7mm TCU with RCBS 145SIL.

[haswipp]

I'm having problems with accuracy with a RCBS 145 Sil. mold in a 7mmTCU. I size to .285 with hard cast(BHN 20). I've tried a handful of powders with the best group around 1" at 50 yards.I always get a fliar. I have a very steady rest, and higher power scope. My goal would be MOA at 100yds. Its on a 14" contender. I made the brass from hornady 223 brass and I'm using REM 7-1/2 primers. Should I try a crimp or softer lead? I use a lee expander die for the brass.

Any tips would be greatly appreciated. Load data would be great also with this cast bullet.



Thanks

[NSB]

Having owned several TC Contenders in 7TCU and having shot thousands of rounds out of them in practice and competition, I don't think you're going to get to where you want to go. I shot silhouette and was in Int. Class and won several state titles. I also shot numerous 40x40s with those guns, even the 10" bbl one. I was never able to get 1moa with them on a regular basis. I was shooting jacketed bullets with them after having even less consistent results with cast. I personally don't believe the guns are capable of shooting 1moa at 100yds. Some may say they are getting it, but I never saw it and no one was beating me in competition with their guns over several years of shooting. It's just not the best platform to expect that type of performance.

[leadhead 500]

The base of the bullets are %150 of the accuracy ! The bases must be perfect with no sprue humps and completely flat. I weigh all of my ones for target and sort them by weight to
+ or - .1 tenth of a grain. I shot a 7-30 waters with the same bullet in a super 14 for a couple of years and had great luck with it

[high standard 40]

1. Have you done a chamber slug? Without knowing the chamber dimensions you can't know what size the drive bands need to be.
My 7TCUs need to be sized .2865"-.287". I had to have "Hollow Point Molds" modify my mold to get that diameter.

2. What size is your bullets nose? I have to size mine .277" to get the bullet nose to bore ride.

3. How deep are you seating the bullet in the case neck? If you size the nose as I do and seat the bullet out as far as possible, you can utilize that bore rider nose to help align the bullet straight with the bore for best accuracy. I have little more than the gascheck seated in the case neck.

4. As mentioned the base of the bullet must be flat and gascheck seated without shaving any lead on the bullet heel.

5. Cases necks should be sizes so as to have .0015"-.002" neck tension.

6. If you shave any lead seating a bullet into the case neck, you have damaged that bullet as far as accuracy goes.

The long and the short of it amounts to this. How bad do you want to get accuracy with your combination of gun and bullet? Are you willing to take the steps to reach that goal?
You have to be willing to accept the fact that sometimes you have to go beyond simply casting, sizing, lubing, and seating.

The first 7TCU I tried cast in shot groups of about 4" at 100 yards with the RCBS 145. I was using COWW alloy and sizing .285". I tried a lot of different things to reduce those groups and for the most part, the 6 things I mentioned above helped me reach my goal. When I do my part, 1 MOA is the usual and my load produces 1850 fps.

[JSH]

I can't add much more than Charlie already did.
I went through numerous 7TCU barrels before I found a factory 10" and 14" that pleased me. This was with jacketed.
You don't mention what powder you are using.
I have looked at the lee belling die, I am not a fan. I will keep using my Lyman m dies, some with custom plugs, thank you.
The throats on the 7 TCU factory barrels are very generous as a rule. If I were chasing accuracy I would opt for a custom barrel. It will save a lot of time and grief in the long run.

The negatives on the TC above I don't know if they are directed at the 7TCU chambering and cast or the platform it's self. None the less the platform is fine. No it's not an XP or an MOA but it can hold its own with the right loading practice and the right person on the trigger. I shoot in region 4 and when I started it had some of the toughest guys to beat. They weren't all shooting some of the higher end guns. I like the 30-30 with cast, it is just a natural for them. I have bested several of my mentors and folks I look upon very highly with a TC over an XP. A 40x40 in the day was quite the accomplishment. Now days a 40 will gleen you very little unless you clean the shoot off targets +10, then that can carry on to smaller targets. The sport has not become easier, the equipment IMHO has been improved upon that much in a relatively short time, 20-30 years.

[jhalcott]

I have three 7tcu barrels, 10,14 & 21"! Allthree have different likes and chamber dimensions. With cast, your cases can be work hardened after a few shots. Along with what was said before cases need extra attention. When i was into sillywets, I weighed every component before loading. I did have a few loads that went MOA or less at 100yards. A chamber cast AND a slug driven thru your barrel will give you a lot of info about YOUR barrel.

[jimb16]

My 14 inch will do 1 MOA, but only with 100 gr jacketed HPs. I haven't gotten better than 2.5 with cast. But I'm still working on it!

[leadhead 500]

Fliers with cast is hard to eliminate !! There are lots of factors, the base of the bullet, lube purging, etc

[jhalcott]

Weighing the bullets will cull out any with voids. Annealing the case necks may help some also. I used a hundred NEW cases for a season of sillywets. All those were weighed to half grain, then prepped like for bench rest. I had special loads for each targget/range.

[quilbilly]

My 7mm TCU 21" bbl carbine regularly will do MOA with the 130 gr cast boolit and occasionally less if my eyes are having a good day but the rifle is scoped. IF I had better eyes, I often wonder if my iron sighted 10" bbl would do as well but those days are over for me I think.

[haswipp]

Thanks for all the information, very much appreciated. Can anyone tell me the most accurate jacketed bullet load you have for a 14" barrel.

Thanks

[Hamish]

This is for a 10" bbl., but,

150 gr jacketed 24.5 AA 2015BR
175 gr jacketed 20.5 AA 2015BR

3031 and 4198 would be the sweet spot with the longer barrel. MP300 may be even better.

[bobthenailer]

I could not get my 7 TCU to shoot cast bullets either I tried 4 different cast bullets and about 5 powders obtaining poor results with cast , I finaly gave up! shoots jacketed excellent .
The bullet was about all the way out of the case before contacting the rifleing (long throat0
My RPM-XL shot cast excellent in 30/20 & 357 mag and my XP-100 in 7-Ishma shot the RCBS 145 sil excellent with shorter throat.

[45-70 Chevroner]

If my 7TCU had shot 1" shooting cast at 50 (which translates to 2" at a hundred) I would not have sold it. My feeling is that is darn good grouping.

[NSB]

Thanks for all the information, very much appreciated. Can anyone tell me the most accurate jacketed bullet load you have for a 14" barrel.

Thanks
Here's what I shot in silhouette. I don't know if it's a "book load" or not, so use at your own risk. I shot a ton of 40x40s with this load. I found several boxes of ammo stuffed away in a cabinet and here's the data on the boxes. 120g Sierra Spitzer, H322 @ 26.0g, Fed 205M primer.