Armory Sponsor
Posted: 12/21/2008 8:57:49 PM EDT
| I took my LMT AR out today to fire some reloads. The rifle was running fine but when I went to manually eject a loaded round it was very hard to eject. I tried some of my brothers reloads and I had the same problem. Then I tried factory Winchester and Remington and had no problems ejecting manually. The gun never had a problem loading,firing or ejecting when I would pull the trigger with any of the ammo. I full length resized with a Lee die and my brother used a Dillon to resize his brass. I know it could be a resizing problem but could it also be a tight chamber? Is it safe to fire such a tight fitting round? |
|
Strart from the beginning......this time........
Check that your brass is trimmed to the correct length. Gauge your re-sized brass to ensure that the correct size has been achieved. Check the overall length of your cartridges when you're done. That should do it for now. Report back. Aloha, Mark |
|
Quoted:
Quoted:
If he overcrimped his handloads, it would cause the same problem. He should check that dirst. Increasing headspace first is a bad idea. How? This was an UNFIRED reloaded round. When you overcrimp, the case body immediately south of the shoulder buckles. The case body just south of the buckled brass baloons outward. This increases the case body diameter and sticks the case in the chamber when you close the bolt. *Why? Cuz the shoulder area is ten times softer than the body. |
|
Quoted:
Strart from the beginning......this time........ Check that your brass is trimmed to the correct length. Gauge your re-sized brass to ensure that the correct size has been achieved. Check the overall length of your cartridges when you're done. That should do it for now. Report back. Aloha, Mark The brass is trimmed to the proper length. The dimensions of the case are with in spec. When compared to a Remington factory round my reload is .001 of an inch wider just below the case head and is also .001 wider just above the shoulder but still not as wide as what my Speer manual shows. I used a Stoney Point headspace gauge to compare the reload with the Remington and that is also within .001 of an inch. The overall length is 2.24 and I barely put a crimp. I did cycle some of my reloads through my Rock River this morning and had no problems with the rounds sticking. Iam guessing that the LMT has a tighter chamber but can .001 of an inch make that much of a difference. |
|
Quoted:
... The brass is trimmed to the proper length. The dimensions of the case are with in spec. When compared to a Remington factory round my reload is .001 of an inch wider just below the case head and is also .001 wider just above the shoulder but still not as wide as what my Speer manual shows. I used a Stoney Point headspace gauge to compare the reload with the Remington and that is also within .001 of an inch. The overall length is 2.24 and I barely put a crimp. I did cycle some of my reloads through my Rock River this morning and had no problems with the rounds sticking. Iam guessing that the LMT has a tighter chamber but can .001 of an inch make that much of a difference. 0.001 inches can make a difference in the wrong place. Don't use the drawings in a load book for anything but a reference. The rifle chamber dictates everything. The dimension you haven't measured is the cartridge headspace. This a reference distance from a datum on the shoulder to the case head. If the length is a little long, the cartridge won't chamber correctly and will be difficult to extract. You need about 0.0015 to 0.002 inches of clearance, or "head space". In this case, 0.001 too long will cause the gun to jam up. Your other gun probably has a slightly longer chamber, just enough. Without a tool, your best approach right now is to crank the die down just a little more to get that clearance. Then when you can, get one this tool to use with your calipers: https://www.hornady.com/shop/?ps_session=d16f9af07549eecd6444291bd567a3b9&page=shop%2Fbrowse&category_id=4ffc0a8772783e83440ac87ed0c3ee5b Measure the length of several fired cases, calculate an average, then set your die to shorten the length by 0.0015 to 0.002 inches. If you set the headspace to 0.005 or 0.008, it's not the end of the world, but don't go shorter than 0.008 inches. |
|
Using a precision micrometer measure the case dimensions of factory ammunition and your reloads.
Usually the culprit with autoloaders is using full-size dies that do not resize cases to near-factory dimensions, plus not removing all case sizing lubricant Cases that have been fired and that have expanded to slightly larger-than-factory dimensions (particularly at the base of the case just above the extractor groove) will be tough to chamber with a dangerous risk of a slam-fire. Once chambered (using the great inertia of the bolt carrier group) the cartridge is force-fit chambered into the weapon and may be extremely tough to extract and eject. The simplest solution is to use a small-base sizing die. The easiest way to check your rounds is to field strip the weapon, and drop your loaded cartidges into the chamber using it as a cartridge gage. If they don't drop in all the way and fall out of the chamber once you tilt your muzzle up your cases are not correctly sized. |
|
You didn't tell us the "history" about your LMT AR rifle.
