore-Chambering-Finish-Reamer/T23211


Tim knows what he is doing, so you are in good hands.

[geargnasher]

Here is the pound cast. It looks like it is not short but just a tight abrupt entrance. The neck measures 0.3465" and the throat is at 0.308" before the rifling even starts.

Tim, I am sending this your way. But what do you see before it gets there? Gear?



http://img.photobucket.com/albums/v21/tommeboy/IMG_0097_zps7a6ea677.jpg (http://smg.photobucket.com/user/tommeboy/media/IMG_0097_zps7a6ea677.jpg.html)

http://img.photobucket.com/albums/v21/tommeboy/IMG_0096_zpsfd853000.jpg (http://smg.photobucket.com/user/tommeboy/media/IMG_0096_zpsfd853000.jpg.html)

WOW.

Yeah, ok, you're screwed. Why anyone would make a chamber neck with ten thousandths neck clearance for jacketed and yet have a jacketed-bullet-sized throat entrance is beyond my ability to reason out. The long, parallel freebore and abrupt angle to the lands isn't on my favorite list, either.

Here's an idea if you have the scratch to pull it off: Design and have cut the world's first CAST BULLET FRIENDLY .308 Winchester chamber reamer! Make the neck .337" and parallel. Shorten the neck to the absolute minimum SAMMI will allow, meaning chamber length minus the maximum drawing tolerance so it's still safe with factory ammunition. Make the throat entrance .310 with a little bit of parallel freebore and no more than a 2 degree included throat angle. Bob's input would be valuable here because I honestly don't know the "best" cast bullet throat shape for a .308, only a couple of different shapes that I've made work well and both had parallel freebore. Also, make the body dimensions to the absolute minimum so you have less trouble with fireforming and resizing. When you screw the barrel back on, make it snug on the go gauge. .308 brass is chronically short and you want to minimize the gap between case mouth and the end of the chamber neck, so tight headspace and making the chamber neck short as possible.

If you can pull that off, you can use factory .308 brass with minimal prep, possibly only taking off the high spots to end up with .0130-.0135" necks. You can then use a variety of available bullet designs and size them about .3095" or so. The chamber neck will be tight enough with factory brass that your bullet/neck will not expand larger than throat entrance diameter when fired.

My Bisley chamber has a neck that's .3440" X .3425", a .309" throat entrance, and something like a 1.5-2 degree INCLUDED throat angle. It's long, gentle, and has no parallel freebore, only about a .120" section where the taper takes out the lands between the end of the chamber and beginning of lands. I don't know if that helps or not since I haven't shot it yet, I'm just passing the info along since you asked. I'm going to have to use blank brass for this one on account of the large chamber neck.

Gear

[tomme boy]

Gear, I am not sure what Tim has for a reamer. We are going to wait till he gets it to see what we can do with it. I'm hoping there is enough shank on the barrel to set it back enough to get rid of that oversized neck. It should have enough to set it back 1/2" if I measured right. I don't know if Tim will be able to pick up on the threads that are there to continue them or not.

[MBTcustom]

It's no problem Tommy. I am absolutely sure I can cut off 1/2", pick up the threads, and cut you a satisfactory chamber if that is required.
I'm not doing anything till I scope it and take a real good look at your slug.
In the XCB threads we have determined that perfect neck fit is not a cure all pill but helps a little. The importance of that pales in comparison with a good, concentric, well designed throat, and that is what I will be looking at.

[tomme boy]

Shoot, I didn't throw the pound cast in the box. Do you need it? Oh yah, have fun getting the box open. It is nailed screwed stapled and taped. Its wood too.

[geargnasher]

[snp]
In the XCB threads we have determined that perfect neck fit is not a cure all pill but helps a little. The importance of that pales in comparison with a good, concentric, well designed throat, and that is what I will be looking at.

My experience and the experience of those actually shooting and posting results in those threads indicate that you have those two things prioritized exactly backwards.

Gear

[MBTcustom]

True for high RPM shooting. Not nessisarily true for accurate shooting at moderate speeds. It's Tommy's call how deep he wants to go.
And for the record, recent groups that were actually posted indicate no substantial change in group characteristics when using brass with looser fitting necks.
Of course, those tests were done with ammo that was very concentric.

