300 BO, 311-155 Coated Failure.

[Rich22]

So I cast up some nice 311-155 bullets with NOE mold. Ran through 3 coats of Hi tek and they passed each test. Then sized to 309 and that went fine. I took it and loaded one up in a 300 blackout case with an OAL of 1.95 since it was obvious from other threads that these suckers need to be seated fairly short. The issue I am finding is that the round does not pass the case gauge (sheridan cut out) but chambers fine. Issue with that is when I eject the case to inspect it, the bullet is damaged with obvious dents and coating removal on the nose. I loaded and shot some 150 sierra's a few days ago that works fine, they were however loaded to 2.15 OAL. The bullet damage does appear to be all the way around the circumference of the bullet. These 155's were loaded on a LNL AP with hornady sizing and seating dies and a lee expander with an NOE expander plug.



Major data


Caliber 300 BO

Bullet size .309
LC Brass
Sota arms upper, 16 inch


Anything I am totally forgeting would be appreciated. 156215156216

[Jupiter7]

You've increased the nose diameter too much. Do not shoot those in an autoloading rifle, asking for setback and boom. They in reality did not chamber "fine", they were forced under spring power and bolt weight.

eta: also not sure what's going on with the rounds you pictured, bottom one shows what looks like either a bullet not seated square or un-evenly trimmed brass. And, you can seat those deeper, I do, case neck covering crimp groove completely, brass trimmed 1.358".

[runfiverun]

what your forgetting is actually shooting them.
who cares if they get scuffed if the holes are on target as close together as you would expect from the rifle.

[Artful]

Ah, did you look at the rounds after seating the boolit in the case? That looks to me like it might be the seating die marking the boolits.

[petroid]

3 coats of Hi-Tek seems a bit excessive. I do 2 coats which works fine. Fattening up the nose will make them unreliable to chamber without forcing them as has been stated. I'm assuming there were no markings on the nose before chambering them, or else Artful is right. I have seen rings on the nose from the seating die, which doesn't affect how they shoot. Make a dummy round and drop it in the chamber and lower the bolt slowly by hand. Use the forward assist to try to fully close the bolt. If it won't go, seat it deeper until it does. If you can't chamber the round without letting the bolt slam home, you are asking for poor reliability and bullets stuck in the chamber when you attempt to extract. If your case gauge is in spec, the round should drop right in as long as you did things right.

[Rich22]

Ah, did you look at the rounds after seating the boolit in the case? That looks to me like it might be the seating die marking the boolits.

I thankfully did, these are without question from the rifle, not the seating die. I did check that. Good idea though

[Rich22]

You've increased the nose diameter too much. Do not shoot those in an autoloading rifle, asking for setback and boom. They in reality did not chamber "fine", they were forced under spring power and bolt weight.

eta: also not sure what's going on with the rounds you pictured, bottom one shows what looks like either a bullet not seated square or un-evenly trimmed brass. And, you can seat those deeper, I do, case neck covering crimp groove completely, brass trimmed 1.358".

Yeah I may have screwed up putting it in right. Brass is from a vendor here that is excellent so I don't believe that to be the problem. I may need to flare the case a bit more. Nose is .3055.-.306 As cast they are .305. If I cannot use these in an AR then they are useless to me.

[Rich22]

3 coats of Hi-Tek seems a bit excessive. I do 2 coats which works fine. Fattening up the nose will make them unreliable to chamber without forcing them as has been stated. I'm assuming there were no markings on the nose before chambering them, or else Artful is right. I have seen rings on the nose from the seating die, which doesn't affect how they shoot. Make a dummy round and drop it in the chamber and lower the bolt slowly by hand. Use the forward assist to try to fully close the bolt. If it won't go, seat it deeper until it does. If you can't chamber the round without letting the bolt slam home, you are asking for poor reliability and bullets stuck in the chamber when you attempt to extract. If your case gauge is in spec, the round should drop right in as long as you did things right.

