Lee CTL312-160-2R undersize for my P14 .303?

[LoopSoosStroop]

These Boolits water dropped mic out to about .312-.313 from my mold. I gas check them and tumble lube in a LLA/Thinners mix, and load without sizing. Alloy is COWW.

When I tried them with about 15gr of MP200 (Equivalent to Unique), they went sideways through a target at 25 m, so obviously there is something amiss.

I don't have the right stuff to slug my bore yet, but when I hammered a cast boolit into the barrel (from chamber and muzzle side) and hit it out again it looks like the rifling hardly starts engraving, and the grooves do not touch the boolit.

This probably means my groove diameter is upwards of .313, prob about .314 or .315. Why does the rifle shoot j-words so well then (MOA at 100 m)? Is it because the jackets are so hard so even the little bit of engraving spins it well?

Anyways, look like I have two options:

1. "Beagle" the mold with alu tape to try and get .314-.315 boolits and try again.

2. Powder coat the boolits to try and get .314-.315.

Any advice?

[LoopSoosStroop]

http://i1309.photobucket.com/albums/s635/vdventpieter/WP_20130812_zpsfeb58474.jpg

http://i1309.photobucket.com/albums/s635/vdventpieter/1_zpsa9eecfd0.jpg

[LoopSoosStroop]

Yeepers, I thought you guys are were a bit more helpful than this, no replies?

[Wayne Smith]

Third option is to buy some onionskin and paper wrap it. Check out the section on that, complete instructions.

[Kraschenbirn]

Difficult to make a hard judgement without a real measurement of your groove diameter but I'd guess you've called it about right and are gonna need larger diameter boolits. The question now becomes "How Large?" and to answer that you WILL have to slug your bore. You can easily gain some diameter by beagling but if you go more than .002-.003 you may begin to see a problem fitting your gas checks. Groove dia. of my Longbranch #4Mk1 runs .3125-.313 and the 185 gr Lee, sized to just over .314 (from a .313 sizer lapped oversize) will equal ball ammo for accuracy.

Bill

[Piedmont]

My P14 has a .316" groove diameter so I wouldn't want to shoot anything smaller than that in mine, and bigger might be better, but .30 gas checks max out at .316", so I would need something that took an 8mm check to go larger.

[MtGun44]

with a .314 groove diam, I'd want a .317 boolit diam.

Bill

[dromia]

Obviously a larger boolit is required and that was likely from the start the Lee's are notoriously undersized in my experience even though Lee's own tolerances are +0.003" but then what Lee says and what Lee makes are usually two different things anyway. Even if dropped as per spec as yours luckily did it was going to be under size for a .303"

However until you know what the bore, groove and throat diameters of you particular rifle are then you are only guessing at what size boolit you need. So get slugging and apply some patience.

[LoopSoosStroop]

Is it possible to get the diameter up to .317 from .312? Eish, probably not.

Another problem is that I have a 5 groove barrel, how on earth do you measure a slug coming from that?

[dromia]

"V" Blocks, they used to be for sale on here. You can still get pretty close with some practice by gently rotating the boolit in your measuring device. Most 303 shooters manage to get a good idea of their bore/groove size 5 groove barrels with out much problem.

Me I would slug, measure and then get a decent mould cut for the purpose from a good mould maker like NOE, Accurate or CBE.

[303Guy]

You can measure the bore by bumping a cast boolit down the bore until it skids the rifling then mike that. The grooves are bit trickier as you've noted. I have a 303 with a bore of .310 and another with a large bore but I don't remember what it is - it's something similar. You could as someone suggested, try paper patching. That would allow you to get jacketed velocity from cast and by the sounds of it, those boolits you have might just be the right size.

Now I know MP200 and your using 15gr of it. I'd say you launching that boolit (from the case) so hard it just skids the rifling without spinning much, even if your boolit is a good fit. It'll spin sideways like you're getting if I've got my facts right (I've been wrong before). I've shot .311 boolits from my .313 groove rifle and they took the rifling just fine but the bore-ride section was loose in the bore so accuracy was poor. I think my charge was 7.5gr or there about.

[LoopSoosStroop]

You can measure the bore by bumping a cast boolit down the bore until it skids the rifling then mike that. The grooves are bit trickier as you've noted. I have a 303 with a bore of .310 and another with a large bore but I don't remember what it is - it's something similar. You could as someone suggested, try paper patching. That would allow you to get jacketed velocity from cast and by the sounds of it, those boolits you have might just be the right size.

Now I know MP200 and your using 15gr of it. I'd say you launching that boolit (from the case) so hard it just skids the rifling without spinning much, even if your boolit is a good fit. It'll spin sideways like you're getting if I've got my facts right (I've been wrong before). I've shot .311 boolits from my .313 groove rifle and they took the rifling just fine but the bore-ride section was loose in the bore so accuracy was poor. I think my charge was 7.5gr or there about.

I have been thinking that my load is a bit harsh, supposed to give abound 1800 fps.

Will load up a few 10 grain charges and see if they work as well, without changing the bullet.