[45 2.1]

Bob's input would be valuable here because I honestly don't know the "best" cast bullet throat shape for a .308, only a couple of different shapes that I've made work well and both had parallel freebore. Also, make the body dimensions to the absolute minimum so you have less trouble with fireforming and resizing. When you screw the barrel back on, make it snug on the go gauge. .308 brass is chronically short and you want to minimize the gap between case mouth and the end of the chamber neck, so tight headspace and making the chamber neck short as possible. Gear A good start, but not there...... You should look at what your sizing die gives and loaded round tells you. What size is your favorite cast boolit (one that has a track record of shooting well, ie small groups)...as cast? As far as the first 308 Cast boolit reamer.. haha, that has been done long ago. All these things go together. I offered to do this a couple of times myself, but meet a stone wall in the attempt. You aren't going to figure it out talking about it either. As far as throats.... you need to study how a throat erodes and wears in.... that will tell you how to design the nose.
My experience and the experience of those actually shooting and posting results in those threads indicate that you have those two things prioritized exactly backwards. Gear +1........ The requirements for shooting very small groups, at low or high velocity are the same. What you feed a well put together rifle (whether factory or custom) determines what you get. For the record......a well put together factory rifle can give you 1/2" to 5/8" groups at 100 yards. A custom one should do 3/8" fairly easily. Until you have that down pat at lower velocities, any HV attempts will be aggravated with fliers and blown groups.

[Larry Gibson]

tomme boy

That chamber also has a very long neck. Before doing other than having Tim open the throat. I suggest making cases to fit the chamber. Use 7x57, 8x57, '06 etc. and form the cases to be a crush fit for headspace and with the neck trimmed to fit that long chamber neck. Turn the necks to remove any high spots only. Ideally you want necks .013 - .016 thick. You will have a case with 30 XCB capacity and almost the same neck length.

As to looser fitting necks, Tim is correct; we give way too much importance to it. The fact is the pressure required to push the harder bullets used by you and me into the throat/rifling swaging it to fit the groove diameter and engraving the rifling into it is far less than that required to obturate the base in any way. If the bullet is aligned and well seated into the throat with a tight fit then the amount of case neck expansion has little adverse affect on the accuracy. I have the pressure traces showing this to prove it BTW.

In my own .308W Palma with 14" twist I am pushing 2700+ fps now at 42,000 psi(M43). The Winchester Palma cases (unturned necks BTW) I use have .006+ neck clearance for expansion in the chamber neck and with shoots 10 shots into what is averaging out at 1.6 moa groups. That goes against the theory expressed (tight necks are necessary for the best accuracy) which is what I also thought until the facts, measured and observed, with the bullet cast of the alloys we are using.

However, at even lower psi's where the bullet will obturate before entering the throat completely then a tighter fitting neck and case necks that fit the length of the chamber neck are essential. However, that is not what we are using and the "facts" are different. I suggest you have Tim throat the leade to a bit larger diameter and make cases with necks that fit the length of the chamber neck before cutting the barrel shank, rethreading and rechambering which may not be needed at all.

Larry Gibson

[tomme boy]

I am looking for 2200-2300fps max. that shoots at 1MOA or less. I am at 3/4" at 1950 fps for 10 shot groups right now. Not with the mold shown above, but with another bullet. It shoots jacketed into less than 1/4" groups. I would love that with cast, but I know I am not that good a caster or reloader to make that happen with cast.

I am going to see what Tim says about the condition of the chamber and throat. It may be a good thing to catch it early and have the throat cleaned up and set back. Like I said. It has just over 3000 rounds on it. I know 98% were cast so the wear is slower. But when I did do a day of shooting jacketed it was ran hard with them.

[geargnasher]

If you want 2300 fps with MOA or better accuracy out of a ten twist, you are going to be terribly frustrated by following the paradigm that Larry and Goodsteel have laid out for you.

Point #1, The RPM Threshold theory, using standard practices, components, and tolerances, states best accuracy won't be found past about 1950 fps in your barrel. A host of cast bullet shooters have proven that to be true. One of those standards found with normal guns and components that puts the accuracy threshold at 140K rpm is a lot of chamber neck clearance, like 6-10 thousandths. HELLO.

