Well, you got a point there, Jay. Hey, I'll probably be calling you late afternoon today to finish that discussion regarding you know what. :flute: :biggrin:
My 2007 308MX and Jay's (Ret_Eng) REP 308MX are carbon copies in chamber dimension, IOW, head space and free bore. Adam and I have discovered the amount of excessive head space varies, the worst of which produces excessive sticky extraction and poor accuracy, yet, Adam (Ranger Point Precision) can remedy these issues and then these rifles perform as intended. The ME's are awesome chamberings in a great lever platform and we both want to disclose to folks who experience such poor performance what the issues are, that they can be remedied, and they then can enjoy just how awesome these ME's are.So is this common to just the Remalin or do you see this on all the 308?
Hey guys- been a while. Stopped in and saw this thread.We generally don’t get more than a trickle of 308 Marlin Express rifles through the shop, but we’ve seen enough of them now to get a close look at the gremlin that haunts them. As many of you know, the 308 platform has been dogged by frequent reports of sticky lever issues and high pressure signs. With a max chamber pressure around 47kpsi, this simply shouldn’t be happening.
Several months back a customer sent us several MXLRs for work, among them a pair of 308s. These were purchased off Gunbroker and shipped to us directly, so our customer was unaware of any issues, but part of our job was to evaluate them before doing any custom work. One of the .308s shot fine, but the other had a stuck lever on the first shot, followed immediately by a dangerous case separation on the second. Always an exiting event.
A couple of quick measurements revealed the problem: the bad rifle had .014” head space on Hornady’s factory ammunition. Since Leverevolution is pretty much the only game in town for 308 ME, we decided the best course of action was to adjust the head space of the rifle to match the ammo. All issues disappeared promptly, and the rifle shot beautifully on its next range test.
More recently, JackTW called me to discuss an apparent head space issue with his 308MX. After several conversations we began to piece together what was going on in the sample of rifles we were able to evaluate. It is a highly unusual problem, compounded by more than one error.
The first problem is that both Jack’s and my sampling of LVR ammo was drastically undersized from SAAMI specs, to the tune of nearly .020”. The second problem was that Jack’s resizing die, if touching the shell holder, more or less replicated this gross under sizing. The third issue as that a small sample of rifle chambers revealed that they too were undersized, but unfortunately not nearly enough to compensate for the drastically undersized ammo/brass. The difference still yielded actual head space in the .010-.014” range.
For those of you not well versed in proper head space etiquette, the simplest way to think of it is the gap between the bolt face and the case head, when the cartridge is fully seated in the chamber. A gap of .000-.002” is highly desirable in precision bolt actions, though typically only achieved with hand loads. A gap of .003-.006” is pretty optimal for sporting and defensive arms, as it helps ensure reliable chambering under less than ideal conditions. Ammo makers generally size their brass a few thousandths of an inch under the SAAMI minimum spec chamber for reliability’s sake. A gap of .007-.010” is detrimental to accuracy and brass life, but generally not unsafe with good brass.
Once head space gets into the .007-.010” range it’s not unusual for misleading pressure signs like flattened primers to occur. In the case of lever guns, sticky levers may also hint falsely at excessive pressure. Gaps larger than .010” transition into dangerous territory, and once into the teens the likelihood of a ruptured case gets very high.
Good info Quietman. Thanks for sharing. I learn something new every day.:damnmate:Hey guys- been a while. Stopped in and saw this thread.
Just in case you didn't know Adam-
This is something I learned when My 338 went back for repair from the head Marlin gunsmith at the time. A number of 338's and 308's went out the door with locking lugs that hadn't been hardened correctly so they'd compress through repeated firings. This was the case with my rifle. First couple extractions were easy and the action gradually got harder to cycle. By the end of only one box of ammo, it took 2 hands to cycle the lever. The degree of improper hardening varied on the batch I was told about, so the issue could show up immediately, or take a while to appear.
So another issue may be the locking lug was one of the bad ones.
More on what I posted before.Thanks Adam, I suspect those with 338MX's that have the same issues have identical problems.
Stay safe with this weather Adam and family.
I'm going to check both my JM 338ME and my 308ME (A Remlin) using the blue tape check. They both test fired just fine but I did notice the 308ME was a little sticky on opening the lever----not where it was real hard to open it. I did not know about the tape test----should be a learning experience for me...........................Adam, I appreciate you taking the time to explain this issue.
Folks, Adam and I have been discussing this issue for some time as my 2007 308MX chamber is under SAAMI Specs making it too tight. I'm currently out of pocket and on my phone. I will be posting some data once I get home.
As most know, I've developed bullets specifically for the 308ME and quickly realized the issues. Jay, Ret_Eng, has been helping with developing load data and various shooting tests for me with his 308MX. Our rifle chambers happen to be a carbon copy. Jay has been a big help to my R&D as well as Adam has been with this chamber issue.
The data I'll be posting will especially help those who roll your own.
Main thing is no barrel droop and is a straight shooter. Use a strong narrow beam flashlight to look at the finish of your chambers to check for any machine\tool marks. If it is pretty good and smooth then blue tape head space check. Be safe as tape head space check is done with real commercial ammo so make sure it is pointing in very safe direction. I took mine outside and had it pointed at the dirt for safety. I only have Hornady LeverRevolution 308MX and 338MX loaded ammo right now.At this point my head is spinning for what I have read so far. Perhaps it will get better as I understand and come to a realism of allowable sport/hunting rifle tolerance. As far as my M.308XLR and 338MX I could not be happier. In fact I have been amazed of the 308exp. & 338exp. rifles and its accuracy. This brings up a question In my mind, is this something new or has this been going on since the beginning of the Marlin brand and other makes too.
Thanks for the tip but if I did a tape HS check outside you will probably see me on the 5:00 news and live round HS check indoor is a no no. I would just have to wait till I go to an outdoor range. Will have to make pre. taped rounds, round #1 taped once R. #2 taped twice and there on. My 308/338 are both straight shooters the 308XLR is a X-ring shooter out to 150 years tested and the 338MX out to 100 years tested with my handloads. Right now I'm wondering about my 35R-XLR though I have no complains. But I'm aware now. To my memory whenever I fired a Hornady's "commercial" round none of the signs stated in this thread were notice that I'm aware of. Will keep closer attention now.Main thing is no barrel droop and is a straight shooter. Use a strong narrow beam flashlight to look at the finish of your chambers to check for any machine\tool marks. If it is pretty good and smooth then blue tape head space check. Be safe as tape head space check is done with real commercial ammo so make sure it is pointing in very safe direction. I took mine outside and had it pointed at the dirt for safety. I only have Hornady LeverRevolution 308MX and 338MX loaded ammo right now.
I have no regrets with both of my rifles even though the 308ME is a blued Remlin. The 338ME is a blued JM (late one). 338 kicks like a 45-70 and could be harsh to some. 308 is no worst than any other 30 cal. that I have fired.
I'm surprised you think the 338ME kicks like 45-70. I never shot a 45-70 but shot my 444s with 300 gr. JHC at max charge it's harsh after a few rounds. I shot 30 rounds sighting my 338MX and being a hard kicker never entered my mind.I have no regrets with both of my rifles even though the 308ME is a blued Remlin. The 338ME is a blued JM (late one). 338 kicks like a 45-70 and could be harsh to some. 308 is no worst than any other 30 cal. that I have fired.