No more 4227 in my 7mmTCU

[jimb16]

The other day I went to the range to try out a bunch of new loads. Among them were a series of 135 gr gas checked loads using 4227.
What a waste of lead! At 25 yards, I couldn't get a group under 3 inches! I tried 9 different charge weights and the BEST was 3,25 inches for 5 rounds. I know it isn't the TC or my loading technique. When I got done wasting my efforts with that powder, I started on a batch loaded with IMR 4895. At the same 25 yards with the same bullet loaded to the same depth etc... The group sizes were between 1/4 and 1/2 inches! Most were single hole groups. Unfortunately I had to stop there without finishing my test rounds. The scope base came loose. I re-epoxied it today so maybe I can get back out ther tomorrow and finish my testing.

[dtknowles]

Can we talk a little more about this epoxy and scope bases? Is this a good technique? I have never had bolted on scope bases come loose, I do use loctite on the screws for heavy recoiling guns. I have used tacky stuff between the rings and the scope tube.

Tim

[jimb16]

I usually use lock-tite on the screws, but for some reason they just don't want to stay tight on this carbine barrel and the base fit isn't quite perfect so the epoxy removes the possibility of any "rocking of the base " which might contribute to the loosening of the screws. The 7TCU can have a rather sharp recoil for such a small cartridge and I think that may be part of the "loosening problem".

[dtknowles]

I see so you aren't trying to glue the base to the barrel, just sort of bedding it. The screws should not back out with Loctite, are they torqued well, what size and how many. Is it a filled epoxy or just plain. Have you tried JB weld?

I would put mold release on the barrel.

Tim

[MT Gianni]

The late Junior is your friend. http://www.castbullet.com/makeit/recoilpr.htm#end

[jimb16]

Just 2 screws and I used Loctite Blue. And it was epoxied with JB Weld Quick set epoxy. And yes, it was basically for bedding the mount.

[dtknowles]

Just 2 screws and I used Loctite Blue. And it was epoxied with JB Weld Quick set epoxy. And yes, it was basically for bedding the mount.

You got a puzzler.

Tim

[leadman]

I had a Super 14 barrel that like to shed the scope also. It was chambered in 444 Marlin! Moved up to #8 screws and still had to JB Weld it on.

[FLHTC]

I usually use lock-tite on the screws, but for some reason they just don't want to stay tight on this carbine barrel and the base fit isn't quite perfect so the epoxy removes the possibility of any "rocking of the base " which might contribute to the loosening of the screws. The 7TCU can have a rather sharp recoil for such a small cartridge and I think that may be part of the "loosening problem".
Throw the base away and get a new one. Are you sure the base isn't bent or that it's not for an Encore instead of a Contender? The TCU cartridges don't have anywhere near the recoil to be problematic with screws coming loose. I've had my base on a 24" 25TCU since the day i got it and never had a problem.

[Sensai]

Back to the powders, there are an awful lot of powders between the two burn rates that you cite. I have never used anything as fast as 4227 in the 7TCU. My favorite is H335, but it has gotten very hard to find. I'm using IMR3031, with good results, now. IMR 4895 seems a little too far the other way. You mentioned "carbine barrel" but I didn't see what length. I'm shooting a 14" Contender barrel and the sweet spot for powders seems to be around the N120 to Terminator burn rates. :mrgreen:

[Hamish]

Throw the base away and get a new one. Are you sure the base isn't bent or that it's not for an Encore instead of a Contender?.

No, not throw the base away. In post number five Gianni posted a link to a very good page where Junior documented not only the problem with the 92A's being ill fitting at times, but several other problem areas with barrel thread depths and sloppy screw fits.

Throw it away,,,,,,exactly what do you learn from that?

[FLHTC]

No, not throw the base away. In post number five Gianni posted a link to a very good page where Junior documented not only the problem with the 92A's being ill fitting at times, but several other problem areas with barrel thread depths and sloppy screw fits.

Throw it away,,,,,,exactly what do you learn from that?

Never having experienced screw depth issues or ill fitting bases in my 30 plus years of owning T/C products, I would have no desire to do otherwise. If the radius on the base wasn't the same as on the barrel, in the trash it goes.

[Sensai]

I'll pay postage for any of these through away mounts. Matching a mount radius and a barrel radius couldn't be easier on a single diameter chamber end barrel. :mrgreen:

[FLHTC]

I'll pay postage for any of these through away mounts. Matching a mount radius and a barrel radius couldn't be easier on a single diameter chamber end barrel. :mrgreen:

Can't say i ever saw one but that's not saying they aren't out there. For what they cost, I just don't see it being worth fooling with.

[jimb16]

The carbine barrel is 21 inches from breach to muzzle. If the rail comes loose again, I'll have to try some other things like longer/deeper screws and a different base. Do you guys think 3031 would be a better powder choice? Or maybe 4198? I've got both on hand. I still want to finish testing the 4895 since it was cutting 1 hole groups before the mount came loose.

[TCLouis]

Junior1942's load with the "Soupcan" and WC820 (AA# 9 speed) is accurate in my 10" but a bit more powder was more accurate, so I use it.

Over time I have had several TC scope mounts where I had to shorten one or more of the screws as they bottomed out just as they drew tight, some did not even tighten fully. To be sure one has to test the screw/hole one at a time

[303Guy]

There are harder epoxies than JB Weld. JB Weld softens with heat as do some others. Blue Loctite is for large diameter threads so is weak enough to loosen when needed. No good for small screws where a high strength one is required. I'd try a high temp, high strength Loctite, (680 or 620 comes to mind but I'd have to find mine and check). I use it to glue suppressor baffles in place as well as securing the suppressor onto the barrel (no threads), it's that strong (and hard) and my suppressors are muzzle breaks.

Getting back to powders, that 4895 ain't broke, no need to fix it. Its working for you so stick with it is what I'd suggest.

[quilbilly]

My 18" 7mm TCU TC carbine loves 4198 with that 130 gr Lee boolit but it also tends to shed the scope bases even though I use the TC duo-ring base specifically for it. What is irritating is that the base only comes loose when I want to show other people how accurate that combo is. The rest of the time when no one is looking, it is fine and shoots sub MOA.

[jimb16]

I use 4189 on my .222 and .223 remingtons. Never thought about trying it on the 7TCU. I'll have to give it a try. And 303guy, thanks for the suggestions. If the base comes loose again, I'll give those a try.

[jimb16]

I got back to the range today to retry the 4895 loads. The lightest was the most accurate cutting two three shot groups with all holes overlapping. Another .5 grains and the groups opened way up. The barrel is dirty, but no apparent leading. I haven't chrono'ed the load, yet, but I suspect it is over 2,000 fps. Aluminun gas checks on the boolits.

[jimb16]

Finally got the chance to try IMR 4198 with the 160 gr boolit. 19.0 gr. turned in a single hole at 50 yards from the Contender 7 TCU carbine. That is for 5 shots. Not too shabby. Now to do some more experimenting; plus/minus a couple of 10ths, powder coating, seating depth etc.... I want to see what it is really capable of doing.

[jimb16]

BTW, 1840 fps.

[Geezer in NH]

Way back when introduced here in NH, where it was made, it was referred to as "Truly Crude Unit" for many reasons. As bad as the 30 Herret IMHO when the 30-30 was better and easier to load.