9mm skidding.....Harder lead?

[flybyjohn]

Hi, new here but had a question and in searching for an answer I keep getting a lot of info telling me that bullets lead the barrel because they are either too soft, sized too small or are being pushed too fast.

Here is my problem. I am new to the 9mm and also new to casting for the 9mm. My 9 is a RP9 with a tight chamber and barrel. The barrel slugs at .355 and my bullets are being sized to .357. .356 sized bullet showed more signs of leading than the .357 and .358 sized bullets seemed to do just fine also however I had to seat them so deep to get them to chamber that I went back to the .357 size. I am using Hitec coating on my bullets. I am using w231 powder and my average velocity is 925 fps. slowing it down much farther and it will not chamber the next round with the stock spring. I have captured quite a few fired bullets to see what was happening and to see if I could find a solution. My lead mixture started off at 50/50 COWW / Pure lead. These bullets tested at a BNH =9 (lots of leading and bullet skidding). I am now using 100% COWW tested at BNH = 18 and am still getting just a little bit of leading.

The skidding can be seen in the pictures and what is happening is the groove left in the bullet is so wide with the skidding that it leaves a nice gap for the gasses to bypass the bullet and melt the lead. When using only COWW the skidding was almost nonexistent but the bullet was still pressing hard against the rifling on one side and rubbing off the Hitec coating and a little lead was left in the barrel.

So the question is do I go a little harder on the alloy (maybe BNH =22) to see if it will stop leading altogether or is there something else I might be overlooking. 207879207880

Pease note that the lands and the grooves in this barrel are almost equal in width so the pictures show how much wider the indentation is in the bullet than the land actually is.

[OS OK]

Excellent post...welcome aboard. Empiricle evidence, can't beat it huh? Classic definition/example of 'skidding'...

Wish I could help with the hiteck but have never used it...I PC mine and always shoot around 12 BHN and don't have this problem, mine will get upwards of 1,050 FPS but still no signs of Pb'ing. The .357" sizing oughta be good but still...no experience with the Hiteck.

flybyjohn...your gonna fit right in here...hope you decide to stay and do more post like this one.

c h a r l i e

[tazman]

I don't think going harder will help much(and I am very fond of hard boolits). Your COWW should be hard enough for your usage.
You might pull the boolits from a couple of loaded rounds and see if the base of the boolit is getting swaged down in size.
Also, pushing them a little harder may swell(obdurate) the base of the boolit and help it seal a bit better.
It appears that the bore of your pistol is a little rough which may be causing some of the scraping. Check your barrel for tool marks and rough spots if you can.

[flybyjohn]

Thanks. the coating on these were my first try and I have learned a bit since then. I think I have a much better applied coating now so I will catch a few more tonight. I also tried to water quench after the last cooking session of the coating. Not sure if the lead is hot enough or not at 400 deg to do any hardening in water but gave it a try. I will post some more pictures after I catch a few tonight and see if I am having the same problems with my latest try at applying Hitec.

[flybyjohn]

The barrel is pretty shinny and smooth now. I spent quite a bit of time on it with some copper bullets and JB past. It still could use some more but the spots in the pictures where the lands have totally removed the coating is where it skidded to. If you open up the picture of the two photos side by side, the left side has some lines drawn on it. The imprint of the land into the bullet is about 1 1/2 to 1 3/4 the width of the land. The coating stayed on where it originally started and then appears the skidding wiped or scraped the coating off at it skidded in the barrel before the bullet picked up enough twist to grab and start rotating.

I had a problem of the brass swaging down the .358 bullets but it doesn't do it to the .357 bullets.

[JimB..]

I wonder if you have a tight spot in the barrel.

Do you use a Lee factory crimp die?

[OS OK]

As that coating is being pushed laterally with the Pb...I think it is uncovering uncoated Pb, then the gassing is vaporizing molecules of Pb that gets laid down on the barrel.

Our PC method of coating I think has some stretching and forgiving aspects to it, whether a PC'd cast will still show this 'skidding' or not is debatable but the gassing doesn't pull the PC off. I've recovered casts that had some splotches of PC missing in random fashion (I over cooked them before I got a reliable oven thermometer) but they still don't Pb the barrel because the thickness of the PC is still there between the cast and the metal of the barrel...sorta like having a jacket of sorts.
We proove that the PC will stay there by hammering them flat and the just stretch with the cast as it flattens.

I'm not trying to sell you on PC, just drawing parallels.

[Grmps]

Welcome to the forum flybyjohn .

I've never seen COWW run 18 BHN, (unless you got some zinc in it)

There are several threads about leading in the 9MM. Type 9MM leading into the Google custom search bar at the top of the forum page
The 9MM has a tapered case and is frequently over crimped thus swedging down the size of the lead bullet.
Pull some of you loaded 9MM ammo and see what size the lead bullet is.

With 9MM I seat and crimp with the same die.
I crimp only hard enough to keep the bullet from moving in the case when I push the cartridge against my loading bench.
Then I run it through a Lee FCD only to where the die barely "kisses" the bullet to assure fit in the chamber without downsizing the bullet.

I run my 9MM around 10bhn with no problems.

Here is a link to bumpo628's lead alloy calculator
http://castboolits.gunloads.com/showthread.php?105952-Lead-alloy-calculators

"I had to seat them so deep to get them to chamber"
not familiar with that particular firearm but your gun may need to be "throated" to allow a better fit.