With anything that goes supersonic I have always thought that three coats was a good idea. I am 100% certain that these came out of the press fine. I will test the amount of force required to seat, good idea, I did not think of that, still fairly new to the AR platform. This was to literally be my first cast rifle bullet. It seems I cannot get the round to gauge due to the width of the bullet, I will check again and see the problem. even post a picture if possible

[Rich22]

3 coats of Hi-Tek seems a bit excessive. I do 2 coats which works fine. Fattening up the nose will make them unreliable to chamber without forcing them as has been stated. I'm assuming there were no markings on the nose before chambering them, or else Artful is right. I have seen rings on the nose from the seating die, which doesn't affect how they shoot. Make a dummy round and drop it in the chamber and lower the bolt slowly by hand. Use the forward assist to try to fully close the bolt. If it won't go, seat it deeper until it does. If you can't chamber the round without letting the bolt slam home, you are asking for poor reliability and bullets stuck in the chamber when you attempt to extract. If your case gauge is in spec, the round should drop right in as long as you did things right.

I realize my number of responses are excessive but here we go. Made a dummy round 1.95, locked open the bolt. Put the round in the chamber, held on to the charging handle and rode that thing down until it closed. It stayed open by about 1/4 inch. I smacked the forward assist and it chambered. If this issue is the length of the round , realistically how much more do I have to go down? I have never heard of load data for even this short a round, let alone shorter. Tried another 1.95. Tried to set the crimp more in case that was the issue. Put it about as much as my Hornady die would go and it did not change anything. Bullets are still coming out damaged, just less so.

[6622729]

I hate that bullet shape. Consider the Lee 312-155-2R instead. I'm using that in 300BO. I'm shooting water dropped wheel weight alloy. I lube with 45/45/10 and seat to 2.010-2.015ish (the crimp groove). Size to 309 and apply gas check. Relube per Lee instructions and load 'em up. This has quickly become my everyday target round.

[blikseme300]

I realize my number of responses are excessive but here we go. Made a dummy round 1.95, locked open the bolt. Put the round in the chamber, held on to the charging handle and rode that thing down until it closed. It stayed open by about 1/4 inch. I smacked the forward assist and it chambered. If this issue is the length of the round , realistically how much more do I have to go down? I have never heard of load data for even this short a round, let alone shorter. Tried another 1.95. Tried to set the crimp more in case that was the issue. Put it about as much as my Hornady die would go and it did not change anything. Bullets are still coming out damaged, just less so.

I am puzzled why you are getting the marks on the CB nose but the outcome of chambering test you describe is normal as the extractor needs to snap over the rim and this is what is keeping the bolt from closing.

I went and did some checking as I have 2 Sota Arms uppers and use the same NOE mold you have and it is my go-to combination for plinking and hog hunting. I use conventional lube and size to .309 with the nose diameter that echos your measurements.

When I did my load development a few years ago I was concerned about the fit of the round to the chamber as I had a number of blown primers but this was traced back to the fact that not all brass head stamps are suitable for conversion as the case wall thicknesses vary and this caused binding in the chamber. I did make up a guage that enabled me to measure that the round was seated properly in the chamber with the BCG removed measuring from the rear of the upper. I compared the depth with some factory ammo to give me a reference and the NOE loads were identical while the rounds dropped freely into the chamber and not forced.

My understanding is that Hi-Tek leaves a very thin coating unlike PC so the slight increase you found should not pose a problem. I have in my crazy professor mode even tested the NOE 316-155 sized to .309 and these chambered properly even though the nose measures .307". These shot the same as the NOE 311-155 so I did not continue using this combination.

My initial CB's were cast using the Lee 312-155 and even though they work well for range work they were less optimal for hunting and the Harris design that NOE produces works much better for hunting in my opinion based upon my experience.