Point #2, You WILL have to learn how to master some unpopular concepts about how to exceed that "threshold" and maintain the group sizes you desire. You will have to learn for yourself how much neck clearance you can get away with, and you'll have to learn some things about alloy, bump, and dynamic fit that some still pretend are irrelevant. If you're content with 1.5-2 MOA accuracy, that's easy, and you won't have to change a thing. However, 3/4" or smaller groups should be no problem for you IF you do a few things right. You will have to decide which way to go, it's your barrel, money, and goals. Keep in mind you have already proven what DOESN'T work with what you have, and with some reading you can find what DOES work for others with similar velocity and accuracy goals to yours, so the course of action should be obvious. You can always ask questions......

Point #3, if it was me, assuming the bore isn't heat-checked near the throat, I'd have Goodsteel lop off about 1/2" of the tenon, chase back the threads (he's very good at this) and rechamber to something with a tight neck, short chamber, larger throat entrance, and more gentle leade angle. Just sayin'.

Gear

[detox]

I have had good results with long worn NATO leade/throat (.3115 diameter, .150 length, worn taper?). This gun will shoot most any snug fitting bullet good. I have shot 3/4" groups with this gun, but not consistently (and neither will you shooting cast).

My other rifle with new Shilen 1/10 twist barrel and minimum SAMMI chamber (shorter .90 length leade, .310 diameter and 1.45 angle per side) is more fussy and prefers the bore rider designs such as the 314299 and RCBS 165 Sil. I lapped the throat area to enlarge, smooth and give it more taper. Lapping also helped the larger .302-.303 bore rider designs to chamber more easily and exit muzzle with tighter fit. I can always ream leade/throat area using a custom PTG Uni throater at a latter date.

Support your local bullet

http://i1225.photobucket.com/albums/ee395/aviserated1/DSCF8111_zps2c11b481.jpg (http://s1225.photobucket.com/user/aviserated1/media/DSCF8111_zps2c11b481.jpg.html)

[tomme boy]

Gear that's what I was thinking in your PT #3. That group I showed at 34 GRS is right at one inch. That should be close to 2300 fps. So I am close.

[Larry Gibson]

"Holy Cow Batman", geargnasher is spouting the RPM Threshold as fact and is using it to argue against me!

I had not read in this thread the barrel was a 10" twist(?). If so the 1 moa or less accuracy at 2200 - 2300 fps may be difficult to attain. it is not that difficult to "master" getting a 10" twist to shoot 1 - 2 moa though as mentioned. You can chase your tail with the hypothetical or you can go with the obvious and the proven. Before I'd invest in all that is recommended I would go with the minimal obvious and proven to see if that holds promise. Letting Tim inspect the chamber and throat before making a decision is and excellent way to go.

Other than throating and making cases that fit the chamber neck, as I previously mentioned, I'd put any additional $s toward a different barrel (12 or preferably a 14" twist 26"+ long) for the cast bullet accuracy you want. With a 12 or 14" twist barreled .308W with a tight chamber (yes I do recommend such if one is getting a new barrel). The moa accuracy at 2300 - 2400 fps will come w/o too much difficulty and you'll not have to "walk the rice paper" to "master" much. I'd then just finish shooting the current barrel with jacketed. BTW; a 12 or 14" twist barrel will shoot the 150, 155, 168 and 175 KKs very well indeed if you want to shoot jacketed also.

Contrary to what some may perceive I am not in very much disagreement with geargnasher on what could or even should be done with that barrel. I just disagree on whether or not to go "all in" or not. If this were 7 card stud tomme boy is sitting there with 2 hole cards and one face up with nothing strong and a long shot at an inside straight. I say call only to see the next card, if nothing develops.....fold.....no sense holding on for that inside straight for all 7 cards.........odds of winning 1 moa or less accuracy with the 10" twist at 2200 - 2300 fps with consistent accuracy are not good. Detox's prediction of "(and neither will you shooting cast)" is the odd's on favorite.

Larry Gibson

[geargnasher]

Get a 14" twist and use the same old techniques that worked at 1900 fps and you'll get close to the same accuracy point, probably good enough for your purposes.

But, if you want to do it in a ten-twist, and it's not that hard, you're going to have to overcome some of the things that are causing the bullet to become unbalanced/deformed/non-concentric during the engraving process. Not rice paper, not magic, not hypothetical at all, just a different way of doing things based on a different understanding of what's going on. I talked about this at length in the HV thread in a couple of different posts. Works for me, anyway.