Did the Hitek bullets pas the smash and rub tests?
The coating looks a little rough which could indicate you are swirling them to long.

there are several threads on Hi-Tek in the Coatings and Alternatives forum

http://castboolits.gunloads.com/showthread.php?240450-HI-TEK-do-s-and-don-ts

http://castboolits.gunloads.com/showthread.php?204174-simple-Hi-Tek-coating


If you can't find the answer there feel free to PM me

[flybyjohn]

Just to clarify, the picture that has the most lead exposed is with BNH 9 lead and the picture that has most of the coating still attached is with the BNH 18 lead. Powder and everything else was held constant. The jump to the harder lead decreased leading 10 fold, I was just wondering if I should go a little harder to see if I can reduce the cutting through the coating all together.

When I slugged the barrel, the slug seemed to push through with even pressure the whole way down the barrel.

[Larry Gibson]

I've never found any COWWs that measured 18 BHN either unless they were WQ'd(?).

Also can you explain to me what you perceive as "skidding" on either bullet?

Also, your alloy of straight COWW has little tin if any in it. What you see as "leading" may be antimonal wash. Mixing 2% tin with the COWWs will fix that and give you a better alloy.

[flybyjohn]

I may have got a zinc one in there but I thought I got them all out. They fill out the molds good. The ingots have a real good ring to them when they drop on the concrete floor where as the stick on weights and range lead have a solid thud to them.

I flair just enough to barely get the base of the bullet in and don't get any scraping while seating and then I crimp just enough to get the brass to just make it to the bottom of the chamber. It usually has a friction fit and takes a slight push to get it flush with the top of the barrel and then a little tugging and wiggling to get it back out.

The coating I am using is the copper stuff and I have tried pouring the bullets out when they are wet and dryer. One time they were still so wet that the coating pooled under the bullets. I think I got it down now though. No matter what stage you poor this copper stuff, they always seem to be a bit rougher than the reds and golds that I have had in the past. Hitec states that the copper has more solids in it and is tougher and builds thickness more than the other coatings. Knowing I was going to be coating 9mm I decided to get the copper.

[flybyjohn]

Larry, yes they were water quenched while casting and then again on the last cooking session of the coating. That was from 400 to 410 degrees into ice water. The harder bullets did not skid near as much as the softer lead, if any at all. there is only one picture of the harder bullet and it is the one with most all the coating still on it and it has even land and groove imprints in it. (the first picture)

If you look really close at the bullet missing the coating, the impression of the land made a full length imprint to the left of the lead patch that is at least half as wide as the lead mark that the land left on the bullet after it stopped skidding in the bullet. To simplify what I am trying to say, the indentation in the bullet is 1 1/2 times the width of the land which leaves a channel for the gasses to pass the bullet.

[Grmps]

Check out
Testing hardness with pencils
http://castboolits.gunloads.com/showthread.php?75455-Testing-hardness-with-pencils

With HiTek, first coat should be less than 1 mil per pound of bullets
Coating solution MUST be well mixed IMMEDIATELY before applying to the bullets (it drops out of solution quickly, especially the coatings with metallic particles in them)
10-15 second swirl is all you need. OK if they are wet when dumped, if the sound changes, you've swirled to long.
coating needs to be 110% dry before baking ( I use a fan to dry then set them on a spacer on my oven for 10 min to warm and make sure they are dry.
https://i.imgur.com/mLBMrYx.jpg

https://i.imgur.com/u5Lwrbl.jpg

Double-check oven temp with an oven thermometer set in the middle of the shelf your baking on to confirm temperature is 400°
https://i.imgur.com/v13pXhA.jpg

[popper]

I use an XDs9, with isocore now. Good capture job. Coating looks a tad thick, center circle in pic is normal, the other circled aren't. IMHO they are too small as the H.T. isn't burnished in the bore part but scraped away in the groove. Normally you get the bore part scuffed back into the groove. I use a different profile nose (RNFP) so plunk test is not a problem.

[runfiverun]

try a second coat of the Hi-Tek.

[tja6435]

I'd do a 2nd and/or 3rd coat of Hi-Tek and I would have the barrel throated so I could seat out .358 bullets where I wanted them, not where the throat is currently dictating.

[flybyjohn]

GRMPS, my first coat is very thin and mixture is measured on a grain scale and acetone is measured with a seringe. 103gr high tech powder with 33 ml acetone. Here is a picture after first coat.
207903 207907
My oven has been rewired and is controlled by a pid temp control with the thermo couple 1/2"under the center of the bullet tray. The convection fan was wired on another circuit to be on a separate switch so it does not go on and off with the oven pid control.
207906
The liquid coating is mixed in a condiment plastic container with a siringe attached to the top and is sucked out immediately after shaking.
207905
After coating the bullets are dried on a rack close to the wood stove with the fan blowing warm air over them. Each load is cooked in the convection oven at 410 degrees for 11.5 minutes. 4 coats are put on each bullet using 4 ml of solution to 5.5 lbs of bullets.

