308 bolt and semi auto

From what I can see the Remington 7400 is gas operated. Potentially not at all relevant, but I own a Remington 1100 gas operated shotgun, that I have cursed a lot. Yes, it operates just fine on a heavy magnum load, but as soon as you lighten up the load it has jamming problems. What I found is that it had to be spotlessly clean to cycle even heavy standard loads. Later when I started to reload my own shotshells I took it on as challenge to come up with light trap loads that would still cycle reliably. What I found is that if I used as fast as possible a powder (that was safe) and made sure it was at maximum allowed pressure, the gun would cycle fine. Not surprising as it is a gas operated gun.

OK, with that in mind, this is what I think. A compressed load usually indicates you are using a slow powder for the case volume bullet size. I would look for a faster powder that you can load safely to the highest recommended pressure. I'm not sure if anyone other than Hodgdon gives pressures for the recommended loads, but look around and see what you can find. At the Hodgdon site, what kind of sticks out as a better powder might be:

Hodgdon Benchmark - 50,800 CUP
IMR 8208 XBR - 60,100 psi

These may not give you as much velocity, but they seem higher in pressure, and that is what the gun probably wants.

Edit: The other issue is when the pressure in the barrel peaks compared to where the gas ports are located. Possibly the slow powder is peaking when the bullet is too far past the ports. See this website for some examples as to how pressure varies as the bullet goes down the barrel.

Just my thoughts,
 
Last edited:
You may want to read this information from the Sierra site. They talk about an ideal port pressure, which I pressume is the pressure the port sees just after the bullet passes. What you may want to do is a more thorough search to see what speed of powder is recommended for the Remington 7400. They are talking about service rifles. It also raises the possibility that your load is too hot, and you are slamming the action back too hard.

"Powder Suitability

Powder suitability takes on a different meaning with Service Rifles. To most reloaders, a powder’s suitability equates to getting good velocities at reasonable pressures. There are other issues to address with gas-operated Service Rifles. Powder burning rates, in particular, must be appropriate for the rifle. As contradictory as this sounds, a load that gives significantly less than maximum pressures can still damage the rifle if an inappropriate powder is selected. That’s right. A perfectly safe load can damage the rifle. What we’re dealing with here is port pressure. Service Rifles are designed to function within both a set range of maximum chamber pressure—like any bolt-action rifle—and a given range of port pressure. This is defined as the amount of pressure remaining in the bore as the bullet passes over the gas port. Controlled by selecting a powder with an appropriate burning rate, the object here is to cycle the action at the correct speed. Excessive port pressure results in the action’s being violently slammed open, possibly damaging it. This is particularly critical in the M1 Garand. With its closed gas system and relatively fragile operating rod, choosing the correct powder is essential to avoid damaging the rifle. Despite the robustness of the M1, the operating rod is about as close as it comes to having an Achilles heel. In this example, it is possible, indeed quite common, for M1 Garands to be damaged with loads that are perfectly safe as far as chamber pressures are concerned. This problem is lessened in the M14/M1A family of rifles, but it’s still a topic that needs to be addressed. Fortunately, it is a very easy problem to avoid altogether. By sticking with those powders originally used in military ammunition, with similar bullet weights and velocities, port pressure problems need never become an issue. With the 308 Winchester/7.62mm NATO in the M14 family (or in M1 Garands rebarreled to the smaller cartridge) or with the 30-06 in the M1, this means sticking to those powders in roughly the same burning range as IMR 4895 or 4064.

The M16/AR-15 family presents fewer issues in regard to this situation, but still warrants some consideration when choosing a powder. If in doubt, take the time to talk with other competitive shooters or gunsmiths specializing in Service Rifle work. At this writing, Hodgdon’s Varget and Alliant’s Reloder 15 are two of the top choices for the AR-15. VihtaVuori N135 and N140 also have a loyal following."
 
After a little more research, I would try your existing powder but take it down some for load, like backing off to 42 grains. If that does not work, then try a bit faster powder like the 8208XBR I suggested earlier or H335. Again try a moderate load first. There are other choices if those are not available. See this burn rate chart from Lapua. And of course don't substitute one powder for the other just because the burn rate is similar. Always get specific powder load data, ideally from the powder manufacturer.
 
It's a semi they need to be lube properly to work, if it work last year but not now it may be dry lube. Clean and relube
 
X2 Ganderite. As for the 7400 it gets a bad rap it doesn't deserve. Personally, I like them. They need to be kept meticulously clean throughout their receivers, even the mags, which are their weak point. The interrupted lugs need to be lubricated properly and the gas system needs to be DRY.

The Remington semi auto center fire rifles were designed to be light for a hunter to carry and maybe offer a bit of reduced recoil for those that need it. I have a lady friend that has shot one for decades and she loves it. I help her husband load for her rifle which is also in 308 Win. She brought it to me about a decade ago because she was having function issues. The rifle had sat in a closet for at least five years previous to that because of this. Needless to say it hadn't been cleaned properly. Her husband cleaned it from the muzzle but neglected to drop the mag or keep absorbing materials in the receiver. Needless to say it was full of crud. These rifles can be a real chore to disassemble for a thorough cleaning. They weren't intended to be broken down regularly by the user IMHO. I don't believe they were intended for heavy usage either.

Anyway, her husband now breaks down the rifle to the point where it isn't completely disassembled but can get at the components that need to be taken care of. They haven't had an issue since we worked up a load for the rifle that functioned consistently and shot well.

Yes, the rifle is very fussy about the loads it wants to digest. We settled on 48.5 grains of W748 over CCI 250 primers topped with 150 grain bullets which were Hornady flat base spire points. This particular rifle doesn't seem to like boat tail bullets of any make and it doesn't work well with bullets over 150 grains. That doesn't mean your rifle has the same issues.

Anyway, the 7400 series rifles IMHO were not designed for heavy bullets or loads. That doesn't mean they aren't safe. However, heavy loads beat the action to hell which eventually causes feeding/extraction issues. This is of course IMHO. I am sure there are folks that have rifles that function flawlessly with any load.

Semi auto rifles take a bit of extra care to keep functional. Neglect is their biggest problem
 
You must log in or register to reply here.
Back
Top Bottom