Polygon Rifling

1

1813benny

Member
Has anyone done any extensive testing or use of barrels w/ polygon rifling for rimfire?

Any info would be appreciated.
Ken
 
polygonal rifleing and lead bullets dont get along. they lead up badly.
 
theories?

Interesting....but why would the change in the shape of the rifling lead more versus a conventional "squared" land shape?

I would have thought that leading was more a factor due to residual tool marks and lack of (or poor) lapping.
 
Lands & Grooves

If it helped in getting a 2500 or a 250 it would be used.
but
it isn't.In knowing top a couple top smiths.It isn't part of what they do.Give them a Lilja or Benchmark and lets go win something.
Some also feel the lands wash away from the gases.
As they say,been around for every but not used that much...in RF
Of course you might have a 1600 barrel. :)
Leading can be from other things beside a rough barrel..
 
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polygonal rifleing and lead bullets dont get along. they lead up badly.
Click to expand...

having a desert eagle with polygonal rifling, in searching for the reason against lead bullet usage, i have heard that lead deposits lead to increased pressures.
 
longshooter....the desert eagle is a different animal in itself. The reason for the recommendation by IMI on not using certain powders and for not using lead bullets has to do with the gas tube used to cycle the action. Lead bullets and dirty powder will clog the gas tube...thus restricting it and causing cycling problems.

Hovis
 
I have a rimfire barrel with polygonal rifling that was made by Shilen years ago. Apparently he dusted a couple of them off the shelf and sent them to my gunsmith who urged me to try one. I've been playing with it for a few months now on and off and have yet to shoot it in a match. It does seem to shoot fairly well but I'm not sure if I can agg 2200 or better which is what you need to win with these days. I was aware of the leading issue with this type of rifling before having it put on but was surprised to have very little leading after frequent checks with the borescope. Just by coincidence I took it out of the safe last week to do some more testing.
 
Yes sir. And that was my contention for a long time, when trying to explain to a maker of lead bullets friend of mine, who wanted me to use his lead bullets extensively in my D.E.

Then i heard that the velocity of the hot gases would mostly keep the gas port clean. And being that it is reported that lead accumulates on the action springs, I started thinking perhaps this is true.

Then I read where it is the accumulation of lead deposits in the bore that is the culprit.

Perhaps there are various problems for a gas gun. perhaps there are problems associated with polygonal.

Here is an portion of article gleaned today form wikipedia;

Lead bullets and polygonal rifling
The manufacturer Glock advises against using lead bullets (meaning bullets not covered by a copper jacket) in their polygonally rifled barrels, which has led to a widespread belief that polygonal rifling is not compatible with lead bullets. Noted firearms expert and barrel maker, the late Gale McMillan, has also commented that lead bullets and polygonal rifling are not a good mix. However, since neither H&K nor Kahr recommend against lead bullets in their polygonal rifled barrels, it is probable that there is an additional factor involved in Glock's warning. One explanation is that Glock barrels have a fairly sharp transition between the chamber and the rifling, and this area is prone to lead buildup if lead bullets are used. This buildup may result in failures to fully return to battery, allowing the gun to fire with the case not fully supported by the chamber, leading to a potentially dangerous case failure. The other explanation is that Glock's barrels may be more prone than normal to leading, which is the buildup of lead in the bore that happens in nearly all firearms firing high velocity lead bullets. This lead buildup must be cleaned out regularly, or the barrel can become constricted and result in higher than normal pressures.

I hope this is helpful. It is all I know about it. whether or not it will affect you in rimfire, I don't have a clue.

Thank you,
Longshooter
 
Since it is known about the possible downside to having poly rifling, what, if any, are the possible good things that could come from it? Less wind drift? More predictable drift? Does poly rifling distort bullet shape more or less than conventional rifling? Just wondering...
 
longshooter,
In a D.E., I shot over 6000 rds of lead bullets. Spring leading is not a problem but getting that lead/carbon out of the gas return sure was. After about 300rds or slightly less with mine, cycling became a problem. I learned that as long as you addressed the lead build up (carbon and lead together seems to make some form of concrete) as soon as you notice a cycling problem, it was easily cured. If you combine lead with a dirty powder, failures can come as soon as 150 rds or less. When I sold my D.E. I had passed over 24000 rds down the tube (by far most were copper jacketed bullets). Leading with the polygon barrel was no problem when I shot lead, just the gas tube. I went through seveal spring sets.