[flybyjohn]

Ok I am not sure everbody could understand what was happening in those original pictures. Here is another shot of a bullet made out of the softer BHN 8 lead shot at 950 fps out of the 9mm.
SOFT LEAD BHN 8 sized at .358
207912

you can see that the indent in the bullet is quite a bit wider than the actual land is and so gasses were running up along side the bullet and melting the lead creating lead in the barrel. I am now using a harder alloy and am getting very little skidding but am still loosing alot of hitec coating from the lands of the barrel.
HARD LEAD BHN 18 sized .357
207915

You can see in this latest picture that the skid is just a long narrow triangle shadow along the left side of the streak of lead up near the top. I can live with this because the bullet seems to be sealing all the gasses behind it but now the question is why are the lands shaving off the Hitec coating.
Here is the same bullet showing the other side, the hitec almost survived on this side of the bullet.
207916

I do agree that the barrel could be throated and maybe my lands taper is to stiff of an angle and needs to be laid back a little.

[OS OK]

It's obvious that the 9 BH is too soft but with these latest pictures I think you have nailed it thinking too abrupt of an angle on the lands and that throating will solve the problem with this latest blend.
We have DougGuy, I think is is his handle who recuts the throats and changes the angle on the lands, he has also discovered chambers and barrels that are not parallel and fixes that too, I think...seems that someone just mentioned that problem.
Everyone who gets their barrel back raves about his work.
I just had a new barrel put in my 1911 and had the barrel throated, didn't have any leading problems with it but now a RNF profile doesn't want to stop the slide just before going 100% into battery.

PS...When someone comes to the forum trying to solve a problem you can see there are many here who love solving a good riddle...I hope others here are noticing what a fine job you are doing posting carefully taken pictures and being so detailed in your comments...that really helps and makes for a really good thread.

c h a r l i e

[tazman]

I think you may have your answer with the idea about the lands being too steep at the chamber. This seems to be a common occurrence in recent pistol manufacturing.
DougGuy is the one to contact. He fixes this type of thing and I can vouch for his expertise. He did 2 barrels for me and cleaned up my issues with them.

[Grmps]

FBJ,
You have been one astute and observant lurker,

I also appreciate the way you outline and document a question and answer.

4 coats, wow. 1 coat will do the job but isn't pretty, HiTek is a stain, the first coat fills the pores and bonds to the lead, the rest is garnish. Most people go 2 coats, more if they want to fatten the boolit.

[runfiverun]

I want to commend the OP on his communication skills.
he answered each suggestion with a reply about what he had previously tried and about his process making it easier to look at things from top to bottom.

not being my usual sarcastic self here.
but it also illustrates that these coatings are not a cover up or magic band aid for doing things right.

[Eddie17]

I’m agreeing with runfiverun, maybe a second coat!
I shoot my 9mm boolits at 15 BHN or more. I PC and size after pc to .357.
My major lead supply is this hard so I use what I have.
PC works for me.

[Larry Gibson]

Thanks for the second set of pictures, easy to see the skidding. Obviously as you surmised and others have said the BHN 9 alloy is too soft. The WQ'd COWWs should be around 18 BHN so that is correctly understood now. Again, thanks for the additional explanation. As to the coats of PC on the bullets I can't say as I don't use the stuff. I prefer to just lube the bullets.

[Outpost75]

Interesting thread... I'm not familiar with the RP9, nor am I with PC. My best results in 9mm with cast have been in NATO STANAG 4090 chamber, with conventional lubricant, shooting as large a bullet as will chamber, best being H&G#7 124 grain at 13 BHN sized. 358" with lightest charge of Bullseye or 231 which cycles reliably. Mostly shooting Beretta 92s and FNGPs, also had good results in SIG P210 and HK94 carbine, most often 3.5-3.8 Bullseye or 4.2-4.5 W231. Accuracy at 50 yds equal to or better than M882 Ball or Olin OSM 147-grain.

Looking at your bullets the PC hasn't adequate shear strength and bullets are too small.

[flybyjohn]

Outpost75, I just wanted to know the reasoning behind you stating that my bullets are too small. If you look at the last two pictures in post 18 there is no indication that any gasses are getting g around the bullet. I’m I missing something or is gas sealing the only reason to make the bullets larger. The bullet itself is making a great seal in the barrel. It is sized .0015 over the barrel diameter right now and I did have them sized .0025 over before with the same outcome as the last two pictures in post 18. I am interested in learning so please let me know your reasoning.

Also I am using Hitec coating not powder coat. A bit different but overall a poly coating over the bullet. They use it in rifle bullets too at velocity over 2500fps. My bullets are coming out of the gun at under 950fps. I personally think the lead is shearing. Just retested a bullet hardness tonight and it test at 20 BHN
I might try to soften the lead a little and see if I still have the problem of lands taking off the coating.

[popper]

It's not the gas cutting, it's the lack of abrasion on the bore part of the recovered boolits. Too small & hard, side never touches the bore and effectively the same as rifling too shallow. I've recovered a few and looked at lots of pics.

[flybyjohn]

Both the lands and the grooves are touching the bullet. The bullet is being sized by the barrel. Here are a few shots of the bullet that was caught after being fired and a bullet pulled from the brass that was loaded. You can see where the crimp just dented the bullet right up at the top. This is the least invasive crimp possible with this bullet and barrel or the round won’t chamber. The top of the brass after crimping measures .380 and gives a friction fit in the chamber.

FIRED BULLET

208076
208077

PULLED BULLET

208078
208079

The reason the mark in the pulled bullet base is that it was a dummy round without primer that I tapped the primer hole and pushed the bullet out of the brass. It was loaded on the same setup as all the other bullets I just did not prime and I dumped out the powder before placing the bullet.

