The firearm thread

[nseagoon]

I've seen a lot of mention to 7-8" for most 45 loads. If you're loading a custom round dedicated for the De Lisle you could probably get a bit more pressure into it and use a slower powder to make better use of a long barrel. There's a lot of headroom for the 230gn .45s before they transition to supersonic. The downside is that lots of slow powder normally means higher muzzle pressure so more noise.

This is essentially the inverse of the issue I'm having with my .300 blackout. If I use a fast powder, I can use stuff-all to get the bullet to the transition speed and have low muzzle pressure, but it's low and dropping by the time it hits the gas port. If I use a little more slower powder then I can push the peak pressure pulse out towards the gas port and have better operating pressure but then I've got to really struggle to stay subsonic with 100% powder burn by the time the gas port is uncovered.

According to QuickLoad, a 6 grains of AP70N is absolute max load at 230gn and 32mm COAL (interestingly, that's almost an entire grain above ADI's recommendations, I'd treat that load with real suspicion in a pistol) and gets you to 1000fps in a 6" barrel. Max load is still only 21kpsi which is bloody low as most things go. I'm not sure how much of that is case strength vs barrel strength, but any rifle barrel is going to be far, far stronger than you need for that. It's whether the .45 brass itself is up to it, which probably depends a lot on how tight or loose the chamber gets cut.

Either way, that provides a reasonable 'minimum' length I guess. I'd be reasonably comfortable that you could get to the transition zone out of a 8" barrel without pushing the round too hard.

For AS 30 or AP50N you wouldn't quite get there in 8-10", but the muzzle pressures would be lower.

Anyway, interesting thoughts.

I'm starting to think I may go for between 8 or 9 inches. the original was just over 8" so maybe the experts were on to something. I know it won't reach supersonic with the loads I'll be making but It could disrupted if it's much over 1000fps and if the air pressure is high (lowering speed of sound), but I don't want it too slow either just to ensure knock down power.

I'm only using 185g SWC at the moment and use 5.2g titegroup. I have heard SWC can be used for hunting but never seen it myself. I might test loads closer to maximum and see what works best with the rifle once it's complete (at the end of the day it's better to be accurate and slow than inaccurate but faster)

I'll probably end up using 230g jacketed as they seem to be inherently more accurate for some reason.

[nseagoon]

I saw a .45ACP lower on trademe and started to consider that. Any thoughts you've got regarding good places to purchase parts that don't ream you too much on the shipping would be appreciated. What do you think the total cost of building up from a stripped lower would be using base level parts?

I saw that too but I'm only going to budget maybe $300 for the lower maximum. it was a glock magazine one which would be more helpful assuming parts are easier available.
that one was stripped though so you'd still have to buy a lower parts kit.
I've heard of one guy buying a solid dummy mag and cutting it out to fit his 9mm mags, maybe I'll try that. I've seen a picture somewhere too that a guy put a block down the front of an AR mag and made a single stack pistol magazine

I don't want to build a propriotery lower I have one E and building a A lower. I want anything to work in either one. So I can put 22, 223, 300 and 45 on either lower and away I go. that may increase some costs, I still haven't found how I'll do a 45 bolt carrier group. I don't believe a 308 bolt fits in a 223 carrier group which is unfortunate because that could be modified to fit 45.
I don't want to go to a 308 lower though. I have the SLR if I want to shoot 308.

[jono035]

I'm starting to think I may go for between 8 or 9 inches. the original was just over 8" so maybe the experts were on to something. I know it won't reach supersonic with the loads I'll be making but It could disrupted if it's much over 1000fps and if the air pressure is high (lowering speed of sound), but I don't want it too slow either just to ensure knock down power.

I'm only using 185g SWC at the moment and use 5.2g titegroup. I have heard SWC can be used for hunting but never seen it myself. I might test loads closer to maximum and see what works best with the rifle once it's complete (at the end of the day it's better to be accurate and slow than inaccurate but faster)

I'll probably end up using 230g jacketed as they seem to be inherently more accurate for some reason.

185gn Lead SWC with 5.2g of titegroup shows up as 1020fps out of an 8" barrel for me, according to QuickLOAD. That's 8" from case head to muzzle, so only about 7" of bullet travel.

