Odd # Rifling Grooves, How To Slug?

[BulletFactory]

Hi there. I got my M&P today, it's a .40 Pro Series with the 5" barrel. Well, I was looking it over, and the barrel has 5 lands, and 5 grooves in it. How do I measure a slug from a bore like this, so I can establish the proper boolit diameter, for proper boolit fit?

[para45lda]

This has been discussed previously. I found this one but there are several.

Wes

http://castboolits.gunloads.com/showthread.php?t=96999&highlight=odd+measure+groove

[PacMan]

Not having a set of v blocks you can adjust your mic. down untill it barely touches the bullet. Then you have to slowly turn the bulet adjusting the mic. until you fine the widest part. Lead being lead you have to be carefull not to mash the bullet.With a little pratice it is not hard to do.

[JonB_in_Glencoe]

This is how I do it.
This is from the 5 th post from the thread para45lda linked to:

To measure without specialized equipment:

# 1 Use a piece of flexible, but fairly stiff shim material (a strip of soda or beer can works well). Measure the thickness of the shim material and double this number.

#2 Wrap this piece of material around the slug and measure the diameter of the wrapped slug. Use a light touch with the measuring instrument, so as to not obtain a false reading.

#3 Subtract the measurement obtained in step #1 from the measurement obtained in step #3.

This gives you the groove diameter of the odd number rifled barrel.

[BulletFactory]

Just so happens, that I have some thin brass sheets that my grandpa had from way back. I dont know what he used them for, they are supposed to be .002, I measured one at .0021, they are ideal for this sort of application.

I want to make this gun work so bad.

Gear. I read a post you made a while ago about the .40. In that post, speaking on slugging a bore, you mentioned that one should not use a wooden dowel to drive the slug. Why is that? A dowel would be the first thing I would think of to do that. What am I missing?

[cbrick]

Gear. I read a post you made a while ago about the .40. In that post, speaking on slugging a bore, you mentioned that one should not use a wooden dowel to drive the slug. Why is that? A dowel would be the first thing I would think of to do that. What am I missing?

Because the dowel will break at a sharp angle. The sharp edge will lodge between the barrel and the slug. Trust me, this will be the biggest PITA you have ever encountered trying to remove either the slug or the wood. Many a happy bore slugger has discoved this all by themselves.

Rick

[theperfessor]

Yep. Wooden dowel rods + lead slugs + hammer = grief

[geargnasher]

That pretty much covers it!

Smith and Wesson and their cutesy 5-groove barrels are a PITA. I use a Vee block and do the math, but it really isn't necessary.

Take case fired from your gun, preferably a factory load, and measure the OD near the mouth. This is your maximum loaded case dimension. Bell mouth the case, but DO NOT resize it, and size your boolits so they are snug in the fired case, but can easily be pushed in with your thumb Bic-lighter style. This is the largest boolit you can use. Use common sense to determine how to size from there.

Gear

[BulletFactory]

Thanks.

What should I use for the slug pusher? I was thinking a brass rod inserted into a piece of clear vinyl hose.

[MBTcustom]

OK, I have to weigh in on this one! I read the other thread and all the guys that were saying that using light pressure on micrometer or calipers while spinning the boolit to take measurments, need to know that that only works sometimes. Only on barrels with wide grooves, are you able to get any kind of an accurate reading, and if you are not using the provided ratchet or friction thimble on the micrometer, its not a measurement; its an educated guess based on a feeling that you are right. I am a machinist by trade, and I had to learn this the hard way when I started working at my current job and they do 100% inspection on all parts I make! I found out real quickly that accuracy is based on repeatable measurement procedures.
Case in point, I had a certain #4 MK1 enfield rifle that had 5 grooves in the barrel. I whipped out my micrometer and measured the slug at .3155. I kept having trouble with the loads and then I had the slug measured by a certified CMM measuring machine with a sapphire probe. The slug measured .3189. All my beliefs, theories, and good feelings about catching the trailing edge of two groove impressions weren't worth a tinkers curse. If I had wrapped shim-stock around the boolit, that would have been closer, but not definitive. (Actually, I believe that gets you within .0005 which may be close enough for most fellers. The best way IMHO to get a good reading is to use a triangular micrometer, or send the slug to someone who does.
As far as a slug pusher, I use a steel rod wrapped with electric tape. Make for darn sure that it has a flat face on it! Any taper on the end of the rod will make the slug act like a brake against the barrel, and you will have to drill it out. (Ask me how I know?)

[geargnasher]

Brass or steel wrapped in electrical tape works fine. Even a section from an old broken multi-section brass or aluminum cleaning rod works.