So with this info , is my bullet still too small?

[wimms]

Interesting. flybyjohn, skid marks are usual with revolvers but rather rare with auto pistols. They explain it with the fact that bullet gains substantial linear velocity before engaging the rifling and requires large rotational acceleration then.

In relation to your issue perhaps your barrel has longer than usual free bore.

It would be interesting to see a picture of your unfired cartridge, and a chamber showing the leade.

What OAL did you chose? I think you'd prefer longest OAL that works reliably for you.

What powder do you use?

[Forrest r]

Both the lands and the grooves are touching the bullet. The bullet is being sized by the barrel. Here are a few shots of the bullet that was caught after being fired and a bullet pulled from the brass that was loaded. You can see where the crimp just dented the bullet right up at the top. This is the least invasive crimp possible with this bullet and barrel or the round won’t chamber. The top of the brass after crimping measures .380 and gives a friction fit in the chamber.

FIRED BULLET

208076
208077

PULLED BULLET

208078
208079

The reason the mark in the pulled bullet base is that it was a dummy round without primer that I tapped the primer hole and pushed the bullet out of the brass. It was loaded on the same setup as all the other bullets I just did not prime and I dumped out the powder before placing the bullet.

So with this info , is my bullet still too small?

Sounds like you have a couple of things going on at the same time. IMHO

You have too light/soft/low pressure load
Too many coats on your bullets and the coating is failing
To much coating that's making you're already short chamber (no leade) even shorter causing you to seat the bullet even further back (shorter oal) in the case.

All's increasing the alloy's hardness did was aid in the knife cutting (scraping) of your coating when the slid rammed the nose of your bullet into your non-existent throat/lands. If you look closely at your excellent pictures you've posted above of the side view of your fired bullet. You can clearly see a cone shaped land mark (wide at the nose of the bullet/normal at the base of the bullet). That's telling you that the base of the bullet sealed but the load didn't have enough pressure to fully expand the entire drive body of the bullet.

Hitec is a polyurethane (hard) coating, the dry powder coat coating is a polyester (soft) coating. I don't use hitec but I've driven bullets coated with pc in rifle loads well over 2800fps and loads 50,000+psi. Both coating can be scraped off, I just find the pc coating more forgiving when it's slammed/forced into a non-throated bbl that has sharp edges.

I've showed this picture beforehttps://i.imgur.com/ZxGtzF4.jpg

That's a taurus pt111 9mm, taurus is known for their large bbl's, that pt11 slugged out at taurus's normal .358". Those are home case 125gr Mihec bullets using nothing more than 8bhn/9bhn range scrap and sized to .356". While the load was not p+ by any means it easily expanded the soft bullet enough to seal the bbl and the hp worked as it should. You're getting 975fps from a 4.5" bbl and 18bhn bullets that have the nose skidding on them. I'm getting around the same velocity from a 3.5" bbl with a 2/1000th's undersized bullet. The difference:
hot load vs light load
8bhn vs 18bhn

If it was me I'd try less coats on your bullets, less coats ='s smaller nose diameter/better for non-throated bbl. Increase the load and seat the bullets a little deeper. Most people see a picture of the plunk test and load them with oal's for "the most accurate"/flush oal. I like to run my oal's +/- 15/1000's below flush (keep the nose of the bullet from being jammed into the throat of the bbl), especially when using an oversized bullet. I'd also use a softer alloy, I've shot countless 1000's of 9mm over the decades using nothing more than range scrap in several different firearms. I do try to keep my loads in the 25,000psi+ range.

Just something to think about.

[flybyjohn]

wimms, I have read through my research that autos with a fast twist and shallow lands do sometimes have a tendency to skid. From what I have read,for lead, 1:10" is a little too much of a twist for lead.

Here is a picture of the chamber and lead. I KNOW BEFORE ANYBODY SAYS ANYTHING that the barrel has a flaw. It is being sent back today to get looked at. These bad tears in one groove of the barrel are not showing any signs of capturing bullet debris or marking the bullets up in any way. The uneven machining of the lands might be a different story. I will get a picture of an unfired bullet tonight but here is the chamber.
I am loading with the following:
Lee Mold .356 lead round nose 125gr, 4 coats hitec coating, sized .357"
Winchester small pistol primer
3.4 gr. w231 powder
1.09" OAL ( 1.070" with bullet sized to .358)
950 fps average velocity
taper crimped to just allow brass to friction fit into chamber.
Pulled bullet from brass measures .357"

208088

[flybyjohn]

Forest r, I am trying to wrap my mind around what you are saying. The Hitec coating is not very brittle that I can see. For the bonding test, a hammer is used to flatten a bullet and the coating stays attached to the bullet even after being deformed. I think the coating is shearing off with the lead.

I also don't think the bullet is hitting the lands when it is chambered. I have looked at many of the chambered, unfired rounds very closely trying to figure out why my .358" sized bullets were not going all the way into the chamber when they were seated to 1.09". On carful inspection, looking specifically for land marks, I did not see any marks on the bullet when pulling them out of the chamber. I never did try to pound one into the chamber but the slide spring slamming the round into the chamber did not leave any marks on the bullet.

