10mm-Auto

10mm Ammuntion => Factory 10mm ammo => Topic started by: Intercooler on July 19 2013 07:02:48 PM MDT

Title: Different type of test. Polygonal versus straight cut rifling
Post by: Intercooler on July 19 2013 07:02:48 PM MDT
   I'm thinking the red loctite on the Limited's front site will hold tomorrow. Now that I know the Limited is Polygonal and the Match is straight cut I want to see if their is a velocity bump. Even if the site comes off I'm taking the stock piece with me to get this completed! The plan is to Chronograph a few to prove/disprove this:

American Eagle 180gr FMJ
Underwood 135gr Sierra HP
Underwood 165gr TMJ
Underwood 180gr TMJ
PBR 200gr FMJ

  Hopefully we can see something when I post the results in the morning.
Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: The_Shadow on July 19 2013 08:12:02 PM MDT
Should be a great side by side test comparison!   8)
Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: Intercooler on July 19 2013 09:06:59 PM MDT
I have Underwood 155 TMJ's too that I found. They needed a retest anyway.
Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: Intercooler on July 20 2013 10:58:51 AM MDT
   That was a long shooting session because I had a blast with the Limited Pro ;D I'm liking the better take-up of the SA trigger in it better than the Match  :o In looking at the results for this test based on the American Eagle and heavier version rounds, their may be a slight increase in velocity for Polygonal rifling. Not enough to even worry about but then again maybe more difference would show shooting Lead?

American Eagle 180gr FMJ
(Match) 1121, 1109, 1108, 1117, 1120. Average = 1120 FPS/ 497 LBS
(Limited Pro) 1135, 1127, 1123, 1130, 1129. Average = 1128.8 FPS/ 509 LBS

Underwood Ammo 180gr TMJ
(Match) 1329, 1322, 1345, 1320, 1327, 1342. Average = 1328 FPS/ 705 LBS
(Limited Pro) 1325, 1332, 1344, 1350, 1322. Average = 1334.6 FPS/ 712 LBS

Underwood Ammo 165gr TMJ
(Match) 1400, 1380, 1365, 1411, 1381. Average = 1387.4 FPS 705 LBS
(Limited Pro) 1426, 1377, 1369, 1409, 1418. Average = 1399.8 FPS/ 718 LBS

Underwood Ammo 155gr TMJ
(Match) 1553, 1488, 1537, 1492, 1465. Average = 1507 FPS/ 782 LBS
(Limited Pro) 1486, 1523, 1478, 1511, 1471. Average = 1493.8 FPS/ 768 LBS

Underwood Ammo 135gr Sierra HP
(Match) 1717, 1650. Average = 1683.5 FPS/ 850 LBS
(Limited Pro) 1692, 1619. Average = 1655.5 FPS/ 822 LBS


I shot a ton of American Eagle out of the Limited Pro and Razorback. This is my favorite round for pure shooting fun!



Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: REDLINE on July 20 2013 11:27:38 AM MDT
Over time I've pretty much come to the conclusion that polygonal rifling does not add velocity to any extent worth considering, if at all.

Glad you tested it though!
Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: Intercooler on July 20 2013 11:56:15 AM MDT
I tend to agree with you unless someone tells me Lead is where it shines.


In looking at that data possibly a 10 FPS increase? Hardly anything or in the fudge-factor! They say where it's better with Polygonal is due to where how it is formed, splits are less prone to occur.
Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: REDLINE on July 20 2013 01:51:58 PM MDT
But how many rounds have to be run through a platform before any wear amount can be discerned?  Obviously various factors would vary the results.  Either way, in the context of 10mm pistol platforms I'm still thinking no realistic issue whatsoever.

Yeah, a 10 FPS increase with some, but am I not seeing correctly that your numbers show a decrease in velocity with the lighter bullet loads using the Limited Pro?

When you say splits, do you mean splits in the barrel?
Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: Intercooler on July 20 2013 02:48:16 PM MDT
Yea splits in the barrel.


I was a little shocked with the lighter weights too but just report the data  :)
Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: REDLINE on July 20 2013 06:21:13 PM MDT
I wonder if those splits are more prone with certain steels over others.
Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: The_Shadow on July 20 2013 08:23:53 PM MDT
Very nice comparison...you done good!
Title: Re: Different type of test. Polygonal versus straight cut rifling
Post by: Intercooler on July 22 2013 05:01:38 AM MDT
I think this test would be possible in a Glock. I would really like to see it done to see how the light weights perform.