Bolt won't close on new brass

[jbpmidas]

Ive had a new .284 Shehane built and I tried this morning to measure my chamber length and make a dummy round for my fireform loads. The new brass won't chamber. Is it normal to require full length sizing of new brass in a match chamber?

 

[Taildrag15X]

Does it have a tight neck?

Had issues with a recent 6mmbr build where a modified case (like Hornady's) wouldn't chamber, I had to turn the neck to get it to fit.

 

[Fat Albert]

Depends on what you mean by "Match Chamber". Is it just on the short side of SAMMI spec. or shorter than SAMMI? Is it just SAMMI with a neck cut small or a throat cut to uses longer than normal bullets. I would first call the maker and find out info on the chamber. If it is the case that the cases are on the long side of SAMMI and the chamber is on the short side then try to fl size them. If your full length sizer is on the long side and your chamber is on the short side or shorter than SAMMI then you might need to have the base of FL die cut back so it will be able to move the shoulder back on the cases.

 

[jbpmidas]

Problem is I don't have a FL sizer. More money to spend I wasn't intending on.

I'm not sure of the chamber specs. I will try FL sizing when the dies come in.

Thanks!

 

[243winxb]

Drawings show 2 different neck diameters. http://www.saami.org/PubResources/CC_Drawings/Rifle/284%20Winchester.pdf And yours ?? http://www.6mmbr.com/7mm284.html

 

[captainzeke]

What brass are you using ? sounds to me like uyou have a tight neck chamber

 

[jbpmidas]

Lapua and Winchester. Neck is .313. OD of neck is .308 on Lapua and .310 on Winchester.

 

[tclaunch]

Winchester brass spec reamer vs Lapua brass speced reamer is also a possibility

 

[normmatzen]

Did you get a "GO" gauge with the new barrel? Does the bolt close on the "GO" gauge?

 

[jbpmidas]

Don't have a Go gauge. Was told it was a Lapua brass reamer with turned necks.

 

[bricktop]

I'd think if it were for neck-turned brass they should have given you a neck diameter so you know what thickness to turn to. No build papers anywhere? On the invoice or receipt?

 

[GT Accuracy]

Probably a zero headspace on the chambering. A lot of smiths, including myself, like chambering this way based off blot closure with a go / no-go gauge to ensure the tightest and most controlled chamber. I do this after chambering a riffle for a customer that had a reamer mismarked.... That was a nightmare

Try bumping your shoulder back a thousandth or two. This will 99% of the time be the issue on a new chamber.

I learned this the hard way jbpmidas. my very first rifle I ever had built, a 6BRX by Richard Franklin closed very hard. After realizing that the BR brass was hitting the shoulder of the chambering I full length sized and set the should back .002. Shot like a house-a-fire after that.

Feel free to send me a PM if you would like more info.


Greg

 

[Shynloco]

jpb,
Have you tried removing the bolt and inserting the casing into the bolt and replacing the bolt into the rifle? I had the same thing happen and it had nothing to do with headspace as commonly thought. What it had to do with was my bolt wasn't allowing the claw of the extractor to go over the casing. My gunsmith ended up milling the claw slightly and the prtoblem was solved and the casing hand feed just fine now. Might give this idea a try because otherwise sounds like a headspace issue OR your casing it too long, OR the shoulders need a bump.

 

[therifler]

are there any stampings on the barrel ? it is customary to include cal. and neck size or to indicate that it is a tight neck (T.N.).you may also check with the builder he is sure to know the neck size.
T.R.

 

[jbpmidas]

I'd think if it were for neck-turned brass they should have given you a neck diameter so you know what thickness to turn to. No build papers anywhere? On the invoice or receipt?

Neck is .313. Gunsmith recommeded OD of necks be .308 and loaded rounds .310, which is what I have.

 

[gunsandgunsmithing]

Your smith probably set it up tight for fireforming, i,e., AI cartridges. While not really necessary for this cartridge, it's still not a bad idea. Cases form nicely from a slight crush fit, and it should only be this tight on the first firing. I'd still recommend a full length sizer anyway and always. Brass and you, will stay happy with just bumping and sizing the brass, IMHO. Do you have a way of deternining how short the chamber is, if indeed it is short,..i.e., barrel widget?--Mike

 

[jbpmidas]

Ordered Hornady dies this evening and I have the Sinclair tool for determining overall chamber length.

 

[GT Accuracy]

Your .313 neck turned to .308/.309 and loaded at .310 is spot on. So it's definitly not neck thickness. After reading everything and all the recommendations i think the members here at 6mm have gotten the correct info out to you. Most likely it is just the shoulders and i would bet dollars to doughnuts its just a zero headspace. I would be more worried if you couldn't close the bolt at all. However, that doesn't seem to be the case.

As mike aka gunsaandgunsmithing said, a slight crush fit is best for forming brass and after the forming the new .284 Shehane brass shouldn't have this issue anymore.

Another option / possibility is an ejector. Most competition rifles that i have built before never get the ejector put back in the rifle. If you have a dual port, or opted for an ejector in a single load / eject action, the extra .001 from the ejector could have a part in this, but a very small part as well. But, it is metal and whenever metal contacts metal .001 can feel like the world.

Hornady dies are very good ones - I highly recommend them and the normal RCBS / Redding for any customer who asks me to provide sizing dies as an ala cart item to their build. I used to stock all the dies for customers guns in shop, but after a few years and realizing that 85% of customers had their F/L sizing dies before the ordering of the rifles via Sportsman's Warehouse or other retail outlets for the parent cases of their wildcat rifles, i just started making custom Wilson dies when asked by a customer.

I would assume your next question will be how to properly bump shoulders and that answer is an easy one. If you know great, if not don't be afraid to ask.

Enjoy your new rifle jbpmidas! Keep us all up to date on accuracy as well.


Greg

 

[mstrophyhunter]

savage action .003between locking lug face and barrel face, .002 between bolt face and go gauge , .313 neck 284 shehane reamer set up same as my my 3- 284 shehanes and 10 are so others that i have put together . on mine i removed .003 from my shell holder to bump shoulder back .003 this only has to be done the first loading when fire forming this leaves brass a very good fit after first forming then i size and load with wilson die that i ream with shehane reamer , run them thru a full lengh 284 die and they will fit

 

[jbpmidas]

Thanks for the replies! Hopefully I will have the FL Sizing die by the end of the week and will be able to break the gun in next week and possibly work up a fire forming load.

This is my first "wildcat" or "improved" cartridge so I am in the very early learning stages, so, again, thank you for the replies!