I am using a very light load of powder charge. It is only about .3 gr above the charge needed to cycle the pistol. The brass falls right at my side, a 5 gallon bucket one foot from my leg would catch 95% of the brass being ejected. I agree with you that the charge is not enough to expand the entire bullets length.

I assumed the bullet was skidding because of the following:
1. The bullet being a smaller diameter and faster projectile was shoved forward into shallow, high twist rate, rifling. The bullet is shoved out of the brass straight forward with no twist, then it hits the rifling and has to start twisting. Being a smaller diameter bullet (than say a .45) the rifling would not have as much leverage to start twisting the bullet, it also is doing it under a higher velocity.
2. The softer lead along with the shallow, high twist rifling would allow the bullet to skid farther before finally getting the bullet up to twist speed and catching fully on the rifling. This skidding created wider channels than the lands, the full length of the bullet allowing gas to bypass the bullet and melted lead in the bore.

My initial idea to fix this extreme skidding (shown in the first post) was to use harder lead so that the lead would catch better on the rifling and to use a slower powder so that the bullet would start down the barrel at a slower velocity, catch on the rifling, and then pick up more speed the farther it got down the barrel after the rifling had fully engaged in the bullet. I did not try a slower powder as of yet.

I hardened the lead alloy and the bullet skidding completely disappeared at the bullet base but as you can see in the pictures there is still is a little skidding up at the nose. The coating with a little lead is being sheared off the bullet by the lands as it rides down the barrel. On the latest recovered bullets, only half the lands took off the coating. I might need to mark my bullets that I catch before firing and see if the same lands are taking off the coating. Maybe it is confined to only a couple lands.

I have always been at the bottom end if not below the starting powder charge. At this point, I can see that a softer bullet and/or more charge may allow the bullet nose to deform easier so that the coating may stay attached to the bullet.

[popper]

That's telling you that the base of the bullet sealed but the load didn't have enough pressure to fully expand the entire drive body of the bullet. I have the same problem with 30/30, tight bore at neck and loose down the bore. Did you mike the front band and the base? My solution is jacketed, really hard alloy or GC on soft alloy. First clue is the back edge of the front band, lands move metal but bore doesn't. If the barrel is to be replaced, nothing to worry about now. A faster powder might help. I'm using WST (3.7gr) in my 9 instead of W231 (4gr) for a 138gr boolit. Mine is a XDs sub and WST gives better recoil response. IMHO, PC is a little more forgiving than HiTek when you have a problem.

[mdi]

My first try would be to use a slightly larger bullet, mebbe .002"-.003" larger (as long as the finished round will chamber and a Lee FCD is not used). Eliminate one possible cause at a time...

I have cast for my 3, 9mms and tried many alloys, 12 to 19 BHN, coatings and sizes, but it's more involved to make 9mm shoot well with cast. I have succeeded, but I have to use 3 different processes on the bullets for the 3 different guns (my Ruger can shoot nearly any bullet cleanly with 45-45-10, my old Tokerev likes fat bullets w/C-Red lube , .359"+, and my HMK likes hard bullets sized to .357" with any wax based lube). For my "just in case" stash of ammo I just went with 124 gr JHP which works well in all three.

[runfiverun]

after looking at this again, and thinking back on some other issues and going from my past results.
I think before I got too worked out of shape I would try another powder.

231 just seemed wrong to me in the 9mm.
I mean it seemed right on the surface, but it just shot,,, I dunno too soft maybe?
anyway I am not a fan of it in the 9mm [with cast or reduced it seems fine with jacketed at top speeds] and have always had better luck with a faster powder.

[flybyjohn]

The 3.4gr w231 over the 125 gr makes my 9 mm feel like my 45acp @760fps.

I tried a few rounds with 3.0 gr VV n310 970 fps and it definitely was more snappy feeling. 3.4 gr pushed it at 1050's but was to snappy for plinking steel targets. I think I was getting pretty high with pressure.

Doing the research, many people use the w231 in 9mm for light loads.

I am sending this barrel back due to the bad machining in the groove but I suppose I will have to figure our these same problems whether or not I get a new barrel.

I have some 50/50 COWW/stick on WW in the pot now that I was making 45 with. I will mould up a few 9mm with it and, coat and try them out again using a bit more powder to see what difference more pressure and softer lead will make.

[wimms]

What caught my eye is the full length shearing. Thats not how I understand it's supposed to happen. If you consider how the boolit goes into rifling, it almost immediately starts to experience rotational torque that increases as the rifling cuts into the body. So the skid marks of initial rifling engagement necessarily have to be converging towards the base, and usually are with very short converging distance.

But in your case, soft boolit seem to have sheared the initial engraving while already fully in the rifling. This seems to indicate very violent acceleration of the boolit at some point. I assume you do not see any overpressure signs?

Perhaps the boolit was driven into the rifling by the primer alone, completely stopped there as the powder did not ignite properly, sticked with rather high static friction, then powder developed the heat and pressure so fast that when it overcame the static friction the boolit experienced extreme acceleration that caused more rotational torque than the soft lead could handle and that displaced the engraving grooves.

Internal ballistics is a tricky balance between rapidly expanding gases, accelerating boolit and expanding volume behind the boolit. Boolit being in wrong place at a wrong time can cause unexpected pressure and acceleration spikes.

You may have better results with heavier boolits or slower powder. Also increasing powder charge should make its ignition faster and more consistent, ensuring that the boolit doesn't stop after leaving the case. You want smooth and limited boolit acceleration.

