Fine tune: 9mm, 125gr, .357, BullsEye, BHN 20

[Wheeljack]

I buy cast bullets from Penn bullets. 125gr LRN I'm useing BullsEye right now. I have leading problems with 3.3gr of powder. Penn suggested slower powder, so that is on my list. I haven't figured out the perfect OAL but 1.125 is what I'm using. The 3.3gr load is not giving me enough obturation, so I thought that maybe 4.0gr of Bullseye would be good. After Bullseye I was thinkling about HP38. Opinions welcome.

[LUCKYDAWG13]

3.8gr of B/E works great in my 92fs with a 125gr boolit

[bcp477]

3.3 grains of Bullseye, under a 125 grain boolit, is quite a light load. I use 3.7 grains myself, also with a 125 grainer, with NO leading whatsoever. Unless your bullets were VERY soft indeed, your problem lies elsewhere. You state that your boolits are BHN 20 - that is NOT soft at all. The pills I use are BHN 12, by the way.

There is a possibility, though small, that the light 3.3 grain load will simply not obturate your BHN 20 boolits - and that a hotter charge might cure the problem. I seriously doubt that a slower powder, in and of itself, is the answer. You might try 3.5, 3.7, etc. grains of BE.....and see if the leading goes away, or gets worse. If it doesn't go away by the time you get to 4.0 grains, then your problem is not the powder charge.

Bullet diameter is the likely culprit. Have you slugged your barrel ? 0.357" (your stated diameter) is very likely too small for your particular barrel. Unfortunately, 9mm barrels can vary a lot from the specified groove diameter of 0.355". Some are WAY oversized. If I were you, I would slug your barrel (if you haven't already)....and act accordingly. It is very possible that you need boolits of 0.358" or greater.

As for slower powders, you may get better results with them. Maybe. Bullseye is a perfectly good powder for the 9mm, though. But, IF you are not getting proper obturation with Bullseye, I doubt that you'll get it with a softer load (a slower powder at comparable pressure). I also use HP38...and like it very much. The most accurate load I've found, in my 9mm's, is 4.0 grains of HP38, under 125 grain pills, of 0.356" diameter. Actually, 0.357" works just as well in my pistols, because the barrels are nice and tight, both slugging right around 0.355".

So, to sum up..... I'd recommend that you make sure that 0.357" is large enough for your barrel. Also, I'd bump up your Bullseye load to perhaps 4.0" grains, as a maximum, to see of the leading will go away (and therefore, whether boolit hardness is the problem).

[GH1]

I use 6.0 gr BE under 16-18 BH 158 gr cast bullets. As was already stated, bullet diameter is probably the culprit behind your leading, although 20 is a bit hard.
GH1:)

[390ish]

I was sizing at 358 and getting leading in both a Sig 226 and Ruger p-89, alox on a Lee 120 TC. Not a TL mould. Leading with sized at .358 and .357. Fairly mild load of unique. Leading from stem to stern. Not horrible like with TL moulds, but enough that I felt the need to clean it out. Air cooled WW. Think I should go to .356?

[Wheeljack]

To confuse things more, I slugged a .357 but that was from land to groove. My barrel has only 3 groves, 60 degrees apart, so I can't measure from land to land. It seems that groove to groove would be over .357 and land to land less, like maybe .355. I think the first thing I will try would be a 4gr load of Bullseye. If that doesn't help, I try a .358 bullet. Increasing the charge, I hope, will give me better obturation (I hate that word) and no gas cutting.
GH1, that 6 gr of Bullseye behind 158gr is at least a +P load. Be careful.
390ish, come along with me and try a hotter load for your rounds. Unique can go up to 5gr..

[390ish]

Thanks, I will go hotter. Think I am at 4.3 grains right now.

[bcp477]

I was sizing at 358 and getting leading in both a Sig 226 and Ruger p-89, alox on a Lee 120 TC. Not a TL mould. Leading with sized at .358 and .357. Fairly mild load of unique. Leading from stem to stern. Not horrible like with TL moulds, but enough that I felt the need to clean it out. Air cooled WW. Think I should go to .356?