[Driver man]

I shoot 303 cast using unique and about 13 grains gives me best results. Over 13 grains causes me problems with accuracy including instability.

[LoopSoosStroop]

Ok, some results from further experimenting.

Best I could do at 25 yards with PC boolits, 10 gr MP200. Will improve with better case prep.

http://i1309.photobucket.com/albums/s635/vdventpieter/WP_201308263_zps403ec3e6.jpg

http://i1309.photobucket.com/albums/s635/vdventpieter/WP_20130826_zps0019d01b.jpg

http://i1309.photobucket.com/albums/s635/vdventpieter/WP_201308262_zps7a3efb04.jpg

Best result with a PP boolit sized to .314 loaded with 35gr S355. Six shots:

http://i1309.photobucket.com/albums/s635/vdventpieter/35grS355PP_zps4fa00a41.jpg

Will continue with the PP boolits and S355, see if I can get decent results at 100 m.

[mikeym1a]

Yeepers, I thought you guys are were a bit more helpful than this, no replies?
You have a P14, which is a .303, which has a nominal bore of .311. Obviously, it is bigger. You will have to slug the bore to find out. If there is a sporting goods house close by, go buy a bag of .36 cal pistol balls. Oil the bore, and push one through it, just don't use a wooden dowel. Once you know the land and groove diameter, you can make plans. I have the same mold, and it came in with two different sized cavities. I tried lapping it out with valve grinding compound. I had 'some success'. I size them, and wrap them. Haven't been able to shoot much, so don't know how accurate they are. I've new molds on order which should be a better fit on order. go here: http://castboolits.gunloads.com/showthread.php?206520-HM%B2-30-31-cal-160gr-6-CAV-Ed-Harris-Design&highlight he says he has .316 molds left in stock. That may be your answer. ;)

[bruce drake]

Plastic coat? What are you using to coat those LEE boolits? Whatever you used has really improved the bullet fit to your bore in comparing the before and after target pictures in this thread.

[Win94ae]

Why does the rifle shoot j-words so well then (MOA at 100 m)? Is it because the jackets are so hard so even the little bit of engraving spins it well?

That is my best guess.
I sometimes shoot .308 jacketed bullets out of my AK and the lands barely engage the bullet, it looks like smudges on the retrieved bullets.
80301
The center bullet shows the land mark which isn't sharp at all, but grips it just enough to get the job done.

[LoopSoosStroop]

Plastic coat? What are you using to coat those LEE boolits? Whatever you used has really improved the bullet fit to your bore in comparing the before and after target pictures in this thread.

Powder coat. But the paper patched ones work even better.

[LoopSoosStroop]

That is my best guess.
I sometimes shoot .308 jacketed bullets out of my AK and the lands barely engage the bullet, it looks like smudges on the retrieved bullets.
80301
The center bullet shows the land mark which isn't sharp at all, but grips it just enough to get the job done.

Good post, confirms my thoughts. These jacketed bullets run nowhere near the grooves but still produce enough pressure to work well.

[leadman]

You can enlarge the cavities in the Lee mold by spinning the boolits in the cavities with a little lapping compound or kitchen cleanser on them. Not hard to do at all, and with the PC should work for you. You also could try the Hi-Tek coating in Red Copper as 3 coats can be made to add .002" to the boolit.
If you want to enlarge the cavities warm up the mold and cast a pair of boolits that are well filled out. Mark one for a cavity so you can tell them apart. Cool the mold, put the boolits in their respective cavities, close the sprue plate. Use a drill bit that will work with a screw that you are going to put in the bace of the boolit (I use drywall screws). Start a hole in each base. I open the sprue plate to drill about 1/4" to 3/8" into the base. Remove chips, put one screw in the base, remove boolits from the mold. If using kitchen cleanser make a firm paste with water and smear some on the bands and nose (do not get it on the gas check shank). Put the boolit in the cavity and use an electric screwdriver or slow drill to turn the boolit in the cavity while keeping slight pressure on the handles. Paste will get between the mold halves so stop and clean them off. Repeat for the second cavity. You will have to repeat this several times to get .001" or more.
I have found that if I try to lap the mold out too far it tends to go out of round so check for this so you can stop before it is too far gone.

I have that same mold but it drops close to .314" so maybe if you call Andy Lee at 262-673-3075 he could check and see if there is one as large as mine at the factory.
Also adding some antimony or linotype to your COWW will enlarge the boolit some.

The 5 groove boolit can be measured by wrapping a thin feeler gauge like a .0015" around the boolit then measuring it and deducting .003".

[LoopSoosStroop]

I dont want to buy another mold just yet, I'm in South Africa, the exchange rate and shipping kills us. Also dont want to change my mold, might work well in the 7.62x39 I'm hoping to get one day.

Plan is to play with paper patching a bit more and see if I get results.

Here are my patched boolits:

http://i1309.photobucket.com/albums/s635/vdventpieter/WP_20130827_zps75d54570.jpg

Two layers of brown paper wet rolled with Sprite. Run through a Lee .314 sizer with Lee case lube. Final size abut .315-.316.