Generally faster powder is used with heavier boolits and slower powder with lighter ones.

[flybyjohn]

As far as overpressure signs, the primers don't look any different than the factory Federal ammo I fired. The brass is not oversized after shooting and the recoil with the lighter loads is much softer. The powder fouling gets dirtier the lighter the load, which I think would be the opposite if it was extremely high pressure. Here is a bullet that was shot at a very low velocity, too low for the gun to cycle. It did not skid or loose any coating. No sure of the velocity as I was just trying to find the lowest load that would cycle. I am pretty sure it was the harder lead though.

208222

[flybyjohn]

I am going to make up a few softer alloy bullets again and shoot it at different powder charges and catch the bullets. I will start at 3.2 gr which is the absolute minimum it needs to cycle and work 5 round up in .2 gr intervals. Then I can look at all the bullets in succession and see just how the skidding varies by speed at that bullet hardness. I will document a bit better this time to make everything more consistent. Maybe then we can see what might be happening.

[OS OK]

I guess that I missed it when you said how your catching those rounds so undamaged?

How'd you do it?

[flybyjohn]

Something I came up with that works for lower velocity bullets. Wouldnt try it on high vel rounds though. I have a 6" pvc pipe that is stuffed full of plastic Walmart bags. I bag a bunch of bags in one bag and then load all the full bags into the pipe. Most bullets make it 3' but some a little more. After the shot, I start pulling bags out of the end. Each bag will tell you if the bullet made it through by leaving a pulled out tit on each bag. The one that doesn't have a hole is the bag it is in. The bullet is almost perfect being caught this way.

[Forrest r]

Never had any issues with small/thin lands in bbl's. I have a couple of custom 1 in 10 twist bbl's that have extremely small, thin lands for 357's (4" & 6"). They easily handle anything from mild to wild.

Some recovered bullets shot from different firearms/calibers with loads from mild to full house mag & 9mm loads. This is with pc'd bullets.
https://i.imgur.com/kALCcSf.jpg

I've recovered 100's of bullets and they always have something to say. What that picture above showed me is the difference between air cooled range scrap (+/- 9bhn) vs water dropped (+/- 13bhn). Some bullets shattered while others had excellent expansion/retention with hp's. The non hp bullets noses either compress/deform or stay unaltered. It's always the same theme again and again.

Playing around with a 308w testing alloys for hunting. Was looking for an alloy that would have the bullet deform & stay intact. As I changed alloys I increased to pressures/velocities, a bullet shattering is no good.
https://i.imgur.com/9TAAbA8.jpg

When I got to the 2300fps bullet I found a alloy worth testing with several different bullet designs. That 2300fps bullet is a lee 230gr bullet that had a 50,000+psi load pushing it. That softer 230gr bullet also showed signs of the coating becoming easier to scrape off.

What all those bullets pictured above have in common is compression & more importantly compression where it counts, in the lube grooves. Lube grooves are designed to compress and push the lube outward and forward. While coated bullets don't need lube their bases still compress. With coated bullets you want to match the alloy with the bullet's diameter to allow the bullet to expand/compress/seal the bbl.

Will a bullet 3/1000th's over the bbl diameter seal a bbl??? Absolutely!!! The issue becomes how will that oversized bullet react to any imperfections, rotational torque, pressures at different points of the bullets body, etc.

Several years ago I had an excellent conversation with a member on this website. We discussed lube grooves (square vs round) and he was kind enough to send me this photo. If you look closely you can see the lube grooves are compressed on the recovered bullets compared to the as cast bullets pictured above them.
https://i.imgur.com/M8QJ3DM.jpg

You need to compare the lube groove of your recovered bullets to the un-fired cast/coated bullets. No compression ='s no worky. Something else to keep in mind when choosing loads for a bullet. A bullet that has a long/large area of it's body like a wc has a lot more resistance/bbl contact then your bullet. More contact ='s less pressure needed for obturation bullet/bbl fit. The bullet you're using has 1/2 of the bullets body at best in contact with the bbl. Less contact ='s soft alloy + high pressure.

When you get your new bbl back I'd bump your load up to get in the +/- 25,000psi range. I use a bullets in the +/- 9bhn range for 3 different 9mm's. The green bullet in the picture is a lot like the bullet you're using body/design wise. Both bullets are loaded for the same 9mm.
https://i.imgur.com/8DH6L77.jpg

Not a hand picked/cherry picked target by any means. It's nothing more than a test target used to test those 9bhn/125gr greeen bullets pictured above using a 25,000+psi load. That load/powder is also a powder a fast burning that has a high quick start pressure that's excellent for getting the bullet to seal the bbl in a hurry. You can have 25,000psi loads with wst and AA#7. The wst smacks the bullet while the AA#7 pushes the bullet. The wst will seal quicker/faster.
https://i.imgur.com/N6XBlbc.jpg

Anyway, you have a lot going on with your firearm and reloads. When you get your bbl back I'd go back to a softer alloy and bump the load up.