Gear

[462]

". . . you mentioned that one should not use a wooden dowel to drive the slug. Why is that? A dowel would be the first thing I would think of to do that. What am I missing?"

A sticky:http://castboolits.gunloads.com/showthread.php?t=102629

A brass rod is perfect.

[462]

Wow, three people answering at once.

[adrians]

Brass or steel wrapped in electrical tape works fine. Even a section from an old broken multi-section brass or aluminum cleaning rod works.

Gear

this is what i use,, i find a round head screw that fits in the threads and locktite it in.
use aluminum or brass screws if ya got em .
i don't use steel screws......... for obvious reasons.
the screw will "hollow out " the slug base a tad (if soft enough.) and give a good seal.
thats my story and i'm sticking to it,,,,:evil:;):twisted:

[BulletFactory]

I put a piece of heat shrink electrical tubing around the rod that I use to clean the bore on the M1A, I think that would work well for this. The black colored stuff is the right size for a brass cleaning rod when its fully shrunken into position. Looks cool too.

[mdi]

Not having a set of v blocks you can adjust your mic. down untill it barely touches the bullet. Then you have to slowly turn the bulet adjusting the mic. until you fine the widest part. Lead being lead you have to be carefull not to mash the bullet.With a little pratice it is not hard to do.
As a machinist/machine operator this is how I measured parts with "bumps" or light chatter. With a little practice you can get really close...

[405]

If I had wrapped shim-stock around the boolit, that would have been closer, but not definitive. (Actually, I believe that gets you within .0005 which may be close enough for most fellers. The best way IMHO to get a good reading is to use a triangular micrometer, or send the slug to someone who does.
)

Good advice! I've settled on the shim wrap method and if I have that "feeling" or in doubt I'll drive 2-3 slugs thru then measure and average. But, as far as cast bullet fit and function-- plus or minus .0005" should be way plenty good enough.

[Reload3006]

OK, I have to weigh in on this one! I read the other thread and all the guys that were saying that using light pressure on micrometer or calipers while spinning the boolit to take measurments, need to know that that only works sometimes. Only on barrels with wide grooves, are you able to get any kind of an accurate reading, and if you are not using the provided ratchet or friction thimble on the micrometer, its not a measurement; its an educated guess based on a feeling that you are right. I am a machinist by trade, and I had to learn this the hard way when I started working at my current job and they do 100% inspection on all parts I make! I found out real quickly that accuracy is based on repeatable measurement procedures.
Case in point, I had a certain #4 MK1 enfield rifle that had 5 grooves in the barrel. I whipped out my micrometer and measured the slug at .3155. I kept having trouble with the loads and then I had the slug measured by a certified CMM measuring machine with a sapphire probe. The slug measured .3189. All my beliefs, theories, and good feelings about catching the trailing edge of two groove impressions weren't worth a tinkers curse. If I had wrapped shim-stock around the boolit, that would have been closer, but not definitive. (Actually, I believe that gets you within .0005 which may be close enough for most fellers. The best way IMHO to get a good reading is to use a triangular micrometer, or send the slug to someone who does.
As far as a slug pusher, I use a steel rod wrapped with electric tape. Make for darn sure that it has a flat face on it! Any taper on the end of the rod will make the slug act like a brake against the barrel, and you will have to drill it out. (Ask me how I know?)

You sir are one hundred percent correct. But there is one other way for a very accurate measurement of an odd groove boolit and that would be to get a v block a one inch dial indicator and a rod of known diameter. put the rod in the vee block zero the indicator and then measure the boolit. using the diameter of the known bar as your standard either subtract or add to get your final dimension.

[BulletFactory]

My smith measured it for me, it came out .401.

I asked him what the .0000 dimension was, he said that it came out .401 flat.

Seems a little big to me, could this be right? The biggest thing I can feed the XD is .4007, any bigger, and it won't chamber.

Looks like I'll have to get a different sizer die for the M&P, and use the one I have for the XD. :-|

[geargnasher]

Won't chamber? As in anything bigger than .4007" stuffed in the brass makes the loaded outside diameter too large to fall in the chamber?

I had that problem with an M&P where anything larger than somewhere betweeen .401-.402" boolits would stop about 1/8" shy of going home on their own, and with the slide pushing it, would jam. This is with Speer brass, Winchester brass wasn't quite as thick, at least the lot I picked up off the range wasn't. I discovered that the chamber was tapered pretty drastically, and a heavy taper-crimp to swage the forward part of the case and front band of the boolit down slightly with .402" boolits did the trick. That gun had a .401" groove dimension also as best I could measure, and with .401" boolits it leaded slightly with several different powders and loading levels. I'd 1,000 times rather have a Glock, myself, they seem to work better with cast even with the stock barrel.