I use a combination of dies on a LnL AP to load consisting of a modified Lee auto disk using a 38spl body with a custom expander that mimics the M-die followed by a Hornady seater and then a Lee collet FCD (The crimp is light and just removes the belling that the expander created). I have had bad experiences using other types of crimping dies on bottle-necked cartridges as it is too easy to buckle the brass if the brass are not all the same length. I have and use a Wilson case guage and my loaded rounds pass checking but the chamber is the ultimate guage IMHO.

I would load a few and go shoot them and let Mr Gun and Mrs Target tell you what's what.

[Hickok]

Rich, make a dummy round with NO Hi-tek coating, just a bare boolit, and then take a black magic marker and color the boolit. Insert into the chamber and eject. Should tell you if your Hi-Tek coating is too thick. You will get some scrub marks on the black magic marker coating in the chambering/ejection process.

On the AR rifle, you will have to bump the FA to get the bolt to fully lock when riding the bolt to chamber a cartridge, this is normal. The extractor needs a bump to snap over the rim.

I truly believe your coating is too thick, as your pictures indicate a ring entirely around the full diameter of the boolit. The boolit shows no marks of engraving the rifling in the leade. Keep us posted on your progress.

[petroid]

If the bolt closes without slamming it you are fine. Go ahead and shoot some. You may find that as you shoot, some won't chamber reliably. If that is the case, seat a little deeper

[dilly]

Another thing to consider is the possibility of nose only sizing. One method of doing it is NOE's fancy push through sizer that can do nose only sizing.

[Rich22]

I hate that bullet shape. Consider the Lee 312-155-2R instead. I'm using that in 300BO. I'm shooting water dropped wheel weight alloy. I lube with 45/45/10 and seat to 2.010-2.015ish (the crimp groove). Size to 309 and apply gas check. Relube per Lee instructions and load 'em up. This has quickly become my everyday target round.

I would love that bullet shape - lube groove - gas check and made by a quality manufac. I told Al that if he does a non lube groove spitzer 30 cal I am in.

[Rich22]

I am puzzled why you are getting the marks on the CB nose but the outcome of chambering test you describe is normal as the extractor needs to snap over the rim and this is what is keeping the bolt from closing.

I went and did some checking as I have 2 Sota Arms uppers and use the same NOE mold you have and it is my go-to combination for plinking and hog hunting. I use conventional lube and size to .309 with the nose diameter that echos your measurements.

When I did my load development a few years ago I was concerned about the fit of the round to the chamber as I had a number of blown primers but this was traced back to the fact that not all brass head stamps are suitable for conversion as the case wall thicknesses vary and this caused binding in the chamber. I did make up a guage that enabled me to measure that the round was seated properly in the chamber with the BCG removed measuring from the rear of the upper. I compared the depth with some factory ammo to give me a reference and the NOE loads were identical while the rounds dropped freely into the chamber and not forced.

My understanding is that Hi-Tek leaves a very thin coating unlike PC so the slight increase you found should not pose a problem. I have in my crazy professor mode even tested the NOE 316-155 sized to .309 and these chambered properly even though the nose measures .307". These shot the same as the NOE 311-155 so I did not continue using this combination.

My initial CB's were cast using the Lee 312-155 and even though they work well for range work they were less optimal for hunting and the Harris design that NOE produces works much better for hunting in my opinion based upon my experience.

I use a combination of dies on a LnL AP to load consisting of a modified Lee auto disk using a 38spl body with a custom expander that mimics the M-die followed by a Hornady seater and then a Lee collet FCD (The crimp is light and just removes the belling that the expander created). I have had bad experiences using other types of crimping dies on bottle-necked cartridges as it is too easy to buckle the brass if the brass are not all the same length. I have and use a Wilson case guage and my loaded rounds pass checking but the chamber is the ultimate guage IMHO.

I would load a few and go shoot them and let Mr Gun and Mrs Target tell you what's what.

The more I think about it the more I think the issue has to do with the crimp. I will try to work on that some more but I am having minimal luck.

