Polygonal Rifled Barrel

[MikeS]

Hi All.

I have a Jericho 941 (aka Baby Eagle) in .45ACP that has a polygonal rifled barrel. Would this design barrel have problems shooting lead boolits like the Marlin micro-groove rifling does? Or would this style of barrel shoot lead better, or would it make no difference at all? Thanks in advance for any info on this.

[captaint]

Mike - First, welcome to the forum. Second, as I understand it, the MicroGroove barrels don't have a problem, really. The boolits just have to fit. Then they shoot well. Also, I can't imagine you will have a problem either. Just slug the barrel and try sizing the boolits .001 over groove diameter to start. Go shoot and enjoy and see what happends!!! Mike

[MikeS]

That's the problem, with polygonal rifling there really aren't traditional lands and grooves just a polygon that twists down the barrel. How would you measure such a barrel?

[Duckdog]

I sghoot lead through my CZ82 with polyoginal barrels and there is not an issue. I would slug the barrel as normal, or just try to see if your bullets are accurate. I get zero leading in those barrels.

[msinc]

I have always read not to use lead in polygonal barrels. I had a Steyr GB pistol several years ao that was polygonal and tried it anyway. The gun shot accurate and I had no problems but it did lead up really bad. I just never fired alot of rounds at a time and kept on shooting. I have always read that the problem is the eventual build up of lead causing high pressure. I must have just been lucky. It doesn't seem worth the cleaning these days...I have a few Glocks but bought aftermarket barrels.

[bobthenailer]

I have 2 khra pistols one in 45 acp and another in 9mm they both have poly barrels !
i shoot cast almost exclusviley in them with no problems ! just ck them every once in awhile for any leading build up and you should not have any problems .

[HammerMTB]

There is a whole thread on shooting lead in a glock, that is really about the polygonal rifling in the bbl. I shoot lead in my glocks, and have no leading. It does not require an aftermarket bbl. The boolit just needs to fit the bbl.

[2wheelDuke]

I've read plenty of reports of people firing lead from polygonal bores with no issues.

I tried it in my Glock 21 and while it was accurate, it leaded up pretty bad and was a pain to clean.

I think the problem may have been inadequate lube. I do plan to try again with speed green instead of jpw/lla on the Lee 230gr TC's like I tried at first.

If not, I'll just have to get an aftermarket barrel.

[Bullshop]

HammerMTB got it right in his last sentence, it has to fit the barrel.
I have had excellent results with factory Glok barrels and boolits. If you are getting leading my first suspicion is that the boolit diameter is too small.
If the fit is insufficient at the pressure used to get a positive seal you will get blow by at the intersecting points of each flat surface which will cause leading. In my own experiance .002" over standard diameter usually was enough. However weather you can do that or not will depend on the diameter of your chamber and if it will allow a cartridge with a larger than standard OSD to enter. That and the actual diameter of the barrel interior. Sometimes juggling brass brands can help solve a chambering problem.
I have a Walther barrel with polygonal interior on a Savage action chambered for the 22/250 and I hope to gain more experiance in the use of this type rifling system.

[Iron Mike Golf]

That's the problem, with polygonal rifling there really aren't traditional lands and grooves just a polygon that twists down the barrel. How would you measure such a barrel?

There are grooves. They are shallow and rounded. So you'll need to spend some time with your slug and a micrometer to find the widest diameter. I have a 941 and I'll slug mine tonight. Not sure if there's an odd number of "grooves" or it's even.

OK, mine slugged at .402.

[Spector]

I have been shooting cast boolits through my Glock 21 for 20 years now.

200 gr SWC, 213 gr. RF, 230 gr. TC and 255 gr. RF lead PB boolits.

I started out with the Lee 200 SWC and water dropped WW alloy. Great accuracy, but leading that seemed to be a pain to remove after a 100 to 150 round shooting session. I tried some of the other boolits mentioned, still got some leading and it was still a pain to remove. But let me say it was easier to remove from the poloygonal rifling than from standard lands and grooves.

Anyway I finally read about the importance of boolit fit, boolit fit, boolit fit. I lapped out a Lee mold and not much seemed to change. Then I lapped out my Lee .452'' boolit sizing die and I noticed less lead. I think I still need to lap out my mold a little more and lap my boolit sizing die a little more too, but the lead l am getting now is very little and easily removed with a tight patched jag.

It used to seem like the lead was almost soldered or tinned into the barrel. Now the lead seem like easily pushed out flakes. I also discovered Choir Boy type pot scrubbers a couple of years back will remove the most stubborn lead deposits very efficiently.

Boolit fit, boolit fit, boolit fit.

I just shoot 45 ACP, but have pushed 255 gr. PB boolits to 980 fps using HS 7 powder. It bulged the cases where they are unsupported, but no other problems except uncomfortable recoil and shorter case life.

Perhaps the 9mm Para or 40 S&W cartridges are different animals due to their much higher opperating pressures, but the 45 ACP is a ***** cat. Your mileage may vary, but that has been my experience.........Mike

[Iron Mike Golf]

I don't have a .40 cal mold yet, but I do plan on shooting cast in my 941.

+1 on boolit fit.

[noylj]

It would seem that one should try an as-cast water-quenched bullet and simply tumble-lube with LLA. This will give you the largest bullet you will get unless you add more antimony and tin. If the as-cast doesn't lead badly, then you might want to size the bullet. Personally, I would stay with what works.
Likewise, you would probably do best with a harder bullet, but that brings the bullet diameter down.
If your barrel has hexagonal cross-section, you can slug it and measure the largest cross-section. If it is pentagonal, you can try to spin the bullet in the mic and sort of "catch" the size.
If you get leading, then you can diagnose the problem from there.

[mpmarty]

I shot IPSC from 1985 to 2005 with a Glock 21 and cast boolits. Never had a leading problem. averaged around 1000 rounds a month.

[DJ1]

I have shot lead for years out of Glock 21 and 22. Bullet fit is important. A lewis Lead Remover is also Extreemly benificial while figureing it all out.

DJ1