Edit: I agree about the Glock mags, for sure, but that does mean that inherently it's going to be a hassle that requires mags to be blocked out to 7 rounds or it's going to end up E-cat. I don't have any Glock mags, so that helps as it would have to be specific.

I had a bit more of a play with the .303 insert idea. I've got a printed part now that clips in and out like an existing mag, but looks like it will feed .45ACP directly out of it, no secondary mag required...

It doesn't have a base, follower or spring currently. I figure in the near term it's probably easiest to get those from a mag rebuild kit or something.

[nseagoon]

185gn Lead SWC with 5.2g of titegroup shows up as 1020fps out of an 8" barrel for me, according to QuickLOAD. That's 8" from case head to muzzle, so only about 7" of bullet travel.

Edit: I agree about the Glock mags, for sure, but that does mean that inherently it's going to be a hassle that requires mags to be blocked out to 7 rounds or it's going to end up E-cat. I don't have any Glock mags, so that helps as it would have to be specific.

I had a bit more of a play with the .303 insert idea. I've got a printed part now that clips in and out like an existing mag, but looks like it will feed .45ACP directly out of it, no secondary mag required...

It doesn't have a base, follower or spring currently. I figure in the near term it's probably easiest to get those from a mag rebuild kit or something.

I'm starting to lean further towards just over 8" and the load data seems to support it. as you said mentioning quickload.
I'm thinking 8 1/4" I think I'll check with vulcan as I can't remember the twist rate, i've seen certain barrels change their accuracy when certain lengths due to something to do with the twist but I don't think I'll be going any longer than 8 3/4"

the mag issue will only be a concern for the ar15 upper which is some time away. can anyone confirm for sure the 308 bolt doesn't fit in the standard ar15 BCG? otherwise I'll have to look for a 6.8 or 455 bolt, most pistol cartridge bolt groups are one piece and are harder to export from the states due to 1 finding a company that can export, and 2 having it under the $100USD threshold.

This 303 insert, does it have moulded feed lips so you just pop a follower and spring underneath? sounds nifty.

I'm starting to look forward to May, a couple of life changes and I'll have a functioning De Lisle Carbine.
the most taxing part for me will be developing the suppressor. I've built a couple of muzzle forward ones for a .22 in the past with limited success, I helped a mate build one on a 9mm that was slightly more successful. I'll be doing a light weight aluminium over barrel with muzzle brake and I'll see how many baffles and the distances required between them to get the thing out to legal length.
if it all turns to custard I'll have learned how not to do things and worst case scenario I'll have Robbie Tiffen or DPT manufacture one for many $$$. I'll make it interchangable between the AR upper and the De Lisle. AR won't be happening until at least the end of the year.

[jono035]

I've seen mentioned in several places that the 308 bolt doesn't fit, hence the need to modify.

Yeah, the insert at the moment has the feed lips printed into it. I've got a new version waiting to try at home and the one I printed on Sunday feeds OK but from a very low position, so it's tough to tell without an actual barreled action. I'll try put together some photos when I get home. I also ordered a couple of single stack 45 mag rebuild kits from Brownells to play with. I could print a follower but sometimes the ridges on the prints catch on each other. Nothing some sanding wouldn't cure I guess...

Will be interesting what you find out on twist vs length because it should only be twist vs final velocity by my understanding.

I've been wanting to try chamber and turn a barrel blank for ages so maybe this will be an excuse to finally try it.

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[nseagoon]

I've seen mentioned in several places that the 308 bolt doesn't fit, hence the need to modify.

Yeah, the insert at the moment has the feed lips printed into it. I've got a new version waiting to try at home and the one I printed on Sunday feeds OK but from a very low position, so it's tough to tell without an actual barreled action. I'll try put together some photos when I get home. I also ordered a couple of single stack 45 mag rebuild kits from Brownells to play with. I could print a follower but sometimes the ridges on the prints catch on each other. Nothing some sanding wouldn't cure I guess...

Will be interesting what you find out on twist vs length because it should only be twist vs final velocity by my understanding.

I've been wanting to try chamber and turn a barrel blank for ages so maybe this will be an excuse to finally try it.

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I'll try remember to measure blank tonight. I should have 1/3 available which will only cost a box of beers and i'll have to have a look at the finished product at some point :-)

When I send it down south in May I'll get Robbie to cut the unused length in two before sending it back.

