One of my guns has a tight chamber ... GSG MP-40 ... CCI Blazer 115 gr worked well ... reloaded ... lee carbide 4 die set ... HiTek 115 gr ... 3.1 gr Clays with COL of 1.10 (1.09")
There have been a lot of good information provided by members but I can see how OP may not be utilizing that information to resolve the problem of finished rounds not fully chambering when factory rounds do.
Short Answer - I have experienced similar problem (Especially with larger sized coated bullets) as I reload for several aftermarket/match barrels with different chamber wall diameter and leade/freebore length before the start of rifling. The cause of the problem turned out to be:
- Diameter of the bullet/out-of-round bullet - Coated bullets are sized larger around .356"+ but can become oval in shape to .357"+ (Maybe from shipping damage/being dropped or from manufacturing?) when measured several times around the bullet.
- Thickness/inconsistency of case wall - Depending on the headstamp, I found case wall thickness can be inconsistent in thickness at case mouth and more importantly, further down the case neck where base of bullet gets seated. Since the taper crimp die only works around the case mouth, bulging of case neck further down during seating where taper die can't reach could cause the finished round to rub the chamber wall. And case wall thickness could be not even around the case and when inconsistent case wall thickness is stacked on top of out-of-round bullet, finished round could get even more oval to rub with chamber wall.
- Tilting of bullet during seating - Even with round bullet and consistent thickness case wall brass, bullet tilting during seating can cause the case neck of finished rounds to be out-of-round expressed by bulging of case neck on one side instead of being even around the bullet base.
So I solved this problem by using bullets that are round/within spec, using brass with consistent thickness wall (especially around bottom of bullet base) and not tilting bullet during seating.
For a more permanent fix, you could hone your chamber to open it up a little.
I have done this -
https://www.thehighroad.org/index.p...l-for-9mm-glock-19.653464/page-2#post-8093783
But I suggest OP try different solution options that worked for me before considering modifying factory barrel and likely voiding the warranty.
Long Answer - SAAMI specs have minimum to maximum and while factory barrels have typically been made more generous to SAAMI max dimensions, in recent years more and more manufacturers have started to make barrels closer to SAAMI minimum dimensions. So while factory ammunition manufactured to SAAMI minimum dimensions continue to work with these "tighter" barrels, our reloads that worked in more generous SAAMI max barrels may not work in these "tighter" barrels.
Another thing that has occurred over the years is shortening of leade/freebore length (Space bullet jumps from case neck to start of rifling). So bullets, even FMJ/RN that worked fine loaded to SAAMI max now must be loaded shorter to clear the start of rifling of newer factory barrels with shorter leade. FYI, this thread illustrates differences in various factory/aftermarket barrel leades and OAL of different bullets that must be used to clear the start of rifling -
https://www.thehighroad.org/index.p...let-max-working-oal-col-for-reference.848462/
And if you are using 1.100" OAL simply because that's what Hodgdon load data lists for 115 gr Lead RN, you should conduct the "plunk test" to determine the max/working OAL. Here's a post that covers determining max/working OAL along with step-by-steps of load development -
https://www.thehighroad.org/index.p...124-gn-bullet-load-data.875597/#post-11652985
It's not just my loads, it has also done it with factory ammo ... Could it be the chamber has very lo tolerances that even as you fire 50 rounds or so, it gets dirty enough not to chamber a new round?
That could be as blowback action carbines can experience faster fouling buildup as gas leak around the case mouth/neck when bolt/buffer move away from the chamber. Us reloaders and 3Gun match shooters addressed this issue by increasing the combined bolt/buffer weight to extend the dwell time the bolt/buffer stay in contact with the chamber for more complete powder combustion (less soot on case) along with using different powders/charges (I found faster burning powders to improve soot on case issue and accuracy potential).
I see that you are using faster burning Clays but at start charge of 3.1 gr. With blowback action carbines, I found I get improved powder burn and greater accuracy at near max/max load data. As to reliable feeding/chambering (That may be what you are experiencing also as expressed by GSG MP40 review below), you may need to use higher powder charge to push the bolt/buffer/spring back further to cycle/strip rounds from the magazine and fully chamber.
Here's a TAG review of GSG MP40 that expressed problems of failure to feed/chamber and soft primer strikes with factory ammunition. Your problem may turn out to be gun related, not reloading related but we will talk about reloading related issues on this post -
https://www.thetruthaboutguns.com/gsg-mp40-gun-review/
The brass that seems to have problems are the S&B and another marked CBC. I'm not sure what that is. I'm filtering those out of my supply. btw, I also had problems with the S&B in my Taurus GX-4.
In this myth busting thread, CBC and S&B brass were found to have thicker case wall at case mouth and case neck -
https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-4#post-10926900
Instead of more typical 0.011" average thickness at 0.100" below case mouth where taper crimp is applied, CBC and S&B cases were 0.01256" and 0.0126". More importantly, 0.200" below case mouth where typical 115 gr FMJ/RN bullet bases are seated to, CBC cases had the thickest wall at 0.0144" where typical thickness was 0.012"-0.013".
So with thicker .356" sized coated bullets seated to 1.100" OAL, you are going to bulge the thicker case neck more to rub with chamber wall which would prevent full chambering of the finished rounds. If your coated RN bullet profile (ogive) allows longer OAL, you can try to see if longer OAL rounds will work with the barrel. If not, you will need to cull the brass with thicker walls, use different profile bullet or smaller .355" sized bullets. (See comparison picture of different profile bullets)
BTW, here's a listing of average case wall thickness 0.200" below case mouth from the above link:
.0144" - CBC
.0138" - PPU
.0137" - GECO
.0135" - HRTRS
.0135" - Tulammo
.0133" - S+B
.0132" - WIN
.0131" - GFL
.0130" - AGUILA
.0130" - PERFECTA
.01225" Starline
.0122" - PMC
.0121" - R-P
.0115" - .FC.
.0111" - SPEER
.0110" - BLAZER
Just checked a factory round, it was..36 at the mouth and..37 after
Since case wall thickness is around 0.011" at case mouth, I usually add 0.022" to the diameter of the bullet for taper crimp amount (Which will essentially return the flare back flat on the bullet and skosh more). So for .356" sized bullet, I use .378" taper crimp.
To ensure accuracy of your calipers and that you are using the calipers properly, I suggest use of .355" pin gage and practice with eyes closed -
https://www.thehighroad.org/index.p...ks-for-digital-calibers.821135/#post-10545265
I also use Lee carbide die set where third die is combination seat/taper crimp die and fourth die is Factory Crimp Die.
I do not need to use the FCD as various .355"/.356" sized bullets (lead, coated lead, plated, jacketed) work well even in the "tightest" barrel I have with shortest leade. Below is picture of .356" sized MBC 124 gr Hi-Tek coated RN with longer bullet base seated deeper at 1.050" and finished rounds will fully chamber in my Lone Wolf barrel with shortest leade -
https://www.thehighroad.org/index.php?threads/missouri-9mm-rn-help.870451/#post-11545654
If your finished rounds are out-of-spec/out-of-round as outlined in the "short answer", you could use the FCD to "fix" the case neck by post-sizing the finished round back to SAAMI specs but I prefer to load without the FCD.
I've heard some Glocks have tight chambers.
I believe this applied to 40S&W Glock barrels where over the generations, chamber mouth and case base support improved.
For 9mm Glocks barrels, I believe chamber size/rifling/leade length remained the same with the exception of Gen5 Glock Marksman Barrel which utilizes different rifling type and shorter leade -
https://www.thehighroad.org/index.php?threads/beginner-reloading-problems.877215/#post-11688158