[dubber123]

I wasn't going to respond as I don't have a ton of 9mm cast experience. Forrest certainly seems to, but what I have found in my testing hasn't indicated any particular need for an overly hard boolit, and I'm not powder coating. My normal alloy is air cooled WW's, about 14 Bhn per an LBT tester. I did shoot a few groups with boolits made from shotgun shot pilfered from cheap trap loads to prove a point. Now the common thought is that shot is hard, well not the cheap stuff.. My regular 9mm boolit is a 150 grain RF, but out of shot, they weighed 155. 5 grains is a lot to gain, and that tells me there was a LOT more pure lead in that cheap trap load shot. I never tested them, but I'm betting SOFT.

I'm not as good a shot as Forrest, but the gun, an inexpensive Zastava M-88A with a 3.7" barrel shot under 1.5" at 20 yards using the car roof for a rest, and I did it several times. The load used produced well over 900 fps, which is not low pressure using the fast powder I was loading. This matches Forrests findings of bumping up a boolit to seal the bore. I'm not generally a fan of super soft boolits, but it worked in this instance, the bore was clean, and accuracy was as good as my regular load. If you have boolits skidding, my first thought would be undersized boolits, I hope you get it figured out.

[Lloyd Smale]

have to agree with larry. As a matter of fact ive had linotype buys that only tested 18bhn. 5050 ww/lino usually goes 16-18bhn and that's with good lyno. Never had a batch of ww test any harder then 12bhn. Most of it tests closer to 10. How are you testing it? Ive got both a cabin tree tester and a saeco. Now if your water dropping your ww you should be about right on the number at 18. If your bullet is testing 18 (water dropped as you said) its hard enough for about any handgun application and is hard enough where I doubt that's your problem at 9mm velocitys. One thing to watch in loading 9mm is to make sure you start the bullet in the case straight. With small bullets in my club fingers I have to allways keep that in mind because the 9 is about the worse offender when it comes to having bullets seat crooked. The way they enter the rifling a little off center can make marks that look just like stripping. Actually I too don't see enough evidence of stripping to think that is causing you any trouble. Keep in mind too that its a ruger not a les baer and the rifling might be cut with one land a tad wider then another. Again it shouldn't cause any real problem at handgun range. What are you calling bad leading. Is it actually building up more and more as you shoot to the point it effects accuracy. Or is it just a lead wash that gets no worse. About any gun shooting lead will have a light wash in it and I don't even concern myself with removing it. How many rounds before it effects accuracy. My guideline is if I can shoot the amount of bullets I usually shoot in two range sessions without groups opening up again I don't worry about it. If it is you can still use your alloy as long as your getting accuracy. Just buy a box of jacked bullets and load them up and shoot one about every 50 rounds and it usually will push any lead build up out. Same can be done with a gas checked bullet or even a very hard plain based bullet. Also being a ruger id consider right from the git go shooting maybe a 100 jacketed bullets through it, clean it thoroughly and then shoot cast. That usually smooths up the barrel a bit and make a slightly rough barrel a little more cast friendly.
I've never found any COWWs that measured 18 BHN either unless they were WQ'd(?).

Also can you explain to me what you perceive as "skidding" on either bullet?

Also, your alloy of straight COWW has little tin if any in it. What you see as "leading" may be antimonal wash. Mixing 2% tin with the COWWs will fix that and give you a better alloy.

[ioon44]

The COWW I have used has always run 10 to 12 BHN , and work grate in .45 APC with the Hi-Tek coating. For 9 mm and .40 S&W I have better results with 6-2-92 alloy.

As far as barrels I have a SR 9 that I had to sent the barrel back 3 times to get a barrel that didn't have a huge amount of machine marks in the barrel. Ruger customer service was really good to work with, but the rough barrels should never have left the factory.

[Forrest r]

Thank you dubber123 for the kind words but I'm not that good of a shot anymore, gotta use a rest now to shoot bugholes:killingpc.

I quit buying lino-type years ago, just to much difference it it. I still do use mono-type and will mix mono/pure for any specific needs. Mono-type tends to be more consistent. I do also still use lead/tin alloys for some of the hp's I cast. Just got given another #60 of 50/50 so I'm pretty much set for life.

IMHO
I think there's to much made out of alloys/bhn's/pressures. Since the 80's I've used nothing but range scrap for 90%+ of my casting needs. Pretty complicated, make #100 batches and then the real hard part. Either air coll or water drop??? Yup 8/9bhn or +/- 13bhn. Shot countless 1000's of bullets in several caliber in a bunch of different firearms over the decades. Plain old nra 50/50 lube. Heck now it's to darn easy to find accurate loads with the modern coatings. Makes all the finding the right combo of the bhn/lube/load (pressure) so much easier.

I'm sure to op will get everything dialed in when his bbl comes back. For some odd reason I thought the rp9 was a remington pistol? O-well, getting old

[flybyjohn]

It is Remington. You are not that old yet.

[wimms]

As far as overpressure signs, the primers don't look any different than the factory Federal ammo I fired. The brass is not oversized after shooting and the recoil with the lighter loads is much softer. The powder fouling gets dirtier the lighter the load, which I think would be the opposite if it was extremely high pressure. Here is a bullet that was shot at a very low velocity, too low for the gun to cycle. It did not skid or loose any coating. No sure of the velocity as I was just trying to find the lowest load that would cycle. I am pretty sure it was the harder lead though.

flybyjohn,

In my understanding such full length radial shear can happen only from radial torque and that can occur only by means of excessive acceleration. Acceleration is directly proportional to pressure, so some kind of pressure spike must occur. It may be so short-lived that it does not show up on primers taking literally microseconds, but it could be sufficient to cause a skid, perhaps over only just 1/2 inch of boolit travel at some point within the barrel. Where is the leading in the barrel?

