RickT

CMMG RDB: I can run full Endomags, but load only on an open bolt to avoid scoring the top round with the bolt lugs (and the mag is hard to lock into place on a closed bolt). Reload mags I limit to 28 rounds in case of closed bolt.

One final thought regarding CMMG OAL: it's not unusual to see OPs request help with bullet weight, powder load and OAL. My 8" CMMG barrels have an extreme short leade. I've had no issues with factory ammo, but in my experience the driving band of factory stuff does no extend beyond the case and the ogive is such that the bullet tapers pretty rapidly outside the case mouth. I can load the old style Bayou 124gr bullets to 1.14" or more with very little of the driving band surface exterior to the case, but the BBI 125gr bullets, which function 100%, I load to 1.11". 115gr Bayou, the new profile, need to be loaded a bit shorter yet. So, YMMV, but this has been my experience.

115gr coated with 3.8gr N320 here also in my 9mm 1911. I'll be returning to SP now that I'm on my last jug of leftover N320. I find N320 to be much dirtier than SP at these low PF.

That seems like and incredibly soft load and I'm surprised you don't see failures to eject. I haven't switched back to SP yet, but with N320 I seem to need about 0.2gr more than SP for reliable cycling. My 115gr N320 load would be 4.2gr using coated bullets in an 8" barrel. My current 124gr BBI load is 4.3gr N320. I'm a hack B shooter so YMMV, but the gun, as mentioned above, is very flat shooting with these sorts of loads. I gave up on applying the "softer is better" logic that I use for my 1911 to the PCC.

What are the dynamics of a straight blowback design that cause FP failure? Are FP failures just as common in "stock" blowback designs versus changes (carrier weight, spring configuration,...) that might be used in a competition gun?

If the gun has been back to CMMG (how recently?) I'd be surprised that the bolt doesn't use the MK10 ejector spring. Both my uppers run with standard extractor springs, but others have had success with the extra power extractor spring. You definitely need the upgraded ejector spring. I don't suppose this can somehow be related to the magazines you're using? I'd think CMMG tests with Glock mags. A final observation: filling Endomags to capacity in combination with softer reloads can see an FTE on the first round probably due to the pressure of the next round on the bolt slowing things down a bit. Don't know about Glock mags although I do have a Glock-configured early Guard rifle.

What ammunition are you running? If reloads, what PF? I've got two SBR lowers (AR with Endomags) with 8" CMMG uppers. Using the MK10 ejection sprint and a standard AR extractor spring they run 100% as long as I'm not running soft reloads. Even for steel challenge there is no point in soft reloads as the gun shoots much flatter with ammo with at least as a bit of zip. This as two benefits. First, the aforementioned flatter shooting. Second, if you are shooting 9mm reloads you probably reuse the cases many times. Variation in power load, neck tension caused by mixed brass and the occasional cracked case can produce an FTE, while increasing the powder charge eliminates two of these potential issues.

Until they crack. Exception would be for a PCC match where I would bin the rounds to selected cases that had not been excessively first. My 1911 will eject basically anything, but my PCC has a bit of a tendency to FTE on a cracked case.

The advantage of the Aluminum is that you don't need a hex tool to change the battery (and you will be changing the battery fairly frequently.)

I have a TT diamond in one of my RDB rifles. Not sure exactly the TPW I'm using now, but when I went down to 1.5 lbs. the pull weight began to creep and eventually doubled. It's been fine upwards of 2 lbs.

Follow up: I upped my 125gr load from 3.8 to 4.3gr of N320 using 125gr BBI. 90 rounds later with absolute no issues and I was shocked that the rifle shot much flatter. I could fast double on a 18x24 plate at 50 yards with virtually no correction for the second shot. The soft load really drove the sight off the target. I plead guilty to falling prey to the steel challenge mantra "softer is better" which does not appear to apply to my CMMG SBR. I know .5 gr is a big jump, but well within the published load range and impulse is still considerably less than factory ammo. I'm going to repeat this test with a slightly stouter 145gr load, currently only 3.2gr of N320.

Some additional information: Did some additional testing with both my 8" barrel CMMG. They run 100% with every type of factory ammo I had on hand from 115 gr. through 147gr including defensive rounds. Ejection pattern very consistent between the two rifles. I get the occasional FTE with hand loads ranging from 115gr through 124gr up to 145gr. Since I don't shoot USPSA these are not factory loads and I'm now convinced that these FTE are due to the large SD I would expect from mixed headstamp cases with no control over the number of times they have been reloaded. I do get infrequent cracked cases, but frequency is less than that of the FTE. I'm going to bump up these loads to more closely match factory performance. I'm am about to run out of some back of the cabinet N320 after which I'll return to Sport Pistol and introduce a new variable. Yes, I know I should be using my Labradar chrono, but my I'm lazy and my 1911 eats everything and doesn't seem to care about SD, cracked cases, etc. Next time I bring a rifle to practice I'll set up the chrono and see what I get.

No doubt there are multiple ways to skin the FTE cat. I does appear the ejector spring is the real key. When it all works it's sweet.

It's easy to calculate the quantity if you feel like weighing a 400 lb. bucket, but in order to estimate the weight (and thereby the number of bullets) you need to estimate the average density of bullets by either a)weighing a sample volume or b)guessing at the fill factor.

