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Cast boolits in a 4(T)
Posted: Thu Jan 27, 2011 9:40 pm
by ovenpaa
I am going to try some of Dodgyrog's cast boolits in my 4(T) they are 190 grain .315" and I was going to put some N140 behind them with CCI primers.
I usually run 174SMK's or 180 Spitzers with a tad under 40 grains of N140, can anyone suggest a start load for me? The rifle will be used for anything from McQueens ar 200/300m to 1000 yard snaps.
Re: Cast boolits in a 4(T)
Posted: Fri Jan 28, 2011 12:34 am
by Alpha1
I am not sure I would use N140 with a cast bullit in a no4T Adam is the guy you need to talk to he shoots a no4T with cast bullits with excellent results at most distances.
Re: Cast boolits in a 4(T)
Posted: Fri Jan 28, 2011 7:39 am
by dromia
Have you taken a chamber/throat/lead/groove slug/cast of your rifle?
If not I would concentrate on the 2-300 yrd uses first. Boolit fit is king and until you know your rifles dimensions it will be a lottery getting the right boolit.
However for the lower pressure rounds you can usually get away with just good groove fit so hence my recommendation to stick to the 16-1800 fps loads that will do you fine out to 300 yrds. Slower velocities improve the BC of boolits/bullets.
My loads of choice would be to start at 18 gns of VV N110 or 22 gns of VV N120 working up in 1/2 gn increments to 22 and 26 gns respectively.
Any large rifle primer will do although the old Murom K-1s were the most consistent for a lower ES but I haven't seen them around for a while. What cases will you be using as volume will effect the loads.
Consistent case trim length is important as is consistent case neck thickness to ensure consistent case neck tension. I ensure consistent volume and case neck thickness by batching brass rather than turning or such like.
Depending on what trimmer you are using consistent rim thickness is needed too.
Neck sizing only, after fireforming for the rifle, is a must. I use the Lee collet die after fettling for function and size.
The boolit should be seated out to touch or be just engraved by the lands, if there is any throat wear this might be difficult with the boolit you have as it was designed for an unfired .303" throat. If you cannot touch the lands whilst retaining good boolit retention then the boolit must be sized to fit the throat, so long as it will still chamber.
Failing that a slight bell on the case mouth will help with chamber concentricity obviously the exact amount will need experimentation but the case should give slight resistance as it is chambered.
Use a Lyman "M" type die for case neck expansion so as to avoid resizing the boolit when seating, only use a flare die if you want a slight bell to the case mouth as an aid to concentricity. You seem to have some skill with a lathe so appropriately sized spuds should be easy for you.
Do not crimp.
Ultimately only your rifle and the target will tell you what you need. So get some down range as results will help refine the load, as always only change one thing at a time in load development.
Piece of p*** really.
Re: Cast boolits in a 4(T)
Posted: Fri Jan 28, 2011 9:13 am
by ovenpaa
So you run multiple resizing dies in thou increments to build the optimum boolit?
I have my soft lead at the ready so I will cast a few slugs this weekend and see what the bore measures at.
I only neck size my .303's and use a Redding type S for this.
18 gns of VV N110 or 22 gns of VV N120 working up in 1/2 gn increments to 22 and 26 gns respectively.
These give very low charge densities but I assume that is OK.
Case wise I will probably use HXP or S&B as I have a few which have been fire formed to my chamber. I will check the consistency of the neck thickness this weekend as well to see which ones give the most consistent measurement, I have some Rem and Privi brass as well so I am spoilt for choice. I can volume check as well just to see if they vary by much.
I will wait until I have the boolits and then check the COAL, I have only put maybe 100 rounds through the rifle and that was mostly to see how I got on with it and nothing beyond 650 yards, the throat looks OK but until I measure the COAL I will not know if I can build to full length.
Failing that a slight bell on the case mouth will help with chamber concentricity obviously the exact amount will need experimentation but the case should give slight resistance as it is chambered.
Use a Lyman "M" type die for case neck expansion so as to avoid resizing the boolit when seating, only use a flare die if you want a slight bell to the case mouth as an aid to concentricity. You seem to have some skill with a lathe so appropriately sized spuds should be easy for you.
So you do this to centre the boolit in the throat? Not something I have done before so ideally I should take a cast of the chamber to see how much of a bell it needs but failing that see if I can just bell it out in thou increments until it touches the chamber, I have a SincInt mandrel die so probably the best thing to do is build a mandril with a very slight taper on it and then adjust until I get the correct flare or maybe modify an existing die some how, I will take a look this weekend.