[leadman]

It appears to me that you are putting too much coating on the boolits also. The lumpy appearance is what I am looking at. The first coat should be just enough to stain the boolit and almost be invisible until baked. Do this pass the acetone wipe and smash test?
For use in a rifle you need an alloy from 18 bhn and up.
When I want to shoot high velocity in a rifle depending on the velocity I want I go all the was up to heat treated linotype. I only do 2 coats and water quench also after each coat. This usually gives me around 32 bhn. The alloy is strong enough to take 3,619 fps in my AR15 with the Lee Bator bullet.
If using a soft alloy in a rifle it is possible to bulge the nose during seating so something to watch for.

When I tested the Gold 1035 for Donnie Mickelek and Joe I found this was superior to the other coatings available from Hi-Tek at the time. I tested both the liquid and the powder, preferring the powder.

[Rich22]

It appears to me that you are putting too much coating on the boolits also. The lumpy appearance is what I am looking at. The first coat should be just enough to stain the boolit and almost be invisible until baked. Do this pass the acetone wipe and smash test?
For use in a rifle you need an alloy from 18 bhn and up.
When I want to shoot high velocity in a rifle depending on the velocity I want I go all the was up to heat treated linotype. I only do 2 coats and water quench also after each coat. This usually gives me around 32 bhn. The alloy is strong enough to take 3,619 fps in my AR15 with the Lee Bator bullet.
If using a soft alloy in a rifle it is possible to bulge the nose during seating so something to watch for.

When I tested the Gold 1035 for Donnie Mickelek and Joe I found this was superior to the other coatings available from Hi-Tek at the time. I tested both the liquid and the powder, preferring the powder.

As far as too much coating. First coat is 1 ml of coating /lb coats 2 and 3 are 1.25 ml/lb

As I put in the first post unspecifically, these passed both wipe and smash tests after each of the 3 coating/cooking sequences. If I am going to need a extremely hard alloy like that for rifle with this coating then honestly I may as well give up now. These are about 14 BHN and it is about as hard as I currently have and I am running out of it at that. Unfortunately as far as liquid/powder, I purchased a very large quantity of liquid just before the powder came out so before I go to powder I have over 3 liters left to go through. I will consider the water quench in the future, that I did not consider.

PS: If this is too much coating, please let me know and I can adjust. Everything I have shot previous to this has worked well at those ratios.

Thank you

Rich

[petroid]

You don't need any harder alloy. Shoot some and see what happens

[bnelson06]

I'm betting the ride into the chamber is your problem. The ramps are usually made for a 5.56 and a 30 cal riding up them can scuff them up unless you do some modifications. I'd shoot me up and see how they do.

[Rich22]

One quick update. If just barely pushing them in until they chamber and then extracting, very minor damage. If loaded in slamming bolt home from a mag, very significant damage with a ring of damage .2 in from the nose, this seems to happen regardless of cartridge OAL. Working on loading now

[Fishman]

If you are having problems with this bullet design, then you will have similar problem with the Lee 155. The nose on it gets progressively fatter toward the crimp groove and I'm pretty sure the NOE is the same. It is not a bore riding design. I have had similar problems as you and my suggestion would be to seat the bullet deeper until they chamber. The problem with coated bullets is that the noses aren't sized and they have differential thicknesses of coating. Ten will chamber fine, but one will have a thicker coating and the problem is back. This may be less of a problem with high tech but it is with a powder coating gun in my experience.

The lyman 311413 was produced by NOE and it is a bore rider. Mine are .300 from ogive to crimp groove. It is a pointed design but can be modified with a flat meplat using a file or punch. The important thing is that it works with tight barrels which appear to be somewhat common in the blackout. I believe he problem is the leade into the rifling from the chamber. It is very short and abrupt which limits the diameter and length of the bullet nose in the case.

Try chambering an uncoated dummy round.

[Rich22]

If you are having problems with this bullet design, then you will have similar problem with the Lee 155. The nose on it gets progressively fatter toward the crimp groove and I'm pretty sure the NOE is the same. It is not a bore riding design. I have had similar problems as you and my suggestion would be to seat the bullet deeper until they chamber. The problem with coated bullets is that the noses aren't sized and they have differential thicknesses of coating. Ten will chamber fine, but one will have a thicker coating and the problem is back. This may be less of a problem with high tech but it is with a powder coating gun in my experience.

