my 7x60 wildcat project

Hi Gents,
I thought I would be somewhat greedy and create another wildcat thread, this specifically for the progress of my wildcat mostly from the reloading aspect, as I am currently up to the load development phase.

Unlike most of my other projects of all kinds, this time I have decided to document everything and take photos for posterities sake and share the progress. Perhaps it will be of some interest to someone who is contemplating doing the same, or just for curiosities sake of others. I feel sure that many of my discoveries and mistakes, triumphs and failures will be old news to many of you experienced handloaders here, but this is my first self-created wildcat so its all new to me.

This thread will be word heavy.. with pics. I will try to highlight basic synopsis where practicable...

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Not many days ago I dropped off my rifle, barrel and reamer to fellow forumite, gunsmith and all round good bloke @Jaco Goosen. By the time I arrived home that night he had already sent me photos of the finished chamber! I don't know any tradesman that works that efficiently! A couple weeks later I picked it up. An expertly completed job I have to say, right down to the calibre engraving on the barrel. On top of it all, he tried to undercharge me... unbelievable :D

Anyway, the last couple of days I indulged in adventures in brass forming...

Brass Forming the 7x60

The idea of forming .30-06 or one of the various cartridges of similar dimension appeared in my imagination as a straightforward process. However, initial attempts were anything but. I began with trial and error of adjusting my Redding 7x57 FL sizing die, working my way through a pile of sacrificial .30-06 cases until I could chamber them in the Parker Hale with a slight felt pressure on the bolt handle. During this process I used the usual light smear of Redding sizing wax on the inside neck and outside of the case to ensure smooth die operation, and noticing with trepidation that every case was suffering from the ‘neck crumpling’ or ‘dimpling’ effect that was occurring as the .30-06 shoulder was reformed into the neck of the 7x60.

The next step was to experiment with forming clean brass and figuring out how to avoid the constant crumpling effect. My range of brass included; New Norma 25-06, new Lapua .30-06, once fired Norma 7x64 and a range of well used .30-06, including Norma, Sako, S&W and Winchester.

I had purchased over 100 pieces of the 7x64 Brenneke believing they would form well enough, but would be the most appropriate headstamp, that I could probably modify with a small punch to 7x6•
What I failed to take into account with the Brenneke was that the base diameter is .466, not .471 of the .30-06, which is already smaller than the .472 of the 7x57, which is what the 7x60 reamer is based off. I had mentioned that this was my intention during the design of the reamer, and Mr.Gross did not believe this would be an issue, so I will continue to test the 7x64 brass alongside everything else.

After an evening of brass forming experiments, failures and successes, my results are thus:

Lubrication; It makes the most difference. I started out with the barest minimum of Redding sizing wax on my fingers in the same manner as the way I always size my cases under regular circumstances. Eight or nine times out of ten, no matter which brass was tested, it would result in damaged crumpled necks. At first I did not think it could be ‘over lubed’ as it was no more than a ‘sweaty thumbs worth’, but after wiping the cases my sleeve until it seemed they were dry, I could produce clean shouldered brass. They still needed plenty inside to avoid the jarring on the sizing button though.

Technique; I began by trying multiple passes, partly sizing the case and then backing out. Going in a little further, and so on, until I had worked the press handle to its fullest extent. Once I discovered the correct lube amount, I also found that one single smooth and slow pass of the brass into the die, the right amount of pressure, was all that was needed.

Brass age; It makes no significant difference. I was equally able to damage or dimple either new brass, once fired, or well used brass equally well as each other. Any of this brass was also equally able to form good clean, dimple free shoulders once correct lubing and technique was used.

Calibre of parent case; It matters. 7x64 and 25-06 always results in non-uniform, unattractive stepped necks. The .30-06 cases however, no matter which ones, produced uniformly smooth necks and shoulders.

Summary:
Regular lube inside the case neck, with almost none on the outside.
Size the brass in one pass not multiple.
Brand and age of brass makes no difference to uniformity of results.
.30-06 cases produce reliable neck uniformity than other calibres, regardless of headstamp or age of brass.

During load development, I will load and fire a few cases that have minimal dimpling around the neck and shoulders and the cases with stepped necks, only out of curiosity to see what - if any - the effects of fire-forming will have on these cases. It is unlikely that fire-forming will smooth these pieces in any significant way so they will be disposed of after one use. I acknowledge that it is possible with inside neck reaming and outside neck turning that these cases could be used successfully; however there does not seem to be a reason to pursue this extra effort when the .30-06 brass has already produced perfectly shaped cases that should not need turning or reaming.

Formed cases awaiting trimming.

Perfectly formed Lapua .30-06 brass into 7x60

Attachment 229328Attachment 229333

Early failures : New Lapua .30-06 with crumpled neck due to incorrect lubing and technique

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Ugly necks, 7x64 on the left, 25-06 on the right.

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Good looking .30-06 parent cases formed into 7x60. Brass of various headstamps and age.

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Brass Trimming
Without a machine suitable for taking 2-3mm off a piece of brass in an easy repeatable process, I deferred to my mad-max tech. This consists of clamping an angle grinder and 1mm cut off wheel in the vice, and positioning a battery drill at right angles to the cut off wheel, with a guide rail clamped to the workbench at the back of the drill to retain a consistent cut length. Numerous experiments with using an angle grinder and cut-off disc revealed that the best way to get uniform brass cutting was to allow the grinder to cut only one side of the brass while it rotated in the chuck of a drill, as opposed to cutting right through the brass without rotation. Anyone whos ever tried to cut a tube perfectly without a drop saw will attest to the difficulty of getting a perfect cut. One day I will just get a small drop saw…

Jaco is a good man!!

Quote:

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Originally Posted by Larskramer

Jaco is a good man!!