But then again, I don't expect that you would have to, unless you think it matters. So, can I assume........ It's been broken in? It was clean before you started for the day? Round count for the day at the point of "problem?" That on previous occasions while using the same rifle with same ammo you had no problems? And, yes, chambers have been know to be cut tight and/or with very little leade cut. I can remember one guy who complained that when he ejected a live round, the bullet stayed behind stuck in the rifle's barrel. And, his rounds were magazine length. But.....IF it hasn't happened in the past, why would it all of a sudden be a chamber issue? So........could it be, a dirty chamber? If you suspect it's a re-sized brass issue......you could/might consider a SB die for resizing. But, IF you had no problems in the past (F/L re-sizing), why should it all of a sudden happen now? Changed your settings? Perhaps, more info is in order? Aloha, Mark PS..........BTW are you measuring the offending round or just one of the batch? And, If you're dealing with only .001"......... Have you considered your press flex and/or shellplate and/or die head movement. Then, technique, perhaps a short stroke of the handle? And, even a lack of lube inside the neck of a case while re-sizing/de-capping, has been known to cause trouble, for some reloaders. |
|
I had the same problem.
In my particular case I had a bad sizing die. I could not really confirm this until I bought a gage from Dillon. Replaced the die and set it up with the case gage. [URL=http://]http://www.dillonprecision.com/#/content/p/9/pid/25547/catid/3/Dillon_Rifle_Case_Gages |
|
Quoted:
Quoted:
... The brass is trimmed to the proper length. The dimensions of the case are with in spec. When compared to a Remington factory round my reload is .001 of an inch wider just below the case head and is also .001 wider just above the shoulder but still not as wide as what my Speer manual shows. I used a Stoney Point headspace gauge to compare the reload with the Remington and that is also within .001 of an inch. The overall length is 2.24 and I barely put a crimp. I did cycle some of my reloads through my Rock River this morning and had no problems with the rounds sticking. Iam guessing that the LMT has a tighter chamber but can .001 of an inch make that much of a difference. 0.001 inches can make a difference in the wrong place. Don't use the drawings in a load book for anything but a reference. The rifle chamber dictates everything. The dimension you haven't measured is the cartridge headspace. This a reference distance from a datum on the shoulder to the case head. If the length is a little long, the cartridge won't chamber correctly and will be difficult to extract. You need about 0.0015 to 0.002 inches of clearance, or "head space". In this case, 0.001 too long will cause the gun to jam up. Your other gun probably has a slightly longer chamber, just enough. Without a tool, your best approach right now is to crank the die down just a little more to get that clearance. Then when you can, get one this tool to use with your calipers: https://www.hornady.com/shop/?ps_session=d16f9af07549eecd6444291bd567a3b9&page=shop%2Fbrowse&category_id=4ffc0a8772783e83440ac87ed0c3ee5b Measure the length of several fired cases, calculate an average, then set your die to shorten the length by 0.0015 to 0.002 inches. If you set the headspace to 0.005 or 0.008, it's not the end of the world, but don't go shorter than 0.008 inches. I used a Stoney Point headspace guage which is now called the Hornady LNL headspace guage to compare fire formed brass from the LMT to the reloads. The reloads are all within -.005 of the fire formed brass. Iam going to try a small base die for resizing and see how that works. Thanks for all the information everyone. |
| I bought a RCBS small base die yesterday and put some dummy rounds together. I also put some dummy rounds together using my Lee die and made sure that I bumped the shoulder back on all the rounds .005 to make sure headspace wasnt causing the problem. All of the rounds from the small base die went in and out of the LMT with no problems at all. All of the rounds from the Lee die were a tight fit when trying to extract. |
|
Quoted:
I bought a RCBS small base die yesterday and put some dummy rounds together. I also put some dummy rounds together using my Lee die and made sure that I bumped the shoulder back on all the rounds .005 to make sure headspace wasnt causing the problem. All of the rounds from the small base die went in and out of the LMT with no problems at all. All of the rounds from the Lee die were a tight fit when trying to extract. Now try bumping the shoulder back just a bit on the old die and see if it works. Small base dies are seldom needed. Not saying you don't have one of those situations but I have loaded rounds to fit a Wilson case gauge and standard dies that have been fired with no problems in at least 6 different rifles. |
| You only have to bump the shoulders back 2 or 3 thousandths to get proper headspace. Bump them too far back and you'll get case stretching and thinning above the case web, weakening your case, shortening their life, and prepping the brass for a case separation (the extractor will pull the base of the cartridge out of the chamber but leave the front half of the case from base up in your chamber). |
Armory Sponsor