If you are getting leading at 0.357" and 0.358" diameters.....then going SMALLER will absolutely NOT help (it will make it worse). The rule of thumb is : you can always go a bit oversize with cast, but NOT undersize. So, with a 0.355" barrel and cast boolits, you can usually go 0.356", 0.357"....even 0.358", provided they will chamber, without adverse effects. But, smaller than 0.356" (in this example) will virtually always produce leading.

It very much sounds to me as if you have one of the giant-sized 9mm barrels, of which I've heard, but never seen myself. If 0.358" boolits won't work without leading, this indicates that you have a barrel bigger than 0.357" in groove diameter.....perhaps as large as 0.360" (I've heard of barrels this big...but, as I said, I've not seen one myself). I would strongly recommend slugging your barrels ASAP. You can try a bit hotter charges, to see if lack of obturation might be the issue, but that is much less likely the problem than boolit diameter.

[bcp477]

To confuse things more, I slugged a .357 but that was from land to groove. My barrel has only 3 groves, 60 degrees apart, so I can't measure from land to land. It seems that groove to groove would be over .357 and land to land less, like maybe .355. I think the first thing I will try would be a 4gr load of Bullseye. If that doesn't help, I try a .358 bullet. Increasing the charge, I hope, will give me better obturation (I hate that word) and no gas cutting.
GH1, that 6 gr of Bullseye behind 158gr is at least a +P load. Be careful.
390ish, come along with me and try a hotter load for your rounds. Unique can go up to 5gr..


0.357".... from land to groove ? When you measure your slug (after pushing through the barrel, of course), you measure the LARGEST diameter of the slug - that represents the GROOVE diameter. A slug pushed through the barrel, becomes, in essence, a reverse copy of the barrel interior. The raised "lands" on the slug are actually formed by the grooves in the barrel. There is NO need to measure into the grooves left on your slug - that won't tell you anything useful.

You should be able to get accurate measurements with a good caliper, with the jaws placed perpendicular to the grooves impressed in the boolit. Always measure in several locations around the boolit, then average the results (I usually measure in 4 places, rotating the boolit 90 degrees between measurements).

Judging by your "0.357 from land to groove" dimension....and knowing something about common rifling depths, I would guesstimate that you have a barrel that is definitely larger than 0.357" (groove diameter, which is what counts). If so....and I think that it probably is....you'll need boolits at least 0.3585", perhaps larger. That's the rub. Once you get past 0.358", it is very difficult to find proper boolits ready made for the 9mm. If casting your own, then you'll likely need to enlarge your mould (or get a larger one).

Remember, a bit oversized (0.001 - 0.003" over groove diameter) is usually fine - but NEVER smaller than that with cast. So, you REALLY need to know your barrel (groove) diameter.

[Wheeljack]

I slugged again and I'm in trouble. This barrel measures Groove to Groove at .362. My bullet was .357 and 20BHN. On top of this, I was trying to get light loads. It looks like I will have to have special loads and bullets just for this pistol. I don't cast, so I will have to find the biggest bullet I can find with the hardness of a marshmellow. I enjoy experimenting, but this will put me to the test. Thank you very much for all the good advice.

[390ish]

If you are getting leading at 0.357" and 0.358" diameters.....then going SMALLER will absolutely NOT help (it will make it worse). The rule of thumb is : you can always go a bit oversize with cast, but NOT undersize. So, with a 0.355" barrel and cast boolits, you can usually go 0.356", 0.357"....even 0.358", provided they will chamber, without adverse effects. But, smaller than 0.356" (in this example) will virtually always produce leading.

It very much sounds to me as if you have one of the giant-sized 9mm barrels, of which I've heard, but never seen myself. If 0.358" boolits won't work without leading, this indicates that you have a barrel bigger than 0.357" in groove diameter.....perhaps as large as 0.360" (I've heard of barrels this big...but, as I said, I've not seen one myself). I would strongly recommend slugging your barrels ASAP. You can try a bit hotter charges, to see if lack of obturation might be the issue, but that is much less likely the problem than boolit diameter.

I bumped up my charge. Actually I looked and have been using 231. Moved the charge up to 4.3 grains and no more leading in the P-89 or CZ-75. Had left the 226 @ the office, so I will take that out in a week or two. I really like that Ruger with cast boolits. Thanks for the help!!