Blowby gas

Discussion in 'The Ammo & Reloading Forum' started by Darth AkSarBen, Nov 17, 2008.

  1. Darth AkSarBen

    Darth AkSarBen New Member

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    On my handloads for my .45 ACP that I shoot out of my Taurus 24/7 Pro, I have a question. I am loading with 4.7 gr of Titegroup, CCI LP Pistol primers, and various brass, topped with a 185 gr Ranier, copper clad bullet. Shoots a pretty good group, but on every single case there is evidence of gas blowby that I don't see with commercial ammo. Am I not getting enough powder for case expansion to seal the chamber when I shoot? Do I need to up the charge weight to expand out the brass to seal? Primers look very good, no pressure signs at all.
  2. LDBennett

    LDBennett Well-Known Member

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    Darth AkSarBen:

    If you see excessive powder discoloration on the case's outside surfaces it usually means the case is not acting as well as it could as a gasket for the high pressure gases. Your assessment is correct.

    According to the Hodgdon manual I have, the Maximum charge for your situation is 5.5 grains of Titegroup. If you reduce it by 10% for a starting load (Hodgdon 's recommendation) that is a starting load of about 5.0 grains. Your charge is 4.7 grains. You are below Hodgdon's Starting load.

    I suggest you load up a few rounds at 5.0 grains, a few more at 5.3 grains, and a few more at 5.5 grains. Take them to the range and shoot them starting at the 5.0 load first and view the powder discolorations on the cases. Also look for signs of too much pressure. If you see signs of excessive pressure don't shoot the rest of those loads or any that are more than that level. I think you will find, as I have, that the listed Maximum loads for 45ACP ammo from almost all reloading manuals are quite safe.

    A fun thing to do is to go to the range and look at the range brass found there for 45ACP cases. You probably will see lots of them that appear to be over stressed for pressure as a lot of reloaders push 45ACP beyond recommended Max load levels and appear to get away with it. I DO NOT advocate you do that but test up to the Max load level, if you find it safe, and pick the load level that gives the best accuracy. Accuracy testing will require at least three to five-5 shot groups (more is better) shot off a rest at 50 ft or 25 yds or a range of your choice. I do not recommend trying to do the pressure testing at the same time as the accuracy testing or you might end up having to dismantle a bunch of ammo if the pressure signs show up at the lower load levels.

    Loading below the starting loads is also not a good idea as there have been cases of detonation (powder explodes rather than burns) when cases are loaded below starting levels. You are not near that point but just be aware. It is always best to follow the manual's recommendations and apparently your loads are below Hodgdon's starting load level.

    While a perfect gas seal of the chamber is desireable, some guns and cartridge calibers have a hard time acheiving it. 45ACP is not one of them but 45LC is, as I and others, including a famous magazine writer, can attest.

    LDBennett
  3. Popgunner

    Popgunner New Member

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    The "start" loads given in manuals are usually the point where there is enough pressure to seal the neck well. You may still get a little blowby even at start loads.

    Just don't get too agressive with the Ranier "plated" bullets. The plating is so thin that they have a reputation for leading just as badly as plain soft lead bullets.
  4. Darth AkSarBen

    Darth AkSarBen New Member

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    These Ranier bullets I have, the 185 gr, are pretty tough little bullets. I have one on my desk that has the rifling on it and only a very small part of the tip is deformed, nothing else, and no lead showing, even where the lands and grooves are.
    However, they are noted on their website, and on forums to be soft, somewhere between a FMJ and cast bullet. I'm not looking at getting agressvie, just looking for a decent practice load in 185gr.
  5. LDBennett

    LDBennett Well-Known Member

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    What Rainier bullets are suppose to be are cast bullets which are plated with a flash copper surface. They are suppose to also be "re-struct" which I asume to mean somehow sized after plating (???). The effect is to shroud the lead so that it doesn rub off onto the bore.

    I have been using these bullet since before they were re-strike) almost since their introduction over 10 years ago. I use them as you would cast bullets keeping the velocities to cast bullet levels so I have never seen any leading caused by them.

    My whole purpose in using them was to eliminate barrel leading in my cast bullet loads which they have down very nicely. Nothing is more tedious then digging lead out of a bore with a pick when noting else will remove it. I avoid the problem completey with the Rainier bullets.

    I have found that most of my 45ACP and 9mm semi-auto guns like FMJ bulk bullets better than the Rainier bullets for feeding. I use Winchester and Remington FMJ bullets for these calibers. My revolvers get the Rainier bullets.

    LDBennett
  6. Darth AkSarBen

    Darth AkSarBen New Member

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    I have not had any problems with the Rainier bullets feeding in my Taurus 24/7 Pro .45 The only time I noticed it was when I put in a new factory extractor and had to hand fit and polish it in so that it would work. "As is" from the factory, it wouldn't load any bullets. I had to increase the angle of attack (so to speak) of how the extractor met the brass and provide a slight chamfer at the bottom where the round first meets the extractor so that it sort of "rolls" into the grove on the .45 During this adjustment and of trial and error was the only time I had FTF on my Taurus. The old original extractor that came with the pistol was way too loose and never had a decent grip on the case, though it would extract during firing. Point is with all this, is that the Rainier feed fine if the extractor is tuned in there just right. There was an article I read about the extractors on .45s and it showed where to polish and where to have the slight chamfer.

    As for the load, I tried 5.0 grains of Titegroup. Shot it and it did reasonably well for accuracy. Brass was still considerably stained from the shooting. The recoil and the report was very good, on par with what one might expect from a decent low-mid range load. Primer are not a bit flattened and cases did not show any signs of excessive pressure, including the primer.

    I could go up just a few grains to 5.2 or 5.3 of Titegroup and see if that makes any difference. One guy, on another forum I was asking this about, says I am worrying over nothing. A little smudge won't hurt accuracy, and the group arrangement shows that there is not a great Standard Deviation in pressure/ velocity because of it.

    Muzzle flash appears very good with the present 5.0 gr Titegroup load with these Rainier bullets. BTW, I noticed a very slight ring where I crimp them on one of the recovered bullets. It was all intact and there was no lead showing and lands and grooves were very good imprinted in it. I could take a picture of the bullet with my Nikon D80 and post if you wanted to see that slight ring.

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