The lyman 311413 was produced by NOE and it is a bore rider. Mine are .300 from ogive to crimp groove. It is a pointed design but can be modified with a flat meplat using a file or punch. The important thing is that it works with tight barrels which appear to be somewhat common in the blackout. I believe he problem is the leade into the rifling from the chamber. It is very short and abrupt which limits the diameter and length of the bullet nose in the case.

Try chambering an uncoated dummy round.

Tried chambering raw dummy round sized .309 at 1.95. Bullet passed chamber gauge and chambered roughly equivelent to the coated. It shows same damage as the others. I also tried 1.90 which any less than I am thinking is insanity, same result. I have a 311-247 mold which does have a .300 nose diameter which may work but will likely not cycle without a new powder which I do not have.

[popper]

It's the nose shape. I use the 31-142C which has a reduced nose diameter and every once in a while I get a ding like that. It is unreliable as the alloy is getting scraped when entering the chamber throat and will build up at the shoulder. Jamming the lands also makes it difficult to remove a loaded round without leaving the boolit in the barrel.

[millerwb]

Had a similar problem in my 300. Was using a RCBS mold. Found out my problem was a feed ramp issue and not a bullet issue. CB was catching on the feed ramp just out of the mag. Always put a crescent shaped gouge on the CB.

[Rich22]

Had a similar problem in my 300. Was using a RCBS mold. Found out my problem was a feed ramp issue and not a bullet issue. CB was catching on the feed ramp just out of the mag. Always put a crescent shaped gouge on the CB.

I have read several that say they get this to work right , that is what got me to buy the mold in the first place. If someone would do a 125gr no lube groove design for Hi tek I think it would be the thing I would replace it with. Reasonably, is there any way I can get this to work without issue even if not perfect performance, my distances are very short.

[Fishman]

The aforementioned NOE nose sizer might fix it. I haven't tried it. I am pretty sure the problem is a too fat bullet nose.

[popper]

Bet that 'ring' doesn't go all the way around the boolit. Slip it in then drop the bolt, no ring. From the mag, ring. Nose problem, trying to get it to enter 'straight'. Big problem is the scrape leaves some lead in the throat and sooner or later they will get stuck. You could seat deeper or get a nose swage die. My nose is 0.297 and I still get one of those every so often. Make sure your case rims don't have any roughness which will strip the under round forward to the front of the mag.

[Fishman]

Bet that 'ring' doesn't go all the way around the boolit. Slip it in then drop the bolt, no ring. From the mag, ring. Nose problem, trying to get it to enter 'straight'. Big problem is the scrape leaves some lead in the throat and sooner or later they will get stuck. You could seat deeper or get a nose swage die. My nose is 0.297 and I still get one of those every so often. Make sure your case rims don't have any roughness which will strip the under round forward to the front of the mag.

Very interesting observation Popper. I think I have experienced that issue without understanding how it happened.

[Rich22]

The aforementioned NOE nose sizer might fix it. I haven't tried it. I am pretty sure the problem is a too fat bullet nose.

It quite possibly is but I would much rather change molds then possibly spend the time to add another sizing process to what will end up being 10s of thousands of bullets. Much more efficient and time (cost) effective IMO

[Rich22]

Bet that 'ring' doesn't go all the way around the boolit. Slip it in then drop the bolt, no ring. From the mag, ring. Nose problem, trying to get it to enter 'straight'. Big problem is the scrape leaves some lead in the throat and sooner or later they will get stuck. You could seat deeper or get a nose swage die. My nose is 0.297 and I still get one of those every so often. Make sure your case rims don't have any roughness which will strip the under round forward to the front of the mag.


