BP Suggestions or Design

[denphillips2]

Hi,
I am finally starting my build. Need a breech plug design to go off of.
The quick build list is:
Rem 700CF with a standard boltface (.473)
Brux 45cal 18 twist.
Would like to use a cut down .308 or 45ACP case for primer carrier.
Just got the Swinglock FF die, need to find some lube.
Have many different bullets(including Parkers) to try, but will need some load data soon.

So, I have looked at doing something like Edge did in his XS7 with the 5/8-18 grade 8 set screw. If there is a better way or design that you can think of, I am all ears. I have access to CNC machinery also.

Want to get this done this week so I can get the barrel on and headspaced so I can possibly shoot it next weekend.

Also, where would, and should I look for a carbide bushing for a vent liner?

Thanks in advance for your help!!!!
Denny

[cuda]

Does the 700CF have a removeable bolt face like the Savage. If so you could make a new one for a 209 primer. Like the ones made to fit the Savage and Stevens bolts that hold a 209 primer and use a Savage BP. You can get a Savage BP from Luke with the carbide bushing installed. Easier than messing around with the cut down cases.

[denphillips2]

No the 700 does not have a removable bolt head.

I don't mind messing around with cut down cases.
I have messed around with hornet cases in my Omega before, and I think that a rifle primer is better for more consistent ignition. The cut down case will also seal better and be easier to load and extract.

[willbird]

I'm listening in denphillips2, I have sort of the same plans although I did not buy a barrel yet. FWIW I have been leaning towards using 209 primers in altered cases. Just got 1k of federal 209's this weekend and they were actually cheaper than federal LRM match primers. A couple folks were going to send me drawings or pictures of breech plugs.

Bill

[denphillips2]

Hi Bill,
I think I am leaning towards the plug like edge did with the 5/8-18 set screw. Going to fit it up to take either a cut down rifle case, or a 45ACP. Don't know which yet. If I do it right, I suppose both. Going to take good notes. I don't have a carbide bushing, but might see if I can harden up some O-1, or something similar for a bushing. For the bushing size, looks like a .031" hole should be the ticket. I was really liking what Nat Lambeth was thinking about doing with the breech plug. I talked to him last night, and he is going with the Knight breech plug for his first build. He is working on it right now also.
With this BP design, I just worry about the gas cutting across the BP and case with higher pressure loads. Not planning on worrying about the recoil.... ;o)

Ordering set screws from McMaster Carr tonight.

[willbird]

I think the flathead screw drilled with the .031 hole for a bushing makes a lot of sense :-). Do you have a link to the post by Edge about the setscrew ?? I am not understanding how a hardened bushing would be less prone to erosion than a soft one of the same material :-). No materials engineer here. But Both TI and Inconell 100 (aeromet is a similar metal) both resist heat very well, inconell 100 is the same strength basically at 1000f as it is at room temperature, same for TI.

What length set screw are you using ??

[gar]

with the Knight breech plug,the important part is getting the cut down cases to be the same thickness from the base to the inside of the case so the headsapace can be set to a consistent pressure of approx. 8 to 10 lbs when the bolt is cammed down. Have shot my rifle 2-300 times aand still on same nipple and no vent screw. If any blowback toss the primer holder and check the nipple. Rich Franklin's design and works well for higher pressure loads. Good luck with your endeavor which ever way you go.

[edge]

I have a lot of different designs that work in various barrels.

I have a multi-piece design that uses a shortened Savage breech and designed for a lugged rifle.



I have a barrel that was made to use the RB breechplug in a Savage ML.

I put that on a Marlin XS7 rifle and being lugged I made the BP slightly differently than RB did.







edge.

[willbird]

If it is not a trade secret, could you dimension out the 3 piece design ?? I really like that one, I will probably carve the whole thing from virgin 416 steel. I really like the idea of getting the primer INTO the center post. I'm doing a Remington 700 action. On the 3 piece is the final little step on the powder end actually sliding up in the barrel a bit ?? Also on the 3 piece I'm not understanding what you used to tighten it ??