[jono035]

Perfect. Could always just get Robby to do a second one at the same time, I guess. Any idea what he was charging for that?

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[nseagoon]

Perfect. Could always just get Robby to do a second one at the same time, I guess. Any idea what he was charging for that?

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my quote was less than $500 guesstimate.
That included chambering, turning barrel down, threading and headspacing and threading for suppressor.
My 303 barrel is already removed. I have a home made tool for removing the barrel from a #1mk3 I can loan if required. To remove barrel:
put barrel in vice, put wrench in receiver, apply lots of heat and lots of penetrating oil and lots of force and it eventually pops off. Be liberal with everything.

[jono035]

my quote was less than $500 guesstimate.
That included chambering, turning barrel down, threading and headspacing and threading for suppressor.
My 303 barrel is already removed. I have a home made tool for removing the barrel from a #1mk3 I can loan if required. To remove barrel:
put barrel in vice, put wrench in receiver, apply lots of heat and lots of penetrating oil and lots of force and it eventually pops off. Be liberal with everything.

That'd be really handy, thanks! I was just looking around yesterday for bits and pieces to make up something similar.

Pretty sure mines a Mk3 as well, but beyond that I'm kinda clueless on them. I've been soaking it in WD40 periodically for a few years now with the idea that at some point I'm going to want to yank the barrel out of it...

I'll grab it out of the safe and see how my next mag insert revision works out...

[jono035]

http://youtu.be/5BTQSnxLEwM






Seems to work pretty well. The latching point is short a few mm, so the mag fits nicely but can move up and down a little. That's easily solved and it seems to feed the same at the top and bottom of the magwell.

So far I've only just printed it large enough to fill the magwell to save plastic. Ultimately I'll just print a second piece as a floorplate that screws onto the base. It could end up looking either like a taller version of what it is now or like it has a 1911 mag sticking out the bottom. Either way...

At the moment it's roughly 4m of filament to print, which is about $2, I think?

I had a .22LR magazine for my Stirling that I made with a printed follower and magspring which was kind of hilarious... Probably not up to many rounds of .45ACP, but if you only wanted a 3 round mag you could probably print the whole thing. As it is, you can probably make it any size that you can get a reliable spring for (10 rounds, maybe?).

[nseagoon]

That looks very cool. I was thinking maybe build the mag like a standard 7 or 8 round 1911 mag. Could the well in the back for spent brass go the same depth as the mag? That way in the future multiple mags could be made which would make policing brass for reloading easy. And it would give something secure to grab hold of too as I'm not sure how I'll do handguard because I'm not keen to hold a suppressor or put my hands any where near it especially in early testing

[jono035]

The spring I've got coming is for a 7rd mag, yeah. The well can be whatever size and shape fits really.
I don't think its forward enough to make a regular hand hold but for testing I think it'd work out nicely.

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[nseagoon]

The spring I've got coming is for a 7rd mag, yeah. The well can be whatever size and shape fits really.
I don't think its forward enough to make a regular hand hold but for testing I think it'd work out nicely.

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sweet as, I'll probably manufacture a hand guard and see if I can do something free floating, I wouldn't expect amazing accuracy as I'm planning on using a folding stock (usually they're a bit rattly and loose)

[jono035]

sweet as, I'll probably manufacture a hand guard and see if I can do something free floating, I wouldn't expect amazing accuracy as I'm planning on using a folding stock (usually they're a bit rattly and loose)

Do you think it needs to free-float for the type of useful range you're going to get out of a subsonic projectile? With a 25m zero you're going to need 300mm of hold-over for a 100m target anyway... Also an 8" barrel is going to be pretty bloody stiff, even with a big can hanging on the end. On the plus side, it looks like .45ACP ball would only drop ~100fps and about 15% of its energy over that range which is pretty reasonable.

[awa355]

In the upcoming calving season, my son will likely have the occasional calf to put down. He doesnt have a firearms licence but is going to enter the process. He wants to be able to put a calf down quickly and humanely. I passed in my licence several years ago.

He will look for a .22 rifle, but I wondered if a high powered air rifle would suffice. Or do the top end air rifles also require a licence?