80gr LRN & HP-38 in a .327 Federal, very poor accuracy

[LeadHead72]

Just wondering if anyone here shoots 80gr LRN in the Federal Mag. I picked up a Blackhawk chambered in .327 (these guns have a 5.5" barrel) and decided to load up some plinkers this weekend. I realize that light of a bullet is not ideal for the .327 but I had a bunch of them on hand (not sure of the brand and they mic at .313") and decided to try them since they should shoot at least reasonably well. The only small pistol mag primers that I have are CCI and I chose HP-38 powder after perusing Hodgdon's data. Their starting/max loads are 5.1 and 5.8gr so I loaded 6 rounds each at 5.1, 5.3 and 5.5gr in Starline brass with a reasonably firm crimp. At 30 feet they were all over the place with literally NO grouping at all! There was minimal soot on the case mouths and no pressure signs with the brass easily extracting (some would fall out on their own). There wasn't much light left in the day to do more experimenting so I called it quits for the tme. At this point I have not slugged the chambers to know the exact diameter of the throats but I don't think Ruger had issues with these .327's.
Any suggestions?

[shooting on a shoestring]

My experience with my Ruger Blackhawks, Single Sixes and DA revolvers is that they ALL have needed the cylinder exits (cylinder throats) corrected to be consistent with the rest of the throats on the cylinder and to be adjusted to be a thousandth or two over barrel groove diameter. Additionally I’ve started re-reaming the chambers with a caliber specific chamber finishing reamer. The difference before and after is anywhere from hardly noticeable to dayum!

I did see you are using commercial cast boolits at 0.313”. That’s probably a part of your problem. That diameter is very likely to small. Also commercial cast boolits are notorious for being to hard and lubed with lube that is designed to stay in the grooves for shipping but not designed to be a good tacky lube for shooting revolvers.

So, my advice is start with measuring your barrel groove diameter and get your cylinder throats 0.001” larger. The. Get your boolits 0.001” larger than your throats. At that point you’ll be ready to start load development.

Also, using magnum primers with HP-38 is not needed and maybe moving the boolits before the powder ignites sufficiently to maintain the pressure and hence have erratic ignition. Also those are pretty light charges in a long case with short boolits so there will be considerable free space in the case for the powder to get away from the primer and add more erratic ignition and the resultant velocity spread.

Glad to hear you got one of the 327 Blackhawks. They’re pretty rare. I’d love to find one I could buy. I’m pretty deep in 327’s but that’s one I don’t have….yet.

Lots of people use DougGuy to adjust their cylinder throats. By all accounts he does good work. He uses a Sunnen hone setup which is really good way to do the job.

Im a bit more redneck and I only do mine. But I was a machinist in a former life. So I use a combination of guided chucking reamers to get the throats to the size I want and use a flex hone to get a finish I want.

Best of luck. Keep us posted on how you go about getting your Blackhawk to making small groups. Never know when you’ll learn something we can use too.

[shooting on a shoestring]

Oh….and I just re-read your post that your cases have minimal soot. 327 can run 45,000 psi compared to 357 at 36,000 psi. So, another thing you have is low pressure in heavy brass. Might try bumping up the pressure. That might help upset those small boolits to help fill the throats. Of course it might make things worse. One way to find out…do it.

[LeadHead72]

Thank you for your replies, it sounds like I need to find someone with a set of pin gauges to see what my throats are measuring but I was under the impression the Blackhawks in .327 were pretty good as a general rule. Perhaps that impression was my overactive imagination? Not sure...
When I mentioned minimal soot I meant that there was just a little so it didn't seem like there was a low pressure problem. As for mag primers, that's what Hodgden was recommended so my assumption was that they should be used. OTOH, perhaps HP-38 just isn't a good option for these light bullets. Yes, it's yielding only approximately 1/3 case fill but all of the powders listed by Hodgdon shows max loads of no more than 7.0gr in this bullet weight range.
This time of the year with its short days is a bit annoying and it will probably be a little while before I can get back to it. Also need to break out the chronograph to see what's going on.

[shooting on a shoestring]

I’ll tell you I’m biased against pin gauges. They will only tell you the diameter of a round rod that will go into the hole you’re measuring. But holes are not round. Yep there’s no such thing as a perfectly straight line nor a perfectly round hole. That’s especially true about revolver cylinders.