Gear

[freebullet]

Larry wrote "Holy Cow Batman, geargnasher is spouting the RPM Threshold as fact and is using it to argue against me! "
Lol, I had to read his post twice because I wasn't sure he was really saying what I thought he was.

[Larry Gibson]

What is not understood is that bullets cast with COWWs AC'd, WQ'd, mixed with Pb at 50/50 and WQ'd do require better fit of the case neck to the chamber neck to exceed the RPM Threshold in 10" twist rifles. Thus we thought it was so with all alloys and twist barrels. Fact is with harder proper alloys and proper alignment to bore and fit to the throat the tightness of the fit of the case neck to the chamber neck is not as essential. There is no "bump" and there is not obturation with such. The bullet is swaged down to fit the groove diameter and to engrave the rifling. The psi required for such (even with pure linotype bullets is far less than that required for bump up or obturation in the neck. The bullet is far down the bore before that level of psi is reached. Not a SWAG, not Quickload but actual measurement of the time/pressure curve. Some of us are proceeding to higher velocities with accuracy using cast bullets because we learn not what we think is happening but rather what is factually happening. Thus we don't pontificate on old beliefs, myths, wives tales or what works at lower velocity. We test, we observe, we learn and we progress.

Larry Gibson

[geargnasher]

Post 33, TB mentioned ten twist.

It's not a poker game at all if you know what to do.

Gear

[Larry Gibson]

Post #33 is the winner........I did ask it as a question.

Point is; with a 12 or 14" twist barrel what tome boy wants to do is rather easy. It is also easy enough with a 14' twist barrel to get moa or less accuracy with 10 shot groups at 2450 + fps. Nothing to really "master" at all is the point. If he is going to spend money redoing a barrel when a new barrel may be about the same then why buy frustration dealing with the faster twist........seems pointless is all.

Larry Gibson

[btroj]

How is a new barrel about the same cost as setting one back? Seems to me the difference is the cost of a barrel and a good one isn't cheap. Three hundred bucks isn't hard to spend on a barrel, not at all.

[Larry Gibson]

It's not the same cost. Never said it was. Said I'd put the $ s towards a new barrel, avoid the frustration and get what I wanted the cast bullets to do. Numerous members have asked you amigo's exactly how to get the accuracy you all claim at the velocity you all claim. All we've seen is pontificating and ignoring the questions. Why don't you answer the questions and tell them exactly how you do it?

It's easy to get moa accuracy at 2500 +/- fps with cast bullets. No frustration with it, especially when rebarreling. Tomme boy's rifle shoots very well with jacketed and only good to the RPM Threshold with cast bullets. There are a couple things to do that are inexpensive. I suggest he do those first. If that holds promise then it might be worth going whole hog. If that doesn't work then he's gone whole hog for naught. His odds of making a silk purse out of that sows ear for cast bullet shooting consistently accurate upwards of 2200-2300 fps are slim.

Not my rifle though. I've given my advice.

Larry Gibson

[btroj]

Post #33 is the winner........I did ask it as a question.

Point is; with a 12 or 14" twist barrel what tome boy wants to do is rather easy. It is also easy enough with a 14' twist barrel to get moa or less accuracy with 10 shot groups at 2450 + fps. Nothing to really "master" at all is the point. If he is going to spend money redoing a barrel when a new barrel may be about the same then why buy frustration dealing with the faster twist........seems pointless is all.

Larry Gibson

If he is going to spend money redoing a barrel when a new barrel may be about the same

Sure sounds like saying a re chamber and new barrel are about the same cost.

As for my shooting, I'm preparing for deer season. I have a full time job. I have other items that require my time. I also am getting ready for some dang cold weather, we are looking at highs in the 20 in a week. That isn't great shooting weather, mirage is a problem as is the sheer cold factor.

[MBTcustom]

There are no easy answers. If you want to dance, you have to pay the band.

One way is to use the twist you have, make small changes to the chamber if possible, and then spend a large amount of time and money on equipment, powders, brass, molds, and alloys.

Another way is to invest in a slow twist barrel and installation. This cuts down on the time required dramatically, and gets you shooting HS cast lead pretty quickly.

Another way is to learn to paper patch. Again with the time and money, but mostly time.

The easiest way is to use full length gas checks, pre-installed on swaged lead bullets. ie: Jacketed.
Fast, easy, foolproof, and expensive, but when compared to the money and time invested in the other options, its the best way to get 1000 aimed shots on paper at high speed.

