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rcgrube,
Relavent information when adjusting away from the suggested COL (which happens a lot on this forum).
My question is, the pressure increases but how does one tell by how much without a pressure gur setup?
Primer condiition is a notoriously inaccrate method for judging pressure in pistol rounds. A chronograph doen\’t show an increase in M.V. with a decrease in OAL?
At least not in my limited experimentation. No appreciable change in M.V. for 135gr MatchWinners loaded over Accurate #2 and Accurate #5 for cartridge lengths from 1.067\” to 1.100\” was recorded. There was maybe a small improvement in groups for the 1.070\” COL.
Knowing shorter rounds can produce higher pressures is academic unless a reloader can assess the affect using their loading components.
Robert,
So what were you\’re results? Any chrony data.
I tried Accurate #5 with a COL of 1.120\” and got an average of 980 fps from a G17 and 92FS. Accuracy wasn\’t that great in either gun.
As most of you have probably discovered since Carmon S. Howard posted that data for the RMR bullets can be found in the Western Powder Reloading Guide 8, the same data can be found online at:
That includes data for the 135gr FMJ Match Winner
You can go to LabRadar\’s website to read a description of what the unit can do.
https://mylabradar.com/product/chronograph/
If you click on the \”Download\” tab at the top of that page you can select the \”Labradar\” tab and down load the User Manual V1.5 from there.
For some reason they don\’t mention the Bluetooth connectivity to a smart phone in the manual.
For demos you can go to YouTube and search \”Labradar channel\”. The videos discuss it\’s setup and use.
I\’ve had mine since 2018 (paid $649 on sale) and have used it to chrono over 4500 rounds since. The V1 has come down in price I assume because the Labradar LX is now competing with it and the Gamin Xero C1 pro.
IMHO the original Labradar Chrono has more capabilities than the newer unit. To be fair the V1\’s sensitivity to smaller projectiles (e.g. .223) may not be as good. I assume that from the videos on YouTube. But it still tracks them out to 75 yards at least. If you\’re shooting pistol the target must be at least 15 (preferably 25) yards away for the V1 to be accurate and the newer one infers it can be closer.
I emailed LabRadar and their sales department assured me the V1 is not being discontinued.
If you have questions about the V1 I\’ll be happy to try and answer them.
IMHO, add $200 to the price of your next ProChrono and pick up a LabRadar Chrono (the original, not the new one) from Midway instead. The carry case is a nice add-on, just about any tri-pod will do and get a USB power bank for primary power (carry 6 AAs as back up). You\’ll drop $450-500, but you\’ll never shoot it and it gives you way more info than those all-in-one units.
SC\’s list of possible culprits causing the length variation is spot on, but does not address bullet to bullet dimension variations. I\’m not sure if the Lee bullet seater uses the bullet nose or the ogive as the surface is contacts when seating. If it seats using the bullet nose and the bullets vary in length (which can happen) the COAL will also vary. The ogive wrt base location is more consistent, I\’m guessing, due to the way the bullet are formed.
If you\’re measuring COAL I suggest you invest in a Hornady Lock-N-Load Basic Bullet Comparator set (or its equivalent). They go on sale periodically at places like Midway USA.
.
My takeaway from RMR is the company has no problems with the LFC dies being used with their 3GH bullets.
mdi255,
For clarity I am using Lee Part #90817, 223 Lee Factory Crimp Die for my .223/5.56. I also use them with other rifle cartridges.
It does use a collet to apply the crimp, but collet is not part of the die family nomenclature.Probably trying to avoid confusion with the Lee Collet Neck Sizing Die (e.g Part #90954) which uses a collet to squeeze the neck of a resized piece of brass against a mandrel to improve neck uniformity and improve neck tension consistency. I find the collet neck sizer works best when used in conjunction with a small base body die (e.g. Redding #74111) to bump the shoulder back to SAAMI spec. and not touch the neck.
I do use a collet neck sizer on 300 AAC Blackout brass formed from 5.56 LC brass. The brass is formed by removing the decapping assembly from an RCBS Small Base AR resizer die (die set #11107) and running lubed 5.56 cases through the die. The cases are then delubed and cut using a HF min-chop saw and a jig that\’s no longer available. I then anneal, trim to length, debur and final neck size them using the collet neck sizer (no lube necessary). The TTL and deburring can be done after the neck tensioning. I haven\’ noticed any difference.
I also use Lee Carbide Factory Crimp Dies (available for handguns cartridges only), which apply a taper crimp or roll crimp depending on the cartridge (e.g. 9mm is taper, .357/.38 is roll) and final resizes the cartridge with a carbide ring at the opening (it resizes as you raise the ram). It replaces the Lee Bulge Buster that you\’d buy separately and insert into a Lee Carbide Seating Die.
I use both kinds of LFC dies because they are not dependent on cartridge trim length like the Redding taper/roll crimp dies I used for years.
Although I may split a lot of brass and use the LFC on half and the taper crimp die on the other (all other components being the same) and see if there is any apparent advantage of one over the other.
Just for clarity I use a nylon coated cleaning rod, not a steel rod like Ian. I use a Parker Hale jag (rounded tip) on the rod to contact the bolt face and then the bullet nose. Make sure the firing pin isn\’t protruding from the bolt face while making the first measurement. I use Possum Hollow cleaning rod stops rather than brass stops. A micrometer adjustable bullet seater takes the guess work out of setting the proper bullet depth for the dummy round.
The speedy method isn\’t that speedy.
I\’m not sure that link is going to work. I have problems linking things in these forums.
The video is called \”How To Accurately Determine Cartridge Overall length\” by Ian Wilson (there are other videos showing the same procedure). Ian shows you how to determine the Maximum Cartridge Overall Length (COAL) using a projectile of the proper diameter and a cleaning rod. Once you\’ve calculated that, if you have a comparator you can measure the distance from cartridge base to bullet ogive of the dummy round. That measurement to the ogive is good for any caliber compatible bullet you\’ll use in that rifle. It\’s not dependent on bullet profile. If you change comparators you\’ll have to measure the dummy round again as comparators are just that, comparators. They are not exact measuring devices.