I have heard this now several times and understand as far as seating them deeper, my question is ok but how deep? I have experimented with 1.90. If deeper than that, So then what nose size am I looking for? .300 or less? .297? I honestly thought when I bought this mold that it would work for this round. I am starting to think I was very mistaken, range report to come in the next post

[Rich22]

So I took some advice here and loaded up some rounds with the NOE 155 and set off for the range. This was easily the worst range session of my life. I'm just glad that no one got injured and the gun didnt blow up. I used loads of H110 ranging from 14.8-15.5 grains. I had numerous malfunctions and I think there was only two instances where it worked correctly.


Just some basic examples


Load, 15.3 gr 1.95 OAL , 2 shots, 1st shot fired, did not extract and then the second round in the mag fired and then stovepiped






gr at 1.98 OAL. 1 fired ok and managed to lock the bolt open 1 did not extract at all





Load 14.8gr @ 1.95 OAL, I put 4 cases in the mag. I loaded and pulled trigger and it worked well so far, except that the case did not want to leave the chamber, I managed to work the bolt several times and I got the round out of the chamber that it was stuck in but the next round that tried to go into battery had been severely damaged both bullet and case when the other case did not extract. I fired the last two undamaged rounds in the mag and it worked well except for what I determined to be a MUCH heavier than normal cloud of smoke which smelled just like cooking Hi Tek.


To rule out that it was the gun issue instead of the rounds issue I went and got some loads I made with 150gr sierra jacketeds and I rapid fired 4 in to a space about 3 inches across so evidently the issue is with the bullet or crimp or something. What realistically can I do with this bullet to get it to work or cut my losses, sell it, and start working on a lighter spire point design with a 300 nose diameter or smaller.


I will add pictures of some of the malfunctions156421156423156424

[petroid]

To truly find out why you are having trouble I would do a pound cast of the chamber. Thus will give you the dimensions of YOUR chamber and you can determine what the problem is

[blikseme300]

Pound cast will answer some questions but the thing that that jumps out at me is the picture of the damage to the round in the picture above. If the damage and deformation occurs during chambering then this would need to be addressed first.

[popper]

Try shooting some dropped into the chamber, not loaded from mag, get firing and LB working correctly, then try the mags. You didn't say what mag you are using - metal GI? - I changed to lancer 40WT mags that work great. I've heard H110 is temperamental at light loads, I use >16 gr. with a 145gr boolit, you are on the low side of jacketed loads. What gas system? Too much gas (pressure) may make unlock early and expand the case so it doesn't eject properly. Do you have some 4227 to try? I really like the Hornady 150gr SP (#3031?) which is like your sierrra. That 'puff' of smoke is the HiTek - I changed to PC as i could barely get the HiTek to work reliably @ 1800 fps or so. PC does the same thing at really high fps in the AR10.
Oh, the 31-142C is a 3R ogive to feed better, 0.18" meplat, PB. Accurate could put a GC on it and then it would be more like 140gr. I've heard some like the light SP GC AK boolit NOE makes.

[Rich22]

Pound cast will answer some questions but the thing that that jumps out at me is the picture of the damage to the round in the picture above. If the damage and deformation occurs during chambering then this would need to be addressed first.

It was the only one with any kind of damage to the brass, It occurred at the same time as the previously fired round did not extract at all, my point being is that was a one off event, and with a major malfunction, not a consistent occurence.

[Rich22]

Try shooting some dropped into the chamber, not loaded from mag, get firing and LB working correctly, then try the mags. You didn't say what mag you are using - metal GI? - I changed to lancer 40WT mags that work great. I've heard H110 is temperamental at light loads, I use >16 gr. with a 145gr boolit, you are on the low side of jacketed loads. What gas system? Too much gas (pressure) may make unlock early and expand the case so it doesn't eject properly. Do you have some 4227 to try? I really like the Hornady 150gr SP (#3031?) which is like your sierrra. That 'puff' of smoke is the HiTek - I changed to PC as i could barely get the HiTek to work reliably @ 1800 fps or so. PC does the same thing at really high fps in the AR10.
Oh, the 31-142C is a 3R ogive to feed better, 0.18" meplat, PB. Accurate could put a GC on it and then it would be more like 140gr. I've heard some like the light SP GC AK boolit NOE makes.