[edge]

Dec 12, 2012 10:18:38 GMT -5 willbird said:

If it is not a trade secret, could you dimension out the 3 piece design ?? I really like that one, I will probably carve the whole thing from virgin 416 steel. I really like the idea of getting the primer INTO the center post. I'm doing a Remington 700 action. On the 3 piece is the final little step on the powder end actually sliding up in the barrel a bit ?? Also on the 3 piece I'm not understanding what you used to tighten it ??

No secret, just that every rifle is a little different.



That step is sub bore diameter by a couple of thousandths and does go into the bore.
(On my barrels I do bore a step, on my 45 I bored it 0.460 and the step is 0.455)

Personally I would use a more readily available thread size than the Savage 11/16 - 16

The 5/8-18 BP is very easy to make, stronger and not that much longer.

Removal is using the Savage tool, IMO another reason to go with the hex



edge.

[fishhawk]

Luke can sell you one of the carbide bushings I had made for the Savage plug. It is .375" long, .251" diameter, with a .030" hole. He also has the 5/16"-18 socket jam screws. The bushings are $31, jam screws $1.

[denphillips2]

Edge,
What do you think of that size carbide vent? With the 5/16 keeper screw on the BP with the 3/8 hex, would that ne a little thin? I suppose I could press it and press a plug behind it like you did. I like the idea of a keeper screw.
Anyway, how do I get ahold of Luke?
Thanks!
Denny

[fishhawk]

You can find Luke (lwh723) at the top of the smokeless page in yellow, just click on Arrowhead Sporting Goods

[denphillips2]

Found him! Thanks!
He has the .250 x 3/8" bushing with a .031" hole.
My only concern is if it is too large for the BP with the hex head? I like the idea of the retaining screw behind the bushing. But with a 3/8" hex and a 5/16", that doesn't leave a lot of wall thickness.

Thoughts?

[willbird]

Thanks so much Edge :-). I'm sure I have the tap for the 5/8-18 out in the shop :-). So maybe a few dims would be nice on the 5/8-18 plug.

Never having used a savage tool maybe I should heel your advice there heed your advice there ;-).

[edge]

Put the carbide vent in the thick section, not in the hex.
I have used carbide and ceramic vents for about 8 years and would never go back



You need to make your BP in accordance with your Boltface / barrel relationship.
I can dimension mine but the relationship of my Marlin will not be the same as your Savage or Remington.

These are the important dimensions for my 40 caliber plug.



The ID's will depend on how you decide to prime, bushing or vent liner.
I use a 45 ACP with LRM but a 209 can be used with some modification.
My bushing is 3/16 diameter.

edge.

[willbird]

OK here is what I have worked up for a 3/8 hex and 5/8-18 thread...that is a #8 flat head screw as a vent liner, would have to grind a drill to form the pocket with the 82 degree c'sink at the bottom, no big deal, been there done that before :-). 3/8 hex is shown in cross section with the flat at 12 oclock.



I was drawing while you were posting Edge, yes I do understand the final dims must be made to fit the action in hand, just like a cartridge job :-).

I'm still looking at using a cut down rifle case, with the 209, and letting the 209 fit up in the BP.

[denphillips2]

Very good Edge, I understand what you are saying. I just sent an email to Luke to order one of the bushings and keeper screws. I'll let you know how mine looks when I get it done.

Thanks guys!

[fishhawk]

Dec 12, 2012 22:54:02 GMT -5 denphillips2 said:

Found him! Thanks!
He has the .250 x 3/8" bushing with a .031" hole.
My only concern is if it is too large for the BP with the hex head? I like the idea of the retaining screw behind the bushing. But with a 3/8" hex and a 5/16", that doesn't leave a lot of wall thickness.

Thoughts?

On the Savage plug, the bushing and lock ring are put in the powder end of the plug. Here's one in an SMI plug.

[denphillips2]

Thanks fishhawk!
That is what I am going to do.