Gear

[BulletFactory]

Well, it takes a magazine full to get them not to chamber fully. It was that chamber shearing problem that was giving us fits a while back. The edge of the throat would shear the boolits if I got them over .4007, so I could never get a boolit large enough to stop the leading.

[Reload3006]

My smith measured it for me, it came out .401.

I asked him what the .0000 dimension was, he said that it came out .401 flat.

Seems a little big to me, could this be right? The biggest thing I can feed the XD is .4007, any bigger, and it won't chamber.

Looks like I'll have to get a different sizer die for the M&P, and use the one I have for the XD. :-|

for all intents and pruposes 3 ten-thousandths of an inch is .401 that is so small give five people the same measuring tools and you would get 5 different answers Also just holding the boolit will change the answer a tenth or too.

[BulletFactory]

I shot some reloads first time today through the M&P, and as I had suspected, I got leading. Knowing that the boolits were too small, the results were predictable. No lube star on the muzzle, and leading throughout the bore.

OAL 1.123
WW, AC 12 BHN
WST powder 4.8 gr.
WSP primers
Mixed brass
.4007
165gr, Accurate 40-160b

[BulletFactory]

I was thinking about trying unique powder, would that be more appropriate for the hardness Im using?

Easier to change powders than alloy, or trying to heat treat in my oven. I dont have enough control of things to heat treat.

[45nut]

the thing to remember when you use wood is to use short sections,, as in 2" or less. Example,, a long thin dowel you can bend and nearly loop, a short section of the same dowel is as strong as steel or more.
one more note,, I have a few v-blocks available for those folks that have a need to measure often made by Pepe Ray here.
$20.00 shipped and I will include a couple stickers as a bonus.

[nanuk]

You sir are one hundred percent correct. But there is one other way for a very accurate measurement of an odd groove boolit and that would be to get a v block a one inch dial indicator and a rod of known diameter. put the rod in the vee block zero the indicator and then measure the boolit. using the diameter of the known bar as your standard either subtract or add to get your final dimension.

good idea there Reload

Even I can understand that

[jimkim]

Why don't you just use your optical comparator?:bigsmyl2:

[BulletFactory]

Got my new mold today, ordered a sizing die, but I might not need it.


Its a LEE TC, casts at 180. Averages .4027.

When I place an unsized bullet into the chamber, and lightly press the end of it with a 2" dowel, it gives a very light "pop", and sits itself into the throat. It pops back out easily without tools, and leaves 2 shiny spots on the boolit, one on each side, 90 degrees from the mold half marks.

Will this work? Or will I wind up with a buildup of lead at the edge near the throat?

One of the boolits, the front cavity, is a smidge tighter, I dont know if it's a problem or not. I don't want to have a chamber shearing issue again. If they were a liiittle smaller, I doubt I'd need to size them at all.

[BulletFactory]

Yeah, Im going to have to size them, just a little bit. I made 3 dummy rounds, and chambered them with the slide. They showed signs of light chamber shearing.

I'll have to enlarge the sizer die to .402.

I cast the boolits tonight, WW AC, so they are still a little soft, they came in at 10BHN. After a few days they go up to 12.1.

I'm a little worried though, when I measured a pulled boolit, they came out too small, from .400 to .4007 sometimes on the same boolit. My bore is .401. Not good. Before they are loaded, they are coming in at around .4027. Im running an expander from deltaenterprises, maybe I'll have to get him to make a bigger one?

I will have to wait a couple days to see if the pulled boolits get hard enough to resist the swaging that is being caused by the seating process.

If they do not, I will have to make them harder, trouble is, I dont have a stove that is accurate enough for heat treating. When I water drop them, they get really hard, around 22BHN, I'd like to see them at 16 to 18 I think.

If I have to go harder, I'll have to change powders, I don't think the WST has the umph to obturate a boolit that hard. I was thinking about unique, because I wont have to change the powder charge between the 165 and 180 grain boolits.

If I have to water drop and the BHN goes into the low to mid 20's, what powder would you recommend?

Or, I could go with a bigger expander die, and stay with the unique and ACWW at 12.1BHN?

What should I do?

[BulletFactory]

Sometimes the rounds fail to chamber, even while firing. I'm not sure why, they sometimes get stuck half way in the chamber.

[BulletFactory]

It was the extractor. The bottom edge (first part to contact case) was too sharp. It was taking a little chunk of brass off each case. I pulled the extractor, and filed just enough off of this corner to round it off. Should solve the problem.

I wondered why there were tiny little pieces of brass inside the gun.