Cylinder throats are usually egg shaped a bit. Reason being, revolver cylinders are hollow in lots of spots and they have some heat treating, and they are cut with power fed reamers.

Pin gauges will only let you know the diameter of the minimum of the egg shape and not the maximum of the egg shape.

Small hole gauges allow you to measure a diameter, turn 90 degrees and re-measure the same hole across a different direction. By rotating the small hole gauge you can feel it get tight or loose while it’s in the hole and get an idea of where the minimum and maximum are of the egg shape. Then you can measure both of those, compare and find out how out of round your throats are.

Small hole gauges in the range of 0.3” to 0.4” are in the form of a split ball on a little handle. A small knob on the end of the handle turns a screw which pulls a wedge into the split ball to expand it outward. You insert the hole gauge into the hole and turn the knob until the split ball contacts the walls of the hole with a little bit of friction. You pull the split ball out of the hole and measure it with a 0-1” micrometer.

With a few minutes of practicing you can get very repeatable results.
Split balls aka small hole gauges new cost about $60 a piece. A new Starrett 0-1” micrometer costs about $175. Often you can find these in great shape in pawn shops for WAY less.
They last a lifetime even if you’re young.

If this is deeper than you want to dive. No problem. I’m easy to ignore.

[LeadHead72]

Hmmm, I'd never heard of those ball gauges before. I already have professional grade calipers so maybe I should invest in a set of those as well. Any recommendations on which ones to get or NOT to get (obviously skipping the cheap Chinese stuff)?

[gpidaho]

I own several Ruger handguns both revolvers and autoloaders. All of them need or needed throat work to properly fit lead bullets. Simply put, Rugers as they come from the factory are designed and built to shoot jacketed ammunition not lead bullets. Our fellow "Booliteer" Doug Guy has worked over the throats on five of mine and they are all much more "cast friendly" now. Well worth doing. Gp

[contender1]

Lots of good info above.

I also own a Ruger Blackhawk in .327 Mag. I was smart enough to order one immediately upon hearing about them.
I normally use a 115 grn cast bullet in mine,, and have not had any issues with accuracy in mine.

[megasupermagnum]

I own, or have owned an LCR, two SP101's, a GP100, and Henry rifle all in 327 federal. Every revolver is remarkably consistent at .314" throats. The Henry is .315". I shoot .314" bullets in all of them. I've heard of a number with throats .313". Very few came with .312". Against what gpidaho says, Ruger, and especially 327 federal's are very good cast shooters straight from the factory. I'll go so far as to say Ruger does the best of the common brands.

Now onto your question. One of the biggest reasons light bullets doesn't work great in this caliber is because they have so little bearing surface. Shot at lower velocities they should be fine. A quick search to Hodgdon shows 5.5 gr HP-38 is a starting load for a 85 grain bullet. It is safe, but it's also listed 1300 fps. With a better designed plain base bullet, and one fit to the throat, they can shoot good here. More than likely you have a slightly undersized bullet, with hardly any bearing surface.

I think you have a simple case of trying to shoot these way too fast. Use 32 H&R data if you have to. You probably won't be able to match the OAL, but seat the bullet so all the bearing surface is inside the case. Hodgdon shows a lighter load in 327, an 83gr bullet seated 1.200 OAL, 3.6gr @ 1,006 fps and 4.6gr @ 1,217 fps. I'd probably look in the 3gr to 4 gr range for accuracy with that bullet.

[Larry Gibson]

Concur with megasupermagnum's post. Before getting to wrapped around the axle on fixing what isn't broke simply reduce the load of HP-38 down to 3.0 - 3.8 gr in .2 gr increments. The Hornady start load is a bit too much for that little bullet.

[dverna]

I have never bought into the hard bullet and hard lube theory for poor accuracy. I have shot 10's of thousands of commercial bullets at plinking velocities (800-1000 fps) in more than one gun and caliber.

Good advice from Larry. Load those bullets down and you should be fine.

Good advice regarding having Doug work your guns if you are good enough to tell the difference, but most of us are not that good and/or the guns are not that bad. If you are spraying patterns, I doubt he has the magic to get you down to 2" groups.

At least try a larger sized and longer bullet before investing in having the gun worked over. If you are still not satisfied, Doug is good at what he does.