[denphillips2]

Fishhawk,
I am ordering the bushing tonight.
Luke said to ask you for the dimensions of the bushing and the 5/16"-18 keeper. I am going to try and get the BP made up this weekend without the bushing, but made to fit the bushing. Do you slip fit it, or press fit it. With it out on the above picture, I am guessing slip fit?

I am figuring out the rest of the dimensions to fit my action tomorrow.

Thanks!
Denny

[fishhawk]

The bushing is .375 long and close to .251 in diameter. The lock ring is .160 tall. I first drill about .500" deep with a C or D bit. Then bottom the hole with a mill that will bore no larger than .2505" to a depth such as .550" that will handle the bushing and the lock ring that total .535". I then tap for the lock ring 5/16"-18 only deep enough for the lock ring to fully tighten against the bushing. I then finish the hole with a .251" reamer that I flattened the end to square the bottom of the hole. The reason I ream last is because the tap raises the metal of most plug materials that needs cleaned up before the bushing will tight slip fit in.

[willbird]

Did some drawing of a bushing style one using the dims being discussed, with an altered 45 acp case in place with a 209 primer.

[Jon]

Looks like a long distance from primer to powder. Check DD rule of 1.2 which seems to work well

[willbird]

Chopped the 45 case to .700 and shortened a few things up, put the bushing in from the other end like Edge's similar plug. Went to LRM instead of 209.



What is the DD rule of 1.2 ??

[edge]

willbird, a couple of suggestions if you don't mind.

I greatly prefer a 209 for reliability. Dave D. prefers a LRM.
I would also install the bushing from the front, though a bit deeper than in your sketch in reply #22.

I would prefer it not be in the 3/8 hex area in as much as it is 1/4 in diameter.

Sketch in reply #22 should have a bit of a taper at the nipple end to align it as you rack the case forward with the bolt ( unless you intend to push it in with your fingers instead ).

The inside of a 45 becomes about 0.410 in the web area so without a taper you may bind up on the ID.

If you look at my hex sketch, where the hex meets the 5/8 diameter I have a RED tapered section.
That taper is a few thou larger than the case mouth and acts as a secondary seal to keep everything clean.

Two other advantages of a 209 primer are sealing at the case which allows for a less precise headspacing while still ensuring ignition and cleanliness.
The second advantage is the it moves the primer closer to the powder. The primer sticks out up to 0.150 depending on the case web thickness.

edge.

PS You can cut your brass shorter but I would not go overboard on it.
Here is one of my early attempts:



The case must be inserted onto the plug with your fingers as it will fall into the lug area if it is not secure in the boltface.
If you don't want to rack the case like a shell then shorter is a legit option but you also need a good extractor and don't forget to remove the ejector pin.

[willbird]

Mmmkay that gives me something to think on, the secondary seal sounds good. How long do the carbide bushings last ? I was thinking of making one to the same dims from aeromet 100 or inconell 100...maybe I will give up on that after trying to worry a hole in it with a .031 drill. I have machined the stuff but it was all cnc machinery...none of that at home. I also have some 1/4 TI kicking around here somewhere too...they used to simply throw it away at a past employer.


Sticking to the carbide bushing dims will let me make one up from some other material to play with.


I am going to make up a test setup from bar stock instead of a barrel blank when I get close. The ejection in the rem has me worried more than anything else, they can be nasty with cases like the 300 whisper/30 blackout. So if it will swallow a longer case I can try shorter stuff for function easily...nothing wasted but time and some 1.5" 12L14 :-).

Honestly I like the 209 ideas better, they are cheaper than LRM match at retail anyway.

Once I get a final "envelope" worked out I can bang out a half dozen of the plugs with no internal machining...then try all kinds of things from that point, things go better in batches...6 might take as long as 2 singles :-).

Do you think 416 stainless is an adequate material ??

[willbird]

OK here is another go....worked on capturing the sealing taper, and got the bushing in from the front again :-). Back to a 209



Bill

[edge]

Looks pretty good to me

edge.

[willbird]

OK for a reality check, brought the action and barrel in around it.