Good point on the mags: Gen 3 Pmags, I did not try any dropped into chamber, holdover from my Glock experience where thats a big error. I knew I was loading quite light, Standard procedure for me when shooting new bullets and new seating depths etc. It is a carbine gas. I have tried remington factory subsonics using the 220s before and this thing will not function correctly with that little gas. I never had major interest in a suppressor for this caliber so I never cared much since I would use supers or even large sub style bullets loaded just barely super if I wanted something different. I do have a small amount of 4227, just not nearly enough to make it a "standard" load since I have figured with my lack of rifle experience I am going to need many thousands of rounds to get my proficiency level up to par. The Hornady's are nice as are the sierras, just far too expensive to run consistently for practice. I've looked at the AK bullet from NOE(I think) just seems that it will drop too large to size down without multiple steps to get to the .309-.310 range. I am wondering if a .18 would be small enough or if it really should be a true spire. I am hoping to get the hi tek to work for all my loads since, after trying it, PC just doesn't work for me, I am horrible at spraying and picking out each bullet 1 at a time out of powder with hemostats wont work since my hands give out after 20 of them.

[Fishman]

Just so you know you aren't alone, I took my .300 blk out today to see if I was having Popper's issue. Cleaned the chamber but got no lead. Grabbed a 100 pack of 311414 loads that I had worked up previously but had caused chambering issues the last range trip. Well, no dice. I had to nudge two home with the forward assist and only 2 of five went bang first try. The 4th round was chambered with the forward assist and still no bang. When attempting to remove it, the bullet was left in the chamber, the powder was dumped in the action, and out came the brass.

Turns out that these 413's measure .304 at the ogive. Clearly I got some lead on the mould block faces on that casting session. A big ring of lead was shaved off around the bullet at the ogive.

So I tested some that I loaded with the ACE 150 design. No go either. This time it was the short portion of full diameter (.310) in front of the case mouth.

So in the case of this barrel, the nose of the bullet can't exceed .300, and I can't have more than .05" of the full diameter bullet outside of the case.

Others have much more forgiving barrels. It sounds like your barrel is more like mine.

I know I can make the ACE design work by seating slightly deeper. Future barrels I purchase will be more forgiving.

[stubbicatt]

I do not shoot this cartridge, but as I read this I suspect that the nose riding portion of your bullet is too large in diameter. Easy way to check is to push the nose of the bullet into the muzzle of the rifle and see if it engraves even a little bit. If it does, that might be your issue.

HTH

[popper]

Did you file down the ribs on the Pmags? Don't quote me, I think NOE has a 308 version of the AK boolit. I've gotten my moulds from Accurate but his smallest meplat is 0.18. With that limitation, he will make anything you want, to your size and alloy. NOE is a little less $ but more 'standard' moulds. Both are top quality.
H1110 is, I've heard, a little peaky at low load densities - I stay toward mid to max jacketed data. 4227 is much more forgiving. I almost got the gold 1035 to work, just didn't like the occasional flyer - any junk on the base edge caused it - so I recommend putting on GC after final cooked coat. Just loaded 20 rnds with 1680 - finally on the shelf now - to try with 155gr Amax, should run about 1900 fps.

nose of the bullet can't exceed .300 That is why I did a custom mould with smaller nose - after I got a standard nose mould. That nose goes 2700 fps in my 308, no problems - but that boolit is GC.

[bnelson06]

One quick update. If just barely pushing them in until they chamber and then extracting, very minor damage. If loaded in slamming bolt home from a mag, very significant damage with a ring of damage .2 in from the nose, this seems to happen regardless of cartridge OAL. Working on loading now

This should tell you right away what is happening. It's the ride into the chamber. The bolt picking up a round and chamber ins it is a violent trip.