[Bjornb]

I have 2 brand new rifles in .308W. One is a Savage Model 10, light varmint barrel. The other is a Ruger Gunsite Scout. Both have 1:10 twist. They both have reasonable throats, allowing me to load the NOE XCB bullet with only about 1/8 inch below the neck.

These rifles both shot MOA out of the box with jacketed bullets, and they are getting better with use. They will, however, not shoot cast beyond 2000 fps, they both open up past 2 inches, and this is when using all loading methods I also use with my XCB rifle.

I'm not willing to go to the dance OR pay the band, so these rifles will be designated jacketed shooters only. Sometimes the hurdles are just too high. Just my $.02.

[Hannibal]

There are no easy answers. If you want to dance, you have to pay the band.

One way is to use the twist you have, make small changes to the chamber if possible, and then spend a large amount of time and money on equipment, powders, brass, molds, and alloys.

Another way is to invest in a slow twist barrel and installation. This cuts down on the time required dramatically, and gets you shooting HS cast lead pretty quickly.

Another way is to learn to paper patch. Again with the time and money, but mostly time.

The easiest way is to use full length gas checks, pre-installed on swaged lead bullets. ie: Jacketed.
Fast, easy, foolproof, and expensive, but when compared to the money and time invested in the other options, its the best way to get 1000 aimed shots on paper at high speed.

Well said, Sir. Well said.

[btroj]

Don't give up Bjorn, there is a way, just need to find it.
Sometimes the challenge just needs to be taken on. Always taking the easy way isn't as satisfying as doing the difficult.

I didn't buy a barrel looking for easy answers. I want the challenge, I welcome the challenge.

I remember well telling Tim I figured it might take 1500 to 2000 rounds to really have an idea. So far I have fired about 200 so I have lots of work left to do. I don't see it as failure, I see it as a progression of knowledge.

This entire site is founded on the idea of doing the most we can with cast. The site was, in the early days, the purview of those who pushed the envelope. I welcome the challenges that the old timers here out forth, doing th things most say can't be done.

Doing easy things just just doesn't cut it for me. Where is the satisfaction in doing the same things everyone else can do?

[Larry Gibson]

Let's see.....the OP wants to shoot 1 moa or less accuracy with cast bullets out of his 10" twist rifle at 2200-2300 fps.........and now we are telling him to just keep trying and enjoy the trip and get only an "idea" after 1500 - 2000 rounds?

Sorry, but I prefer to tell the OP directly, without pontification how to get there if possible. I also prefer to tell the OP that he may just not get there from here with that rifle......without pontification.

Rest of the post deleted.......good grief.........

Larry Gibson

[btroj]

Pontificate-1.
(in the Roman Catholic Church) officiate as bishop, especially at Mass.

But larry, I'm not even Catholic. I will make it up to you, if you are ever in the Omaha area stop by and I will let you kiss my ring.

[geargnasher]

Dang, Larry, who tripped your trigger? No call for the insults and sour attitude. Besides, I thought you said you had "given your advice" already.

Anyway, the methods to easily get sub-MOA up to 2300 fps have been described by many people here. In fact, a couple of essentials to MY method of doing it were explained here, but poo-poo'd and blown off. Something about neck clearance and something else about alloy/powder/bullet shape and bump. Remember that? Don't think those things are important to get a ten-twist up to sub MOA 2300? Fine, go buy a new 14-twist barrel then or be frustrated trying like everyone else who doesn't pay attention to those of us telling how WE do what we do. I also mentioned two posts I made just recently on another thread where I described in great detail how I do it. If nobody believes it or wants to try, I can only say I'm sorry for all of you who feel it necessary to rebarrel to a 14 twist to achieve the same results, maybe, if your ammo is good enough for that, which means a lot of the same things have to be done right as in a faster twist because just slowing the RPM obviously won't band-aid poorly crafted ammunition.

By the way, Tomme Boy, that barrel would have been fine if you'd just throated it to about .312" and used some LC blank brass of recent manufacture so you could make it plenty long enough to reach the end of the chamber and have enough meat to easily make the necks .017" thick for a thousandth loaded clearance with .311" bullets and used the bullet 45 2.1 recommended. Or you could throat to .311" and size just a bit smaller. Yeah, I know, I got rid of both of my .30 Sil moulds too, but mainly because of the gas check shank dimension and shape that made it pure hell to get Hornady checks on straight, not because they didn't shoot bugholes. I have several thousand cast up and use them to prove to myself that a gun CAN shoot when I get frustrated with other designs, mainly my own.