Hovis
 
Hovis,

oooookkk.

If your happy, I'm happy.

I simply followed the recommendation of the manufacturer (jacketed only).

No lead mess. No worry.

My pistol sees only jacketed or copper coated.

I only know what I have learned thru research on this subject, and what you have just told me.

Can the thread continue now?

Thank you,
longshooter
 
Sorry longshooter if I stepped on your toes or something....didn't mean to.

Polygon rifling does not lead more than any other type of rifling. The type of lead and the type of lube and quanity of the lube used on a lead bullet has more to do with leading than the type of rifling. Poly rifling does inflect less stress on bullets.

It seems one of the primary reasons for poly rifling is bore life. Some artillery bores now use poly rifling for longevity, I have seen nothing that proves enhanced accuracy but the ability to sustain acceptable accuracy over a longer period seems to be true, as far as artillery barrels go.

Hovis
 
HovisKM,

It's ok. No problem.

Actually, if I could have read your post two years ago, I might have tried lead, and kept an eye on gun functioning, barrel leading etc. It could have helped with more shooting, for less cash. Maybe I still will.

I have wondered why poly barrels wouldn't be more accurate, with what might be considered less upset to the bullet surface.

Don't mean to hijack the thread, but one question. How difficult was it to keep the gas tube clean?

Thank you,
Longshooter
 
Had an HK P7 a few years ago (poly rifling), and it leaded up very badly with home brewed semi wadcutters. Swithched to JHP's and never looked back. HTH. JH
 
longshooter said:
HovisKM,

It's ok. No problem.

Actually, if I could have read your post two years ago, I might have tried lead, and kept an eye on gun functioning, barrel leading etc. It could have helped with more shooting, for less cash. Maybe I still will.

I have wondered why poly barrels wouldn't be more accurate, with what might be considered less upset to the bullet surface.

Don't mean to hijack the thread, but one question. How difficult was it to keep the gas tube clean?

Thank you,
Longshooter
Click to expand...


Really enjoying the discussion about the D.E.'s, miss not having one and am thinking about buying another. As far as the lead, I kinda killed two birds with one stone. Since I shoot a lot of centerfire benchrest, I buy cleaning fluid by the gallons normally. I just plugged the muzzle with a cork, stood in on the muzzle and filled the barrel with cleaning fluid. Do this where it won't make a mess, I usually did it out side. It forces the cleaning fluid into the gas port and after it starts to leak out pretty well, I pour out the cleaning fluid and applied compressed air backwards through the gas port. If you do this often enough, it keeps it real clean. I let mine get plugged completely once and it took a while, using a fine wire and fluid to get it clean. I ended up buying a bulk of Hornady XTP's cheap and shot them from there on out.

I don't know why poly don't seem to be as accurate, maybe it's actually harder to hold tolerances?? I just don't know. It seems like it could be buttoned very accurately. I don't know about you pistol but mine was the most accurate pistol I had ever owned, if you didn't flinch.

Sorry about hijacking the thread.

Oh...I just remembered...It seems one of the engineers at Aberdeen Proving Grounds told me that the artillery rounds took longer to stabilize and that they needed more bearing surface than standard rounds with land/grooves. Could be wrong on that.

Hovis
 
longshooter said:
Hovis,

oooookkk.

If your happy, I'm happy.

I simply followed the recommendation of the manufacturer (jacketed only).

No lead mess. No worry.

My pistol sees only jacketed or copper coated.

I only know what I have learned thru research on this subject, and what you have just told me.

Can the thread continue now?

Thank you,
longshooter
Click to expand...

And this relates to .22 benchrest shooting how????
 
I believe H&K do not recommend the use of lead bullets in their pistols!
Jacketed only!!
 
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