Take a look at these Pressure Trace graphs:
208356

You can see delayed ignition there. RSI talks about low density charge being the cause for this.

My understanding is that when free space below boolit is critically under-filled with powder, during horizontal firing position it lays at the lower half of that space and primer ignites the powder only partially, mostly on the surface as opposed to through the whole bulk of it, gas produced with partial ignition is not sufficient to push the boolit and it gets stuck in the rifling. Now the powder pellets are in different stages of burn, are burning at different rates, the volume of space behind the boolit is rather large and the powder behaves quite differently from what it is supposed to do when all pellets ignite simultaneously behind continuously accelerating boolit.

I don't know if sudden pressure spikes can develop because of this, but I suspect it's possible. There is some evidence that large air/powder ratio can actually cause detonations.

One reason why heavy boolits can use faster powder (counter-intuitive isn't it) is because of their size, they take up more of the case volume and load density with less powder remains sufficient for reliable ignition. Smaller boolits need to load more powder by volume, and to remain within safe acceleration limits need to use slower powder.

Boolit weight with its resistence to acceleration is what creates the limited volume for expanding gases and is the cause for both pressure and temperature, and rate of burn. Lighter boolits simply move away with higher acceleration thus limiting the pressure, but may cause excessive radial torque. Heavier boolits limit acceleration and also radial torque. Too much fast powder behind a heavy boolit causes excessive pressure simply because it does not accelerate away fast enough to make room for the gases expanding at accelerating rate.

Some people add wads to keep the powder in the rear of the case so that primer blast goes through all the powder. This helps to blast as many pellets as possible at the same time so that ignition happens simultaneously. That is what makes powder work as designed and documented. Fouling could also be just a sign of delayed ignition.

Notice that despite delayed ignition boolit exit velocity was said to be very similar in above graphs, so chrono cannot be really used to get an idea of what happens inside the barrel. Same result can be reached through rather different sequence of events.

But, your soft boolits are sheared, and this means that at some point they faced excessive radial torque/acceleration. Larger charge may help by simply filling the case better and avoid boolit stoppage by means of better ignition, bringing the whole process of burn closer to designed sequence. Harder boolit simply withstands more torque, but it may also change the sequence of events and ignition delay.

Have you experienced a squib? Primer alone is capable of driving the boolit into the barrel. You can make a deliberate squibs without any powder with either of your alloys and test them. You'd need to hammer them out. Look for how far into the barrel soft vs hard alloy gets and feel how hard it is to get either back out. Also take a look at the engraving marks.

Most probably you'd notice that soft boolit gets stuffed deeper into the barrel, simply because it has lower friction. This means that there is more volume behind it that partially ignited powder gases have to fill, aggravating the delay and the shape of the pressure curve. Even neck tension holding the boolit has effect on initial sequence of events.

There is a minimum charge for a boolit weight of any powder. It is given because below it the ignition becomes unreliable and the behaviour of the powder unpredictable.

From pictures your barrel has very short leade so I don't think your boolits gain enough velocity to ram into the rifling and shear at that point. Pressure spike most probably occurs when they are fully engraved already.

[OS OK]

Thanks for your effort in posting this wimms...that was an excellent read.

"Now I can 'mull onit' for a while . . . c h a r l i e

[vzerone]

have to agree with larry. As a matter of fact ive had linotype buys that only tested 18bhn. 5050 ww/lino usually goes 16-18bhn and that's with good lyno. Never had a batch of ww test any harder then 12bhn. Most of it tests closer to 10. How are you testing it? Ive got both a cabin tree tester and a saeco. Now if your water dropping your ww you should be about right on the number at 18. If your bullet is testing 18 (water dropped as you said) its hard enough for about any handgun application and is hard enough where I doubt that's your problem at 9mm velocitys. One thing to watch in loading 9mm is to make sure you start the bullet in the case straight. With small bullets in my club fingers I have to allways keep that in mind because the 9 is about the worse offender when it comes to having bullets seat crooked. The way they enter the rifling a little off center can make marks that look just like stripping. Actually I too don't see enough evidence of stripping to think that is causing you any trouble. Keep in mind too that its a ruger not a les baer and the rifling might be cut with one land a tad wider then another. Again it shouldn't cause any real problem at handgun range. What are you calling bad leading. Is it actually building up more and more as you shoot to the point it effects accuracy. Or is it just a lead wash that gets no worse. About any gun shooting lead will have a light wash in it and I don't even concern myself with removing it. How many rounds before it effects accuracy. My guideline is if I can shoot the amount of bullets I usually shoot in two range sessions without groups opening up again I don't worry about it. If it is you can still use your alloy as long as your getting accuracy. Just buy a box of jacked bullets and load them up and shoot one about every 50 rounds and it usually will push any lead build up out. Same can be done with a gas checked bullet or even a very hard plain based bullet. Also being a ruger id consider right from the git go shooting maybe a 100 jacketed bullets through it, clean it thoroughly and then shoot cast. That usually smooths up the barrel a bit and make a slightly rough barrel a little more cast friendly.

Lloyd, I've alway felt that the 380 is much worse then a 9mm to be able to get the bullet seated straight.