Chrony results for 10mm AR and Kimber TLE II

[Graybeard]

So I finally got to run some factory and handholds over my chronograph with my new RWM DI 10mm AR 16" barrel and my Kimber TLE II.

I'll start with the factory stuff first. I have a stash of old ( at least 15-20yrs) Silvertips, and I used some newer production Hornady 180gr XTPs.

175gr Silvertips, silver box background:
Kimber 1261, 1267, 1251, 1265, 1265, 1243  AVG 1259fps
  AR     1435, 1421, 1414, 1410, 1444, 1424  AVG 1425fps net gain of averages= 166fps

175gr Silvertips, white box background:
Kimber 1280, 1291, 1288, 1280, 1286, 1295 AVG 1287
  AR     1506, 1486, 1496, 1466, 1491, 1499 AVG 1491 net gain of averages= 204fps

180gr Hornady factory load:
Kimber 1177, 1167, 1181, 1184, 1178, 1181 AVG 1178
  AR     1340, 1309, 1313, 1328, 1323, 1340 AVG 1325 net gain of averages= 147fps

Handload powder charges were individually weighed, except the Longshot load. That was done on my progressive press and designed as a plinking load for my AR. 800x load is a duplicate of an Underwood load, per Shadow's pulldown. All handloads were using new Starline brass and CCI LPP.

180gr XTP, 9.4gr 800X, 1.260 COAL
Kimber 1307, 1292, 1335, 1309, 1297, 1316 AVG 1309
  AR     1452, 1467, 1501, 1484, 1469, 1503 AVG 1479 Net gain of averages= 170fps

180gr RMR FMJ, 9.0gr Power Pistol, 1.250 COAL
Kimber 1313, 1316, 1275, 1284, 1294, 1307 AVG 1298
  AR     1449, 1447, 1472, 1482, 1450, 1466 AVG 1461 net gain of averages= 163fps

180gr RMR FMJ, 9.2-9.4gr Longshot, 1.250 COAL
Kimber 1315, 1333, 1289, 1315, 1346, 1327 AVG 1320
  AR     1472, 1433, 1462, 1453, 1459, 1457 AVG 1456 net gain of averages= 136fps

No really big surprises from this data. But a couple of little ones. One of the Hornady factory rounds failed to cycle the AR. I was surprised at the speeds I was getting from the Power Pistol load in the Kimber. The Silvertip, white box background, definitely met advertised specs and was right on the heels of the Underwood clone.

Going forward I plan to make up some hotter stuff for the AR. This was an attempt to see what works well in both guns.





 

[Dave84]

Great results. I didn't know 9.2-9.4 grains of long shot was so fast out of a 1911. Did a batch of 9.3 once. Thought maybe I was at 1280. Had no way to know. I usually just do 9.0 grains seeing as it's reused brass.

[Graybeard]

That was my first chance to run LongShot over the chronograph and the first time with this chronograph. The white box Silvertips and the factory XTPs were right on for advertised velocities, so I think the chronograph is working well.

The RMR 180gr FMJ bullets appear to have a brass jacket. Possibly less friction? Your estimation of 1280fps with 9.3gr of LongShot may be right on the money with a different bullet.

A few years ago I worked up slowly to a 180gr XTP load with 10.0gr of 800X using my Delta Elite. Didn't get quite the speed I got out of my Kimber with the 9.4gr load posted above. Same batch of 800X and XTPs. I think that clearly illustrates that different guns/chambers can definitely get you different results.

[Pablo]

Thanks for posting this. I somehow missed this valuable thread!

[Graybeard]

I'm happy to Pablo. I'll have some more to post in 2-3 weeks.Hotter stuff for the AR and probably some different bullets.

[Pablo]

I'm happy to Pablo. I'll have some more to post in 2-3 weeks.Hotter stuff for the AR and probably some different bullets.

Well let me in on the magazine secret mine still fight with me. And now I can't seem to find any more grease gun mags on the market. Thanks!

[Graybeard]

After testing today, I can get it to run reliably with 20rnds in the mags. A couple of them loaded with 30rnds ran for 2 or 3 shots and then jammed. Seems like under greater spring tension the feed lips hold on just a little too long.

So far, I disassembled the mags and noticed the followers had been ground down on the corners. Seemed obvious that was done because of the lips being bent in during conversion to 10mm. I polished the ground areas, cleaned everything, Frog Lubed the followers, and reassembled them. I also opened up the front of the lips, just slightly, after mirror polishing those. That took me from running 15 reliably to 20.

Next thoughts are removing metal from the front of the feed lips and try to make them look more like the lips on a 1911 mag. Another thought was anneal the top 5 or 6 coils and try to make a variable rate spring. Not planning on doing either of those until I get a couple more mags I can destroy in the process.

If I can get to 30rnds running every time I will definitely let you know. https://www.keepshooting.com/m3-grease-gun-magazine.html In stock, $30.95