Fill factor is a bit uncertain and no box store bucket would stand up to 400 lbs, but Specific Gravity of Lead 11.35 Weight of 1 gallon of water 8.34 lbs Fill Factor 0.85 pure guess Weight of bucket of bullets 402.30 lbs Number of Grains/Pound 7000 gr/lb Bullet Weight 124 gr Number of bullets in a 5 gal. bucket 22711 Biggest uncertainty is the fill factor. Take a small container of known volume, fill it with bullets and use 231 cubic inches/gallon to directly, and more accurately, calculate what the bucket (contents) would have weighed if the bucket hadn't cracked and spilled its contents on the floor.

Ordered on the 6th, arriving tomorrow (13th)

RangerTrace, thanks for the info. I won't be putting the Tek-Loks on this belt. If my AR mag pouches don't fit I'll send the belt back. I have a Kore Essentials EDC belt (excellent BTW) and the pouches fit on that, but the belt loops get in the way of positioning the two pouches I need to use.

I use a BOSS hanger to the holster side of things is solid. Blade Tech tek-lok configured "pouches" work just fine and I do have pouches for PMags using tek-lok. I'm just looking for a different belt which works with some different pouches that use plastic clips the bottom hook of which require a great deal of force to squeeze over the lower edge of the belt. I took a close look at the Shooter's Connection belt pictures. Looks like it will work fine since it doesn't have that build up at the uppper and lower edges. I'll just leave it set up for PCC.

I have a CR Speed belt that I've been using for5-6 years. It's been fine and continues to be fine for SS Steel Challenge, but I'm looking for a belt that doesn't have the wider "rim" along the upper and lower edges; I have some AR mags with clips that don't really accommodate the rim and I'm reluctant to force things. If I can't find a different belt I'll try compressing the rim with pliers. It's also true that the velcro on the CR belt does tend to slip a bit with the weight of my 1911.

I have both my 8" CMMG uppers running well with my two AR-15 lowers. I've gotten good support from CMMG working through ejection issues seemingly related to some outdated spring configurations in the bolt. I'm running a standard buffer configuration. If you use the tan PMags don't load them to 30 rounds. The spring pressure is sufficient to spread the lips of the mag body. I can't insert full tan mags in my ADM lower. Black mags are fine. Don't load mags on a closed bolt as a standard practice. The bolt lugs will score a coated bullet and scratch FMJ. This does not occur during live fire. The slightly damage round will cycle just fine, however. The CMMG Mk10 ejector spring and a standard (not extra power) extractor spring are key to achieving reliable extraction. When I was trouble shooting my second upper I tried a BCM extractor spring and that was an absolute no-go. I recently ran 147gr Lawman, 115gr reloads and 145gr reloads through the newer upper. I had one FTE on the first round of a ful mag. I attribute this to the high pressure on those first two rounds. I had no other issues and the following 28 rounds of the 115gr mag cycled just fine. I'll do some additional testing and will continue to load to 30 rounds in practice. YMMV of course. Different buffer configurations and ammo will alter the bolt cycle and may affect ejection. In my situation the #2 upper is slated for suppressed home defense to the 147 Lawman is a proxy for the Federal HST HD rounds. I'll run the 145gr ammo in Steel Challenge and USPSA; very low recoil and LRBHO seems 100%.

Let's tweak this a bit. How about just CFPO and CFPI? There's no PF in SC so who cares (much) about holster position, slide cuts, compensators? Manufacturers will get plenty of exposure in the larger sport of USPSA. And allowing centerfire in the "rimfire" divisions would allow folks new to handguns to compete without having to draw a hot gun.

Regardless the cause the trend is clear and the long standing notion that Steel Challenge was is an on ramp to USPSA is not longer the case. Why not reduce SC to eight divisions: RFRO, RFRI, RFPO, RFPI, PCCO, PCCI, CFPO and CFPI? Eliminate holster position restrictions so USPSA OPN shooters don't have to change gear. If a PROD shooter wants to use a race holster go for it. And while we're at it replace OL with a more interesting stage not requiring movement; again, this is not an action pistol entry sport so why bother with the uniqueness that is OL. Oh, and figure out what to do with ISR and OSR; these sightings are fairly rare, but it's probably important to do something to encourage the survival of the species.

Cataract surgery here also in my right eye only. I used Sight for Sport Eyes to have new lenses put in the snap-in RX adapters for my Rudy Project glasses. I think the cost was $120, very reasonable. I also had a set done with distance in both eyes for PCC. As noted I may have the left lens of my iron sight inserts redone, but since it's only an issue with Outer Limits it's probably not worth the effort.

Good for testing; I have 2.0 and 2.5 diopter and I'll use the 2.0 to see if that resolves the binocular rivalry. For sustained use I currently use the Rudy Project purple photochromic lenses.

Not yet a zombie thread so I'll take a stab at adding an observation. I have the usual setup for iron sights: 2/3 meter focal distance in the right eye and distance in the left eye. This works just fine in my Rudy Project glasses, but I did notice something today. When practicing the box transition for Outer Limits my brain would switch to my left eye since the visual field is much clearer. I had to consciously squint a bit to get my right eye into the game. I might be better off with the same focal distance in each eye (in my case of course) to prevent this from happening. Anyone else observed this? I do have some safety glasses with 2.0 diopter full field, close to my astigmatism-free right eye prescription so I might try this next practice session to see if that changes things. In any event i've not found blurry targets to be much of an issue in steel challenge.