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Indeed! btw Lars, the two jugs of H4350 I bought from you last year will be used in the 7x60

what happens if you try 280 brass??? or 270????

Quote:

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Originally Posted by Micky Duck

what happens if you try 280 brass??? or 270????

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Don't know, I don't have any. It could go either way perhaps.

ooh I really like this idea. How much more case capacity do you get?

Btw what was your donor rifle originally, looks almost identical action to my 7x57

Sounds good mate!!! Jacos going to do a chamber for me shortly when the reamer arrives

Now that I have brass, I am moving into loads.

7x57
Sierra 140gr H4350 47.6 Max 2800 fps
Speer 130gr H4350 50.0 Max 2930 fps
Speer 145gr H4350 50.0 Max 2820 fps
Hornady 139gr H4350 48.3 Max 2700 fps

280 Rem
Sierra 140gr AA4350 48.6 Min 2500 fps 52.0 Max 2700 fps
Speer 130gr H4350 50.0 Min 2827 fps 54.0 Max 3073 fps
Speer 145gr H4350 50.5 Min 2779 fps 55.0 Max 2949 fps
Hornady 139gr H4350 42.9 Min 2500 fps 52.7 Max 2900 fps

There is a crossover of 50.0gr of H4350, being the max load for 7x57, and a min load for the .280. This in theory should be my safe starting point for the 7x60's case capacity; where I am below max, but also above minimum. (With 140gr bullets... I have some S&B to start with, and some Nosler 140gr which I would like to be for the final load)
I am yet to run any of this data into load software but it will be something I check.

Now that I get to this point, I have had a realisation of probably the biggest blunder so far in the design process; I paid no attention what so ever to proposed bullet choice and freebore length when creating the reamer specs. Looking back over my specs diagram I see that I did not even have a COAL measurement at all, or any such indication of preferred bullet weight or length. I'm not sure If I just assumed it wouldn't matter, or that I imagined using such a wide degree of projectile weights that I would just leave it up to Manson Reamers to figure out. I really don't know what I was thinking.

I did some experiments with 140gr & 154gr bullets, and found that a Hornady 154gr interlock has to sit quite far out to hit the rifling, so I guess on the upside the world is my oyster in terms of going as heavy as I want with bullet choice. In reality though, this is not really what I wanted. I aim to stay around 120-140gr, and the 154gr interlock as the largest bullet I will use. I guess I will have plenty of freebore then!

Quote:

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Originally Posted by 7mm tragic

ooh I really like this idea. How much more case capacity do you get?

Btw what was your donor rifle originally, looks almost identical action to my 7x57

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I am yet to calculate case capacity, though I should probably get onto that as I'd like to run some numbers through quickload.
The donor is a Parker Hale, with the Zastava type action. 98 Mauser style with no thumb cutout and no charger clip cutout typical of commercial type 98's. I have 3 of these now... the other two will probably see the same fate as this one!

freebore isnt a bad thing..will/should HELP to keep pressures down (like a weatherby) it might be more a case of what projectiles you can actually get.

Quote:

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Originally Posted by -BW-

Now that I have brass, I am moving into loads.

7x57
Sierra 140gr H4350 47.6 Max 2800 fps
Speer 130gr H4350 50.0 Max 2930 fps
Speer 145gr H4350 50.0 Max 2820 fps
Hornady 139gr H4350 48.3 Max 2700 fps

280 Rem
Sierra 140gr AA4350 48.6 Min 2500 fps 52.0 Max 2700 fps
Speer 130gr H4350 50.0 Min 2827 fps 54.0 Max 3073 fps
Speer 145gr H4350 50.5 Min 2779 fps 55.0 Max 2949 fps
Hornady 139gr H4350 42.9 Min 2500 fps 52.7 Max 2900 fps

There is a crossover of 50.0gr of H4350, being the max load for 7x57, and a min load for the .280. This in theory should be my safe starting point for the 7x60's case capacity; where I am below max, but also above minimum. (With 140gr bullets... I have some S&B to start with, and some Nosler 140gr which I would like to be for the final load)
I am yet to run any of this data into load software but it will be something I check.

Now that I get to this point, I have had a realisation of probably the biggest blunder so far in the design process; I paid no attention what so ever to proposed bullet choice and freebore length when creating the reamer specs. Looking back over my specs diagram I see that I did not even have a COAL measurement at all, or any such indication of preferred bullet weight or length. I'm not sure If I just assumed it wouldn't matter, or that I imagined using such a wide degree of projectile weights that I would just leave it up to Manson Reamers to figure out. I really don't know what I was thinking.

I did some experiments with 140gr & 154gr bullets, and found that a Hornady 154gr interlock has to sit quite far out to hit the rifling, so I guess on the upside the world is my oyster in terms of going as heavy as I want with bullet choice. In reality though, this is not really what I wanted. I aim to stay around 120-140gr, and the 154gr interlock as the largest bullet I will use. I guess I will have plenty of freebore then!

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Pardon my question if it seems ignorant but could the barrel be shortened at the chamber end and the chamber recut ? Would this be a means to shorten the freebore ?
Cheers

only if there is still enough meat left on outside of chamber area to rethread it to fit back into action......

As far as I understand it (Jaco will know the answer here) The freebore is cut by the reamer, so the reamer would have to be modified in order to shorten the freebore.

Mickey Duck is right, extra freebore probably wont matter. All of my other calibres I have loaded for (7x57, 8x57, 6.5x55) have shot perfectly well with a lot of freebore. I think I was just imagining that with a custom chamber I would be loading close to the lands, but in practice I won't notice the difference.

@akaroa1 will chime in here Im sure as he does similar changes to cases and Im picking he will suggest anneal anneal anneal