[LeadHead72]

Thanks, guys, you all may be correct on the charge size. It does make me ask the obvious question, however; why would Hodgdon give a starting load of 5.1 for that bullet if it is such a grossly inflated number? In all honesty it makes me a little a little nervous to drop to such a low charge compared to what the book says.

[megasupermagnum]

Some bullets could be able to handle that. Honestly, I've never seen a 80 grain bullet shoot good in 327 federal, even jacketed. Some people like speed, and care little about accuracy.

The numbers I quoted are straight from Hodgdon's website, straight from their book. HP-38 is a decent choice for these lower power loads too, so you should be able to find something that works good.

[LeadHead72]

Thanks, guys, I somehow skipped the "H&R Mag data" part of his comment but now it makes sense. Will have to play around with it some. While heavier bullets are of course better for this cartridge, I ended up with these bullets quite some time ago and have no other .32's use them with, so it just seemed natural to load some plinking rounds.

[P Flados]

I shoot quite a bit of of light boolit loads in my 4.2" SP-101 327. I tried heavier stuff, but I found no advantage with them for plinking and poking holes in paper.

My 78 gr boolits with PC get loaded to just above 32 H&R power level and shoot good.

I also load a 56 gr with tumble lube for a really light plinker. I had to work my way down to 32 S&W long power level to avoid leading.

For plinkers with 231, you should be able to work down to what ever it takes to get your bullet to shoot better.

It is a shame that the powder makers do not seem to want to publish data for all of the flavors of ammo that will fit a 327.

Just for reference, my old Lyman Pistol and Revolver manual has loads that go way down with 231. This includes:

- 77 gr in a 32 ACP with charges of 1.5 to 2.5 gr
- 77 gr in a 32 S&W long with charges of 2.0 to 3.5 gr

[Outpost75]

For mild loads in the .327 use starting level loads listed for .32-20 Winchester, using the fast-burning pistol or shotshell powders which ignite easily and tolerate free airspace in the case well. About 3 grains of Bullseye, TiteGroup, WST or 452AA does the trick.

[trapper9260]

I have a BH in 327 and it shoots just as well as my Handi rifle that I had made before Henry came out with their rifle and I can shoot everything in it that I do in the BH . I also have a SP 101 in it just working to fine tune the loads. I got my BH when they first came out. After it show up in the NRA mag is when I seen it first and then got it .

[megasupermagnum]

It is a shame that the powder makers do not seem to want to publish data for all of the flavors of ammo that will fit a 327.


Why would they? There's decades of 32 H&R data out there. That's like saying they should waste time publishing 357 magnum reduced loads, even though 38 special has been around forever. The 32's even have the advantage of having 32 S&W long for really light loads. And if you want loads that just barely poof out of the barrel, regular 32 S&W. Sure you have to adjust slightly for the longer case length. Big whoop.

[LeadHead72]

I have a BH in 327 and it shoots just as well as my Handi rifle that I had made before Henry came out with their rifle and I can shoot everything in it that I do in the BH . I also have a SP 101 in it just working to fine tune the loads. I got my BH when they first came out. After it show up in the NRA mag is when I seen it first and then got it .

Interestingly, that's the pair I own, too. My 3-inch SP101 is the older model with windage-only adjustable rear sight.

[Divil]

Different caliber but neither my .357 Blackhawk nor .357 GP-100 shot any of my 138gr. RN boolit loads nearly as well as my cast 140gr. FP/GC, Missouri Bullet commercial cast coated 140gr. FP, or Speer 135gr. TMJ offerings. I loaded them in magnum brass with target velocities of 1000-1100 fps. It didn’t lead due to a nice full caliber flat base, but it was at best a very mediocre grouping boolit with all the powders I tried in my revolvers. Perhaps a RN boolit moving at faster than .38 special speeds isn’t an inherently accurate proposition?

[dimaprok]

...It is a shame that the powder makers do not seem to want to publish data for all of the flavors of ammo that will fit a 327. Just for reference, my old Lyman Pistol and Revolver manual has loads that go way down with 231. This includes:
- 77 gr in a 32 ACP with charges of 1.5 to 2.5 gr
- 77 gr in a 32 S&W long with charges of 2.0 to 3.5 gr

Well if he is loading 327 mag this load data won't do any good. If you use powder that's not position sensitive you can download it all the way down as long as bullet doesn't stick in the barrel. I've used one grain of Bullseye in 38 special to "slug" the bore.

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