Fascinating, I am looking forward to trying this as the process for building accurate rounds with cast is pleasantly different
Re: Cast boolits in a 4(T)
Posted: Fri Jan 28, 2011 11:07 am
by dromia
ovenpaa wrote:So you run multiple resizing dies in thou increments to build the optimum boolit?
Usually I have lube/size dies made to fit my particular needs if they are not available of the shelf. They can also be used to bump up diameters.
I have my soft lead at the ready so I will cast a few slugs this weekend and see what the bore measures at.
You really need to do this at least, throat/lead/groove slug is better
I only neck size my .303's and use a Redding type S for this.
Believe it or not the the Lee collet mandrel type is better and cheaper, the mandrel ensures consistent inside neck diameter and can be easily reduced a few thou if you need it for more tension or have thin brass. However neck sizing without the mandrel collet die will go a long way to help with boolit concentricity and take up any headspace.
18 gns of VV N110 or 22 gns of VV N120 working up in 1/2 gn increments to 22 and 26 gns respectively.
These give very low charge densities but I assume that is OK.
Densities will be around 50%, at this level I've not found these powders position sensitive
Case wise I will probably use HXP or S&B as I have a few which have been fire formed to my chamber. I will check the consistency of the neck thickness this weekend as well to see which ones give the most consistent measurement, I have some Rem and Privi brass as well so I am spoilt for choice. I can volume check as well just to see if they vary by much.
I use HXP, case volume is a tad less but this helps with the powder density. I just weight them for volume consistency after trimming
I will wait until I have the boolits and then check the COAL, I have only put maybe 100 rounds through the rifle and that was mostly to see how I got on with it and nothing beyond 650 yards, the throat looks OK but until I measure the COAL I will not know if I can build to full length.
Failing that a slight bell on the case mouth will help with chamber concentricity obviously the exact amount will need experimentation but the case should give slight resistance as it is chambered.
Use a Lyman "M" type die for case neck expansion so as to avoid resizing the boolit when seating, only use a flare die if you want a slight bell to the case mouth as an aid to chamber concentricity. You seem to have some skill with a lathe so appropriately sized spuds should be easy for you.
So you do this to centre the boolit in the throat? Not something I have done before so ideally I should take a cast of the chamber to see how much of a bell it needs but failing that see if I can just bell it out in thou increments until it touches the chamber, I have a SincInt mandrel die so probably the best thing to do is build a mandril with a very slight taper on it and then adjust until I get the correct flare or maybe modify an existing die some how, I will take a look this weekend.
Yes, boolit fit is king so concentricity is essential as any boolit deformation in the rifle will lead to poor results on the target. A throat slug will give you a starting diameter but I mainly go by feel on chambering, the trick is consistency in case prep as this gives consistency to the amount of bell. The "M" die can be used if you don't need much bell but its final flare step is steep. The "M" type die is essential as it doesn't bell the case but it creates a step in the case mouth and gives a parallel neck expansion, this ensures the boolit is seated square to the case and isn't resized when seated. Tapered neck expanders on their own will not work well with cast boolits.
Fascinating, I am looking forward to trying this as the process for building accurate rounds with cast is pleasantly different
Re: Cast boolits in a 4(T)
Posted: Fri Jan 28, 2011 3:38 pm
by ovenpaa
So I can build a mandrel with parallel sides and a lead at the front and then a say 30 degree taper to another parallel, I am sure I can modify a die to suit (More fun to build it myself) How far down do you form the step, a matter of a few thou I assume.
Re: Cast boolits in a 4(T)
Posted: Fri Jan 28, 2011 4:02 pm
by dromia
Normally you want the caseneck section to be a couple thousandths smaller then your boolit 'size to' for good retention without deformation. Then the seating step above it to be a couple thousandths OVER that size. Depending upon the cartridge you normally want the expander to be long enough to expand the entire caseneck for the seated length of the boolit, while creating the step at the casemouth to a depth (or length) of about 0.050" - 0.070" or so.
I'd then make the taper die/spud separate, a slight 1 degree 30 minute or so taper is all that is required.
Re: Cast boolits in a 4(T)
Posted: Fri Jan 28, 2011 5:01 pm
by Sandgroper
Fascinating. I'm keeping notes for when I start. :geek:
I think I'll wait until my next week of leave, that way I can give it my full attention.
BTW, I've managed to get just over 5kg of lead from the WW I collected before Christmas, which was more than I expected.
Re: Cast boolits in a 4(T)
Posted: Fri Jan 28, 2011 6:51 pm
by Alpha1
Check this web site out for info on Lyman M dies
http://www.lasc.us/Brennan_LymanMDies.htm
Re: Cast boolits in a 4(T)
Posted: Fri Jan 28, 2011 7:02 pm
by ovenpaa
A picture is worth a thousand words!