Soooo, here's what you do: Cast the bullets from water-quenched 50/50 alloy and age a month before shooting. Use a Forster BR seater die to seat your bullets straight (hone the neck of the sliding sleeve as required for the larger bullets) and an RCBS cast bullet expander for 1.5-2 thousandths neck tension and only crimp enough to remove the bellmouth. Federal 210 primers and 43-44 grains of H-414 got me 3/4" and between 22-2300 fps easily. That's right in the ideal "bump" range of the alloy and powder burn rate in a .308 with that bullet weight and amount of swaging taking place in the throat. Make your brass fit the whole chamber in all dimensions with next to no slop, make sure none of your reloading processes screw up the concentricity of the case, make sure your gas checks are on exactly square and fully seated, weigh your bullets to one tenth +/- grain to minimize voids, and you'll get where you want to go with a ten twist, and that's not really with any "advanced" tricks. If any of this sounds like 45 2.1's broken record, it's because it is, he's been telling about this since before castboolits existed, though perhaps not on a grade-school level of spoon-feeding. A few other members have, too.

Or rebarrel. Or shoot jacketed. Or throat it good and paper-patches and commercial brass. Or get it chambered properly (Goodsteel will treat you right on the reamer cost), use commercial brass, and follow my instructions above. None of us can decide since it isn't our barrel.

Gear

[MBTcustom]

Gear, no offence whatsoever, but I intentionally barreled my XCB rifle in a 10 twist just so that I could prove everything you just wrote. My ammo is perfectly concentric, the boolits were aged the recommended amount of time, the necks were perfect, the length was perfect, I used several different lubes, and I used both Bobs boolit and the XCB boolit that I designed for the chamber.
Also had several others using my boolits and running tests. Did it in several of my rifles. Never, not once ever did I achieve high RPM accuracy. Got close a few times, but there was no way I could pretend that the groups (while sometimes under 2") were not double or triple the size they were at lower speed, and the worst part was they were not consistent. Almost like an engine idling rough.
We all know what is going on here. The RPM is just an easy way to judge both how badly the boolit was damaged at launch, and how badly the centrifugal force is going to play with that damage.
Using slower twist barrels makes sense on several levels. 1. the boolit gets a gentler start into the rifling, much the same as has been mentioned by Bob with the long Mauser throat, except that you get a good clean, precise engrave right off the bat. 2. you get that well engraved boolit spun up to stability without being all "three stooges" about it. I mean seriously, a cast lead boolit is inherently shorter than a jacketed bullet and spinning it at jacketed RPMs is like a bad joke. Like if I put a 1-8 twist on my 300 win mag. Why in name of all that is sacred and holy would anybody do that? You would trap yourself in a situation where absolute perfection (even with jacketed) was a necessity. Why not slow your roll and be smart about it? Why insist on racing drag cars with mud gripper tires?
I would humbly point out that the guy that has gotten to shoot high velocity the cheapest and quickest so far is Bjornb. He just bought a rifle with a 1-14 twist, had me chamber it in XCB. Boom. Instant fruition. Compared to the amount of money I have personally spent on this quest, and the hoops I have jumped through trying to get some sort of a process written down that actually work I really had to ask myself the question: "do I really want high speed? or do I want high RPM?" Who really gives a darn about high RPM? I can see going with the fastest twist that is reasonable, but why would anybody intentionally insist on beating their head against a brick wall? It has been shown (rather impressively) that racing slicks are whooping the heck out of mud tires at daytona. If anybody ever takes a trophy using mud tires, is anybody going to be impressed? Well, the driver gets to sing "I did it myyyyyy way" but other than that, whats the draw?
Personally, I believe in using the right tool for the job.

[btroj]

Sometimes a guy just doesn't own the "right" tool and has to make do with what he has. Do we abandon them and tell them rebarrel or go away?

My barrel has the twist it has. I will be living with it because I can assure you it won't be replaced, most likely ever.

I will admit that I haven't put in the time and effort so far to really understand what is happening. This entire XCB thing has become something I wish I had never gotten involved with. I may not have learned much about shooting cast at HV but I have learned much about people.

[MBTcustom]

This thread has been closed at the request of the OP.